Intra-individual variations and time trends 1991–2001 in human serum levels of PCB, DDE and hexachlorobenzene

Background: An important question is whether human serum levels of persistent organic pollutants has continued to decrease during the last decades. The aim of this study was to assess intra-individual variations over time of serum levels of 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB-153), 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethene (p,p′-DDE) and hexachlorobenzene (HCB), considering the impact of a number of possible determinants.Methods: Blood samples were drawn for the same 39 subjects in 1991 and 2001. Interviews were made at both occasions. Lipid adjusted serum concentrations of CB-153, p,p′-DDE and HCB were determined in both sets of blood samples using gas chromatography–mass spectrometry. The fatty acid composition of the serum lipids was analyzed by means of gas–liquid chromatography.Result: The CB-153 concentrations in serum had averagely decreased with 34% in between 1991 and 2001 (p < 0.001). Of individual determinants only increasing BMI was associated with decreasing CB-153 levels (β = −1.0, 95% CI −1.8, −0.2, p = 0.01), explaining 13% of the variation. The average decrease of p,p′-DDE was 55%, and could only weakly be associated with a relative increase of BMI (β = −1.0, 95% CI −2.3, 0.2, p = 0.09), explaining only 5% of the variation. The average decrease of HCB was 53%, and was associated only with high fish consumption in 1991, explaining 12% of the variation.Conclusions: The results support a continuing decrease in human body burdens of PCBs, DDE and HCB during the 1990s. The explanatory factors relative change of BMI and fish consumption explained only a minor part of the time-related variations in serum levels.