Childhood Obesity Link to Prenatal Exposure to Perfluoroalkyls

Children had greater overall adiposity and a more rapid increase in body mass index z-scores (BMIz) in early childhood if their mothers had been exposed to higher concentrations of perfluorooctanoic acid (PFOA), according to a prospective cohort study published online November 11 in Obesity.

"Perfluoroalkyl substances [PFAS], which have been used in oil and water-resistant textile coatings, nonstick cookware, food-container coatings, floor polish, firefighting foam, and industrial surfactants, are a class of suspected obesogens that are persistent in the environment and humans," write Joseph M Braun, MSPH, PhD, RN, of Brown University School of Public Health in Providence, Rhode Island, and colleagues.

"Some experimental rodent and in vitro studies show that PFAS exposure may cause impaired glucose homeostasis, increased body weight, and altered adipocyte differentiation while others do not," they write.

In this research, which involved subjects from HOME — a prospective cohort study designed to examine the impact of early-life exposure to prevalent environmental chemicals — they demonstrate a dose-response relationship between exposure to PFAS and obesogenic influences, which "is consistent with a threshold effect," they note.

Was Cincinnati Drinking Water Contaminated?

The researchers measured PFOA and perfluorooctane sulfonic (PFOS), perfluorononanoic (PFNA), and perfluorohexane sulfonic (PFHxS) acids in prenatal serum samples of 468 women who were 16 to 26 weeks pregnant at nine prenatal clinics in Cincinnati, Ohio, between March 2003 and January 2006. The majority (87%) of the samples were collected at 16 weeks' gestation.

After researchers excluded multiples, stillbirths, and study dropouts, 309 singleton children remained. The researchers compared the PFAS concentrations and the BMIz scores, waist circumference, and body fat in 285 of the children (73% of original cohort) between ages 2 and 8 and in 204 (52%) of the children at age 8 years.

Data came from a total of 1021 study visits that included 243 children at age 2 years, 219 children at age 3 years, 167 children at age 4 years, 188 children at age 5 years, and 204 children at age 8 years.

The researchers adjusted for both sociodemographic covariates (maternal race, age, education, marital status, employment, and household income) and perinatal variables (maternal depressive symptoms, maternal BMI at 16 weeks' gestation, parity, and cotinine serum levels for tobacco-smoke exposure). They also accounted for prenatal vitamin use and frequency of fruit, vegetable, and fish consumption during pregnancy.

In their serum analysis of PFAS concentrations, the scientists also adjusted their findings for prenatal urinary bisphenol A (BPA) concentrations, since BPA is also a suspected obesogen.

Median PFOA concentrations in the cohort were more than double compared with data from pregnant women in the 2003–2004 and 2005–2006 US National Health and Nutrition Examination Surveys (NHANES).

"The higher serum PFOA concentrations among women in our cohort could be due to ingestion of drinking water contaminated with PFOA released by the DuPont Washington Works plant in Parkersburg, West Virginia," about 250 miles upstream of Cincinnati along the Ohio River, the researchers write.

The plant was emitting over 80,000 pounds of PFOA annually into the environment as recently as 2000, they report. "This contamination may affect other communities along the Ohio River, including the city of Cincinnati, because they draw their drinking-water supplies from the river," they observe.

Dose-Response Relationship

"The association between PFOA concentrations and all three adiposity measurements was positive up to the 50th percentile of PFOA concentrations and then declined at concentrations above the 50th percentile," Dr Braun and colleagues report. "We observed a similar dose-response relationship when we examined PFOA tertiles and child adiposity."

Compared with children whose mothers fell in the first tertile of PFOA concentrations, body fat was greater in children born to mothers in the second tertile (3.6%) and third tertile (1.5%).

Children born to women in the second tertile were 84% more likely to be overweight or obese at age 8 years compared with children whose mothers were in the first tertile (relative risk [RR], 1.84) Children from the third tertile were 54% more likely to be overweight or obese compared with children in the first tertile (RR, 1.54).

Similarly, median waist circumference of children from the second tertile was 4.3 cm greater than the median in children from the first tertile. Children from the third tertile had a median 2.2 cm greater waist circumference than that of first tertile children.

And greater BMIz gains from ages 2 to 8 were also seen in children of mothers in the second and third tertiles compared with children of women in the first tertile (P < .05).

Results remained similar after adjustments for urinary BPA concentration, breastfeeding duration, and gestational weight gain.

However, more research is needed, say Dr Braun and colleagues: "Other prospective cohort studies with longitudinal and detailed measures of child adiposity should confirm these findings."

The research was funded by the National Institute of Environmental Health Sciences. Dr Braun received payment for a reanalysis of a child lead exposure study for the plaintiffs in a public-nuisance case related to childhood lead poisoning. The authors declared no relevant financial relationships.

via: http://www.medscape.com/viewarticle/854852