Worldwide occurrence of mycotoxins in foods and feeds--an update.

In a review presented at the first FAO/WHO/UNEP Conference on Mycotoxins in 1977, the occurrence of aflatoxins, zearalenone, ochratoxin A, citrinin, trichothecenes, patulin, penicillic acid, and the ergot alkaloids was indicated to be significant in naturally contaminated foods and feeds. The information presented on aflatoxin contamination greatly exceeded that for all other mycotoxins combined. This study reviews the worldwide levels and occurrence of mycotoxins in various commodities since 1976. Comparatively few countries have lowered the acceptable levels for aflatoxins in susceptible commodities. However, intensified efforts are needed to establish control of aflatoxin levels in the global food supply, particularly in peanuts, tree nuts, corn, and animal feeds. Extensive deoxynivalenol (DON) contamination of grains, especially wheat, was demonstrated. Co-contamination of grains by Fusarium toxins, especially DON and nivalenol, with zearalenone to a lesser extent, was reported. However, more information on co-occurrence of Fusarium toxins in cereals should be developed. When contamination of feeds by ochratoxin A was significant, this toxin occurred in swine kidney and smoked meats in high levels. On the basis of occurrence and/or toxicity, patulin and penicillic acid contamination of foods does not appear to be of real concern. More recent developments suggest, however, that expanded monitoring studies of Alternaria toxins, moniliformin, citrinin, cyclopiazonic acid, penitrem A, and ergot alkaloids are indicated.

Control of chemical contaminants in foods: past, present, and future.

In the late 1930s and early 1940s, almost the only analyses carried out for chemical contaminants in foods were for lead arsenate and other arsenical pesticides in fruits. Since then, a tremendous expansion has occurred in the types of chemical contaminants found in foods and in the activities of the U.S. Food and Drug Administration and other organizations responsible for monitoring and controlling the presence of these contaminants in the food supply. This paper describes the findings and control of additional chemical contaminants in foods, including synthetic pesticides, PCBs (polychlorinated biphenyls), other industrial chemicals, fungal metabolites such as aflatoxins, toxic metals, and radionuclides. The common characteristics of problems connected with these different types of contaminants include uncontrolled entry into the food supply, incidents causing extreme public worry, and near impossibility in removing these contaminants from the food supply. Problems may also arise from new technologies and environmental developments. New approaches beyond ordinary regulatory activities are being used to meet these problems. Broader analytical methods requiring less time and faster and more sophisticated toxicological methods are needed to assess the hazard of these environmental food contaminants.

Survey of radionuclides in foods, 1978-1982.

Samples from the U.S. Food and Drug Administration's total-diet, market-basket program, samples of imported foods, and samples collected near nuclear power plants were analyzed for radionuclides. Most radionuclides were below the limit of detection for a majority of the samples; however, data are reported for 3H, 90Sr and 137Cs in certain samples. Generally a downward trend is observed for 90Sr when data for the 5-yr period were compared. The total dietary intake of either 90Sr or 137Cs is well within Range I of the Federal Radiation Council (FRC) radiation protection guides for these radionuclides.

A review of the dietary intakes of chemical contaminants.

Data on the dietary intakes of certain contaminants have been received from eleven collaborating centres participating in the Joint FAO/WHO Food Contamination Monitoring Programme. The data cover the period from 1971 to 1983 and include information on the intakes of a series of organochlorine and organophosphorus pesticides, polychlorinated biphenyls, cadmium, lead, and aflatoxins.When compared with the acceptable daily intake (ADI) or provisional tolerable weekly intake (PTWI) of the pesticides/contaminants in question, the data indicate that, in some countries, the exposure to certain organochlorine pesticides may constitute a significant portion ofthe ADI. Because of the concentration of these compounds in the fatty portions of food, a high animal fat intake will increase the dietary exposure to organochlorine compoundsDietary intakes of cadmium and lead constitute an appreciable percentage oft he PTWI for these two contaminants. As the intakes of cadmium and lead per kilogram of body weight are highest for infants and children, every effort should be made to reduce the levels of these two contaminants in the food supply.

Levels of lead in the United States food supply.

As a result of the Food and Drug Administration's (FDA) concern about lead in the food supply, considerable data have been developed in recent years by FDA, other agencies, and industry on the levels of lead in foods. Data obtained on the lead content of milk, eggs, meat, fish, and shellfish indicate that the mean levels in these unprocessed foods varied from 0.02 to about 0.4 ppm, with the lowest level in milk. The major food processing source of lead in food is the lead-soldered can. FDA had assigned top priority to the reduction of lead in foods for infants because of their greater susceptibility to the toxic effects of this metal. The lead levels in foods for infants are now only 1/5 to 1/10 of what they were when FDA expressed its concern about lead to the manufacturers of canned infant formula, evaporated milk, canned infant juices, and glass-packed infant foods. FDA priority interest has now shifted to reduction of lead in adult canned foods, especially those eaten by young children. The mean levels in such foods have decreased from 0.35-0.40 ppm in 1974 to 0.20-0.25 ppm in 1980.

Levels of arsenic in the United States food supply.

At the present time, the Food and Drug Administration (FDA) accords the highest priority to mercury, lead, cadmium, arsenic, selenium, and zinc in its program on toxic elements in foods. The only regulatory levels for arsenic in foods in the U. S. are the tolerances which have been established for its residues in specified foods, resulting from the application of arsenical pesticides on food and feed crops and from animal feed additives. FDA has monitored for arsenic in its Total Diet Survey since the inception of this program. The data from this program indicate that the average daily intake for arsenic (as As(2)O(3)) has decreased from about 130 mug/day in 1968 to about 20 mug/day in 1974. Most of the arsenic is found in the meat-fish-poultry food class of the total diet. In individual foods, the highest levels were found in fish, with a mean level of about 1.5 ppm (as As(2)O(3)) in the edible portion of finfish. Much lower levels were found in all the other food types analyzed; of these, the highest levels found were a mean level of 0.08 ppm in chicken and 0.16 ppm in rice. FDA toxicologists do not believe that the average daily intake of arsenic, or its levels in the different food commodities, pose a hazard to the consumer.

Heavy metal exposure from foods.

The Food and Drug Administration has a continuing program of monitoring foods for their content of lead, cadmium, mercury, zinc, arsenic, and selenium to determine trends of increasing or decreasing levels. The monitoring protocol is that of the Total Diet Study, in which "market baskets" of typical foods and beverages consumed by 15- to 20-year-old American males are collected in various geographical locations at regular intervals during the year, divided into food classes, composited, and analyzed. Cadmium has the most widespread distribution of the six heavy metals and mercury the most limited. The analytical values for lead may be underestimated because of limitations of the methodology; these do not apply to the other five elements. A tabulation by year shows that the levels of these elements in foods do not vary significantly from one year to the next. Average intakes of lead, cadmium, and mercury are below the WHO/FAO tolerable intakes for adults; such tolerable intakes have not been established for arsenic and selenium. Increases in concentrations of these elements in foods would be considered undesirable, however.

Food exposures to lead.

Exposures to lead have emanated from various sources, including food, throughout human history. Occupational and environmental exposures (especially pica) appear to account for much of the identified human disease, however, food-borne exposures deserve further investigation. Lead residues in food can result from: biological uptake from soils into plants consumed by food animals or man, usage of lead arsenate pesticides, inadvertent addition during food processing, and by leaching them improperly glazed pottery used as food storage or dining utensils. Estimates of total dietary exposure should reflect frequency distribution data on lead levels in specific food commodities in relation to the quantities actually ingested by various sample populations to distinguish degrees of risk associated with particular dietary habits. Earlier estimates of average total dietary intake of lead by adults have been reported to range from above 500 mug/day downward with more recent estimates suggesting averages of 200 mug/day or lower. The strengths and weaknesses of these data are discussed along with analytical and sampling considerations. FDA programs related to food surveillance, epidemiology, and toxicological investigation are briefly described.