Richard Denison, Ph.D., is a Senior Scientist.
A peer-reviewed paper released today documents that nonwhite toddlers in North Carolina carry nearly twice as much of certain toxic flame retardant chemicals in their blood compared with white toddlers. The finding adds to a growing body of evidence that exposures to toxic chemicals are higher in communities of lower socioeconomic status.
Numerous other studies have found higher levels of the flame retardants known as polybrominated diphenyl ethers, or PBDEs, in children and adolescents relative to adults. The current study – authored by Stapleton et al., and appearing in Environmental Health Perspectives – may be the first, however, to demonstrate differential exposure based on socioeconomic status.
The authors studied a group of about 80 toddlers 1-3 years old living in North Carolina. PBDEs were detected in 100% of the blood samples drawn from the toddlers, as well as in all samples of house dust and 98% of hand wipes tested by the authors.
The authors note that children’s exposure to PBDEs is especially concerning “due to their known endocrine disrupting and neurodevelopmental properties as observed in animal studies.” They also note recent human studies reporting correlations between blood levels of PBDEs and motor, cognitive and behavioral performance in children. PBDEs were the primary focus of a scathing expose of chemical industry deception and manipulation of science that ran recently in the Chicago Tribune, about which I blogged earlier.
Time Magazine has an excellent article on the new research and the larger context.
Interestingly, the higher levels of PBDEs found in the blood of nonwhite toddlers could not be explained by higher levels in house dust in the homes in which those toddlers reside, as the authors found no statistically significant difference in the concentrations of the PBDEs the measured in house dust samples across their cohort. House dust is known to be a major, but not the only source of PBDE exposure. The authors note that in this study they did not take into account dietary differences or variability over time or other differences in exposure patterns that may help explain the differential blood serum levels they observed.
Other important conclusions of the authors about PBDE exposure:
- Exposure via the indoor environment is substantial, and much of that exposure in toddlers is likely occurring via hand-to-mouth activity.
- These factors likely explain the higher levels seen in toddlers than adults, because toddlers engaged in more hand-to-mouth activity and spend longer amounts of time at home.
- One particular PBDE congener was an exception and showed higher levels in toddlers of higher socioeconomic status; the authors postulate that exposure via breastfeeding – the duration of which studies indicate is higher in women of higher socioeconomic status – may be a more important pathway for this particular PBDE.