Organohalogenated contaminants (OHCs) in human serum of mothers and children from Pakistan with urban and rural residential settings

This study aimed to provide first data on the concentrations of different classes of organohalogenated contaminants (OHCs) in human serum from Pakistan, an area with limited information on environmental pollution. Serum samples (N = 85) were collected from mothers (N = 34; age ranged 23-51 years), their children (N = 34; age 3-10 years) and general group (N = 17; age 13-65 years) with rural and urban residential settings. The concentrations of studied OHCs in serum decreased as follows: organochlorinated pesticides (OCPs) > polychlorinated biphenyls (PCBs) > polybrominated diphenyl ethers (PBDEs). Novel brominated flame retardants (NBFRs) were not detected, except for 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE) < 0.2-8 ng/g lipid weight (lw). Low levels of HO-PCBs (< 0.2-20 ng/g lw) were detected, while HO-PBDEs were < 0.2 ng/g lw. ∑PCBs (2-105 ng/g lw) together with ∑PBDEs (0.2-6.7 ng/g lw) contributed ~ 5% of the total OHCs body burden. The concentration(s) of major contributors (> 80%) of OCPs ranged from < 1-3645 ng/g lw for 1,1′-bis-(4-chlorophenyl)-2,2-dichloroethene (p,p′-DDE), < 1-445 ng/g lw for β-hexachlorocyclohexane (β-HCH) and from 5 to 200 ng/g lw for pentachlorophenol (PCP). p,p′-DDE, the major OHC, was significantly higher (p < 0.05) in rural children than in all other groups. In serum of rural children, the major OHCs were significantly higher (p < 0.05) than the mothers. The current study indicates continuous exposure to humans with already regulated OHCs and highlights the need for further monitoring of these OHCs in the region.