Tank exposure studies

The test substance may be acquired in a number of ways. One common method is to purchase the product from a chemical dealer. This method of acquiring the test substance for a worker exposure or re-entry study allows one to proceed rapidly with the execution of the field portion of the study without the serious delays encountered while waiting for a test substance to be manufactured, assayed, and shipped to the site. Although having a test substance formulation which has been assayed under GLP standards and for which a certificate of analysis has been shipped to the test site is desirable, there are several instances when this is not practical. For example, one may encounter a worker exposure study where the pesticide to be evaluated is sold only in mini-bulk or even large bulk quantities holding as much as 2000 gal. In this case, duplicate 5-10-g or 5-10-mL retainer samples should be taken from the bulk or mini-bulk tanks for assay after the worker exposure study is in progress. 

Endosulfan does not bioaccumulate to high concentrations in terrestrial or aquatic ecosystems. In aquatic ecosystems, residue levels in fish generally peak within 7 days to 2 weeks of continuous exposure to endosulfan. Maximum bioconcentration factors (BCFs) are usually less than 3,000, and residues are eliminated within 2 weeks of transfer to clean water (NRCC 1975). A maximum BCE of 600 was reported for a-endosulfan in mussel tissue (Ernst 1977). In a similar study, endosulfan, isomers not specified, had a measured BCE of 22.5 in mussel tissue (Roberts 1972). Tissue concentrations of a-endosulfan fell rapidly upon transfer of the organisms to fresh seawater for example, a depuration half-life of 34 hours (Ernst 1977). Higher BCFs were reported for whole-body and edible tissues of striped mullet (maximum BCF=2,755) after 28 days of exposure to endosulfan in seawater (Schimmel et al. 1977). However, tissue concentrations decreased to undetectable levels 48 hours after the organisms were transferred to uncontaminated seawater. Similarly, a BCE of 2,650 was obtained for zebra fish exposed to 0.3 pg/L of endosulfan for 21 days in a flow-through aquarium (Toledo and Jonsson 1992). It was noted that endosulfan depuration by fish was rapid, with approximately 81% total endosulfan eliminated within 120 hours when the fish were placed in a tank of water containing no endosulfan. 

Three of five men, who lost consciousness within a few minutes of entering a partially drained underground liquid manure storage tank, died before reaching the hospital autopsy showed that two had massive liquid manure pulmonary aspiration, while the third had fulminant pulmonary edema without manure aspiration (Osbem and Crapo 1981). Markedly elevated heart-blood sulfide-ion levels indicated significant hydrogen sulfide exposure. Air samples analyzed about a week after the accident detected only 76 ppm of hydrogen sulfide, but the study authors noted that the environmental conditions were probably different (e g., warmer weather, less-concentrated manure). 

Analytical chemistry is a critical component of worker safety, re-entry, and other related studies intended to assess the risk to humans during and subsequent to pesticide applications. The analytical aspect takes on added significance when such studies are intended for submission to the U.S. Environmental Protection Agency and/or other regulatory authorities and are thus required to be conducted according to the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Good Laboratory Practice (GLP) Standards, or their equivalent. This presentation will address test, control, and reference substance characterization, use-dilution (tank mix) verification, and specimen (exposure matrix sample) analyses from the perspective of GLP Standards requirements. 

B. E. Suta, "Assessment of Human Exposures to Atmospheric Benzene from Benzene Storage Tanks," Center for Resource and Environmental Systems Studies, Report No. 119, SRI International, Menlo Park, California, 1980. 

Following dialysis and treatment by SEC, the sample extracts were solvent exchanged into sterile DMSO. Subsequently, four rainbow trout Oncorhynchus mykiss [RBT]) were placed in each of seven tanks (each tank is considered as a treatment and a replicate is an individual fish within a tank) in 18 °C well water (280 mg hardness as CaCOs) using flow-through conditions. RBT were fed once daily throughout the study. Following a 48 hour acclimation, RBT were injected interperitoneally with 100 pL of a 1 1 mixture of an SPMD extract or appropriate controls in DMSO or corn oil. Controls included non-deployed SPMD extracts, SEC blanks, and DMSO blanks. The same injection procedure was repeated 6 days later. RBT were sacrificed 11 days after initial exposure to the extracts, and the plasma, liver, gills, and brain were immediately removed from each fish and maintained at -80 °C until assayed. 

Respiratory Effects. No studies were located regarding respiratory effects in humans after inhalation exposure to 1,3,5-TNB. One retrospective study (Okubo and Shigeta 1982) of acute occupational exposure to 1,3-DNB dust particles was located. Six workers were removing crystallized 1,3-DNB from a tank and were protected with gauze masks and rubber gloves. Exposure occurred over a period of 6 days. By the end of the exposure period, some of the workers complained of slight dyspnea upon exertion. Inhalation was considered to be a primary route of exposure because a relatively small skin area (face and neck) was exposed. Limitations of this study include lack of information on the concentration of 1,3-DNB in the air, the amount of particulate 1,3-DNB deposited on workers skin, and the exact duration of exposure. 

After acute exposures to chlorine gas, both obstructive and restrictive abnormalities on pulmonary function tests have been observed. Eighteen healthy subjects exposed after a leak from a liquid storage tank had diminished FEVi, EEF 25-75%, and other flow rates within 18 hours of exposure. Follow-up studies at 1 and 2 weeks demonstrated resolution of these abnormalities in the 12 subjects with an initial chief complaint of cough, whereas the 6 subjects with a chief complaint of dyspnea had persistently reduced flow rates. Repeat studies in 5 months were normal in all patients studied except for mildly reduced flow rates in two patients who were smokers. ... 

Other data on levels of exposure to butadiene have been collected during health surveys and epidemiological studies (Table 12). At an SBR manufacturing plant in the United States in 1979, the only two departments in which levels were greater than 10 ppm [22 mg/nr I were the tank farm (53.4 ppm [118 mg/m ) and maintenance (20.7 ppm [46 mg/m3]) (Checkoway Williams, 1982). In samples taken at one of two United States SBR plants in 1976, levels above 100 ppm [220 mg/m ] were encountered by technical services personnel (115 ppm [253 mg/m- ]) and an instrument man (174 ppm [385 mg/m3]) (Meinhardt et al., 1978). Overall mean 8-h time-weighted average (TWA) exposure levels differed considerably between the two plants, however 1.24 ppm [2.7 mg/m ] in one plant and 13.5 ppm [30 mg/ni in the other (Meinhardt et al., 1982). 

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