Personal exposure levels

Trichloroethylene levels monitored in expired breath of 190 New Jersey residents were correlated with personal exposure levels, which were consistently higher than outdoor air levels and were instead attributed to indoor air levels (Wallace et al. 1985). Other studies have expanded upon and confirmed these findings, concluding that indoor air is a more significant exposure source of trichloroethylene than outdoor air, even near major point sources such as chemical plants (Wallace 1986 Wallace et al. 1986a, 1986b, 1986c,... 

Exposure Levels in Humans. Human exposure levels to acrylonitrile can only be estimated based on average concentrations in air, food and water. Direct studies of personal exposure levels for individuals with exposures judged to be average and above average (e.g., people living near industrial sources or hazardous waste sites) would be helpful in improving total dose estimates, and in identifying exposure pathways of concern. 

Exposure data from 15 monomer extraction sites for the year 1995 (Table 7) indicated that in general personal exposure levels were below 5 ppm [11 mg/m- ]. Data from earlier years (1984-93) showed less than 10% of the measured concentrations exceeding 5 ppm [11 mg/m3] (Table 8) (ECETOC, 1997). 

Aamio P, Yli-Tuomi T, Kousa A, Makela T, Hirslkko A, Hameri K, Raisanen M, Hillamo R, Koskentalo T, Jantunen M (2005) The concentrations and composition of and exposure to fine particles (PM2.5) in the Helsinki subway system. Atmos Environ 39 5059-5066 Adams HS, Nieuwenhuijsen MJ, Colvile RN (2001a) Determinants of fine particle (PM2.5) personal exposure levels in transport microenvironments, London, UK. Atmos Environ 35 4557 566... 

Adams HS, Nieuwenhuijsen MJ, Colvile RN, McMullen MAS, Khandelwal P (2001b) Fine particle (PM2.5) personal exposure levels in transport microenvironments, London, UK. Sci Total Environ 279 29 14... 

Another important noise measurement is the daily personal exposure level of the worker, l-EP,d> which is measured over an 8-hour working day. Hence, if a person was exposed to 87dB(A) over 4 hours, this would equate to a Lep.ci of 84dB(A) since a reduction of 3 dB(A) represents one half of the noise dose. 

The ACGIH recommended maximum time-weighted average concentration in the workplace atmosphere for eight-hour daily exposure is 10 ppm. OSHA has set the permissible exposure level at 2 ppm. It maybe desirable to exclude alcohoHcs, persons with chronic disorders of the Hver, kidneys, and central nervous system, and those with nutritional deficiencies from working with chloroform. 

Ethylene oxide is sold as a high purity chemical, with typical specifications shown ia Table 14. This purity is so high that only impurities are specified. There is normally no assay specification. Proper sampling techniques are critical to avoid personal exposure and prevent contamination of the sample with trace levels of water. A complete review and description of analytical methods for pure ethylene oxide is given ia Reference 228. 

Has the employer implemented the use of engineering controls, work practices, and personal protective equipment to reduce and maintain employee exposure to or below published exposure levels for hazardous substances and health hazards not regulated by 29 CFR Part 1910, Subparts G and Z (e.g., heat stress, lifting hazards) [OSHA Reference. 120(g)(2)]... 

The lymphocytes from 31 patients exposed to various organophosphate pesticides were examined for chromosomal aberrations (Van Bao et al. 1974). Five of the patients were exposed to methyl parathion only. Blood samples were taken 3-6 days after exposure and again at 30 and 180 days. A significant (p<0.05) increase was noted in the frequency of stable chromosomal aberrations in acutely intoxicated persons (although such cells are eventually lost from the cell population). Two of the methyl parathion-exposed persons had taken large doses orally in suicide attempts. The study limitations include small sample size, absence of a control group, lack of quantification of exposure levels, and possible... 

Wallace LA, Pellizzari ED, Hartwell TD, et al. 1985. Personal exposures, indoor-outdoor relationships, and breath levels of toxic air pollutants measured for 355 persons in New Jersey. Atmos Environ 19 1651-1661. 

The significance of the exposure levels shown in the tables and figures may differ depending on the user s perspective. For example, physicians concerned with the interpretation of clinical findings in exposed persons may be interested in levels of exposure associated with "serious" effects. Public health officials and project managers concerned with appropriate actions to take at hazardous waste sites may want information on levels of exposure associated with more subtle effects in humans or animals (LOAEL) or exposure levels below which no adverse effects (NOAEL) have been observed. Estimates... 

Thermal burns result from the radiant heat emitted by a hydrogen fire and absorbed by a person, which is directly proportional to many factors including exposure time, burning rate, heat of combustion, size of the burning surface, and atmospheric conditions (mainly wind and humidity). For instance, thermal radiation flux exposure level of 0.95 W/cm2 may cause skin burns in 30 s. Cryogenic burns may result from contact with cold fluids or cold vessel surfaces. Exposure to large liquefied hydrogen spills could result in hypothermia, if proper precautions are not taken [17]. 

Leeser et al. (1990) study, because it was the lowest no-observed-adverseeffect level (NOAEL). Using the 8-h value of 1 ppm as the basis for time scaling to shorter durations, the conservative relationship of C3Xt=k was chosen for the derivations. The 10-minute (min) AEGL-1 was set equal to the 30-min value so as not to exceed the highest personal exposure concentration of 3.3 ppm in the well-conducted Leeser et al. (1990) study. 

A-nitrosodimethylamine (NDMA). A-Nitrosomorpholine (NMOR) is also produced in this process, but the origin of this pollutant is unknown. Samples collected from different tanneries showed airborne nitrosamine contamination ranging from 0.05-47 Xg/m3 NDMA (mean 3.4 pg/m3) and 0.05-2.0 pg/m3 NMOR (mean 0.2 pg/m3)64. Studies have indicated the possible risk of nasal cancer to workers exposed to NDMA at a daily exposure level of 440 pg NDMA/person/day and 20 pg NMOR/person/day65. Animals exposed to long-term inhalation of NDMA were found to have formed malignant tumours of mainly the liver and kidney66. 

Exposure Levels in Humans. Bromomethane is not normally measured in human tissues such as blood or urine, even in people exposed to high levels. This is because bromomethane is removed from the body very quickly after exposure ceases. Consequently, this is not likely to be a useful means of monitoring exposure of humans to low levels of bromomethane. Increased levels of bromide have been detected in blood of persons exposed to bromomethane in accidents or in the... 

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