Prior research reports inverse associations between maternal prenatal urinary phthalate metabolite concentrations and mental and motor development in preschoolers. No study evaluated whether these associations persist into school age. In a follow up of 328 inner-city mothers and their children, we measured prenatal urinary metabolites of di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBzP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate in late pregnancy. The Wechsler Intelligence Scale for Children, 4th edition was administered at child age 7 years and evaluates four areas of cognitive function associated with overall intelligence quotient (IQ). Child full-scale IQ was inversely associated with prenatal urinary metabolite concentrations of DnBP and DiBP: b = −2.69 (95% confidence interval [CI] = −4.33, −1.05) and b = −2.69 (95% CI = −4.22, −1.16) per log unit increase. Among children of mothers with the highest versus lowest quartile DnBP and DiBP metabolite concentrations, IQ was 6.7 (95% CI = 1.9, 11.4) and 7.6 (95% CI = 3.2, 12.1) points lower, respectively. Associations were unchanged after control for cognition at age 3 years. Significant inverse associations were also seen between maternal prenatal metabolite concentrations of DnBP and DiBP and child processing speed, perceptual reasoning and working memory; DiBP and child verbal comprehension; and BBzP and child perceptual reasoning. Maternal prenatal urinary metabolite concentrations measured in late pregnancy of DnBP and DiBP are associated with deficits in children’s intellectual development at age 7 years. Because phthalate exposures are ubiquitous and concentrations seen here within the range previously observed among general populations, results are of public health significance.

In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. Because findings are not easily generalizable to the US, we examine this relation in a US population. In 272 children in grades 3–5 from three Maine school districts, we examine associations between drinking water As (WAs) and intelligence (WISC-IV). On average, children had resided in their current home for 7.3 years (approximately 75% of their lives). In unadjusted analyses, household well WAs is associated with decreased scores on most WISC-IV Indices. With adjustment for maternal IQ and education, HOME environment, school district and number of siblings, WAs remains significantly negatively associated with Full Scale IQ and Perceptual Reasoning, Working Memory and Verbal Comprehension scores. Compared to those with WAs < 5 μg/L, exposure to WAs ≥ 5 μg/L was associated with reductions of approximately 5–6 points in both Full Scale IQ (p < 0.01) and most Index scores (Perceptual Reasoning, Working Memory, Verbal Comprehension, all p’s < 0.05). Both maternal IQ and education were associated with lower levels of WAs, possibly reflecting behaviors (e.g., water filters, residential choice) limiting exposure. Both WAs and maternal measures were associated with school district. The magnitude of the association between WAs and child IQ raises the possibility that levels of WAs ≥ 5 μg/L, levels that are not uncommon in the United States, pose a threat to child development.

Exposure to non-persistent chemicals in consumer products is ubiquitous and associated with endocrine-disrupting effects. These effects have been linked to infertility and adverse pregnancy outcomes in some studies and could affect couple fecundability, i.e. the capacity to conceive a pregnancy, quantified as time to pregnancy (TTP). Few epidemiologic studies have examined the impact of non-persistent chemicals specifically on TTP, and the results of these studies have not been synthesized. We undertook a systematic review to summarize the strength of evidence for associations of common non-persistent chemicals with couple fecundability and to identify gaps and limitations in the literature, with the aim of informing policy decisions and future research. We performed an electronic search of English language literature published between 1 January 2007 and 25 August 2017 in MEDLINE, EMBASE.com, Global Health, DART/TOXLINE, POPLINE and DESTAF. We included human retrospective and prospective cohort, cross-sectional and case-control studies that examined phthalates, bisphenol A, triclosan, triclocarban, benzophenones, parabens and glycol ethers in consumer products, and considered TTP or fecundability as an outcome among women, men and couples conceiving without medical assistance. We excluded editorials, opinion pieces, introductions to special sections, articles that described only lifestyle (e.g. caffeine, stress) or clinical factors (e.g. semen parameters, IVF success). Standardized forms for screening, data extraction and study quality were developed using DistillerSR software and completed in duplicate. We used the Newcastle-Ottawa Scale to assess risk of bias and devised additional quality metrics based on specific methodological features of fecundability studies. The search returned 3456 articles. There were 15 papers from 12 studies which met inclusion criteria, of which eight included biomarkers of chemical exposure. Studies varied widely in terms of exposure characterization, precluding a meta-analytic approach. Among the studies that measured exposure using biospecimens, results were equivocal for associations between either male or female phthalate exposure and TTP. There was preliminary support for associations of female exposure to some parabens and glycol ethers and of male exposure to benzophenone with longer TTP, but further research and replication of these results are needed. The results provided little to no indication that bisphenol A, triclocarban or triclosan exposure was associated with TTP. Despite a growing literature on couple exposure to non-persistent endocrine-disrupting chemicals and fecundability, evidence for associations between biologically measured exposures and TTP is limited. Equivocal results with different non-persistent chemical compounds and metabolites complicate the interpretation of our findings with respect to TTP, but do not preclude action, given the documented endocrine disrupting effects on other reproductive outcomes as well as fetal development. We therefore advocate for common-sense lifestyle changes in which both females and males seeking to conceive minimize their exposure to non-persistent chemicals. CRD42018084304.