DETECTABLE LEVELS OF SERUM AFLATOXIN B-1-ALBUMIN ADDUCTS IN THE UNITED-KINGDOM POPULATION - IMPLICATIONS FOR AFLATOXIN-B-1 EXPOSURE IN THE UNITED-KINGDOM

This study aimed to estimate aflatoxin B-1 (AFB(1)) exposure in the Un ited Kingdom population by measuring levels of serum AFB(1)-albumin (a lb), using immunoassay and high-performance liquid chromatography (HPL C) with fluorescence detection. A self-questionnaire on dietary habits from 104 volunteers (47 men and 57 women) in York was completed, and blood samples were collected. Serum alb was extracted, and AFB(1)-lysi ne (lys), the digest product of AFB(1)-alb, was isolated and measured. A sensitive ELISA (detection limit, similar to 1.4 pg of AFB(1)-lys) was developed, A good correlation was found between calibration of ELI SA results and scintillation counting, for rats dosed with [H-3]AFB(1) (r = 0.972; P < 0.001), This ELISA was subsequently used to analyze h uman serum alb, For United Kingdom human sera, the mean adduct levels were 29.3 +/- 14.8 pg AFB(1)-lys equivalents (eq) mg albumin (males) a nd 26.9 +/- 14.4 pg AFB(1)-lys eq/mg alb (females), Confirmation of th e ELISA data was sought using reversed-phase HPLC with fluorescence de tection. HPLC chromatograms of digested York serum alb were compared t o digested serum alb for humans from Qidong County, People's Republic of China, and from AFB(1)-dosed rats, These all gave similar HPLC prof iles. Each sample contained fluorescent material that coeluted with an d just before the AFB(1)-lys standard. Fluorescent fractions were foun d to be inhibitory in a separate anti-AFB(1)-lys ELISA, indicating tha t these earlier fluorescent peaks contained AFB(1) residues. Our resul ts suggest that measurable internal AFB(1) exposure may be occurring i n some United Kingdom individuals, albeit at lower levels than those s een for areas with high AFB(1) exposure. The source of this exposure m ay reflect the known difficulties in accurately monitoring regulated i mported foodstuffs and/or the lack of regulations on other potentially contaminated imports. However, no positive correlations were found be tween our AFB(1)-lys measurements and any dietary questionnaire inform ation. Animal studies, as well as human studies, have been important i n developing exposure and internal adduct relationships in humans, Bas ed on this literature, our AFB(1)-alb data indicate a mean daily expos ure of 3 mu g of AFB(1) and a mean internal dose in liver DNA of 5.9 a dducts/10(7) nucleotides. We believe this may be an overestimate of th e AFB(1) exposure level in the United Kingdom, and further studies are needed to accurately relate external dose and internal AFB(1) biomark ers in humans.