Levels of persistent organic pollutant residues in human adipose and muscle tissues in Singapore

Persistent organic pollutants (POPs), due to their persistence and bioconcentration in lipid-rich tissue, bioaccumulate in food chains, resulting in elevated concentrations in humans. This study was performed to determine and compare levels of POPs in human adipose and muscle tissues in the female population of Singapore. In total, 36 human adipose tissues and 8 human muscle tissues were collected from volunteer expectant mothers admitted to the National University Hospital Singapore for cesarean section delivery between August 2003 and January 2005. Samples were analyzed using a validated and quality-assured gas chromatography-mass spectroscopy (GC-MS) method in conjunction with microwave-assisted extraction (MAE). Analytes recoveries from certified reference materials, that is, IRMM-446 (polychlorinated biphenyls [PCBs] in pork fat) and BCR-430 (organochlorine pesticides in pork fat), were between 70 and 130%, indicating reliable analytical precision for this methodology. MAE efficiency for polybrominated diphenyl ethers (PBDEs) was compared to Soxhlet extraction (SE) efficiency and yielded comparable results (variation < 13%). Analytical results indicate that p,p '-DDE of the dichlorodiphenyltrichloroethane (DDT) residues group is the predominant compound in adipose tissue, followed by beta-hexachlorocyclohexane (beta-HCH) among HCH isomers, then hexachlorobenzene (HCB) compound and specific PCB and PBDE congeners. Among the 36 adipose tissues, the lipid contents in adipose tissue were in the range of 60% to 95%, while in the 8 muscle tissues, lipids were undetectable. However, the profile of PCBs and pesticide residues present in muscle tissues were similar to those in adipose tissues.