Evaluation of different methods to determine total serum lipids for normalization of circulating organochlorine compounds

Objectives Serum levels of persistent organochlorine compounds may be predictive of their body burden, if adjusted by total serum lipids. Their value may be predicted by three different formulae, requiring only values of serum cholesterol and triglycerides. The study was aimed at: (i) evaluating the validity of these formulae; (ii) evaluating the influence of different estimates on serum levels of lipid adjusted persistent organochlorine compounds. Methods We determined the levels of cholesterol, triglycerides and phospholipids by enzymatic assays on serum samples from 121 subjects living in a polluted area of Northern Italy. On the same samples and on an additional set from 69 pregnant women of the same area, we determined also polychlorinated biphenyls, hexachlorobenzene and p,p'-dichlorodiphenyldichloroethylene. In women, analytes were determined also on adipose tissue samples. Results Formulae provided results comparable to those obtained as sum of cholesterol, triglycerides and phospholipids. In women, we found highly significant relationships among lipid adjusted pollutant levels in serum and adipose tissue, independently from the used formula. Conclusions Formulae allow a valid adjustment of organochlorine compounds in serum. The algorithm proposed by Phillips et al. provides some slight advantage over the others, in terms of simplicity of use.