Occupational exposure characteristics

Skin is also important as an occupational exposure route. Lipid-soluble solvents often penetrate the skin, especially as a liquid. Not only solvents, but also many pesticides are, in fact, preferentially absorbed into the body through the skin. The ease of penetration depends on the molecular size of the compound, and the characteristics of the skin, in addition to the lipid solubility and polarity of the compounds. Absorption of chemicals is especially effective in such areas of the skin as the face and scrotum. Even though solid materials do not usually readily penetrate the skin, there are exceptions (e.g., benzo(Lt)pyrene and chlorophenols) to this rule. 

The specific values of the physical and biological characteristics such as breathing patterns for occupational exposure and active and resting patterns for environmental exposure are given in the footnotes to the Tables. A few remarks should be made concerning the parameters used which affect the dose calculation significantly. 

Subsequently, individual data on exposure are converted to dose by using conversion factors (OECD/NEA, 1983). The choice of the appropriate numerical value depends on physiological parameters (e.g. respiratory minute volume) as well as physical characteristics of the inhaled aerosol (e.g. particle size). Mean values range typically from about 5 mSv/WLM (non-occupational exposure) to about 10 mSv/WLM (occupational exposure). 

In a study conducted at the Lovelace Inhalation Toxicology Research Institute (ITR1), rats were exposed for up to 30 months, 7 h/day, 5 days/wk, to diesel exhaust containing 0, 0.35, 3.5, or 7.1 mg soot/m3 of air. The diesel engine exhaust was generated as indicated in the section of this paperon "Physical/Chemical Characteristics of Diesel Soot." The lowest exposure concentration, 0.35 mg soot/m3, is directly relevant to some occupational exposures and is 10 to 100 times higher than any current or anticipated environmental exposures. Observations of the animals were made at 6-mo intervals and included measures of dosimetry (mg soot/g lung),... 

Redlieh, C.A., West, A.B., Fleming, L., True, L.D., Cullen, M.R. Riely, C.A. (1990) Clinical and pathological characteristics of hepatotoxicity associated with occupational exposure to dimethylformamide. Gastroenterology, 99, 748-757... 

Langard S. 1993. Role of chemical species and exposure characteristics in cancer among persons occupationally exposed to chromium compounds. Scand J Work Environ Health Suppl 1 81-89. 

Properties. Osmium tetroxide forms pale yellow crystals with a very characteristic odour (a possible description is that of a mixture of ozone and damp hay). It has a considerable vapour pressure at room temperature and so must be kept in stoppered container or (preferably) in sealed ampoules. The vapour is toxic (TLV 2.5 p.p.m.).558a The long-term occupational exposure limit (OEL) is 0.002mgm 3. 558b... 

M.B. Schenker of Institute of Toxicology, University of California Davis in Davis, California is leading a multidisciplinary study supported by National Cancer Institute (NCI). This study will examine whether environmental asbestos deposits in California are associated with increased rates of mesothelioma. The study will address geological occurrence of asbestos and potential human exposure based on population patterns and known occupational exposure, and epidemiological characteristics of the disease in the state. The project will plan a case-control study to rigorously test the hypothesis that mesothelioma in California is independently associated with environmental asbestos exposure. 

Several cases of acute trichlorfon poisoning from suicidal, accidental, or occupational exposure have occurred. Signs and symptoms of intoxication include those characteristic of AChE inhibition, such as weakness, exhaustion, excessive salivation, sweating, vomiting, chest pain, miosis, and muscle spasms. In severe cases, convulsions and unconsciousness develop, and death ensues from respiratory failure. In some cases, victims surviving because of medical interventions developed a delayed polyneuropathy with weakness of the lower limbs after a few weeks of exposure. 

Intermediate-Duration Exposure. Occupational exposure to 2,4-DNP resulted in death from pyrexia in some cases, and fatigue, elevation of body temperature, increased respiratory rate, profuse perspiration, and weight loss in some of the workers (Gisclard and Woodward 1946 Perkins 1919). Exposure occurred by the inhalation and also probably by the dermal route. Gastrointestinal symptoms (nausea, vomiting) were also noted (Perkins 1919). Autopsy of the fatal cases did not reveal any characteristic lesions, other than pulmonary edema, which was thought to be secondary to vasomotor effects. Hence many of the effects of 2,4-DNP in humans do not appear to be route-specific. No exposure levels were reported in these studies. 

Effect. The increase in basal metabolic rate and weight loss, along with the characteristic clinical signs and symptoms (increased perspiration, sensation of warmth) seen with oral and occupational exposure of humans to 2,4-DNP appear to be fairly sensitive indices of the profound metabolic disturbances caused by 2,4-DNP. 

Broder I, Corey P, Cole P, et al. 1988a. Comparison of health of occupants and characteristics of houses among control homes and homes insulated with urea formaldehyde foam. II. Initial health and house variables and exposure-response relationships. Environ Res 45 156-178. 

Viaene MK, Pauwels W, Veulemans H, et al Neurobehavioural changes and persistence of complaints in workers exposed to styrene in a polyester boat building plant influence of exposure characteristics and microsomal epoxide hydrolase phenotype. Occup Environ Med 58 103-112, 2001 Welp E, Kogevinas M, Andersen A, et al Exposure to styrene and mortality from nervous system diseases and mental disorders. Am J Epidemiol 144 623-633,1996 White DM, Daniell WE, Maxwell JK, et al Psychosis following styrene exposure a case report of neuropsychological sequelae. J Clin Exp Neuropsychol 12 798-806, 1990... 

In some cases occupational exposures to phthalates have been associated with adverse health effects. A case-control study among a population of Danish workers employed in PVC production for 5 years or greater demonstrated a significant increase in the risk of multiple myeloma.Phthalate mixtures containing BBP have been associated with respiratory or neurological effects and cancer,increased incidence of menstrual disorders, and spontaneous abortions. " A stutfy of college students with no known exposure to phthalates found a ne tive correlation between DBP concentration and sperm density or total number of sperm. - However, this study did not consider con-founders nor did it provide ample evidence for a causal relationship of sperm characteristics to DBP levels. There were no human health data available for DEHP, DIDP, DINP, DnHP, norDnOP. 

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