Parents’ exposure to chemicals at work may be linked to birth defects

Researchers at Perth’s Telethon Institute for Child Health Research say a new study that has found a possible association between parental occupations and a common birth defect warrants further investigation.

The research has been published online in the international journal Occupational and Environmental Medicine.

Study co-author Dr Natasha Nassar said the findings were an important starting point, but the results were preliminary and require further investigation.

"Our research found that mothers who may be exposed to heavy metals in their occupations were two and a half times more likely to have a son diagnosed with hypospadias, a common birth defect that affects the penis, " Dr Nassar said.

Women working in the dental industry, defence forces, as laboratory workers and in petrol stations were identified as being potentially exposed to heavy metals.

She said that women who were exposed to phthalates were also at higher risk. 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. Women working in the hairdressing, beauty or plastics industry were identified as being potentially exposed to phthalates. While this group was more likely to have an affected child, the result was not statistically significant.

"However, it is important to know that this analysis is based on job titles. What we don’t know is the timing or the frequency of exposure to chemicals during pregnancy or even whether the parent was in fact exposed, and therefore we stress that these results should not be used to draw any firm associations," Dr Nassar said.

Dr Nassar said the study looked at the parents’ occupations of more than 1,200 boys with hypospadias and compared them with the occupations of the parents of more than 2,500 boys without hypospadias. Potential exposure to 7 different types of (endocrine disrupting) chemicals was assessed for 348 parental occupations and then compared between cases and controls. The problem with endocrine disrupting chemicals is that they mimic female hormones and can disrupt the production of male hormones.

Dr Nassar stressed that women working in these occupations should not be alarmed.

"We should remember that many of the exposures are common and most people are exposed to chemicals in low doses in their everyday lives; at work, at home, in their diet and medications. However exposure to multiple chemicals may have an additive effect or may interact with each other. Some people may have a genetic susceptibility that increases their risk, particularly if these exposures occur during vulnerable periods in pregnancy."

Hypospadias is the second most common birth defect among boys in Western Australia, affecting about one in 130 boys. The rate has been increasing in recent years. Boys with the condition may have trouble urinating and fertility problems as adults. Hypospadias can be corrected with surgery.

The researchers were supported by funding through the National Health and Medical Research Council of Australia.

(Source: Telethon Institute for Child Health Research: Occupational and Environmental Medicine: December 2009)