a cross - sectional study was performed to examine the internal exposure of polychlorinated dibenzo - p - dioxins and polychlorinated dibenzofurans ( pcdf ) in former workers in a nonferrous metal recycling facility . 
 liver enzymes , lipid parameters , and thyroid hormones were measured to check possible biologic effects . compared to background levels , 
 the international toxicity equivalent levels of exposed workers were slightly elevated ( median 42 ppt , range 13 - 281 ppt ) . 
 the workers also had higher total pcdf concentrations ( median 128 ppt , range 30 - 1138 ppt ) . 
 correlation analyses demonstrate significant associations with only one liver enzyme , alanine aminotransferase . 
 there were no such associations with serum cholesterol levels or with serum thyroid hormones . because of the cross - sectional design of the study , firm conclusions can not be drawn . for further evaluation 
 , a follow - up examination appears necessary.imagesfigure 1