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United States Department of Agriculture

Agricultural Research Service

Title: Distribution among Sample Test Results When Testing Shelled Corn Lots for Fumonisin

Authors
item Whitaker, Thomas
item Hagler, JR., Winston - NC STATE UNIVERSITY
item Johansson, Anders - CLINTRIALS
item Giesbrecht, Francis - NC STATE UNIVERSITY
item Trucksess, Mary - US FOOD & DRUG ADMIN

Submitted to: International IUPAC Symposium on Mycotoxins and Phycotoxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 2000
Publication Date: July 18, 2001
Citation: WHITAKER, T.B., HAGLER, JR., W.M., JOHANSSON, A.S., GIESBRECHT, F.G., TRUCKSESS, M.W. DISTRIBUTION AMONG SAMPLE TEST RESULTS WHEN TESTING SHELLED CORN LOTS FOR FUMONISIN. JOURNAL ASSOCIATION OFFICIAL ANALYTICAL CHEMISTS. 2001. v. 84. p. 770-776.

Interpretive Summary: Fumonisin is a carcinogenic and toxic compound produced by molds found in several grains. The Food and Drug Administration is currently considering the establishment of an advisory level that will help the grain industry control the maximum quantity of fumonisin found in food and feed products. As a result of pending FDA regulatory action, grain products are inspected by processors, manufacturers, and USDA to detect and remove contaminated lots from the food and feed chain. It is difficult to determine the exact fumonisin level in large shipments or lots because of the random errors associated with the fumonisin test procedure. Analyzing many samples taken from the same contaminated lot will produce a wide range of fumonisin test results. Generally, more fumonisin test results are below the true lot concentration than above. As a result, it is difficult to accurately classify lots according to their true fumonisin content. It is important to obe able to predict the distribution of repeated fumonisin test results taken from a contaminated lot. Once the distribution of test results can be predicted, methods can be developed to reduce the number of lots miss-classified. This will reduce both health risks to the consumer and economic loss to the grain industry.

Technical Abstract: The statistical distribution known as the compound gamma function was studied for suitability in describing the distribution of sample test results associated with testing lots of shelled corn for fumonisin. Thirty- two 1.1 kg test samples were taken from each of 16 contaminated lots of shelled corn. An observed distribution consisted of 32 sample fumonisin test results for each lot. The mean fumonisin concentration, c, and the variance, s2, among the 32 sample fumonisin test results along with the parameters for the compound gamma function were determined for each of the 16 observed distributions. The 16 observed distributions of sample fumonisin test results were compared to the compound gamma function using the Power Divergence (PD) test. The null hypothesis that the observed distribution could have resulted from sampling a family of compound gamma distributions was not rejected at the 5% significance level for 15 of the 16 lots studied. Parameters of the compound gamma distribution were calculated from the 32 fumonisin sample test results using the method of moments. Using regression analysis, equations were developed that related the parameters of the compound gamma distribution to fumonisin concentration and the variance associated with a fumonisin test procedure. An operating characteristic curve was developed for a fumonisin sampling plan to demonstrate the use of the compound gamma function.

Last Modified: 8/21/2014
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