Common chemical increases risk of boys genital deformity.

Jan 19, 2009

Ormond G, MJ Nieuwenhuijsen, P Nelson, MB Toledano, N Iszatt, S Genelette and P Elliot. Endocrine disruptors in the workplace, hair spray, folate supplementation and risk of hypospadias: case-control study. Environmental Health Perspectives doi:10.1289/ehp.11933.

Pregnant women exposed to phthalates through hairspray and other sources at work have a greatly increased risk of delivering a son with a common reproductive birth defect known as hypospadias. Taking folate supplements might reduce this risk.

The findings from this British study of almost 1,000 infant boys highlights a new and compelling consequence of phthalate exposure and warrants increased caution in the workplace for pregnant women exposed to these chemicals.

Phthalates are chemicals used in a wide variety of products including plastics, detergents and personal care products, such as deodorants, fragrances, nail polish and hairspray. The chemicals affect hormones. Rodent studies find prebirth exposure to phthalates alters cells in the testes and lowers testosterone levels.

Because of health concerns -- especially to developing fetuses, infants and young children -- several governments, including the European Union, Mexico, Canada and the state of California, have banned some phthalates from use. A new law goes into effect in the U.S. on February 10, which partially bans phthalates in toys and other products intended for use by children.

Hypospadias is one of the most common genital deformities affecting baby boys. About 1 out of 300 infants in the US are born with the condition in which the opening of the urethra occurs on the underside of the penis rather than the tip. Surgery can correct the problem.

Little is known about what causes this deformity, yet its prevalence has increased over the past 50 years. Hypospadias is linked to exposure during the first trimester of pregnancy to certain environmental toxicants, mainly those that mimic hormones.

Severe hypospadias can be associated with a suite of other problems, including undescended testis, enlarged prostate, stone formation and infertility.

To determine what factors may be linked to hypospadias, the researchers examined the chemical exposure of 471 mothers in the workplace. They used a "job exposure matrix." This means that they asked the moms detailed questions about their jobs. Then, an industrial hygienist classified them according to what chemicals they were likely to be exposed to in that job. Some of these were hair spray, cleaning agents, plastic fumes, printing ink and phthalates.

Personal information (age, ethnicity, income, maternal occupation, etc), health history and diet (vitamin, supplements or alcohol) were also examined.

This study found an increased risk of hypospadias that was 2-3 times greater among sons born to mothers exposed at work while pregnant to hairspray and phthalates. This is the first study to strongly associate exposure to hairspray, some of which contain phthalates, with this risk.

A similar increase in risk was seen for women working in jobs known to have potential exposure to phthalates -- including hair dressers, beauty therapists, research chemists and women working in certain chemical, pharmaceutical and industrial jobs -- compared to those with no exposure to phthalates at work.

Hairdressers as a group analyzed separately do not have significant increased risk of having baby boys with hypospadias. No correlation was found with being a vegetarian during pregnancy.

The study also found that mothers who took folate supplements during the first three months of pregnancy reduced their son’s risk of hypospadias by 36 percent.

The British study enrolled 471 boys born with hypospadias and 490 boys without the birth defect and compared their mother’s occupational exposures to several different chemicals. No increased risk was found for any of the other chemicals studied.

The findings highlight the need to improve understanding of how people are exposed to environmental contaminants. Health risks can be lowered by identifying where and when the highest exposures occur.

And, the unexpected finding of a protective role for folates has direct applications for public health and prevention of birth defects.