Born sooner and smaller; PFOS affects fetal growth in the womb.

Apr 25, 2013

Chen, M-H, E-H Ha, T-W Wen, Y-N Su, G-W Lien, C-Y Chen, P-C Chen and W-S Hsieh. 2012. Perfluorinated compounds in umbilical cord blood and adverse birth outcomes. PLoS One http://dx.doi.org/10.1371/journal.pone.0042474.

Synopsis by Glenys Webster

Babies with higher PFOS exposures in the womb are born smaller and sooner, reports a new study from Taiwan. The effects were found at levels of the perfluorinated chemical similar to those measured in U.S. and Canadian babies. A persistent compound that repels stains, water and grease, it hasn't been produced in the United States since its manufacturer completed the phaseout in 2002.

Babies exposed to higher levels of the chemical PFOS in the womb were born sooner and smaller than babies with lower exposures, suggests a new study of 429 babies from Taiwan. They also had smaller head circumferences.

PFOS levels in the babies’ umbilical cord blood were similar to those collected from U.S. and Canadian babies in 2004 - 2005. Birth outcomes were unaffected by the other studied chemicals – PFOA, PFNA and PFUA.

This is the first time that PFOS has been related to shorter pregnancies. Effects on birth weight and head circumference support the findings from previous studies.

The results are important because nearly everyone carries PFOS in their blood. Even subtle effects at an individual level can have important public health consequences at the population scale if everyone is exposed.

PFOS is a stain, water and grease repellent chemical that was a main ingredient in 3M's brand of fabric protector until 2002. PFOS-based chemicals were also found in some carpets, papers, paints and varnishes and leather products. The company phased out production in the United States because of environmental and health concerns.

It is still manufactured in China and elsewhere and can be imported into North America in manufactured products. PFOS is still used to make certain types of fire-fighting foams.

People are exposed to PFOS through the diet, from contaminated indoor dust, and by touching products that contain PFOS or related chemicals. Blood levels of PFOS have declined in North Americans since the ban 10 years ago.

PFOS exposure has been linked to reduced fertility in men and women, reduced vaccine effectiveness, disrupted thyroid hormones, and ADHD symptoms in children, among other effects. Effects on birth outcomes have been found in some but not all studies.

Researchers measured levels of PFOS and 3 similar chemicals – PFOA, PFNA and PFUA – in umbilical cord samples collected from 429 Taiwanese babies born in 2004 - 2005. These chemical levels were compared to birth outcomes such as birth weight, birth length and head circumference, as well as the incidence of preterm birth (born before 37 weeks), low birth weight (less than 2,500 grams, about 88 ounces), and being born small for gestational age (the lowest 10th percentile of weight for age).

On average, babies with the highest PFOS levels – in the top 25 percent – in their umbilical cord blood were born 3 days earlier, were 110 grams lighter and had head circumferences 2.5 millimeter smaller than babies with lower exposures – those in the lowest 25 percent. Babies with higher exposures were also roughly 2.5 times more likely to be born preterm, have low birth weights and be small compared to other babies of the same gestational age, after accounting for the mother’s age, education level, pre-pregnancy body mass index and the number of previous births, among other factors.

PFOA, PFNA and PFUA had no effect on birth outcomes. The results appear in the journal Plos One.

This is the first time that PFOS has been related to shorter pregnancies. The other findings confirm trends found in previous work. The results suggest that different fluorochemicals may have different effects on birth outcomes, and strengthens concerns about PFOS exposures in the general population. 

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