THE VALIDITY OF DETERMINATION OF ALPHA-NAPHTHOL IN URINE AS A MARKER FOR EXPOSURE TO POLYCYCLIC AROMATIC-HYDROCARBONS

The actual individual uptake of polycyclic aromatic hydrocarbons (PAH) depends on a multitude of factors, and it may therefore be advantageo us to supplement environmental measurements of airborne PAH compounds with biological monitoring of PAH metabolites to obtain a more reliabl e assessment of exposure and health risk. In the present study the app licability of determination of the urinary alpha-naphthol concentratio n as a marker for exposure to airborne naphthalene and total PAH was s crutinized. The validation is difficult since PAH compounds are widesp read in the environment, and it is extremely difficult to find individ uals exposed to one source of PAH compounds only. A preliminary study on five smokers employed in an office work place with no occupational PAH exposure revealed that the urinary alpha-naphthol concentration wa s closely related to the degree of smoking, i.e., heavily smoking resu lted in the highest urinary alpha-naphthol concentrations (11.8 mu mol /mol creatinine). The close correlation between smoking and elevated c oncentration of urinary alpha-naphthol was subsequently confirmed on g roup basis by comparison of smokers and non-smokers at four different work places, (i.e., two iron foundries with low airborne PAH exposure and two work places with unknown PAH exposure). At all work places the median values of urinary alpha-naphthol of smokers were higher than t he median values of non-smokers, indicating that smoking may be a stro ng confounder when measurements of alpha-naphthol are used to monitor low dose of PAH exposure. In a detailed study of iron foundries the ur inary alpha-naphthol concentration was clearly associated with the low -dose airborne total PAH exposure of the workers. This study also demo nstrated the need for a careful registration of smoking habits, i.e., regardless of the level of PAH exposure. Smokers in average tended to have higher urinary alpha-naphthol concentrations than non-smokers. Th e present study has demonstrated that a newly developed liquid chromat ographic method for measurement of alpha-naphthol in urine may be appl ied in biological monitoring of low dose PAH exposure.