Water exposure

In terms of environmental exposure, water and humidity must be carefully evaluated in electrical applications. In general, if a plastic absorbs a significant amount of water, the electrical resistivity drops. As examples this is the case for nylons and phenolic. Care must be used in selecting a dielectric to insure that the electrical properties such as the insulation resistance and dielectric strength, as well as other electrical properties are adequate under the conditions of field use, particularly if this involves exposure to high humidity conditions. Temperature also causes changes in most electrical products. 

Stehly, G.R. and W.L. Hayton. 1988. Detection of pentachlorophenol and its glucuronide and sulfate conjugates in fish bile and exposure water. Jour. Environ. Sci. Health B23 355-366. 

Figure 4. TLC behavior (0.25 mm, Silica gel GF-254 hexane-ethyl acetate, 9 1) of organic extracts of t4C-cis-chlordane treated cichlids (A) and exposure water (C). Fractions B and D show the compounds released by acid hydrolysis of aqueous phase of fish homogenate and exposure water, respectively.

Exposure water or air flow rate exposure cage geometry air samplers wind direction location (coordinates, and preferably a digital picture) start and end date and time physical appearance after exposure (description, and preferably a digital picture) temperature pH (when organic acids or bases are flie target analytes) suspended matter, and POC and DOC levels (water) or particle (air) levels other observations relevant to QC... 

Starkey. T. E. The Influence of Peroxyacetyl Nitrate on Bean (Phaseobis vulgaris L.) Subjected to Post-Exposure Water Stress. Center for Air Environment Studies. Publ. 400-75. University Park Pennsylvania State University, 1975. 45 pp. 

Type Fire Exposure Water Application Rate... 

The calculated biconcentration factors were taken as the ratio (K1/K2) of uptake rate constants (Kl) to depuration rate constants (K2). The measured bioconcentration factors were taken as the ratio of measured radioactivity in fish to that in exposure water after 24 hours exposure. 

Daphnia magna, based on 14C and exposure water, Dauble et al. 1986)... 

Shortly before exposure to the test chemical, the animals are weighed and exposed to different test chemical concentrations in the designated chamber for 4 hours. The temperature at which the test is performed should be maintained at 22 °C ( 2°C). Ideally, the relative humidity should be maintained between 30% and 70%, but in certain cases (e.g., aerosols), even this may not be practicable. Food should be withheld during exposure. Water also may be withheld in certain cases. The observation period for acute inhalation toxicity in animals should be at least 14 days. For clinical examination and pathology, the parameters listed for acute oral toxicity may be followed. The following conditions should be monitored during the experiment using a standard inhalation chamber. 

Chronic toxicity tests (typically 7-35 days of exposure) Water, pore water, elutriate Freshwater - water flea (C. dubia), fathead minnow (P. promelasy and rainbow trout (0. mykiss) Marine/estuarine - mysid shrimp (A. bahiay inland silverside (M. beryllinay and sheepshead minnow (C. variegatus)... 

The likelihood for the development of symptoms following inhalation exposure and the nature and severity of respiratoiy tiact injuiy depends on a number of factors, which include the chemical namre of the smoke, concentration and toxic potency of inhaled materials, particle size and vapor proportion, duration of exposure, water solubility, respiratory minute volume, and personal characteristics (e.g., differential susceptibility, exertion). During training and operational use, exercise will result in an increased respiratory minute volume (effect of tachypnea and increased tidal volume) and thus a greater inhalation exposure dose. Most of the more soluble inhaled material will tend to predominantly affect the upper airways, and the less soluble materials affect mainly the peripheral airways and alveoli. 

In addition to the wide application of pharmacokinetics in the drug discovery process and in clinical pharmacology, pharmacokinetics has also been found to be extremely useful in environmental science. In toxicological studies, such as pesticide exposure, water contaminants exposure, and air-borne carcinogens exposure, pharmacokinetics becomes a valuable tool in evaluating the-safety level of such compounds in humans or domestic animals. 

---