Another study has found a disturbing link between obesity and a widely used chemical commonly found in the environment. Researchers in Norway and Denmark found daughters of women exposed to perfluorooctanoic acid (PFOA) during pregnancy were up to three times more likely to be overweight. The findings come from a study of Danish women that the Norwegian Institute of Public Health participated in.

In recent decades there has been a sharp increase worldwide in the number of overweight children and adults. It is suspected that diet and exercise alone cannot explain the weight increase. Some researchers believe that increasing levels of endocrine disrupters in the environment may be a contributing factor.

PFOA belongs to a group of chemicals known as polyfluorinated compounds (PFC). These compounds have been widely used in a variety of consumer and industrial products, from carpets and firefighting foam to Teflon and microwave popcorn bags. PFOA persists indefinitely in the environment and trace amounts have been detected in the blood of more than 98% of Americans. PFCs can be transferred from mother to child through the placenta during pregnancy and in breast milk after birth.

Microwave popcorn bags can contain trace amounts of perfluorooctanoic acid (PFOA)

In the Danish study, about 1,000 pregnant women in Aarhus, Denmark were recruited in the late 1980’s. Blood samples from the women were taken in week 30 of their pregnancies and frozen. Twenty years later, the children from those pregnancies were asked to participate in a follow-up study in which their body mass index (BMI) and waist circumference were measured.

The researchers found that daughters of mothers with the highest concentrations of PFOA in the blood during pregnancy were three times as likely to be overweight than daughters whose mothers had the lowest PFOA levels. Elevated levels of insulin and leptin were also found, two hormones linked to obesity. No association was found between PFOA exposure and obesity among the sons of mothers in the study.

“The study indicates that factors such as environmental pollutants, in addition to diet and physical activity, play a role in the obesity epidemic we see today. But this remains to be confirmed by similar studies,” said Line Smastuen Haug at the Norwegian Institute of Public Health.

“It is also important to note that the levels of several of these environmental pollutants in the blood of Norwegian women have decreased significantly since about 2000,” Haug noted. “However, this does not apply to all the substances and so we should try to limit our exposure to persistent pollutants to reduce the risk of adverse health effects.”

A recent study of children in New York City found that girls with the highest exposure to phthalates, a chemical used in soap and shampoo,  had a BMI 10% higher than girls with the lowest exposure.