USE OF AN IMPROVED METHOD FOR ANALYSIS OF URINARY AFLATOXIN M-1 IN A SURVEY OF MAINLAND CHINA AND TAIWAN

An improved monoclonal antibody immunoaffinity chromatography/high-pre ssure liquid chromatography/ fluorescence detection method was develop ed to measure aflatoxin (AF) exposure by quantifying AFM(1) in human a nd rat urine samples, Analysis of different amounts of various AF meta bolites showed that the immunoaffinity resin was highly selective for aflatoxin B-1 (AFB(1)), AFB(2), and AFM(1), Recovery of added AFs incr eased with the amount of immunoaffinity resin and was virtually comple te within the range of 0.01-10 ng of AFM(1) by using 7 mi of resin, Th e detection limit of this method is 0.5 pg/ml urine, Rats dosed with t ritiated AFB, excreted in their urine tritiated AFM(1), among other AF metabolites, as indicated by chemical derivative confirmation and coc hromatography with authentic AFM(1) and agreement of radioactivity and fluorescence quantitation, A linear dose-response relationship was fo und over the range of 0.05-50 mu g/kg of body weight/day, Two humans d osed with 1.0 mu g of pure AFB(1) excreted 6-7% of the dose as urinary AFM(1) over 5-7 days, Pooled urine samples from 30 men from each of 6 9 rural counties in mainland China and 16 survey areas in Taiwan, with two villages per county or area, were analyzed with this improved met hod (170 villages total), The correlation coefficient of urinary excre tion of AFM, compared between villages within all 85 survey areas was 0.50 (P < 0.001), Sixty-five % of the samples contained detectable con centrations of AFM(1) with an average excretion of 3.1 ng/12 h, Assumi ng an excretion rate of 2-6%, this AFM(1) excretion corresponds to a v ery low average daily AF consumption of 0.1-0.3 mu g/day (possible ran ge, 0-11 mu g/day). Patterns of urinary excretion of AFM(1) were simil ar in mainland China and Taiwan.