Polychlorinated biphenyls in domestic dust from Canada, New Zealand, United Kingdom and United States: Implications for human exposure

Ingestion of indoor dust has been highlighted as an important pathway of exposure to brominated flame retardants. Hence, polychlorinated biphenyls (PCBs) were determined in indoor dust from homes in Amarillo/Austin, TX, USA (n=20; median concentration=200ng ΣPCBg−1); Birmingham, UK (n=20; 48ng ΣPCBg−1); Toronto, Canada (n=10; 260ng ΣPCBg−1); and Wellington, New Zealand (n=20; 46ng ΣPCBg−1). Concentrations in Canadian and US samples were statistically indistinguishable, but exceeded significantly (p<0.05) those in both New Zealand and UK dust. Principal component analysis revealed that while UK samples were enriched comparatively in lower molecular weight congeners; samples from other countries contained proportionally more mid-to-high molecular weight congeners. Concentrations of PCBs determined in air from the same 10 Canadian homes showed concentrations (median=4.9ng ΣPCBm−3) higher than those reported previously for UK homes (1.8ng ΣPCBm−3). Interpretation of these data alongside that for dietary exposure from other studies suggest that indoor exposures (i.e. air and dust combined) may be a significant contributor to overall exposure for the majority of the population – ranging from 4.3% to 87% in adults and 1.6–73% in toddlers. While inhalation is the principal indoor pathway under a typical dust ingestion scenario, exposure via dust ingestion exceeds that from either inhalation or diet for a small proportion of North American toddlers.