Reprinted from Journal of the Association of Official Agricultural Chemists May, 1959 407932 431 LAUG AND WALLACE: RADIOACTIVE RESIDUES IN FOODS A Survey of Radioactive Residues in Foods Before and After 1945: Evidence of Possible Fallout Contamination* By EDWIN P. LAUG and WENDELL C. WALLACE (Food and Drug Administration, Department of Health, Education, and Welfare, Washington 25, D.C.) Evidence based on a number of reports indicates that certain foodstuffs, notably dairy products, are receiving radioactive contamination from tropospheric fallout. Presumably, this invasion of the food chain by man-made radioactivity occurs in three ways: (a) direct deposition of the fallout on leaves and fruits of edible plants; (6) translocation by the plants of the fallout which has become mixed with soil and water; (c) consumption were submitted. These foods came from private homes and the food industry; some even from the caches of the Shackleton and Byrd Antarctica expeditions dating back to 1906. In addition, an equal number of post-1945 samples were collected, mostly from retail outlets. The following categories were examined for total beta radioactivity: vegetables, fruits, fruit juices, sea foods, dairy products, bread, been assumed that no significant man-made meat products, wheat, sugars, jams and jellies, cocoa beans, tea, and coffee. Nearly half of the samples were fruits and vegetables, and the predominant number of these were canned. Of the post-1945 samples, the largest number originated in the first five years; comparatively smaller numbers of samples came from the years 1950 to 1957. curred prior to 1945, the year thefirst experi- Experimental of contaminated plant materials by animals whose tissues and other products are subse- quently used for food. This report covers results of a survey conducted over the past two years to determine to what degree foods may have become contaminated with radioactive fallout. It has radioactive contamination could have oc- mental and military nuclear devices were exploded. Foods produced before and after this critical date have therefore been examined for total beta radioactivity adjusted for the presence of potassium 40, a widely distributed naturally occurring radioactive isotope. It is possible that other naturally occurring radioactive substances may contribute to the total. This contribution is extremely small, and while it may vary from food to food there is no reason to expect it to vary with time. Consequently if we consider the radioactive content of all pre-1945 foods as a base line, any increase in foods produced since 1945 can be interpreted as man-made radioactive contamination. This ‘contamination is presently contributed mainly by fallout from weaponstesting, but it can be expected also to reflect the presence of nuclear power plants and other applications. In January 1957, in response to requests by the Food and Drug Administration, nearly a thousand samples of food antedating 1945 * Presented at the Seventy-second Annual Meeting of the Association of Official Agricuitural Chemists, Oct. 13-15, 1958, Washington, D.C, Methodology 1. Sample preparation—aAll foods were well mixed or homogenized to insure uniform distribution of any radioactivity present. An amount of sample in its original state of hydration or dryness (as is) was weighed out so as to yield approximately 200 to 500 mg of ash. Dry ash- ing was done in several kinds of containers (Vyeor, porcelain, silica, glass, platinum, ete.) and care was taken to retire any vessels whose surface had become severely etched. Ashing was usually allowed to proceed for 18 to 24 hours at a temperature of about 550°C. Unoxidized carbon was removed by wetting down the ash with small quantities of water and repeated heating. Wherever possible, fusion of the ash was avoided because of the attendant difficulties of removal from the ashing vessel. The ash yield was weighed to the nearest milligram, and its relation to the original sample calculated as an ash ratio (mg ash per mg of original food). Ash samples were finely pulverized in an agate mortar and stored in stoppered glass vials. 2, Radioactivity measuremenis—Total beta radioactivity was measured with a Tracerlab superscaler equipped with an automatic sample