Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Hypospadias and maternal exposure to atrazine via drinking water in the National Birth Defects Prevention study

Hypospadias and maternal exposure to atrazine via drinking water in the National Birth Defects... Background: Hypospadias is a relatively common birth defect affecting the male urinary tract. It has been suggested that exposure to endocrine disrupting chemicals might increase the risk of hypospadias by interrupting normal urethral development. Methods: Using data from the National Birth Defects Prevention Study, a population-based case-control study, we considered the role of maternal exposure to atrazine, a widely used herbicide and potential endocrine disruptor, via drinking water in the etiology of 2nd and 3rd degree hypospadias. We used data on 343 hypospadias cases and 1,422 male controls in North Carolina, Arkansas, Iowa, and Texas from 1998–2005. Using catchment level stream and groundwater contaminant models from the US Geological Survey, we estimated atrazine concentrations in public water supplies and in private wells. We assigned case and control mothers to public water supplies based on geocoded maternal address during the critical window of exposure for hypospadias (i.e., gestational weeks 6–16). Using maternal questionnaire data about water consumption and drinking water, we estimated a surrogate for total maternal consumption of atrazine via drinking water. We then included additional maternal covariates, including age, race/ethnicity, parity, and plurality, in logistic regression analyses to consider an association between atrazine and hypospadias. Results: When controlling for maternal characteristics, any association between hypospadias and daily maternal atrazine exposure during the critical window of genitourinary development was found to be weak or null (odds ratio for atrazine in drinking water = 1. 00, 95 % CI = 0.97 to 1.03 per 0.04 μg/day increase; odds ratio for maternal consumption = 1.02, 95 % CI = 0.99 to 1.05; per 0.05 μg/day increase). Conclusions: While the association that we observed was weak, our results suggest that additional research into a possible association between atrazine and hypospadias occurrence, using a more sensitive exposure metric, would be useful. Keywords: Hypospadias, Birth defects, Atrazine, Groundwater, Surface water, Endocrine disruptors Background the penis [1]. It has a significant personal and public Hypospadias is a relatively common birth defect of the health impact, as surgical repair is often needed to allow male urinary tract, affecting between 4 to 6 of every for normal urinary and sexual function, and even after 1,000 male births [1]. It occurs as a result of abnormal correction, hypospadias may result in psychosocial and urethral closure during gestational weeks 8–14, and sexual problems later in life [2]. manifests with a urethral opening on the underside of Normal urethral closure during fetal development depends upon binding of testosterone to the androgen receptor and subsequent action by the androgen receptor * Correspondence: jwinston@unc.edu [1]. It has therefore been suggested that endocrine Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA disrupting chemicals might increase hypospadias risk [1]. Full list of author information is available at the end of the article © 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Winston et al. Environmental Health (2016) 15:76 Page 2 of 9 One potential endocrine disrupting chemical that has Methods been examined for an association with genitourinary Study population malformations is atrazine, one of the most widely used Data from this study come from the National Birth agricultural herbicides in the United States [3]. It has been Defects Prevention Study (NBDPS), a population-based suggested that atrazine may affect aromatase levels, and case-control study conducted in ten states with the Cen- by extension alter testosterone metabolism and sexual ters for Disease Control and Prevention. NBDPS identi- differentiation in frogs [4, 5], and there is experimental fies second- and third-degree hypospadias cases, which evidence to support a link between atrazine and genitouri- are considered moderate to severe [1], from birth defect nary malformations in both rats [6] and amphibians [4, 5, surveillance registries and randomly selects controls 7, 8]. These effects in animals may be analogous to some from birth certificates or birth hospital records. NBDPS of the key events that could lead to hypospadias in a de- does not include first-degree, or mild, hypospadias cases veloping fetus, providing biological plausibility for an asso- due to variable diagnosis patterns and medical documen- ciation between exposure to atrazine and hypospadias. tation. NBDPS cases were contributed by each center The evidence to document a specific link between hypo- (an active surveillance birth defects registry), and spadias and atrazine in humans is somewhat equivocal, reviewed by a clinical geneticist there to ensure that all however. Winchester et al. found an elevated prevalence cases met NBDPS study criteria and thus ensure accur- of “other urogenital anomalies,” but not of “malformed ate and consistent case ascertainment across study sites. genitalia” among infants conceived during months of the Second- and third- degree cases of hypospadias from all highest concentrations of atrazine and other chemicals centers were then reviewed in detail by a clinical geneticist measured by the US Geological Survey’sNational Water who focused on this birth defect, and who considered Quality Assessment Program [9]. Chevrier et al. examined medical record information and anatomical descriptions urinary biomarkers of atrazine and general male genital provided by health care providers [13]. anomalies. They found an increase in male genital anom- NBDPS also collects data on a wide number of covari- alies among mothers with quantifiable atrazine or atrazine ates via computer-assisted telephone interview with the metabolites in urine, but their sample size was very small mother. For the years included in the study, the interview (5 cases exposed and 18 case unexposed) [10]. Only two also included a water module which asked questions about published studies to date have looked specifically at atra- drinking water source and water consumption. Additional zine and hypospadias in humans, and they found mixed covariates include maternal address throughout preg- results. The first study, by Meyer et al., assigned maternal nancy, and a number of known risk factors for hypospa- exposure to several agricultural pesticides (including atra- dias, including maternal age, maternal race/ethnicity, zine) by estimating the amount of pesticides applied parity, plurality, maternal choline intake, and use of within a 500–meter buffer of the mother’s home. They did fertility medications [14]. not find evidence of an association between hypospadias The study included hypospadias cases (n= 343, of and atrazine [11]. The second study, by Agopian et al., which 305 were isolated cases where hypospadias was used Texas birth defects registry data and assigned atra- the only observed anomaly, and 38 were cases where zine levels to mothers based on their county of residence other birth defects were observed in conjunction with at birth. They found some evidence of an increased risk of hypospadias) and male controls (n= 1,422) whose second or third degree hypospadias for mothers in the mothers were successfully interviewed from North 25th–75th percentiles of exposure (odds ratio = 1.52; CI = Carolina, Iowa, Arkansas, and Texas. Iowa, Arkansas, 1.25–1.85) and for the 75th–90th percentiles of expos- and Texas contributed data for women with estimated ure (odds ratio = 1.44; CI = 1.11–1.85), but suggested due dates between 1998 and 2005. North Carolina did that further research was needed to confirm the not join the study until 2003, providing data for women mechanism for an association between hypospadias with estimated due dates between 2003 and 2005. Ana- and county level atrazine use [12]. lyses were conducted on isolated and non-isolated cases In this study, we seek to build on existing research combined. Among cases identified in the clinical database, examining the potential relationship between atrazine participation rates in the full interview were 73 % for Ar- and hypospadias by incorporating information about kansas, 44 % for Iowa, 73 % for North Carolina, and 65 % maternal water consumption, as well as other known for Texas. Participation rates for the male and female con- demographic and behavioral risk factors. We use a novel trol groups were 67 % for Arkansas, 63 % for Iowa, 72 % technique to estimate maternal exposure to atrazine in for North Carolina, and 64 % for Texas. drinking water, and take advantage of unique data that The 4 states were selected from the NBDPS study sites include information about behavioral covariates to con- because any association between atrazine and hypospadias trol for confounding and maternal residential address was predicted to be small, and atrazine concentrations in throughout pregnancy to improve exposure assessment. streams were predicted to be higher in Iowa, Arkansas, Winston et al. Environmental Health (2016) 15:76 Page 3 of 9 Texas, and North Carolina than in other study sites [15]. Each public water utility was then assigned an atrazine The time period was selected because data were collected concentration equal to the mean of the predicted atra- for water consumption during this time. zine concentrations for all of the intakes for that utility. Geographic assignment was conducted using ArcGIS version 10.2 (ESRI Inc., Redlands, CA, USA). Atrazine exposure estimation We estimated atrazine concentrations using two United Exposure assignment to study participants States Geological Survey (USGS) models [3, 16]. Because We based our exposure assessment on maternal residen- many public water supplies treat their raw water with tial addresses during weeks 6–16 postconception, which various filtration processes that will reduce concentra- encompass the critical period for urethral development tions of atrazine, these models overestimate atrazine in [22]. Mothers using a public water supply were assigned drinking water. We selected this approach, however, a water utility for each reported residential address by because the models allowed us to consider a full range the University of Iowa Center for Health Effects of of atrazine concentrations, and monitoring data were Environmental Contamination (CHEEC), using public not available for concentrations falling below the US En- water supply service area polygons where available, and vironmental Protection Agency’s maximum contaminant Census place names and borders where service area level of 3 μg/L. polygons were unavailable. They were then assigned an We assigned atrazine concentrations to public water atrazine concentration based on the amount of atrazine supplies based on the type and location of the water in- estimated by the USGS models for that utility. Mothers takes for each utility. Geographic coordinates of surface who reported using well water were assigned an atrazine and groundwater intakes for public water utilities were concentration using the same method as the ground- available for Iowa, Texas, and North Carolina [17–20]. water intakes. Mothers with more than one residential For Arkansas, we used Google Earth to geocode water address during the critical exposure period were intakes using descriptions of intake locations available assigned a weighted value based on the atrazine concen- from the Arkansas Department of Health [21]. For water tration and the number of weeks at each address. We supplies using surface water, we used estimated annual excluded mothers without a full residential history, mean atrazine concentrations in streams predicted by mothers using public water who were not successfully the Watershed Regressions for Pesticides (WARP) model matched to a public water utility, and mothers using a [16]. WARP uses estimated watershed-level atrazine use, utility that was not successfully assigned an atrazine the percentage of the watershed’s agricultural land with concentration by one of the two USGS models. This a soil restrictive layer near the surface, total precipitation reduced our sample size to 123 cases (35.9 % of the during May and June of the sampling year, rainfall original sample) and 415 controls (29.2 % of original erosivity for the watershed, and streamflow caused by sample). We examined distributions across covariates for precipitation on saturated soil in order to generate na- those excluded to help characterize any selection bias tionwide estimates of atrazine concentrations in streams. that might be introduced by these exclusions. We used WARP estimates from the nearest stream We then estimated the daily amount of atrazine con- reach to assign an annual mean atrazine concentration sumed via drinking water by a mother by multiplying to public water intakes. the estimated atrazine concentration in a mother’s raw For water supplies using groundwater, we used site- water supply by the self-reported amount of water variable model predictions from the “Regression Models consumed daily by the mother. The self-reported num- for Estimating Concentrations of Atrazine plus Deethy- ber of glasses consumed ranged from 0 to 24 8-oz latrazine in Shallow Groundwater in Agricultural Areas glasses of water daily. Because it is unlikely that preg- of the United States” [3]. This model uses groundwater nant women are consuming no water, we converted the residence time, atrazine use intensity, artificial drainage women who reported drinking 0 glasses to missing and practices, depth to the seasonally high water-table, con- excluded from further analyses. We then multiplied the tent of the uppermost soil content, soil permeability, number of 8-ounce glasses by 0.237 to convert to liters groundwater recharge rates, and well depth to provide and estimate a total consumption in micrograms. gridded estimates of atrazine concentrations in shallow The distributions of maternal socioeconomic, demo- groundwater. For groundwater intakes, and for mothers graphic, and behavioral characteristics and hypospadias in NBDPS using private wells, we used gridded atrazine cases and controls were examined. We used multivari- predictions from the USGS groundwater model and bi- able logistic regression analysis to estimate the odds ra- linear interpolation to estimate atrazine concentrations tio for a hypospadias birth using two exposure measures based on the grid cell where the intake was located and of interest: estimated concentration of atrazine in a the adjacent grid cells. mother’s raw water supply and estimated daily maternal Winston et al. Environmental Health (2016) 15:76 Page 4 of 9 atrazine consumption. We estimated crude and adjusted differences in this trend when the data were stratified by odds ratios for hypospadias for each exposure measure. state. Specifically, this skewness may be due in part by We estimated odds ratios stratified by state, and then es- the small number of cases in Iowa and Texas, which also timated an overall odds ratio using a random effects had the highest concentrations of atrazine. Mean and model with state as the group variable. Covariates used median concentrations were similar for both cases and for adjustment were selected based on existing literature, controls in North Carolina and Arkansas. The differ- and included private well use (yes, no), residential use of ence among states was greater for the estimated atra- water filtration (yes, no), state of residence (North Caro- zine consumption because a small number of mothers lina, Iowa, Arkansas, Texas), maternal age (14–19, 20– consumed a large amount of water. In all states, the 24, 25–29, 30–34, 35–39, and over 40), maternal race/ mean and median estimated atrazine in water supply ethnicity (non-Hispanic white, non-Hispanic black, His- was well below the EPA’s maximum contaminant level panic, and other), multiple or singleton birth, previous of 3 μg/L. pregnancies (yes, no), maternal education (less than high Table 3 presents odds ratios for the interquartile range school, high school, or more than high school), maternal of exposure, reporting the increase or decrease in the diabetes (yes, no), maternal high blood pressure (yes, odds of having a baby with hypospadias associated with no), maternal body mass index (BMI) (less than 18.5, an increase in atrazine concentration equal to the differ- 18.5–25, 25–30, and over 30), choline use (less than ence of the 75th and 25th percentiles of estimated 187.4 mg, 187.4–249.6 mg, 249.6–336.4 mg, and greater exposure. For Arkansas and Texas, the unadjusted and than 336.4 mg, consistent with Carmichael et al. [14]), adjusted odds ratios for the interquartile range of and use of artificial reproductive technology (yes, no). estimated concentration of atrazine in a mother’s water Analyses were performed using Stata version 13.1 (Stata- supply and a mother’s estimated daily atrazine consump- Corp LP, College Station, TX, USA). tion were elevated. Odds ratios for Iowa and North Carolina were below 1.0, but statewide estimates were Results and Discussion relatively imprecise as evidenced by the wide confidence Distributions of demographic characteristics (state of intervals (Table 3). residence, age, multiple or singleton birth, previous The crude odds ratios for estimated atrazine in water pregnancy, and education), behavioral characteristics supply and atrazine consumption, without stratification (use of private wells, water filtration, choline, and artifi- by state, were close to 1.0. After adjustment for multiple cial reproductive technology), and health characteristics covariates the odds ratios for consumption were slightly (BMI, diabetes, and high blood pressure), for mothers of increased above the null for the interquartile range of hypospadias cases (n= 123) and mothers of male con- exposure. trols (n= 415) are presented in Table 1. Mothers of cases Sensitivity analyses compared characteristics of were more likely to be non-Hispanic white, more highly women who were successfully assigned an atrazine educated, and to have used fertility medications or pro- exposure and women who were not successfully cedures, and infants with hypospadias were more likely assigned an atrazine exposure. These analyses suggest to be a result of a first pregnancy or a multiple birth. that mothers who were excluded from the USGS Mothers of cases were slightly more likely to report metric were less likely to be mothers of hypospadias drinking 5 or more glasses of water a day. While con- cases, less likely to use untreated water from private trols were fairly evenly distributed amongst the 4 states, wells, more likely to live in Arkansas, more likely to 79.6 % of cases lived in Arkansas and North Carolina, be underage 30, andmorelikelytohaveaBMI which is likely to be due to enrollment processes for under 18.5 or greater than 25. The mothers excluded NBDPS [13]. No significant differences in distributions from themetricwerealsomorelikelytoidentifyas were observed for reported use of a private well, residen- non-Hispanic white or non-Hispanic black. See tial use of water filtration, maternal age, maternal BMI, Additional file 1 for additional information. maternal diabetes, maternal high blood pressure, or maternal choline intake. Conclusions Raw distributions for estimated concentrations of atra- After adjusting for maternal socioeconomic, demo- zine for a mother’s water supply and for estimated daily graphic, and behavioral characteristics, we observed a atrazine consumption are presented in Table 2. When weak association between hypospadias and maternal combining the data across all 4 states, mean and median consumption of atrazine via drinking water during gesta- concentrations were higher for controls than for cases tional weeks 6–16 in overall models. This was a slightly for both estimated atrazine in water supply and esti- stronger association than that found by Meyer et al. mated atrazine consumption. In addition, the mean was [11], but a much weaker association than that found by greater than the median for all estimates. We observed Agopian et al. [12]. No association was observed in Winston et al. Environmental Health (2016) 15:76 Page 5 of 9 Table 1 Characteristics of NBDPS hypospadias cases and Table 1 Characteristics of NBDPS hypospadias cases and controls with estimated atrazine exposure, 1998-2005 controls with estimated atrazine exposure, 1998-2005 (Continued) Cases Controls Maternal choline intake 00 Characteristic N % Missing N % Missing <187.4 mg 27 22.0 72 17.4 Demographic characteristics 187.4 – 249.6 mg 30 24.4 85 20.5 State of residence ** 0 0 249.7 – 336.3 mg 34 27.6 104 25.1 Arkansas 49 39.8 85 20.5 >336.4 mg 32 26.0 154 37.1 Iowa 17 13.8 103 24.8 Fertility medications or 04 Texas 8 6.5 101 24.3 procedures* North Carolina 49 39.8 126 30.4 No 111 90.2 393 95.6 Maternal age 0 0 Yes 12 9.8 18 4.4 <20 10 8.1 43 10.4 Health characteristics 20-24 27 22.0 89 21.5 Diabetes 0 1 25-29 25 20.3 118 28.4 No 115 93.5 374 90.3 30-34 42 34.2 105 25.3 Yes 8 6.5 40 9.7 ≥35 19 15.5 60 14.5 High blood pressure 0 0 Maternal race/ethnicity** 0 0 No 95 77.2 344 92.9 Non-Hispanic white 94 76.4 242 58.3 Yes 28 22.8 71 17.1 Non-Hispanic black 16 13.0 32 7.7 Maternal BMI 1 22 Hispanic 8 6.5 106 25.5 <18.5 6 4.9 20 5.1 Other 5 4.1 35 8.4 18.5-25 59 48.4 210 53.4 Maternal education** 0 0 25-30 25 20.5 84 21.4 <High school 5 4.1 86 20.7 >30 32 26.2 79 20.1 High school 30 24.4 111 26.8 p < 0.1 >High school 88 71.5 218 52.5 *p < 0.05 **p < 0.01 Previous pregnancies** 0 0 Categories for maternal choline intake from Carmichael et al. [14] No 55 44.7 122 29.4 Yes 68 55.3 293 70.6 crude odds ratios, or when not accounting for the total amount of drinking water consumed. In state-level Plurality* 0 0 models, positive associations were observed in Arkansas Singleton birth 114 92.7 405 97.6 and Texas, while the opposite trend was observed in Multiple birth 9 7.3 10 2.4 North Carolina and Iowa. Behavioral characteristics Certain limitations should be considered when inter- Private well use 2 9 preting these results. While the USGS models that we No 85 70.3 292 71.9 employed allowed us to estimate atrazine concentrations in raw water supplies, they do not account for treatment Yes 36 29.7 114 28.1 at public water supplies. Water treatment practices may Reported water consumption 00 vary geographically, atrazine concentrations may vary 0 glasses 3 2.4 22 5.3 seasonally, and the USGS models do not capture this geo- 1-4 glasses 77 62.6 217 52.3 graphic or temporal variation. In addition, other contami- 5 or more glasses 43 35.0 176 42.4 nants which we were unable to measure or estimate, Residential filtered tap water 2 9 particularly agricultural byproducts, may be correlated with atrazine in water supplies. No 84 69.4 304 74.9 We did consider other exposure estimation techniques, Yes 37 30.6 102 25.1 first using monitoring data from the US Environmental Protection Agency, and then using the amount of atrazine applied at the county level. Both of these alternatives proved problematic. Monitoring data were not available for atrazine concentrations below the US Environmental Protection Agency’s Maximum Contaminant Level, which Winston et al. Environmental Health (2016) 15:76 Page 6 of 9 Table 2 Distribution of estimated atrazine in water supply and estimated atrazine consumption Cases Controls Mean Median IQR Min, Max Mean Median IQR Min, Max Estimated atrazine in water supply in AR, IA, TX, and NC (μg/L) 0.09 0.02 0.001–0.04 0.0001, 2.0 0.17 0.02 0.002–0.05 0.0001, 4.0 Arkansas 0.03 0.02 0.0004–0.03 0.00009, 0.31 0.02 0.02 0.005–0.03 0.0001, 0.31 Iowa 0.28 0.05 0.001–0.53 0.001, 0.95 0.47 0.45 0.002–0.66 0.0004, 4.02 North Carolina 0.02 0.02 0.0006–0.04 0.0002, 0.07 0.03 0.03 0.001–0.04 0.0002, 0.06 Texas 0.50 0.004 0.0004–0.99 0.0001, 1.98 0.17 0.005 0.001–0.13 0.0001, 3.94 Estimated atrazine consumption in AR, IA, TX, and NC (μg/day) 0.12 0.02 0.001–0.04 0.00004–3.75 0.14 0.02 0.002–0.06 0.00007–4.66 Arkansas 0.03 0.02 0.01–0.03 0.00004–0.22 0.02 0.01 0.003–0.03 0.00009–0.22 Iowa 0.29 0.06 0.001–0.47 0.0006–1.35 0.36 0.08 0.002–0.54 0.0002–2.86 North Carolina 0.02 0.01 0.0005–0.03 0.00008–0.08 0.03 0.02 0.001–0.05 0.0001–0.16 Texas 1.00 0.002 0.0004–3.28 0.0001–3.75 0.18 0.01 0.002–0.09 0.00007–4.66 Winston et al. Environmental Health (2016) 15:76 Page 7 of 9 Table 3 Association between atrazine and hypospadias in the National Birth Defects Prevention Study, 1998–2005 N (cases) IQR Crude OR Adjusted OR State level models for estimated atrazine in water supply Arkansas 134 (49) 0.02 1.05 (0.88, 1.26) 1.02 (0.80, 1.24) Iowa 120 (17) 0.63 0.64 (0.28, 1.42) 0.66 (0.26, 1.67) North Carolina 175 (49) 0.003 0.97 (0.92–1.02) 0.97 (0.88, 1.08) Texas 109 (8) 0.13 1.09 (0.97, 1.22) 1.22 (1.01, 1.48) State level models for estimated atrazine consumption Arkansas 131 (49) 0.03 1.06 (0.83, 1.35) 1.40 (0.34, 5.78) Iowa 106 (16) 0.54 0.85 (0.46, 1.57) 0.46 (0.02, 11.9) North Carolina 171 (48) 0.05 0.50 (0.27, 0.91) 0.02 (0.00, 1.24) Texas 105 (7) 0.09 1.07 (1.01, 1.12) 1.93 (1.02, 3.23) Estimated atrazine in water supply across states 538 (123) 0.04 0.97 (0.94, 1.00) 1. 00 (0.97, 1.03) Estimated atrazine consumption across states 513 (120) 0.05 0.99 (0.96 1.02) 1.02 (0.99, 1.05) All ORs reported for interquartile range, or an increase from the in atrazine concentration equal to the difference of the 75th and 25th percentiles ORs for random effects models using state as the group variable. Random effects models and models for Arkansas, Iowa, and North Carolina adjusted by private well use, residential use of filtered water, maternal age, maternal race/ethnicity, plurality, parity, maternal education, choline use, use of artificial reproductive technology, maternal diabetes, maternal high blood pressure, and maternal BMI. Models for Texas adjusted by only private well use, maternal age, maternal race/ ethnicity, parity, maternal education, choline use, and maternal high blood pressure because of the small number of cases prevented us from considering associations between hypo- exposure were also more likely to be non-Hispanic white spadias and lower levels of atrazine. Further, the total or non-Hispanic black, which were characteristics associ- amount of atrazine applied at the county level would not ated with decreased hypospadias risk in this study. They have allowed us to consider the interaction between atra- were also less likely to use private wells, more likely to be zine concentrations in water supplies and maternal water under age 30, and more likely to have a BMI under 18.5 consumption. The USGS water models allowed us to or greater than 25, which were characteristics that were estimate atrazine concentrations for private wells, which not associated with hypospadias risk in this study. In are not regulated by the EPA, and for individual water addition, a number of women were identified by state cen- supplies with atrazine concentrations below the EPA’s ters as eligible cases or controls, but were not successfully Maximum Contaminant Level. interviewed. It is therefore unclear how exclusion of these We cannot be sure that our models accurately predict women may have influenced our results. Finally, some of maternal exposure to atrazine without a validated, re- the odds ratio estimates were based on smaller sample peated measure of atrazine in maternal urine during sizes and were imprecise. pregnancy, and the lack of more reliable data on atrazine This study also had several strengths. While other exposure undoubtedly led to some misclassification studies have looked at proximity to pesticide application, when assigning maternal exposure status. Our exposure our modeled exposure estimates allowed us to consider estimates also relied on self-reported water consump- exposure via drinking water as a potential mechanism tion, which may be prone to recall bias. Assuming that for a possible association between atrazine and hypospa- atrazine concentration misclassification and recall bias dias. It also took advantage of the unique water con- was largely random between case and control mothers, sumption and other covariate data available through the the results would have tended to be biased toward the National Birth Defects Prevention Study (NBDPS), null, although this does not guarantee that our estimate which allowed us to improve our exposure assessment is an underestimate [23]. While our exposure estimates and control for confounding. therefore should not be used in a quantitative risk as- A further strength of this study was that all of the sessment, the continuous nature of our estimated expos- hypospadias cases were ascertained by population-based ure may be less prone to misclassification than a binary birth defect surveillance systems, and underwent a de- exposure variable and useful for hypothesis generation. tailed clinical review and classification prior to inclusion Another limitation was our inability to assign atrazine in the study. Cases with known genetic or chromosomal concentrations to many of the NBDPS women. Sensitivity abnormalities were excluded. This resulted in a more analyses revealed that women who were not successfully etiologically and pathogenically homogenous case group. assigned an atrazine concentration were more likely to live Our models of maternal consumption of atrazine via in Arkansas, which was associated with increased risk in drinking water (OR 1.02 (95 % CI 0.99-1.05)) may provide this study. Women who were not successfully assigned an limited support for the hypothesis that atrazine may be Winston et al. Environmental Health (2016) 15:76 Page 8 of 9 associated with male genitourinary malformations in Disclaimer The views expressed in this article are those of the authors and do not humans, although we could not exclude the possibility of a necessarily reflect the views or policies of the U.S. EPA, the Centers for Disease null association, given the limitations described above. Our Control and Prevention, or the Texas Department of State Health Services. results are not intended to be used in lieu of an exposure Author details risk assessment, but rather to generate hypotheses about Carolina Population Center, University of North Carolina at Chapel Hill, the trends and patterns of associations between atrazine 2 Chapel Hill, NC, USA. Department of Geography and Carolina Population and hypospadias. Further research including a larger sam- Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. North Carolina Birth Defects Monitoring Program, State Center for Health ple size and better exposure characterization would be use- Statistics, Raleigh, NC, USA. Department of Maternal and Child Health, ful to provide a more definitive characterization of the 5 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Texas potential effects of atrazine. Department of State Health Services, Birth Defects Epidemiology and Surveillance Branch, Austin, TX, USA. Center for Health Effects of Environmental Contamination, University of Iowa, Iowa City, IA, USA. Additional file Department of Pediatrics, Arkansas Children’s Hospital, Little Rock, AR, USA. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Department of Geography and Institute for the Additional file 1: Characteristics of women successfully assigned an Environment, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. atrazine exposure and women who were not successfully assigned an National Center for Environmental Assessment, United States atrazine exposure. (DOCX 19 kb) Environmental Protection Agency, Research Triangle Park, NC, USA. Abbreviations Received: 29 January 2016 Accepted: 21 June 2016 BMI, body mass index; CHEEC, Center for Health Effects of Environmental Contamination; NBDPS, National Birth Defects Prevention Study; USGS, United States Geological Survey; WARP, Watershed Regressions for Pesticides References Acknowledgements 1. Carmichael SL, Shaw GM, Lammer EJ. Environmental and genetic contributors We thank the North Carolina Birth Defects Monitoring Program, the Arkansas to hypospadias: A review of the epidemiologic evidence. Birth Defects Res A Center for Birth Defects Research and Prevention, the Iowa Registry for Clin Mol Teratol. 2012;94:499–510. Congenital and Inherited Disorders, and the Texas Center for Birth Defects 2. Mieusset R, Soulie R. Hypospadias: Psychosocial, sexual, and reproductive Research and Prevention for providing data on study subjects for the consequences in adult life. J Androl. 2005;26(2):163–8. National Birth Defects Prevention Study. We thank Wesley Stone, Robert 3. Stackelberg PE, Barbash JE, Gilliom RJ, Stone WW, Wolock DM. Regression Gilliom, Paul Stackleberg, and David Wolock from the US Geological Survey models for estimating concentrations of atrazine plus deethylatrazine in for providing output from their atrazine models. shallow groundwater in agricultural areas of the United States. J Environ Qual. 2012;41:479–94. Funding 4. Tavera-Mendoza L, Ruby S, Brousseau P, Fournier M, Cyr D, Marcogliese This research received support from the Population Research Training grant D. Response of the amphibian tadpole (xenopus laevis)toatrazine (T32 HD007168) and the Population Research Infrastructure Program awarded during sexual differentiation of the testis. Environ Toxicol Chem. 2002; to the Carolina Population Center (R24 HD050924) at The University of North 21(3):527–31. Carolina at Chapel Hill by the Eunice Kennedy Shriver National Institute of Child 5. Hayes TB, Collins A, Lee M, Mendoza M, Noriega N, Stuart AA, et al. Health and Human Development. This study was also supported by a Hermaphroditic, demasculinized frogs after exposure to the herbicide cooperative agreement from the Centers for Disease Control and Prevention atrazine at low ecologically relevant doses. Proc Natl Acad Sci U S A. (U50CCU422096). 2002;99(8):5476–80. 6. Wu YG, Li SK, Xin ZC, Wang YS, Shou KR, Gao H, et al. The establishment of Availability of data and supporting materials hypospadias rat model and embryteratogenic test of atrazine. Chin J Plast NBDPS is unable to share due to information provided to participants during Surg. 2007;23(4):340–3. the informed consent process, which states that data about participants will 7. Hayes TB, Haston K, Tsui M, Hoang A, Haeffele C, Vonk A. Atrazine-induced not be given to anyone outside the study. hermaphroditism at 0.1 ppb in american leopard frogs (rana pipiens): Laboratory and field evidence. Environ Health Perspect. 2002;111(4):568. Authors’ contributions 8. Hayes TB, Stuart AA, Mendoza M, Collins A, Noriega N, Vonk A, et al. JW conducted study design, data analysis and interpretation, and drafted the Characterization of atrazine-induced gonadal malformations in African manuscript. TL contributed to study design; replication and interpretation of clawed frogs (xenopus laevis) and comparisons with effects of an androgen analyses; and revision of the manuscript. ME and LB contributed to study antagonist (cyproterone acetate) and exogenous estrogen (17beta- design, interpretation of analyses, and revision of the manuscript. RM, PL, estradiol): Support for the demasculinization/feminization hypothesis. PW, BM, AO, and the National Birth Defects Prevention Study contributed to Environ Health Perspect. 2006;114 Suppl 1:134–41. data acquisition and revision of the manuscript. All read and approved the 9. Winchester PD, Huskins J, Ying J. Agrichemicals in surface water and birth final manuscript. defects in the United States. Acta pædiatrica (Oslo). 2009;98(4):664. 10. Chevrier C, Limon G, Monfort C, Rouget F, Garlantezec R, Petit C, et al. Competing interests Urinary biomarkers of prenatal atrazine exposure and adverse birth The authors declare that they have no competing interests. outcomes in the PELAGIE birth cohort. Environ Health Perspect. 2011;119(7):1034–41. Consent for publication 11. Meyer KJ, Reif JS, Veeramachaneni D, Luben TL, Mosley BS, Nuckols JR. Not applicable. Agricultural pesticide use and hypospadias in eastern Arkansas. Environ Health Perspect. 2006;114(10):1589–95. Ethics approval and consent to participate 12. Agopian A, Lupo PJ, Canfield MA, Langlois PH. Case–control study of The analysis of pooled data collected in the National Birth Defects Research maternal residential atrazine exposure and male genital malformations. and Prevention Study, including this research, has been approved by the Am J Med Genet. 2013;161(5):977–82. Non-Biomedical Institutional Review Board at the University of North Carolina 13. Reefhuis J, Gilboa SM, Anderka M, Browne ML, Feldkamp ML, Hobbs CA, at Chapel Hill (Study # 05–1420). Study participants provided verbal informed et al. The National Birth Defects Prevention Study: A review of the methods. consent before participation in the study. Birth Defects Research Part A. 2015;103(8):656–69. Winston et al. Environmental Health (2016) 15:76 Page 9 of 9 14. Carmichael SL, Yang W, Correa A, Olney RS, Shaw GM. Hypospadias and intake of nutrients related to one-carbon metabolism. Urology. 2009;181(1):315–21. 15. Watershed regressions for pesticides atrazine model [Internet]. Available from: http://cida.usgs.gov/warp/home/. 16. Stone WW, Crawford CG, Gilliom RJ. Watershed regressions for pesticides (WARP) models for predicting stream concentrations of multiple pesticides. J Environ Qual. 2013;42:1838–51. 17. Public water supply sources, including ground water and surface water sources. 2009. http://data.nconemap.gov/geoportal/catalog/main/home. page. Accessed 4 March 2013 18. Source water assessment and protection wells. 2008. https://programs. iowadnr.gov/nrgislibx/. Accessed 21 Feb 2013. 19. Public water supply surface water intake sites in the state of Texas. 2010. https://www.tceq.texas.gov/gis/. Accessed 7 Dec 2012. 20. Public water well sites in the state of Texas. 2010. https://www.tceq.texas. gov/gis/. Accessed 7 Dec 2012. 21. Arkansas public water supply list. 2014. http://www.healthy.arkansas.gov/ Pages/default.aspx. Accessed 8 Feb 2014. 22. Luben TJ, Nuckols JR, Mosley BS, Hobbs C, Reif JS. Maternal exposure to water disinfection by-products during gestation and risk of hypospadias. Occup Environ Med. 2008;65:420–9. 23. Jurek AM, Greenland S, Maldonado G, Church TR. Proper interpretnation of non-differetntial misclassification effects: expectations vs. observations. Int J Epidemiol. 2005;34:680–7. Submit your next manuscript to BioMed Central and we will help you at every step: • We accept pre-submission inquiries � Our selector tool helps you to find the most relevant journal � We provide round the clock customer support � Convenient online submission � Thorough peer review � Inclusion in PubMed and all major indexing services � Maximum visibility for your research Submit your manuscript at www.biomedcentral.com/submit http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Environmental Health Springer Journals

Hypospadias and maternal exposure to atrazine via drinking water in the National Birth Defects Prevention study

Loading next page...
 
/lp/springer-journals/hypospadias-and-maternal-exposure-to-atrazine-via-drinking-water-in-mUh8AILoGd

References (28)

Publisher
Springer Journals
Copyright
Copyright © 2016 by The Author(s).
Subject
Environment; Environmental Health; Occupational Medicine/Industrial Medicine; Public Health
eISSN
1476-069X
DOI
10.1186/s12940-016-0161-9
pmid
27422386
Publisher site
See Article on Publisher Site

Abstract

Background: Hypospadias is a relatively common birth defect affecting the male urinary tract. It has been suggested that exposure to endocrine disrupting chemicals might increase the risk of hypospadias by interrupting normal urethral development. Methods: Using data from the National Birth Defects Prevention Study, a population-based case-control study, we considered the role of maternal exposure to atrazine, a widely used herbicide and potential endocrine disruptor, via drinking water in the etiology of 2nd and 3rd degree hypospadias. We used data on 343 hypospadias cases and 1,422 male controls in North Carolina, Arkansas, Iowa, and Texas from 1998–2005. Using catchment level stream and groundwater contaminant models from the US Geological Survey, we estimated atrazine concentrations in public water supplies and in private wells. We assigned case and control mothers to public water supplies based on geocoded maternal address during the critical window of exposure for hypospadias (i.e., gestational weeks 6–16). Using maternal questionnaire data about water consumption and drinking water, we estimated a surrogate for total maternal consumption of atrazine via drinking water. We then included additional maternal covariates, including age, race/ethnicity, parity, and plurality, in logistic regression analyses to consider an association between atrazine and hypospadias. Results: When controlling for maternal characteristics, any association between hypospadias and daily maternal atrazine exposure during the critical window of genitourinary development was found to be weak or null (odds ratio for atrazine in drinking water = 1. 00, 95 % CI = 0.97 to 1.03 per 0.04 μg/day increase; odds ratio for maternal consumption = 1.02, 95 % CI = 0.99 to 1.05; per 0.05 μg/day increase). Conclusions: While the association that we observed was weak, our results suggest that additional research into a possible association between atrazine and hypospadias occurrence, using a more sensitive exposure metric, would be useful. Keywords: Hypospadias, Birth defects, Atrazine, Groundwater, Surface water, Endocrine disruptors Background the penis [1]. It has a significant personal and public Hypospadias is a relatively common birth defect of the health impact, as surgical repair is often needed to allow male urinary tract, affecting between 4 to 6 of every for normal urinary and sexual function, and even after 1,000 male births [1]. It occurs as a result of abnormal correction, hypospadias may result in psychosocial and urethral closure during gestational weeks 8–14, and sexual problems later in life [2]. manifests with a urethral opening on the underside of Normal urethral closure during fetal development depends upon binding of testosterone to the androgen receptor and subsequent action by the androgen receptor * Correspondence: jwinston@unc.edu [1]. It has therefore been suggested that endocrine Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA disrupting chemicals might increase hypospadias risk [1]. Full list of author information is available at the end of the article © 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Winston et al. Environmental Health (2016) 15:76 Page 2 of 9 One potential endocrine disrupting chemical that has Methods been examined for an association with genitourinary Study population malformations is atrazine, one of the most widely used Data from this study come from the National Birth agricultural herbicides in the United States [3]. It has been Defects Prevention Study (NBDPS), a population-based suggested that atrazine may affect aromatase levels, and case-control study conducted in ten states with the Cen- by extension alter testosterone metabolism and sexual ters for Disease Control and Prevention. NBDPS identi- differentiation in frogs [4, 5], and there is experimental fies second- and third-degree hypospadias cases, which evidence to support a link between atrazine and genitouri- are considered moderate to severe [1], from birth defect nary malformations in both rats [6] and amphibians [4, 5, surveillance registries and randomly selects controls 7, 8]. These effects in animals may be analogous to some from birth certificates or birth hospital records. NBDPS of the key events that could lead to hypospadias in a de- does not include first-degree, or mild, hypospadias cases veloping fetus, providing biological plausibility for an asso- due to variable diagnosis patterns and medical documen- ciation between exposure to atrazine and hypospadias. tation. NBDPS cases were contributed by each center The evidence to document a specific link between hypo- (an active surveillance birth defects registry), and spadias and atrazine in humans is somewhat equivocal, reviewed by a clinical geneticist there to ensure that all however. Winchester et al. found an elevated prevalence cases met NBDPS study criteria and thus ensure accur- of “other urogenital anomalies,” but not of “malformed ate and consistent case ascertainment across study sites. genitalia” among infants conceived during months of the Second- and third- degree cases of hypospadias from all highest concentrations of atrazine and other chemicals centers were then reviewed in detail by a clinical geneticist measured by the US Geological Survey’sNational Water who focused on this birth defect, and who considered Quality Assessment Program [9]. Chevrier et al. examined medical record information and anatomical descriptions urinary biomarkers of atrazine and general male genital provided by health care providers [13]. anomalies. They found an increase in male genital anom- NBDPS also collects data on a wide number of covari- alies among mothers with quantifiable atrazine or atrazine ates via computer-assisted telephone interview with the metabolites in urine, but their sample size was very small mother. For the years included in the study, the interview (5 cases exposed and 18 case unexposed) [10]. Only two also included a water module which asked questions about published studies to date have looked specifically at atra- drinking water source and water consumption. Additional zine and hypospadias in humans, and they found mixed covariates include maternal address throughout preg- results. The first study, by Meyer et al., assigned maternal nancy, and a number of known risk factors for hypospa- exposure to several agricultural pesticides (including atra- dias, including maternal age, maternal race/ethnicity, zine) by estimating the amount of pesticides applied parity, plurality, maternal choline intake, and use of within a 500–meter buffer of the mother’s home. They did fertility medications [14]. not find evidence of an association between hypospadias The study included hypospadias cases (n= 343, of and atrazine [11]. The second study, by Agopian et al., which 305 were isolated cases where hypospadias was used Texas birth defects registry data and assigned atra- the only observed anomaly, and 38 were cases where zine levels to mothers based on their county of residence other birth defects were observed in conjunction with at birth. They found some evidence of an increased risk of hypospadias) and male controls (n= 1,422) whose second or third degree hypospadias for mothers in the mothers were successfully interviewed from North 25th–75th percentiles of exposure (odds ratio = 1.52; CI = Carolina, Iowa, Arkansas, and Texas. Iowa, Arkansas, 1.25–1.85) and for the 75th–90th percentiles of expos- and Texas contributed data for women with estimated ure (odds ratio = 1.44; CI = 1.11–1.85), but suggested due dates between 1998 and 2005. North Carolina did that further research was needed to confirm the not join the study until 2003, providing data for women mechanism for an association between hypospadias with estimated due dates between 2003 and 2005. Ana- and county level atrazine use [12]. lyses were conducted on isolated and non-isolated cases In this study, we seek to build on existing research combined. Among cases identified in the clinical database, examining the potential relationship between atrazine participation rates in the full interview were 73 % for Ar- and hypospadias by incorporating information about kansas, 44 % for Iowa, 73 % for North Carolina, and 65 % maternal water consumption, as well as other known for Texas. Participation rates for the male and female con- demographic and behavioral risk factors. We use a novel trol groups were 67 % for Arkansas, 63 % for Iowa, 72 % technique to estimate maternal exposure to atrazine in for North Carolina, and 64 % for Texas. drinking water, and take advantage of unique data that The 4 states were selected from the NBDPS study sites include information about behavioral covariates to con- because any association between atrazine and hypospadias trol for confounding and maternal residential address was predicted to be small, and atrazine concentrations in throughout pregnancy to improve exposure assessment. streams were predicted to be higher in Iowa, Arkansas, Winston et al. Environmental Health (2016) 15:76 Page 3 of 9 Texas, and North Carolina than in other study sites [15]. Each public water utility was then assigned an atrazine The time period was selected because data were collected concentration equal to the mean of the predicted atra- for water consumption during this time. zine concentrations for all of the intakes for that utility. Geographic assignment was conducted using ArcGIS version 10.2 (ESRI Inc., Redlands, CA, USA). Atrazine exposure estimation We estimated atrazine concentrations using two United Exposure assignment to study participants States Geological Survey (USGS) models [3, 16]. Because We based our exposure assessment on maternal residen- many public water supplies treat their raw water with tial addresses during weeks 6–16 postconception, which various filtration processes that will reduce concentra- encompass the critical period for urethral development tions of atrazine, these models overestimate atrazine in [22]. Mothers using a public water supply were assigned drinking water. We selected this approach, however, a water utility for each reported residential address by because the models allowed us to consider a full range the University of Iowa Center for Health Effects of of atrazine concentrations, and monitoring data were Environmental Contamination (CHEEC), using public not available for concentrations falling below the US En- water supply service area polygons where available, and vironmental Protection Agency’s maximum contaminant Census place names and borders where service area level of 3 μg/L. polygons were unavailable. They were then assigned an We assigned atrazine concentrations to public water atrazine concentration based on the amount of atrazine supplies based on the type and location of the water in- estimated by the USGS models for that utility. Mothers takes for each utility. Geographic coordinates of surface who reported using well water were assigned an atrazine and groundwater intakes for public water utilities were concentration using the same method as the ground- available for Iowa, Texas, and North Carolina [17–20]. water intakes. Mothers with more than one residential For Arkansas, we used Google Earth to geocode water address during the critical exposure period were intakes using descriptions of intake locations available assigned a weighted value based on the atrazine concen- from the Arkansas Department of Health [21]. For water tration and the number of weeks at each address. We supplies using surface water, we used estimated annual excluded mothers without a full residential history, mean atrazine concentrations in streams predicted by mothers using public water who were not successfully the Watershed Regressions for Pesticides (WARP) model matched to a public water utility, and mothers using a [16]. WARP uses estimated watershed-level atrazine use, utility that was not successfully assigned an atrazine the percentage of the watershed’s agricultural land with concentration by one of the two USGS models. This a soil restrictive layer near the surface, total precipitation reduced our sample size to 123 cases (35.9 % of the during May and June of the sampling year, rainfall original sample) and 415 controls (29.2 % of original erosivity for the watershed, and streamflow caused by sample). We examined distributions across covariates for precipitation on saturated soil in order to generate na- those excluded to help characterize any selection bias tionwide estimates of atrazine concentrations in streams. that might be introduced by these exclusions. We used WARP estimates from the nearest stream We then estimated the daily amount of atrazine con- reach to assign an annual mean atrazine concentration sumed via drinking water by a mother by multiplying to public water intakes. the estimated atrazine concentration in a mother’s raw For water supplies using groundwater, we used site- water supply by the self-reported amount of water variable model predictions from the “Regression Models consumed daily by the mother. The self-reported num- for Estimating Concentrations of Atrazine plus Deethy- ber of glasses consumed ranged from 0 to 24 8-oz latrazine in Shallow Groundwater in Agricultural Areas glasses of water daily. Because it is unlikely that preg- of the United States” [3]. This model uses groundwater nant women are consuming no water, we converted the residence time, atrazine use intensity, artificial drainage women who reported drinking 0 glasses to missing and practices, depth to the seasonally high water-table, con- excluded from further analyses. We then multiplied the tent of the uppermost soil content, soil permeability, number of 8-ounce glasses by 0.237 to convert to liters groundwater recharge rates, and well depth to provide and estimate a total consumption in micrograms. gridded estimates of atrazine concentrations in shallow The distributions of maternal socioeconomic, demo- groundwater. For groundwater intakes, and for mothers graphic, and behavioral characteristics and hypospadias in NBDPS using private wells, we used gridded atrazine cases and controls were examined. We used multivari- predictions from the USGS groundwater model and bi- able logistic regression analysis to estimate the odds ra- linear interpolation to estimate atrazine concentrations tio for a hypospadias birth using two exposure measures based on the grid cell where the intake was located and of interest: estimated concentration of atrazine in a the adjacent grid cells. mother’s raw water supply and estimated daily maternal Winston et al. Environmental Health (2016) 15:76 Page 4 of 9 atrazine consumption. We estimated crude and adjusted differences in this trend when the data were stratified by odds ratios for hypospadias for each exposure measure. state. Specifically, this skewness may be due in part by We estimated odds ratios stratified by state, and then es- the small number of cases in Iowa and Texas, which also timated an overall odds ratio using a random effects had the highest concentrations of atrazine. Mean and model with state as the group variable. Covariates used median concentrations were similar for both cases and for adjustment were selected based on existing literature, controls in North Carolina and Arkansas. The differ- and included private well use (yes, no), residential use of ence among states was greater for the estimated atra- water filtration (yes, no), state of residence (North Caro- zine consumption because a small number of mothers lina, Iowa, Arkansas, Texas), maternal age (14–19, 20– consumed a large amount of water. In all states, the 24, 25–29, 30–34, 35–39, and over 40), maternal race/ mean and median estimated atrazine in water supply ethnicity (non-Hispanic white, non-Hispanic black, His- was well below the EPA’s maximum contaminant level panic, and other), multiple or singleton birth, previous of 3 μg/L. pregnancies (yes, no), maternal education (less than high Table 3 presents odds ratios for the interquartile range school, high school, or more than high school), maternal of exposure, reporting the increase or decrease in the diabetes (yes, no), maternal high blood pressure (yes, odds of having a baby with hypospadias associated with no), maternal body mass index (BMI) (less than 18.5, an increase in atrazine concentration equal to the differ- 18.5–25, 25–30, and over 30), choline use (less than ence of the 75th and 25th percentiles of estimated 187.4 mg, 187.4–249.6 mg, 249.6–336.4 mg, and greater exposure. For Arkansas and Texas, the unadjusted and than 336.4 mg, consistent with Carmichael et al. [14]), adjusted odds ratios for the interquartile range of and use of artificial reproductive technology (yes, no). estimated concentration of atrazine in a mother’s water Analyses were performed using Stata version 13.1 (Stata- supply and a mother’s estimated daily atrazine consump- Corp LP, College Station, TX, USA). tion were elevated. Odds ratios for Iowa and North Carolina were below 1.0, but statewide estimates were Results and Discussion relatively imprecise as evidenced by the wide confidence Distributions of demographic characteristics (state of intervals (Table 3). residence, age, multiple or singleton birth, previous The crude odds ratios for estimated atrazine in water pregnancy, and education), behavioral characteristics supply and atrazine consumption, without stratification (use of private wells, water filtration, choline, and artifi- by state, were close to 1.0. After adjustment for multiple cial reproductive technology), and health characteristics covariates the odds ratios for consumption were slightly (BMI, diabetes, and high blood pressure), for mothers of increased above the null for the interquartile range of hypospadias cases (n= 123) and mothers of male con- exposure. trols (n= 415) are presented in Table 1. Mothers of cases Sensitivity analyses compared characteristics of were more likely to be non-Hispanic white, more highly women who were successfully assigned an atrazine educated, and to have used fertility medications or pro- exposure and women who were not successfully cedures, and infants with hypospadias were more likely assigned an atrazine exposure. These analyses suggest to be a result of a first pregnancy or a multiple birth. that mothers who were excluded from the USGS Mothers of cases were slightly more likely to report metric were less likely to be mothers of hypospadias drinking 5 or more glasses of water a day. While con- cases, less likely to use untreated water from private trols were fairly evenly distributed amongst the 4 states, wells, more likely to live in Arkansas, more likely to 79.6 % of cases lived in Arkansas and North Carolina, be underage 30, andmorelikelytohaveaBMI which is likely to be due to enrollment processes for under 18.5 or greater than 25. The mothers excluded NBDPS [13]. No significant differences in distributions from themetricwerealsomorelikelytoidentifyas were observed for reported use of a private well, residen- non-Hispanic white or non-Hispanic black. See tial use of water filtration, maternal age, maternal BMI, Additional file 1 for additional information. maternal diabetes, maternal high blood pressure, or maternal choline intake. Conclusions Raw distributions for estimated concentrations of atra- After adjusting for maternal socioeconomic, demo- zine for a mother’s water supply and for estimated daily graphic, and behavioral characteristics, we observed a atrazine consumption are presented in Table 2. When weak association between hypospadias and maternal combining the data across all 4 states, mean and median consumption of atrazine via drinking water during gesta- concentrations were higher for controls than for cases tional weeks 6–16 in overall models. This was a slightly for both estimated atrazine in water supply and esti- stronger association than that found by Meyer et al. mated atrazine consumption. In addition, the mean was [11], but a much weaker association than that found by greater than the median for all estimates. We observed Agopian et al. [12]. No association was observed in Winston et al. Environmental Health (2016) 15:76 Page 5 of 9 Table 1 Characteristics of NBDPS hypospadias cases and Table 1 Characteristics of NBDPS hypospadias cases and controls with estimated atrazine exposure, 1998-2005 controls with estimated atrazine exposure, 1998-2005 (Continued) Cases Controls Maternal choline intake 00 Characteristic N % Missing N % Missing <187.4 mg 27 22.0 72 17.4 Demographic characteristics 187.4 – 249.6 mg 30 24.4 85 20.5 State of residence ** 0 0 249.7 – 336.3 mg 34 27.6 104 25.1 Arkansas 49 39.8 85 20.5 >336.4 mg 32 26.0 154 37.1 Iowa 17 13.8 103 24.8 Fertility medications or 04 Texas 8 6.5 101 24.3 procedures* North Carolina 49 39.8 126 30.4 No 111 90.2 393 95.6 Maternal age 0 0 Yes 12 9.8 18 4.4 <20 10 8.1 43 10.4 Health characteristics 20-24 27 22.0 89 21.5 Diabetes 0 1 25-29 25 20.3 118 28.4 No 115 93.5 374 90.3 30-34 42 34.2 105 25.3 Yes 8 6.5 40 9.7 ≥35 19 15.5 60 14.5 High blood pressure 0 0 Maternal race/ethnicity** 0 0 No 95 77.2 344 92.9 Non-Hispanic white 94 76.4 242 58.3 Yes 28 22.8 71 17.1 Non-Hispanic black 16 13.0 32 7.7 Maternal BMI 1 22 Hispanic 8 6.5 106 25.5 <18.5 6 4.9 20 5.1 Other 5 4.1 35 8.4 18.5-25 59 48.4 210 53.4 Maternal education** 0 0 25-30 25 20.5 84 21.4 <High school 5 4.1 86 20.7 >30 32 26.2 79 20.1 High school 30 24.4 111 26.8 p < 0.1 >High school 88 71.5 218 52.5 *p < 0.05 **p < 0.01 Previous pregnancies** 0 0 Categories for maternal choline intake from Carmichael et al. [14] No 55 44.7 122 29.4 Yes 68 55.3 293 70.6 crude odds ratios, or when not accounting for the total amount of drinking water consumed. In state-level Plurality* 0 0 models, positive associations were observed in Arkansas Singleton birth 114 92.7 405 97.6 and Texas, while the opposite trend was observed in Multiple birth 9 7.3 10 2.4 North Carolina and Iowa. Behavioral characteristics Certain limitations should be considered when inter- Private well use 2 9 preting these results. While the USGS models that we No 85 70.3 292 71.9 employed allowed us to estimate atrazine concentrations in raw water supplies, they do not account for treatment Yes 36 29.7 114 28.1 at public water supplies. Water treatment practices may Reported water consumption 00 vary geographically, atrazine concentrations may vary 0 glasses 3 2.4 22 5.3 seasonally, and the USGS models do not capture this geo- 1-4 glasses 77 62.6 217 52.3 graphic or temporal variation. In addition, other contami- 5 or more glasses 43 35.0 176 42.4 nants which we were unable to measure or estimate, Residential filtered tap water 2 9 particularly agricultural byproducts, may be correlated with atrazine in water supplies. No 84 69.4 304 74.9 We did consider other exposure estimation techniques, Yes 37 30.6 102 25.1 first using monitoring data from the US Environmental Protection Agency, and then using the amount of atrazine applied at the county level. Both of these alternatives proved problematic. Monitoring data were not available for atrazine concentrations below the US Environmental Protection Agency’s Maximum Contaminant Level, which Winston et al. Environmental Health (2016) 15:76 Page 6 of 9 Table 2 Distribution of estimated atrazine in water supply and estimated atrazine consumption Cases Controls Mean Median IQR Min, Max Mean Median IQR Min, Max Estimated atrazine in water supply in AR, IA, TX, and NC (μg/L) 0.09 0.02 0.001–0.04 0.0001, 2.0 0.17 0.02 0.002–0.05 0.0001, 4.0 Arkansas 0.03 0.02 0.0004–0.03 0.00009, 0.31 0.02 0.02 0.005–0.03 0.0001, 0.31 Iowa 0.28 0.05 0.001–0.53 0.001, 0.95 0.47 0.45 0.002–0.66 0.0004, 4.02 North Carolina 0.02 0.02 0.0006–0.04 0.0002, 0.07 0.03 0.03 0.001–0.04 0.0002, 0.06 Texas 0.50 0.004 0.0004–0.99 0.0001, 1.98 0.17 0.005 0.001–0.13 0.0001, 3.94 Estimated atrazine consumption in AR, IA, TX, and NC (μg/day) 0.12 0.02 0.001–0.04 0.00004–3.75 0.14 0.02 0.002–0.06 0.00007–4.66 Arkansas 0.03 0.02 0.01–0.03 0.00004–0.22 0.02 0.01 0.003–0.03 0.00009–0.22 Iowa 0.29 0.06 0.001–0.47 0.0006–1.35 0.36 0.08 0.002–0.54 0.0002–2.86 North Carolina 0.02 0.01 0.0005–0.03 0.00008–0.08 0.03 0.02 0.001–0.05 0.0001–0.16 Texas 1.00 0.002 0.0004–3.28 0.0001–3.75 0.18 0.01 0.002–0.09 0.00007–4.66 Winston et al. Environmental Health (2016) 15:76 Page 7 of 9 Table 3 Association between atrazine and hypospadias in the National Birth Defects Prevention Study, 1998–2005 N (cases) IQR Crude OR Adjusted OR State level models for estimated atrazine in water supply Arkansas 134 (49) 0.02 1.05 (0.88, 1.26) 1.02 (0.80, 1.24) Iowa 120 (17) 0.63 0.64 (0.28, 1.42) 0.66 (0.26, 1.67) North Carolina 175 (49) 0.003 0.97 (0.92–1.02) 0.97 (0.88, 1.08) Texas 109 (8) 0.13 1.09 (0.97, 1.22) 1.22 (1.01, 1.48) State level models for estimated atrazine consumption Arkansas 131 (49) 0.03 1.06 (0.83, 1.35) 1.40 (0.34, 5.78) Iowa 106 (16) 0.54 0.85 (0.46, 1.57) 0.46 (0.02, 11.9) North Carolina 171 (48) 0.05 0.50 (0.27, 0.91) 0.02 (0.00, 1.24) Texas 105 (7) 0.09 1.07 (1.01, 1.12) 1.93 (1.02, 3.23) Estimated atrazine in water supply across states 538 (123) 0.04 0.97 (0.94, 1.00) 1. 00 (0.97, 1.03) Estimated atrazine consumption across states 513 (120) 0.05 0.99 (0.96 1.02) 1.02 (0.99, 1.05) All ORs reported for interquartile range, or an increase from the in atrazine concentration equal to the difference of the 75th and 25th percentiles ORs for random effects models using state as the group variable. Random effects models and models for Arkansas, Iowa, and North Carolina adjusted by private well use, residential use of filtered water, maternal age, maternal race/ethnicity, plurality, parity, maternal education, choline use, use of artificial reproductive technology, maternal diabetes, maternal high blood pressure, and maternal BMI. Models for Texas adjusted by only private well use, maternal age, maternal race/ ethnicity, parity, maternal education, choline use, and maternal high blood pressure because of the small number of cases prevented us from considering associations between hypo- exposure were also more likely to be non-Hispanic white spadias and lower levels of atrazine. Further, the total or non-Hispanic black, which were characteristics associ- amount of atrazine applied at the county level would not ated with decreased hypospadias risk in this study. They have allowed us to consider the interaction between atra- were also less likely to use private wells, more likely to be zine concentrations in water supplies and maternal water under age 30, and more likely to have a BMI under 18.5 consumption. The USGS water models allowed us to or greater than 25, which were characteristics that were estimate atrazine concentrations for private wells, which not associated with hypospadias risk in this study. In are not regulated by the EPA, and for individual water addition, a number of women were identified by state cen- supplies with atrazine concentrations below the EPA’s ters as eligible cases or controls, but were not successfully Maximum Contaminant Level. interviewed. It is therefore unclear how exclusion of these We cannot be sure that our models accurately predict women may have influenced our results. Finally, some of maternal exposure to atrazine without a validated, re- the odds ratio estimates were based on smaller sample peated measure of atrazine in maternal urine during sizes and were imprecise. pregnancy, and the lack of more reliable data on atrazine This study also had several strengths. While other exposure undoubtedly led to some misclassification studies have looked at proximity to pesticide application, when assigning maternal exposure status. Our exposure our modeled exposure estimates allowed us to consider estimates also relied on self-reported water consump- exposure via drinking water as a potential mechanism tion, which may be prone to recall bias. Assuming that for a possible association between atrazine and hypospa- atrazine concentration misclassification and recall bias dias. It also took advantage of the unique water con- was largely random between case and control mothers, sumption and other covariate data available through the the results would have tended to be biased toward the National Birth Defects Prevention Study (NBDPS), null, although this does not guarantee that our estimate which allowed us to improve our exposure assessment is an underestimate [23]. While our exposure estimates and control for confounding. therefore should not be used in a quantitative risk as- A further strength of this study was that all of the sessment, the continuous nature of our estimated expos- hypospadias cases were ascertained by population-based ure may be less prone to misclassification than a binary birth defect surveillance systems, and underwent a de- exposure variable and useful for hypothesis generation. tailed clinical review and classification prior to inclusion Another limitation was our inability to assign atrazine in the study. Cases with known genetic or chromosomal concentrations to many of the NBDPS women. Sensitivity abnormalities were excluded. This resulted in a more analyses revealed that women who were not successfully etiologically and pathogenically homogenous case group. assigned an atrazine concentration were more likely to live Our models of maternal consumption of atrazine via in Arkansas, which was associated with increased risk in drinking water (OR 1.02 (95 % CI 0.99-1.05)) may provide this study. Women who were not successfully assigned an limited support for the hypothesis that atrazine may be Winston et al. Environmental Health (2016) 15:76 Page 8 of 9 associated with male genitourinary malformations in Disclaimer The views expressed in this article are those of the authors and do not humans, although we could not exclude the possibility of a necessarily reflect the views or policies of the U.S. EPA, the Centers for Disease null association, given the limitations described above. Our Control and Prevention, or the Texas Department of State Health Services. results are not intended to be used in lieu of an exposure Author details risk assessment, but rather to generate hypotheses about Carolina Population Center, University of North Carolina at Chapel Hill, the trends and patterns of associations between atrazine 2 Chapel Hill, NC, USA. Department of Geography and Carolina Population and hypospadias. Further research including a larger sam- Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. North Carolina Birth Defects Monitoring Program, State Center for Health ple size and better exposure characterization would be use- Statistics, Raleigh, NC, USA. Department of Maternal and Child Health, ful to provide a more definitive characterization of the 5 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Texas potential effects of atrazine. Department of State Health Services, Birth Defects Epidemiology and Surveillance Branch, Austin, TX, USA. Center for Health Effects of Environmental Contamination, University of Iowa, Iowa City, IA, USA. Additional file Department of Pediatrics, Arkansas Children’s Hospital, Little Rock, AR, USA. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Department of Geography and Institute for the Additional file 1: Characteristics of women successfully assigned an Environment, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. atrazine exposure and women who were not successfully assigned an National Center for Environmental Assessment, United States atrazine exposure. (DOCX 19 kb) Environmental Protection Agency, Research Triangle Park, NC, USA. Abbreviations Received: 29 January 2016 Accepted: 21 June 2016 BMI, body mass index; CHEEC, Center for Health Effects of Environmental Contamination; NBDPS, National Birth Defects Prevention Study; USGS, United States Geological Survey; WARP, Watershed Regressions for Pesticides References Acknowledgements 1. Carmichael SL, Shaw GM, Lammer EJ. Environmental and genetic contributors We thank the North Carolina Birth Defects Monitoring Program, the Arkansas to hypospadias: A review of the epidemiologic evidence. Birth Defects Res A Center for Birth Defects Research and Prevention, the Iowa Registry for Clin Mol Teratol. 2012;94:499–510. Congenital and Inherited Disorders, and the Texas Center for Birth Defects 2. Mieusset R, Soulie R. Hypospadias: Psychosocial, sexual, and reproductive Research and Prevention for providing data on study subjects for the consequences in adult life. J Androl. 2005;26(2):163–8. National Birth Defects Prevention Study. We thank Wesley Stone, Robert 3. Stackelberg PE, Barbash JE, Gilliom RJ, Stone WW, Wolock DM. Regression Gilliom, Paul Stackleberg, and David Wolock from the US Geological Survey models for estimating concentrations of atrazine plus deethylatrazine in for providing output from their atrazine models. shallow groundwater in agricultural areas of the United States. J Environ Qual. 2012;41:479–94. Funding 4. Tavera-Mendoza L, Ruby S, Brousseau P, Fournier M, Cyr D, Marcogliese This research received support from the Population Research Training grant D. Response of the amphibian tadpole (xenopus laevis)toatrazine (T32 HD007168) and the Population Research Infrastructure Program awarded during sexual differentiation of the testis. Environ Toxicol Chem. 2002; to the Carolina Population Center (R24 HD050924) at The University of North 21(3):527–31. Carolina at Chapel Hill by the Eunice Kennedy Shriver National Institute of Child 5. Hayes TB, Collins A, Lee M, Mendoza M, Noriega N, Stuart AA, et al. Health and Human Development. This study was also supported by a Hermaphroditic, demasculinized frogs after exposure to the herbicide cooperative agreement from the Centers for Disease Control and Prevention atrazine at low ecologically relevant doses. Proc Natl Acad Sci U S A. (U50CCU422096). 2002;99(8):5476–80. 6. Wu YG, Li SK, Xin ZC, Wang YS, Shou KR, Gao H, et al. The establishment of Availability of data and supporting materials hypospadias rat model and embryteratogenic test of atrazine. Chin J Plast NBDPS is unable to share due to information provided to participants during Surg. 2007;23(4):340–3. the informed consent process, which states that data about participants will 7. Hayes TB, Haston K, Tsui M, Hoang A, Haeffele C, Vonk A. Atrazine-induced not be given to anyone outside the study. hermaphroditism at 0.1 ppb in american leopard frogs (rana pipiens): Laboratory and field evidence. Environ Health Perspect. 2002;111(4):568. Authors’ contributions 8. Hayes TB, Stuart AA, Mendoza M, Collins A, Noriega N, Vonk A, et al. JW conducted study design, data analysis and interpretation, and drafted the Characterization of atrazine-induced gonadal malformations in African manuscript. TL contributed to study design; replication and interpretation of clawed frogs (xenopus laevis) and comparisons with effects of an androgen analyses; and revision of the manuscript. ME and LB contributed to study antagonist (cyproterone acetate) and exogenous estrogen (17beta- design, interpretation of analyses, and revision of the manuscript. RM, PL, estradiol): Support for the demasculinization/feminization hypothesis. PW, BM, AO, and the National Birth Defects Prevention Study contributed to Environ Health Perspect. 2006;114 Suppl 1:134–41. data acquisition and revision of the manuscript. All read and approved the 9. Winchester PD, Huskins J, Ying J. Agrichemicals in surface water and birth final manuscript. defects in the United States. Acta pædiatrica (Oslo). 2009;98(4):664. 10. Chevrier C, Limon G, Monfort C, Rouget F, Garlantezec R, Petit C, et al. Competing interests Urinary biomarkers of prenatal atrazine exposure and adverse birth The authors declare that they have no competing interests. outcomes in the PELAGIE birth cohort. Environ Health Perspect. 2011;119(7):1034–41. Consent for publication 11. Meyer KJ, Reif JS, Veeramachaneni D, Luben TL, Mosley BS, Nuckols JR. Not applicable. Agricultural pesticide use and hypospadias in eastern Arkansas. Environ Health Perspect. 2006;114(10):1589–95. Ethics approval and consent to participate 12. Agopian A, Lupo PJ, Canfield MA, Langlois PH. Case–control study of The analysis of pooled data collected in the National Birth Defects Research maternal residential atrazine exposure and male genital malformations. and Prevention Study, including this research, has been approved by the Am J Med Genet. 2013;161(5):977–82. Non-Biomedical Institutional Review Board at the University of North Carolina 13. Reefhuis J, Gilboa SM, Anderka M, Browne ML, Feldkamp ML, Hobbs CA, at Chapel Hill (Study # 05–1420). Study participants provided verbal informed et al. The National Birth Defects Prevention Study: A review of the methods. consent before participation in the study. Birth Defects Research Part A. 2015;103(8):656–69. Winston et al. Environmental Health (2016) 15:76 Page 9 of 9 14. Carmichael SL, Yang W, Correa A, Olney RS, Shaw GM. Hypospadias and intake of nutrients related to one-carbon metabolism. Urology. 2009;181(1):315–21. 15. Watershed regressions for pesticides atrazine model [Internet]. Available from: http://cida.usgs.gov/warp/home/. 16. Stone WW, Crawford CG, Gilliom RJ. Watershed regressions for pesticides (WARP) models for predicting stream concentrations of multiple pesticides. J Environ Qual. 2013;42:1838–51. 17. Public water supply sources, including ground water and surface water sources. 2009. http://data.nconemap.gov/geoportal/catalog/main/home. page. Accessed 4 March 2013 18. Source water assessment and protection wells. 2008. https://programs. iowadnr.gov/nrgislibx/. Accessed 21 Feb 2013. 19. Public water supply surface water intake sites in the state of Texas. 2010. https://www.tceq.texas.gov/gis/. Accessed 7 Dec 2012. 20. Public water well sites in the state of Texas. 2010. https://www.tceq.texas. gov/gis/. Accessed 7 Dec 2012. 21. Arkansas public water supply list. 2014. http://www.healthy.arkansas.gov/ Pages/default.aspx. Accessed 8 Feb 2014. 22. Luben TJ, Nuckols JR, Mosley BS, Hobbs C, Reif JS. Maternal exposure to water disinfection by-products during gestation and risk of hypospadias. Occup Environ Med. 2008;65:420–9. 23. Jurek AM, Greenland S, Maldonado G, Church TR. Proper interpretnation of non-differetntial misclassification effects: expectations vs. observations. Int J Epidemiol. 2005;34:680–7. Submit your next manuscript to BioMed Central and we will help you at every step: • We accept pre-submission inquiries � Our selector tool helps you to find the most relevant journal � We provide round the clock customer support � Convenient online submission � Thorough peer review � Inclusion in PubMed and all major indexing services � Maximum visibility for your research Submit your manuscript at www.biomedcentral.com/submit

Journal

Environmental HealthSpringer Journals

Published: Jul 15, 2016

There are no references for this article.