Exposure, occupational models

Lioy P New Jersey University of Environmental and Occupational Health Sciences Institute, Piscataway NJ Refinement of exposure/dose models. Comparison of bioavailability of elemental waste laden soils using in vivo and in vitro analytical methodology DOE... 

Tischer, M. Brendendiek-Kamper, S. and Poppek, U. (2003), Evaluation of the HSE COSHH Essentials Exposure Predictive Model on the basis of BauA field studies and existing substances exposure data. Annals of Occupational Hygiene, Vol 47 No 5 pp 557-569. 

Schneider, T., Vermeulen, R., and Brouwer, D. (1999). A conceptual model for assessment of dermal exposure, Occup. Envimn. Med. 56,765-773. 

Phillips, A.M. and Garrod, A.N. (2001). Assessment of dermal exposure—empirical models and indicative distributions. Applied Occupational and Environmental Hygiene, 16, 323-328. 

Hawthorne, A., et al. (1987) Models for estimating organic emissions from building materials formaldehyde example. Atmos. Environ. 21, No. 2. Lewis, R. G., et al. (1986) Monitoring for non-occupational exposure to pesticides in indoor and personal respiratory air. Presented at the 79th Annual Meeting of the Air Pollution Control Association, Minneapolis, MN. 

Intermediate-duration inhalation studies establishing a threshold and dose-response for neurological and male reproductive effects in the rat would be useful since this is an area of potential concern for humans exposed to -hexane occupationally or near hazardous waste sites. The only other effects documented after inhalation exposure in animal models for this duration are respiratory effects, and these occur at... 

Exposure. The presence of the -hexane metabolite 2,5-hexanedione in the urine is a reasonably reliable marker for exposure to -hexane and has been correlated with air concentrations in the workplace. This is not a specific marker since 2-hexanone is also metabolized to 2,5-hexanedione. The levels of this metabolite in the urine associated with neurotoxicity are not known. A more sensitive marker for exposure may be the presence of pyrolidated proteins in the blood or hair, a result of the reaction of 2,5-hexanedione with the side-chain amino group of lysine (Graham et al. 1995 Johnson et al. 1995). These methods have only been tested after oral exposure to 2,5-hexanedione in the rat model. It would be very useful to know if measurement of pyrrole adducts or cross-linked proteins is also feasible after inhalation exposure to u-hexane in the rat model. Further development and validation of this method in an occupationally exposed population may then be useful. 

Comparative Toxicokinetics. The toxicokinetic studies available indicate that the rat is a good model for human neurotoxicity observed after occupational exposure to 77-hexane. Mild signs can be produced in chickens and mice, but these do not progress to the serious neurotoxicity observed in humans and rats. Toxicokinetic data from other species (absorption, distribution, metabolism, excretion) could provide insight on the molecular mechanism(s) of the species specificity of 77-hexane toxicity and would be valuable for predicting toxic effects in humans. 

Several methods have been developed to estimate the exposure to such emissions. Most methods are based on either ambient air quality surveys or emission modeling. Exposure to other components of diesel emissions, such as PAHs, is also higher in occupational settings than it is in ambient environments. The principles of the techniques most often used in exhaust gas analysis include infrared (NDIR and FTIR), chemiluminescence, flame ionization detector (FID and fast FID), and paramagnetic methods. 

Risk Assessment. The Chinery-Gleason model has the greatest potential for use in estimating exposures to chloroform in a household environment as well as for occupational exposures that result from dermal exposure. 

DAB was genotoxic in the comet assay inducing DNA damage in the stomach, colon liver, bladder, lung, and bone marrow. It is also mutagenic to Salmonella in the Ames test. Because of its demonstrated carcinogenicity in animals, human exposure to DAB by any route should be avoided. In recent years, this compound has been used only in laboratories as a model of tumorigenic activity in animals. It is not produced commercially in the United States and is of little occupational health importance. 

Wagner JC et al An animal model for inhalation exposure to talc. In Lemen R, Dement JM (eds) Dusts and Disease, 389pp. Proceedings of the Conference on Occupational Exposure to Fibrous and Particulate Dust and Their Extension into the... 

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