June 2002 Volume VI, No. 1NEWS FROM INTERNATIONAL AGENCIES The Joint FAO/WHO Expert Committee on Food Additives met in Geneva February 6-15, 2001 to evaluate certain mycotoxins that may contaminate food. The committee was charged with assessing and characterizing the risks associated with consuming foods contaminated by the mycotoxins under consideration. Evaluations were made on aflatoxin M1, fumonisins (FB1, FB2 and FB3), ochratoxin A, and trichothecenes (deoxynivalenol, T-2 toxin and HT-2 toxin.) The report addressed several concerns about each mycotoxin: explanation of the mycotoxin, absorption through excretion, toxicological studies, and final evaluation. Along with the mycotoxin evaluations, the committee put forth general considerations on analytical methods, sampling, associated intake issues, and control. In particular, good surveillance data should be generated using validated analytical methods to ensure reliable results. Methods used should be validated through collaborative studies of analytical performance; however, the committee recognized that it may not always be possible to use a validated method due to expense or an official method being irreconcilable to a particular toxin-matrix combination. The committee also stressed the importance of laboratories’ participation in inter-laboratory comparison studies to ensure analytical quality assurance. Accurate determination of the occurrence of mycotoxins in foods requires practical, economically feasible sampling plans. To date, there is not enough information on sampling variability and surveillance data to ensure effectiveness. The committee recommended a clearly defined sampling plan with samples from selected food populations taken from defined locations. Similarly, the committee recommended that food consumption data be taken from national food balance sheets. The estimate of relative health risks associated with specific proposed maximum limits for a particular mycotoxin was calculated by combining mean data on food consumption with weighted mean contamination levels. Also supplied were general principles on the prevention and control of mycotoxins. Prior to harvest, appropriate agricultural practices should be applied including breeding plants to resist fungus and competitive exclusion with the use of nontoxigenic strains in the field. Postharvest, it is important to dry commodities and keep them dry (below 0.70 water activity) during storage to prevent fungal growth and mycotoxin formation. Cleaning grains and keeping them cool during storage also reduces insect and fungal growth. Carcinogenic potency to the liver (cancers per year/100,000 persons per ng/kg of body weight per day) of aflatoxin M1 estimated from epidemiological and toxicological studies on aflatoxin B1 was 0.001 and 0.03 in humans HbsAg- and HbsAg+, respectively. It was concluded that the additional risks for liver cancer predicted with use of the proposed maximum levels of aflatoxin M1 of 0.05 and 0.5 µg/kg are very small, i.e. 29 cancers per 1000 million persons per year. The group provisional maximum tolerable daily intake (PMTDI) for fumonisins B1, B2, and B3 alone or in combination was 2 µg/kg of body weight per day on the basis of the NOEL of 0.2 mg/kg of body weight per day and a safety factor of 100. For deoxynivalenol, the PMTDI was 1 µg/kg of body weight on the basis of the NOELof 0.100 mg/kg of body weight per day and a safety factor of 100. For T-2 and HT-2 toxins, alone or in combination, the PMTDI was 0.060 mg/kg of body weight per day on the basis of the LOEL of 0.029 mg/kg of body weight per day and a safety factor of 500. For ochratoxin A, the Committee retained the previously established provisional tolerable PTWI of 10 ng/kg body weight per week, pending the results of ongoing studies on the mechanisms of nephrotoxicity and carcinogenicity, and recommended a further review of ochratoxin A in 2004. |