Residential proximity to agricultural pesticide use and cardiovascular disease risk factors among adult Latina women in California's Salinas Valley.

Cardiovascular disease is a leading cause of death worldwide. There is limited evidence that exposure to current-use pesticides may contribute to cardiovascular disease risk. We examined the association between residential proximity to the application of agricultural pesticides and cardiovascular risk factors among 484 adult women in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a cohort based in an agricultural region of California. Outcome assessment was completed between 2010 and 2013. Using participant residential addresses and California's Pesticide Use Reporting database, we estimated agricultural pesticide use within one km of residences during the 2-year period preceding outcome assessment. We used Bayesian Hierarchical Modeling to evaluate associations between exposure to 14 agricultural pesticides and continuous measures of waist circumference, body mass index, and blood pressure. Each 10-fold increase in paraquat application around homes was associated with increased diastolic blood pressure (ß=2.60 mm Hg, 95% Credible Interval (CrI): 0.27-4.89) and each 10-fold increase in glyphosate application was associated with increased pulse pressure (ß=2.26 mm Hg, 95% CrI: 0.09-4.41). No meaningful associations were observed for the other pesticides examined. Our results suggest that paraquat and glyphosate pesticides may affect cardiovascular disease development in women with chronic environmental exposure.

Dioxin exposure associated with fecundability and infertility in mothers and daughters of Seveso, Italy.

STUDY QUESTION: Is there an association between 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure and fecundability and infertility among Seveso women and their daughters? SUMMARY ANSWER: TCDD exposure is associated with a decrease in fecundability and increased risk of infertility in women, as well as their daughters. WHAT IS KNOWN ALREADY: In animal studies, maternal exposure to TCDD is associated with decreased fertility in offspring. Effects of TCDD are mediated by activation of the aryl hydrocarbon receptor (AHR) pathway. STUDY DESIGN, SIZE, DURATION: The Seveso Women's Health Study (SWHS) has followed 981 women exposed to TCDD in a 1976 accident since 1996. In 2014, we initiated the Seveso Second Generation Study to follow-up their children. PARTICIPANTS/MATERIALS, SETTING, METHODS: We obtained information on pregnancy history including time of trying to conceive from SWHS women and their daughters who were 18 years or older. We considered TCDD exposure as initial 1976 serum TCDD concentration and estimated TCDD at pregnancy. We examined relationships of TCDD exposure with time to pregnancy (TTP, the monthly probability of conception within the first 12 months of trying) and infertility (≥12 months of trying to conceive). We also assessed contributions of polymorphisms in the AHR pathway via genetic risk score. MAIN RESULTS AND THE ROLE OF CHANCE: Among SWHS women (n = 446), median TTP was 3 months and 18% reported taking ≥12 months to conceive. Initial 1976 TCDD (log10) was associated with longer TTP (adjusted fecundability odds ratio = 0.82; 95% CI 0.68-0.98) and increased risk of infertility (adjusted relative risk = 1.35; 95% CI 1.01-1.79). TCDD at pregnancy yielded similar associations. Among SWHS daughters (n = 66), median TTP was 2 months and 11% reported taking ≥12 months to conceive. Daughters showed similar, but non-significant, associations with maternal TCDD exposure. LIMITATIONS, REASONS FOR CAUTION: A limitation of this study is time to pregnancy was reported retrospectively, although previous studies have found women are able to recall time to conception with a high degree of accuracy many years after the fact. The number of SWHS daughters who had a live birth was small and we were unable to examine fecundability of SWHS sons. WIDER IMPLICATIONS OF THE FINDINGS: Consistent with previous findings in animal studies, our study found that TCDD exposure may be associated with decreased fertility in Seveso mothers and potentially in their daughters exposed in utero. There may be susceptible genetic subgroups. The literature has largely considered the genetics of the AHR pathway in the context of male fertility but not female fertility, despite strong biological plausibility. These findings should be replicated in larger populations and of different ancestry. Future studies in Seveso should examine the sons and the grandchildren of exposed mothers given the animal literature suggesting potential heritable epigenetic effects. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by grant numbers F06 TW02075-01 from the National Institutes of Health, R01 ES07171 and 2P30-ESO01896-17 from the National Institute of Environmental Health Sciences, R82471 from the U.S. Environmental Protection Agency and #2896 from Regione Lombardia and Fondazione Lombardia Ambiente, Milan, Italy. J.A. was supported by F31ES026488 from the National Institutes of Health. The authors declare they have no actual or potential competing financial interests. TRIAL REGISTRATION NUMBER: N/A.

Prenatal dioxin exposure and thyroid hormone levels in the Seveso second generation study.

BACKGROUND: In animal studies, perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters thyroid homoeostasis and thyroid hormone concentrations; epidemiologic evidence is limited. OBJECTIVES: We aimed to determine the association of prenatal exposure to TCDD with thyroid hormone concentrations in the Seveso Second Generation Study, a unique cohort of children born to TCDD-exposed women resulting from a 1976 chemical factory explosion in Seveso, Italy. METHODS: We included 570 children (288 female, 282 male) with complete follow-up data, including a fasting blood draw. Serum levels of total and free thyroxine (T4), free triiodothyronine (T3), and thyroid stimulating hormone (TSH) were measured using immunoassays. We defined prenatal TCDD exposure as: 1) maternal initial TCDD concentration measured in serum collected soon after the explosion and 2) maternal TCDD estimated at pregnancy. RESULTS: Compared to the lowest quartile (Q1), maternal initial serum TCDD was associated with lower free T3 (Q2: adj-ß = -0.13, 95%CI -0.26, 0.00; Q3: adj-ß = -0.22, 95%CI -0.35, -0.09; Q4: adj-ß = -0.14, 95%CI -0.28, 0.00; p-trend = 0.02). In participants with high thyroid antibody status, inverse associations between maternal initial serum TCDD and free T3 were significantly stronger than in participants with normal antibody status (p-interaction = 0.02). We also observed a positive association between maternal initial serum TCDD and TSH concentrations in participants with high thyroid antibody status (Q2: adj-ß = 11.4%, 95%CI -25.2, 66.1; Q3: adj-ß = 49.0%, 95%CI 3.0, 115.5; Q4: adj-ß = 105.5, 95%CI 36.6, 209.2; p-trend < 0.01) but not in those participants with normal antibody status (p-interaction < 0.01). Similar results were found for TCDD estimated at pregnancy. DISCUSSION: Our results suggest prenatal exposure to TCDD, a potent endocrine-disrupting compound, may alter thyroid function later in life. Populations with additional thyroid stress may be particularly susceptible to in utero exposure of thyroid disrupting chemicals.

In utero dioxin exposure and cardiometabolic risk in the Seveso Second Generation Study.

BACKGROUND/OBJECTIVES: In utero exposure to endocrine-disrupting compounds such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may alter risk of obesity and related metabolic disease later in life. We examined the relationship of prenatal exposure to TCDD with obesity and metabolic syndrome (MetS) in children born to a unique cohort of TCDD-exposed women resulting from a 1976 explosion in Seveso, Italy. SUBJECTS/METHODS: In 2014, nearly 40 years after the explosion, we enrolled 611 post-explosion offspring, 2 to 39 years of age, in the Seveso Second Generation Study. In utero TCDD exposure was defined primarily as TCDD concentration measured in maternal serum collected soon after the explosion and alternately as TCDD estimated at pregnancy. We measured height, weight, waist circumference, body fat, blood pressure, and fasting blood levels of lipids and glucose, which were combined to assess body mass index (BMI) and MetS. RESULTS: Children (314 female, 297 male) averaged 23.6 (±6.0) years of age. Among the 431 children ≥18 years, a 10-fold increase in initial maternal TCDD concentration was inversely associated with BMI in daughters (adj-ß = -0.99 kg/m2; 95% CI -1.86, -0.12), but not sons (adj-ß = 0.41 kg/m2; 95% CI -0.35, 1.18) (p-int = 0.02). A similar relationship was found in the younger children (2-17 years); a 10-fold increase in initial maternal TCDD was inversely associated with BMI z-score (adj-ß = -0.59 kg/m2; 95% CI -1.12, -0.06) among daughters, but not sons (adj-ß = 0.04 kg/m2; 95% CI -0.34, 0.41) (p-int = 0.03). In contrast, in sons only, initial maternal TCDD was associated with increased risk for MetS (adj-RR = 2.09, 95% CI 1.09, 4.02). Results for TCDD estimated at pregnancy were comparable. CONCLUSIONS: These results suggest prenatal TCDD exposure alters cardiometabolic endpoints in a sex-specific manner. In daughters, in utero TCDD is inversely associated with adiposity measures. In sons, in utero TCDD is associated with increased risk for MetS.

Neurocognitive and physical functioning in the Seveso Women's Health Study.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is neurotoxic in animals but few studies have investigated its effects on the human brain. Related dioxin-like compounds have been linked to poorer cognitive and motor function in older adults, with effects more pronounced in women, perhaps due to the loss of neuro-protective estrogen in menopause. On 10 July 1976, a chemical explosion in Seveso, Italy, resulted in one of the highest known residential exposures to TCDD. In 1996, we initiated the Seveso Women's Health Study, a retrospective cohort study of the health of the women who were newborn to 40 years old in 1976. Here, we investigate whether TCDD exposure is associated with physical functioning and working memory more than 20 years later. Individual TCDD concentration (ppt) was measured in archived serum collected soon after the explosion. In 1996 and 2008, we measured physical functioning (n=154) and working memory (n=459), respectively. We examined associations between serum TCDD and motor and cognitive outcomes with multivariate linear regression and semi-parametric estimators. A 10-fold increase in serum TCDD was not associated with walking speed (adjusted ß=0.0006ft/s, 95% Confidence Interval (CI): -0.13, 0.13), upper body mobility (adjusted ß=-0.06, 95% CI: -0.36, 0.23), or manual dexterity (adjusted ß=0.34, 95% CI: -0.65, 1.33). We observed an inverted U-shaped association in grip strength, with poorer strength in the lowest and highest TCDD exposure levels. There was no association between TCDD and the Wechsler digit and spatial span tests. Neither menopause status at assessment nor developmental timing of exposure modified associations between TCDD and working memory. Our findings, in one of the only studies of TCDD's effects on neuropsychological and physical functioning in women, do not indicate an adverse effect on these domains, with the exception of a U-shaped relationship with grip strength. Given the limited assessment and relative youth of the women at this follow-up, future work examining additional neuropsychological outcomes is warranted.

Prenatal exposure to TCDD and atopic conditions in the Seveso second generation: a prospective cohort study.

BACKGROUND: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a toxic environmental contaminant that can bioaccumulate in humans, cross the placenta, and cause immunological effects in children, including altering their risk of developing allergies. On July 10, 1976, a chemical explosion in Seveso, Italy, exposed nearby residents to a high amount of TCDD. In 1996, the Seveso Women's Health Study (SWHS) was established to study the effects of TCDD on women's health. Using data from the Seveso Second Generation Health Study, we aim to examine the effect of prenatal exposure to TCDD on the risk of atopic conditions in SWHS children born after the explosion. METHODS: Individual-level TCDD was measured in maternal serum collected soon after the accident. In 2014, we initiated the Seveso Second Generation Health Study to follow-up the children of the SWHS cohort who were born after the explosion or who were exposed in utero to TCDD. We enrolled 677 children, and cases of atopic conditions, including eczema, asthma, and hay fever, were identified by self-report during personal interviews with the mothers and children. Log-binomial and Poisson regressions were used to determine the association between prenatal TCDD and atopic conditions. RESULTS: A 10-fold increase in 1976 maternal serum TCDD (log10TCDD) was not significantly associated with asthma (adjusted relative risk (RR) = 0.93; 95% CI: 0.61, 1.40) or hay fever (adjusted RR = 0.99; 95% CI: 0.76, 1.27), but was significantly inversely associated with eczema (adjusted RR = 0.63; 95% CI: 0.40, 0.99). Maternal TCDD estimated at pregnancy was not significantly associated with eczema, asthma, or hay fever. There was no strong evidence of effect modification by child sex. CONCLUSIONS: Our results suggest that maternal serum TCDD near the time of explosion is associated with lower risk of eczema, which supports other evidence pointing to the dysregulated immune effects of TCDD.

Prenatal DDT exposure and child adiposity at age 12: The CHAMACOS study.

OBJECTIVE: Using data from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) birth cohort study, we assessed the association of in utero exposure to dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenylethylene (DDE) with child adiposity at age 12. METHODS: We included 240 children with o,p'-DDT, p,p'-DDT, and p,p'-DDE concentrations measured in maternal serum collected during pregnancy (ng/g lipid) and complete 12-year follow-up data. Age- and sex-specific body mass index (BMI) z-scores were calculated from CDC growth charts. Children with BMI z-scores ≥ 85th percentile were classified as overweight or obese. RESULTS: At 12 years, BMI z-score averaged 1.09 (±1.03) and 55.4% of children were overweight or obese. Prenatal DDT and DDE exposure was associated with several adiposity measures in boys but not girls. Among boys, 10-fold increases in prenatal DDT and DDE concentrations were associated with increased BMI z-score (o,p'-DDT, adj-ß=0.37, 95% CI: 0.08, 0.65; p,p'-DDT, adj-ß = 0.26, 95% CI: 0.03, 0.48; p,p'-DDE, adj-ß = 0.31, 95% CI: 0.02, 0.59). Results for girls were nonsignificant. The difference by sex persisted after considering pubertal status. CONCLUSIONS: These results support the chemical obesogen hypothesis, that in utero exposure to DDT and DDE may increase risk of obesity in males later in life.

Serum dioxin concentrations and thyroid hormone levels in the Seveso Women's Health Study.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant. Although experimental evidence suggests that TCDD alters thyroid hormone levels in rodents, human data are inconsistent. In 1976, a trichlorophenol plant exploded in Seveso, Italy. Women living in highly exposed areas were followed through the Seveso Women's Health Study. TCDD concentrations were measured in 1976 (n = 981) and 1996 (n = 260), and levels of total thyroxine, free thyroxine, free triiodothyronine, and thyroid-stimulating hormone were measured in 1996 (n = 909) and 2008 (n = 724). We used conditional multiple linear regression and marginal structural models with inverse-probability-of-treatment weights to evaluate associations and causal effects. TCDD concentration in 1976 was inversely associated with total thyroxine level in 1996 but not in 2008. Associations were stronger among women who had been exposed before menarche. Among these women, associations between total thyroxine and concurrent 1996 TCDD were slightly weaker than those with 1976 TCDD. A model including both 1976 and 1996 measurements strengthened the relationship between 1976 TCDD and total thyroxine but drove the association with 1996 TCDD to the null. TCDD exposure was not associated with levels of other thyroid hormones. TCDD exposure, particularly exposure before menarche, may have enduring impacts on women's total thyroxine levels. Initial exposure appears to be more influential than remaining body burden.

Prenatal exposure to dichlorodiphenyltrichloroethane and obesity at 9 years of age in the CHAMACOS study cohort.

In-utero exposure to endocrine-disrupting compounds, including dichlorodiphenyltrichloroethane (DDT) and its metabolite dichlorodiphenylethylene (DDE), has been hypothesized to increase the risk of obesity later in life. We examined the associations of maternal serum concentrations of DDT and DDE during pregnancy with body mass index, obesity, waist circumference, and percentage of body fat in 9-year-old children (n = 261) in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) Study, a longitudinal birth cohort study in the Salinas Valley, California (2000-2010). We found associations between prenatal exposure to DDT and DDE and several measures of obesity at 9 years of age in boys but not in girls. For example, among boys, 10-fold increases in prenatal DDT and DDE concentrations were associated with increased odds of becoming overweight or obese (for o,p'-DDT, adjusted odds ratio (OR) = 2.5, 95% confidence interval (CI): 1.0, 6.3; for p,p'-DDT, adjusted OR = 2.1, 95% CI: 1.0, 4.5; and for p,p'-DDE, adjusted OR = 1.97, 95% CI: 0.94, 4.13). The odds ratios for girls were nonsignificant. Results were similar for body mass index z score, waist circumference z score, and odds of increased waist circumference but were less consistent for percentage of body fat. The difference by sex persisted after considering pubertal status. These results provide support for the chemical obesogen hypothesis.

Serum dioxin concentrations and time to pregnancy.

BACKGROUND: Pollution may play a role in population trends of declining semen quality and regional differences in time to pregnancy (TTP) in industrialized societies. Dioxins including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been suspected. In 1976, an explosion near Seveso, Italy resulted in the highest TCDD exposure known in residential populations. Twenty years later, we conducted a retrospective cohort study, the Seveso Women's Health Study. METHODS: Of 981 participants, 472 women attempted pregnancy after the explosion, and 278 delivered a livebirth not associated with contraceptive failure. Individual serum TCDD levels were measured from samples collected soon after the explosion and extrapolated to the conception attempt. We examined the relation of TCDD levels to time to pregnancy (parameterized as the monthly probability of conception within the first 12 months of trying) and to infertility (defined as conception after at least 12 months of trying). We modeled fecundability with discrete-time Cox proportional hazards regression, and we modeled fertility with logistic regression. We tested the sensitivity of the conclusions to differing definitions of eligibility and outcome. RESULTS: Median TCDD level was 50 parts per trillion, median time to pregnancy was 2 months, and 17% reported taking 12 or more months to conceive. For every 10-fold increase in serum TCDD, we observed a 25% increase in time to pregnancy (adjusted-fecundability odds ratio = 0.75 [95% confidence interval (CI) = 0.60-0.95]) and about a doubling in odds of infertility (adjusted odds ratio = 1.9 [95% CI = 1.1-3.2]). Results were similar for extrapolated TCDD and sensitivity analyses. CONCLUSIONS: We found dose-related increases in TTP and infertility associated with individual serum TCDD levels in the women from Seveso, Italy. These findings may have implications for fertility in industrialized areas.

Age at menarche in Seveso daughters exposed in utero to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is associated with delayed pubertal development in animal studies. No epidemiologic study has investigated this association. We examined the relationship of in utero exposure to TCDD with reported age at onset of menarche in female children born to a unique cohort of TCDD-exposed women resulting from an explosion in Seveso, Italy, on 10 July 1976. METHODS: In 2014, nearly 40 years after the explosion, we enrolled postexplosion offspring, 2 to 39 years of age, in the Seveso Second Generation Study. Age at onset of menarche (years) was collected for 316 daughters by maternal report or self-report at interview. In utero TCDD exposure was defined by maternal TCDD serum concentrations extrapolated to the pregnancy. RESULTS: At interview, 287 daughters were postmenarche and reported age at menarche averaged 12.1 years (±1.3 years). Overall, we found no change in risk of menarche onset with a 10-fold increase in in utero TCDD exposure (hazard ratio [HR] = 0.86; 95% confidence interval [CI] = 0.71, 1.04). When we considered maternal menarche status in 1976 as a potentially sensitive developmental exposure window, in utero TCDD (log10) was associated with later age at menarche among daughters whose mothers were premenarche (HR = 0.71; 95% CI = 0.52, 0.97) but not postmenarche (HR = 0.89; 95% CI = 0.71, 1.12) at the time of the explosion (P int = 0.24). CONCLUSIONS: These results suggest that in utero TCDD exposure may alter pubertal timing among daughters of women who were prepubescent at the time of the Seveso accident.

Prenatal dioxin exposure and glucose metabolism in the Seveso Second Generation study.

BACKGROUND: Exposure to endocrine disrupting compounds such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during susceptible developmental windows may alter risk of metabolic disease later in life. Animal studies of in utero and lactational TCDD exposure report associations with alterations in insulin sensitivity and energy homeostasis, but epidemiologic evidence is limited. We examined the relationship of prenatal TCDD exposure with markers of glucose homeostasis in the Seveso Second Generation study, a unique cohort of children born to TCDD-exposed women resulting from a 1976 explosion in Seveso, Italy. METHODS: We included 426 children who were 18 years or older with complete follow-up data including a fasting blood draw. Insulin and glucose were measured and the updated homoeostatic model assessment was used to estimate insulin resistance (HOMA2-IR) and beta-cell function (HOMA2-B). Prenatal TCDD exposure was defined in two ways, as initial maternal serum TCDD concentration and TCDD estimated at pregnancy. RESULTS: The children (222 female, 204 male) averaged 28.6 (±6.0) years. We found a 10-fold increase in TCDD estimated at pregnancy was inversely associated with insulin (adj-ß = -1.24 µIU/mL, 95% confidence interval (CI): -2.38, -0.09) and HOMA2-B (adj-ß = -10.2% decrease, 95% CI: -17.8, -1.9) among daughters, but not sons (insulin: adj-ß = 0.57 µIU/mL, 95% CI: -0.84, 1.98, P for interaction = 0.04; and HOMA2-B: adj-ß = 0.8% increase, 95% CI -10.7, 13.9, P for interaction = 0.11). Similar effect modification was observed for TCDD estimated at pregnancy and HOMA2-IR (P for interaction = 0.13). The models for initial maternal serum TCDD showed similar effect modification by child sex. The observed associations in daughters showed evidence of mediation by body mass index, which we have previously found to be associated with prenatal TCDD exposure in female offspring. CONCLUSION: These results suggest prenatal exposure to TCDD is associated with lower insulin resistance and beta compensation in female offspring, and show evidence of mediation by body mass index.

The 2nd to 4th digit length ratio (2D:4D) among children of Seveso women exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

BACKGROUND: Exposure to endocrine-disrupting chemicals (EDCs) during sensitive developmental windows, such as in utero, may influence disease later in life but direct measurement of fetal hormones is not feasible. The ratio of the length of the second finger digit to the fourth digit (2D:4D), a sexually dimorphic trait, is a biomarker of androgen levels and the androgen/estrogen balance in utero. However, it is unclear whether in utero EDC exposure might alter 2D:4D ratio. AIMS: We examined 2D:4D ratio in Seveso children in relation to in utero exposure to a potent EDC, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) using linear regression. STUDY DESIGN: The Seveso Women's Health Study (SWHS) is a historical cohort study, following the health of women exposed to TCDD during a 1976 explosion in Seveso, Italy. Individual-level TCDD was measured for SWHS in serum collected soon after the accident. In 2014, the SWHS children born after the explosion were enrolled in the Seveso Second Generation Study. SUBJECTS: 594 SWHS children born post-explosion to 397 mothers. OUTCOME MEASURES: Right hand 2D:4D ratio. RESULTS: On average, 2D:4D ratio for males was significantly lower than for females (p < 0.05). Overall, in utero TCDD exposure, either as maternal initial serum TCDD concentration or as TCDD extrapolated to pregnancy was not significantly associated with 2D:4D ratio in Seveso children. Results from all adjusted sensitivity analyses remained non-significant. CONCLUSIONS: Our results suggest in utero exposure to TCDD is not associated with alteration in 2D:4D ratio.

Prenatal dioxin exposure and neuropsychological functioning in the Seveso Second Generation Health Study.

BACKGROUND: Prenatal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure has been shown to alter sexual differentiation of the brain in animal models, impacting pubertal development, behavior, cortical dominance, and cognition. The effects of early life exposure to dioxin-like compounds on human neurodevelopment, however, are less clear and warrant further investigation. METHODS: The Seveso Women's Health Study (SWHS), initiated in 1996, is a well-characterized cohort of 981 Italian women who lived in proximity to an industrial accident in July 1976 that resulted in one of the highest residential TCDD exposures on record. In 2014-2016, we enrolled offspring born after the accident into the Seveso Second Generation Health Study. Children aged 7-17 years old (n = 161) completed a neuropsychological assessment spanning executive function and reverse learning (Wisconsin Card Sort), non-verbal intelligence (Raven's Progressive Matrices), attention and hyperactivity (Connor's Continuous Performance (CPT), and memory (Rey's Auditory Verbal Learning). We used multivariate regression with robust standard error estimates accounting for clustering of siblings to model the associations between these outcomes and prenatal exposure defined as TCDD measured in maternal serum collected soon after the explosion and estimated to pregnancy. RESULTS: The children (82 male, 79 female) averaged 13.1 (±2.9) years of age. Adjusting for covariates, a 10-fold increase in maternal serum TCDD was not adversely associated with reverse learning/set-shifting, memory, attention/impulsivity, or non-verbal intelligence. In sex-stratified models, prenatal TCDD was associated with more non-perseverative errors in boys but not in girls (pint = 0.04). TCDD was also associated with attention deficits on the CPT but only among children with the shortest breastfeeding histories. CONCLUSIONS: While overall, there were no significant associations, the observed differential neurotoxic sensitivities to TCDD by sex and lactation history may warrant confirmation in future studies.

The Seveso accident: A look at 40 years of health research and beyond.

A 1976 chemical factory explosion near Seveso, Italy exposed residents to high levels of 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD or dioxin). Dioxin is a known human carcinogen and potent endocrine disruptor. It is highly lipophilic and has a long half-life in humans. Much of what we know and can learn about the risks of dioxin exposure on human health arose from the tragic circumstances of Seveso. This review aims to describe the Seveso accident, summarize the results of 40 years of research on the health of the Seveso population since the accident, and discuss next-stage research on the health of Seveso residents, their children, and grandchildren.

AHR gene-dioxin interactions and birthweight in the Seveso Second Generation Health Study.

Background: 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) is proposed to interfere with fetal growth via altered activity of the aryl hydrocarbon receptor (protein: AHR; gene: AHR) pathway which regulates diverse biological and developmental processes including xenobiotic metabolism. Genetic variation in AHR is an important driver of susceptibility to low birthweight in children exposed to prenatal smoking, but less is known about these genetic interactions with TCDD, AHR's most potent xenobiotic ligand. Methods: The Seveso Women's Health Study (SWHS), initiated in 1996, is a cohort of 981 Italian women exposed to TCDD from an industrial explosion in July 1976. We measured TCDD concentrations in maternal serum collected close to the time of the accident. In 2008 and 2014, we followed up the SWHS cohort and collected data on birth outcomes of SWHS women with post-accident pregnancies. We genotyped 19 single nucleotide polymorphisms (SNPs) in AHR among the 574 SWHS mothers. Results: Among 901 singleton births, neither SNPs nor TCDD exposure alone were significantly associated with birthweight. However, we found six individual SNPs in AHR which adversely modified the association between maternal TCDD and birthweight, implicating gene-environment interaction. We saw an even stronger susceptibility to TCDD due to interaction when we examined the joint contribution of these SNPs in a risk allele score. These SNPs were all located in noncoding regions of AHR, particularly in proximity to the promoter. Conclusions: This is the first study to demonstrate that genetic variation across the maternal AHR gene may shape fetal susceptibilities to TCDD exposure.

Obesity in relation to serum persistent organic pollutant concentrations in CHAMACOS women.

BACKGROUND: Environmental exposure to endocrine-disrupting chemicals (EDCs), including persistent organic pollutants (POPs), has been hypothesized to increase risk of obesity. Using data from the Center for Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, we examined the longitudinal relationship between serum concentrations of a POPs mixture and several obesity measures. METHODS: Concentrations of 17 POPs were measured in serum collected in 2009-2011 from 468 CHAMACOS women. Anthropometry measurements and personal interviews were completed at up to three study visits between 2009 and 2014. We assessed the relationship of serum POPs concentrations with adiposity measures longitudinally using generalized estimating equation (GEE) models. We implemented Bayesian Kernel Machine Regression (BKMR) to elucidate the effects of joint exposure to the POPs mixture. RESULTS: In GEE models, positive associations with BMI were found for dichlorodiphenyltrichloroethane (Q4 vs Q1: adjusted-ß = 3.2 kg/m2; 95%CI 1.5,4.9), ß-hexachlorocyclohexane (Q4 vs Q1: adjusted-ß = 3.6 kg/m2; 95%CI 2.0,5.2), and PBDE-47 (Q4 vs Q1: adjusted-ß = 1.9 kg/m2; 95%CI 0.3,3.5), while PBDE-153 was inversely associated (Q4 vs Q1: adjusted-ß = -2.8 kg/m2; 95%CI -4.4,-1.2). BKMR results, while largely consistent with single pollutant models, revealed the shape and direction of the exposure-response relationships, as well as interactions among pollutants within the mixture, that could not be discovered by single-pollutant models. CONCLUSION: In summary, we found significant associations of serum POPs with several adiposity measures using both conventional regressions and BKMR. Our results provide support for the chemical obesogen hypothesis, that exposure to EDCs may alter risk for later obesity.

Serum dioxin concentrations and quality of ovarian function in women of Seveso.

BACKGROUND: Although 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been associated with alterations in ovarian function and hormones in animals, it has not been studied in humans. On 10 July 1976, an explosion exposed residents of Seveso, Italy, to the highest levels of TCDD in a population. Twenty years later, we initiated the Seveso Women's Health Study to study reproductive health. OBJECTIVE: We related TCDD levels measured in sera collected near the time of explosion and ovarian function (ovarian cysts, ovarian follicles, ovulation rate, serum hormones) at follow-up. METHODS: We included 363 women who were 20-40 years of age and nonusers of oral contraceptives. We examined the relationship of 1976 serum TCDD levels with ultrasound-detected ovarian follicles among 96 women in the menstrual follicular phase and serum hormone levels (estradiol, progesterone) among 129 women in the menstrual luteal phase at follow-up. Ovulation was defined by serum progesterone levels > 3 ng/mL. RESULTS: The median serum TCDD level was 77.3 ppt, lipid-adjusted. Serum TCDD was not associated with number or size of ovarian follicles. Of women in the luteal phase, 87 (67%) ovulated. Serum log(10)TCDD was not associated with odds of ovulation [adjusted odds ratio = 0.99; 95% confidence interval (CI), 0.5 to 1.9]. Among those who had ovulated, serum log(10)TCDD was not associated with serum progesterone [adjusted beta (adj-beta ) = -0.70; 95% CI, -2.4 to 1.0] or estradiol (adj-beta = -1.81; 95% CI, -10.4 to 6.8). CONCLUSIONS: We found no clear evidence that 1976 TCDD exposure was associated with ovarian function 20 years later in women exposed to relatively high levels in Seveso, Italy.

Serum dioxin concentrations and age at menopause.

2,3,7,8-Tetrachlorobenzo-p-dioxin (TCDD), a halogenated compound that binds the aryl hydrocarbon receptor, is a by-product of numerous industrial processes including waste incineration. Studies in rats and monkeys suggest that TCDD may affect ovarian function. We examined the relationship of TCDD and age at menopause in a population of women residing near Seveso, Italy, in 1976, at the time of a chemical plant explosion. We included 616 of the women who participated 20 years later in the Seveso Women's Health Study. All women were premenopausal at the time of the explosion, had TCDD levels measured in serum collected soon after the explosion, and were > or = 35 years of age at interview. Using proportional hazards modeling, we found a 6% nonsignificant increase in risk of early menopause with a 10-fold increase in serum TCDD. When TCDD levels were categorized, compared with women in the lowest quintile (< 20.4 ppt), women in quintile 2 (20.4-34.2 ppt) had a hazard ratio (HR) of 1.1 (p = 0.77), quintile 3 (34.3-54.1 ppt) had an HR of 1.4 (p = 0.14), quintile 4 (54.2-118 ppt) had an HR of 1.6 (p = 0.10), and quintile 5 (> 118 ppt) had an HR of 1.1 (p = 0.82) for risk of earlier menopause. The trend toward earlier menopause across the first four quintiles is statistically significant (p = 0.04). These results suggest a nonmonotonic dose-related association with increasing risk of earlier menopause up to about 100 ppt TCDD, but not above.

Dioxin-Like TEQ of women from the Seveso, Italy area by ID-HRGC/HRMS and CALUX.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are widespread environmental contaminants that exist as complex mixtures and are frequently detected at part-per-trillion (ppt) levels in humans. Using isotope dilution high-resolution gas chromatography/ high-resolution mass spectrometry (HRGC/HRMS), we measure the PCDDs, PCDFs, and PCBs in serum of a population of 78 women residing in an area near Seveso, Italy where a TCDD explosion occurred in 1976 and where furniture is manufactured. The average total dioxin-like toxic equivalents (TEQ) of these women was 25.3 ppt, lipid-adjusted, comparable to other parts of Europe. TCDD levels, however, were higher among the few women who resided in the exposed area in 1976. We examined the possibility of using the CALUX (chemical-activated luciferase gene expression) bioassay to estimate total TEQ in a small volume of plasma from this population. A total of 32 archived plasma specimens were selected for CALUX bioassay, based on the distribution of Total TEQ by HRGC/HRMS. The CALUX bioassay was performed blind to HRGC/HRMS results with 2 ml plasma per replicate analysis. Of 32 samples, 10 were below detection limits in the CALUX bioassay. For the 32 samples, the CALUX-TEQ averaged 25.4 ppt, lipid-adjusted (range: 0-127.6) and was not significantly different from the HRGC/HRMS Total TEQ average of 31.2 ppt, lipid-adjusted (range: 12.7-88.3) (t = 0.88, P = 0.38), however, the two measures were not significantly correlated (R(s) = 0.04, P=0.82). More validation of the CALUX bioassay with larger sample volume is needed before application as an exposure measure in large-scale epidemiologic studies of health effects of dioxin-like compounds.