Samples collection, applications exposure

Distributions of pesticide concentrations in potential food items for avian species are required to estimate the contribution of food to exposure of birds in different regions where the test chemical may be used. On treated fields, detectable CEF residues were found in 102 of 207 earthworm samples. No earthworm samples collected from control fields (N = 28) contained detectable CEF. Average CEF concentrations in earthworms reached maxima 1-4 days post-application (Table 3). Mean CEF residues in earthworms fell below 0.1 qg g after 8 days post-application. This... 

Of those matrices measured, worms collected from treated fields present the most significant potential route of exposure for those species of wildlife which rely on them as a major food source. Worms were the matrix, aside from soil, with the highest frequency of detection (49% of samples collected on treated sites post-application) and the highest mean concentrations (0.025-0.15 qg g on treated sites). 

The purpose of this article is to present a detailed description of the current field methods for collection of samples while measuring exposure of pesticides to farm workers. These current field methods encompass detailed descriptions of the methods for measuring respiratory and also dermal exposure for workers who handle the pesticide products directly (mixer-loaders and applicators) and for re-entry workers who are exposed to pesticide dislodgeable residues when re-entering treated crops. 

EPA Study. The first published report of studies on 2,it,5-T applicators was by Shafik et al. of EPA in 1971 (] ) They analyzed urine samples collected from people occupationally exposed to 2,lt-D and 2,it,5-T, and reported higher exposure in spray operators than in those who had less direct contact with the herbicides. 

The First Study. Forest-applicator exposure to MSMA and cacofirst studied by Tarrant and Allard (9). They collected individual urine samples on Monday mornings ari7 Friday afternoons for 9 consecutive weeks from five applicators (each using a different combination of application method and chemical) and one control. Workers were supplied with clean clothes daily, including two pair of cotton gloves (to be changed at noon, or earlier if one pair became substantially contaminated with herbicide). Complete data were obtained for weeks 2, 3, 4, 7, and 8 (except for the injection hatchet-cacodylic acid combination, which was not included in the analysis). 

In accordance with the type of crop protection procedure, the stages of the work had different cycle times. For herbicide application, the complete task was done in approximately 18 minutes, while, in the fertilizer application was finished in only 5 minutes. Samples collection allowed us to identify the Vibration Dose Value in RMS (RMS VDV), maximum peak level (Peak), and value of daily exposure (8-hour reference period) to WBV (A(8)). EMB-201A aircraft applying herbicide, (sample = 01 36 41, n = 5792), showed RMS VDV = 8,053 m/s and Peak = 141,490 m/s. Also applying herbicide, EMB-202 aircraft (sample = 01 31 40, n = 5493), showed RMS VDV = 11,098 m/s and Peak=96,774 m/s. Finally, EMB-202 aircraft applying fertilizer (sample = 01 17 11, n = 4624) showed RMS VDV = 9,470 m/s and Peak = 120,277 m/s. Figure 1 show data points corresponding to the combined axis (X, Y and Z) Vibration Total Value (RMS VTV) for these three situations respectively. 

The results of environmental monitoring exercises will be influenced by a variety of variables including the objectives of the study, the sampling regime, the technical methods adopted, the calibre of staff involved, etc. Detailed advice about sampling protocols (e.g. where and when to sample, the volume and number of samples to collect, the use of replicates, controls, statistical interpretation of data, etc.) and of individual analytical techniques are beyond the scope of this book. Some basic considerations include the following, with examples of application for employee exposure and incident investigation. 

As with urine, saliva (spumm) is easy to collect. The levels of protein and lipids in saliva or spumm are low (compared to blood samples). These matrices are viscous, which is why extraction efficiency of xenobioties amoimts to only 5 to 9%. By acidifying the samples, extraction efficiencies are improved as the samples are clarified, and proteinaceous material and cellular debris are precipitated and removed. Some xenobioties and their metabohtes are expressed in hair. Hair is an ideal matrix for extraction of analytes to nonpolar phases, especially when the parent xenobioties are extensively metabolized and often nondetectable in other tissues (parent molecules of xenobioties are usually less polar than metabolites). Hair is a popular target for forensic purposes and to monitor drug compliance and abuse. Human milk may be an indicator of exposure of a newborn to compounds to which the mother has been previously exposed. The main components of human milk are water (88%), proteins (3%), lipids (3%), and carbohydrates in the form of lactose (6%). At present, increasing attention is devoted to the determination of xenobioties in breath. This matrix, however, contains only volatile substances, whose analysis is not related to PLC applications. 

The duration of collection of biological samples from farm workers is determined by the excretion pattern of the active ingredient or its metabolites. Generally, collection will encompass a period of time prior to exposure to about 1-3 days beyond exposure. Background samples should be taken from workers for the 24 h prior to the first application of the test product. This will allow an up-to-date examination of the background levels of the parent or metabolites in the worker s urine. 

Whichever technique is used, it is recommended that urine samples from volunteers be taken for an extended period of time that encompasses the entire post-exposure excretion of the active ingredient or its metabolites. In addition, it is recommended that the study volunteer refrain from handling the active ingredient for an extended period after the application phase or re-entry phase of the study is completed and until the collection of urine samples is completed. This will allow for the excretion pattern of the active ingredient or metabolites to achieve a profile that is more easily interpreted by the investigator. 

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