This study addresses the measurements of glyphosate exposure received by 14 workers employed at two tree nurseries. The applicators, weeders, and scouts monitored all wore normal work clothing, which for applicators was a protective suit, rubber gloves and boots. Measurements were made of the glyphosate that was dislodged from conifer seedlings during water rinses taken twice weekly from May through August. Only 1 of these 78 dislodgeable residue samples were positive for glyphosate. Nine cotton gauze patches were attached to the clothing of each worker one day per week during this same period. Hand washes were taken on the same day that patches were worn. Most patches and hand washes from applicators and weeders contained measurable amounts of glyphosate. Analyses of individual patches showed that the body portions receiving the highest exposure were ankles and thighs. For scouts only 1 of 23 hand washes contained glyphosate. To provide a measure of the exposure occurring via all exposure routes (dermal, ingestion, and inhalation) an analysis was made of the total urine excreted. For most workers a daily total urine collection was made for 12 consecutive weeks. Urine analysis, the biological monitoring tool used to assess the total amount absorbed via all avenues, did not reveal any positive samples. The lower limit of method validation for glyphosate in the urine samples was 0.01 micrograms/ml. High rainfall, or irrigation as needed, in conjunction with normal field dissipation avenues and worker training were cited as contributing factors for the low amounts of glyphosate exposure found.(ABSTRACT TRUNCATED AT 250 WORDS)
A new residue method for the analysis of glyphosate and (aminomethyl)phosphonic acid has been validated with an interlaboratory study. Five different analysts from Monsanto Co. and other laboratories participated in testing of five different matrixes: alfalfa forage, cabbage, grapes, soybean grain, environmental water. These were chosen to represent the wide variety of matrixes analyzed for glyphosate-related residues. The cornerstone of the method is concentration and isolation via chelation ion exchange, with subsequent quantitation by HPLC with postcolumn reaction detection. The method was validated over the concentration range from 0.05 to 5.00 ppm with overall analytical recoveries of 80.9 ± 13.8% for glyphosate and 79.2 ± 13.8% for (aminomethyl)phosphonic acid. The coefficient of variation for both analytes was 17%, which fits well with that predicted for the analysis of compounds in this concentration range.
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