Mounting evidence

Workers in a wide range of industries may be exposed to chemicals and metals that can harm the unborn child. Research on substances that can impair fetal development or damage DNA is advancing. Here are summaries of some recent studies:

2015: Genital defects and occupational exposures to endocrine disruptors

Researchers studied more than 600 boys in the south of France and found that mothers exposed to endocrine-disrupting chemicals were more likely to have sons with genital defects. The risk for exposed boys was 68 percent higher than for those who hadn’t been exposed. The children were more likely to be affected if their mother worked as a cleaner, hairdresser or beautician or lived in a heavily polluted area. The defect, hypospadias, is a condition where the opening of the urethra is on the underside of the penis and can usually be helped by surgery. Previous studies in England and Italy found that mothers exposed to endocrine-disrupting chemicals were three to four times as likely to have sons with hypospadias. Read the abstract here.

2014: Childhood brain tumors and occupational exposure to solvents

Researchers in Australia found an increased risk of childhood brain tumors in households in which parents were exposed to solvents at work. Solvents comprise a wide range of chemicals including benzene, toluene and hexane. Exposures can occur in a variety of jobs, such as painting and dry cleaning, and in industries such as chemical manufacturing and petroleum refining. The study found that maternal exposures to solvents at any time before birth suggested an increased risk of childhood brain tumors, though the risk was greatest with exposure to chlorinated solvents. Paternal exposures to all solvents prior to the child’s birth appeared to create a risk as well, with the strongest link occurring when the father was exposed to benzene or other aromatics in the year before conception. Read the abstract here.

2012: Maternal chemical exposure associated with abdominal birth defect

Exposure to a group of chemicals called polycyclic aromatic hydrocarbons (PAHs) is likely in work settings such as oil and gas production, coal-fired power plants and restaurants. Using national birth defect data and maternal occupational histories, researchers studied whether mothers exposed to PAHs at work were more likely to give birth to children with gastroschisis, a condition in which a baby’s intestines stick outside of its body. They found that PAH-exposed mothers over 20 years old were more than twice as likely to have children with gastroschisis. Read the abstract here.

2011: Pesticide exposure impacts child cognitive ability

A study of Latino farmworker families in Salinas Valley, California, measured maternal exposures to widely used organophosphate pesticides and their effects on children’s cognitive abilities from birth to seven years of age. Prenatal exposure to the pesticides — assessed by measuring dialkyl phosphate metabolites (DAP) in urine from mothers and children — was associated with lower scores in working memory, processing speed, verbal comprehension, perceptual reasoning and IQ. A tenfold increase in DAP concentrations was associated with a decrease of 5.6 IQ points, and there was a seven IQ-point difference between children in the highest quintile of prenatal DAP levels and those in the lowest quintile. Read the abstract here.

2008: Scientific review of environmental exposures and adverse pregnancy outcomes

In light of mounting evidence that ambient exposures to chemicals could cause birth defects, scientists did a review of research assessing the impacts of chemical hazards and other environmental agents on pregnancy outcomes. Among the findings the review highlighted was a strong link between maternal occupational exposure to industrial solvents and birth anomalies: In 1999, a 10-year study of pregnant women in Toronto revealed a 13-fold risk of major malformations in offspring of exposed women compared with controls. The review also made note of research showing a connection between cardiac defects in children and parental exposures to the solvent trichloroethylene. Read the abstract here.