Michigan Food Monitoring Program
1997
Michigan Department of Agriculture

The goal of the Michigan Department of Agriculture's  (MDA) Michigan Food Monitoring Program is to characterize and assess potential pesticide exposure through the food chain in Michigan followed by appropriate risk management decisions.  This program continues to analyze raw agricultural commodities for the presence of pesticides.   In 1997, nine commodities were included in this program including strawberries, blueberries, tomatoes, bell peppers, cabbage, carrots, apples, grapes and potatoes.   This document describes the sample collection, analytical methodology, analytical results, and program conclusions.

Sample Collection

MDA regional field staff collected samples from various post-harvest locations including the producer, distributor and, when necessary, the retailer.  However, every attempt was made to collect the sample as close to the "farm gate" as possible.  Regardless of where the sample was collected, the producer of that commodity was always identified.  Sixteen to twenty 5 to 10-pound samples of each commodity were collected and then submitted to the MDA Laboratory for analysis.  A total of 160 samples were collected.

Analytical Methodology

Two multi-residue analyses were employed.  One method referred to as the "Luke" procedure was used to determine a wide range of pesticides that contain the elements of phosphorous, chlorine or nitrogen.   Pesticides detected by this method would include organophosphate compounds such as parathion and malathion.  The second method selected was capable of detecting N-methylated carbamates such as carbaryl and methomyl.  Both methods were used in the screening mode.  A screening analysis refers to the extraction and analysis of a commodity to determine the presence of any compound known to be recovered by the method.   To assure method performance throughout the analytical process, a matrix spike containing representative compounds of the class of recoverable compounds was included. To prevent false positives, every compound detected by screening was confirmed by additional testing including structural analysis by mass spectroscopy.

Analytical Results

Table 1 summarizes the analytical results.  The commodity tested is listed in the first column followed by the sample size, pesticides detected, the range of concentrations, the FDA tolerance for the pesticide and the number of samples found to exceed the tolerance. 

Conclusions

A total of 160 samples were analyzed in 1997 of which 74 (46%) had detectable residues.   Four of these samples (2.5%) were found to exceed tolerance.  In each case, no tolerance existed.  Therefore, any detectable concentration would exceed tolerance for regulatory purposes is assumed to be zero.  The concentrations found for these pesticides were extremely small. 

Table 1