Chemrisk.Com Area of Expertise

Volatile organic compounds (VOCs) are hydrocarbon chemicals that readily evaporate into air at ambient temperatures and pressures. In the environment, the potential for VOCs to evaporate is determined by a number of factors including water solubility, temperature, vapor pressure and exposed surface areas. Potential exposure to VOCs can occur due to vapor emissions from outdoor emission sources, evaporation from open storage units of liquid product, off-gassing consumer products, or indoor air impacted by vapor intrusion from soil or groundwater VOC contamination. Several methods can be used to estimate exposure including literature reviews, environmental fate and transport models, simulation studies and environmental sample collection. Although the predominant exposure pathway for VOCs is inhalation of ambient air, exposure can also occur as a result of dermal uptake or ingestion.

ChemRisk^® professionals have evaluated VOC exposures and risks in both environmental and occupational settings. We are proficient in hazard assessment, exposure scenario development and risk characterization methodologies and models required to assess VOC worker, consumer, sensitive sub-population and ecological risk. Our scientists have performed evaluations for a wide variety of VOCs including extensive experience with benzene, chlorinated hydrocarbon solvents and formaldehyde.

We recognize the special considerations necessary for solvent and volatile organic chemical evaluations, and have specialized in the following areas:

Indoor and outdoor air dispersion modeling
Simulation studies
Mass transfer relationships to characterize evaporation
Probabilistic (Monte Carlo) assessments
Physiologically-based pharmacokinetics (PB-PK) modeling
Child-specific risk assessment
Regulatory environmental fate and transport models
Background levels in the ambient and indoor environment
Relative source contribution
Environmental chemistry, partitioning and half-lives

Benzene
Benzene is ubiquitous in ambient air and has been used as an industrial solvent in a variety of different processes for more than one hundred years and is also present as part of complex mixtures such as mineral spirits, diesel fuel or gasoline. There has been awareness for decades that significant exposures to benzene could result in suppression of one or more of the blood forming elements and with a sufficient dose and duration may result in acute myeloid leukemia (AML).

Chlorinated Solvents
Trichloroethylene, tetrachloroethylene and dichloromethane (methylene chloride) are three examples of chlorinated hydrocarbon solvents that have been commonly used in industry and in consumer products. These solvents are used for tasks such as degreasing metal parts, dry-cleaning or stripping paint. Dichloromethane is also used to decaffeinate coffee and has several uses in the food flavorings industry.

Formaldehyde
Formaldehyde is the simplest type of aldehyde, and can be formed both naturally and in industrial processes. It is a constituent of car exhaust and cigarette smoke, and has historically been used as a disinfectant, preservative, and component of composite wood resins.

Scientists at ChemRisk^® have more than 100 years of combined professional experience studying these chemicals and have published more than 35 papers which address exposure potential in various industries or the health effects. In addition to environmental fate and toxicological assessments of individual VOCs, our staff has completed more than 100 risk assessments evaluating the possible health effects of complex mixtures of VOCs when present in soil, groundwater, drinking water, workplace air, the home, and the ambient air. Our staff frequently serves as consulting or testifying experts in litigation where historical exposure to VOCs has been alleged.

Some of our relevant project experience in this area includes:

conducting a simulation study to determine the presence of benzene vapors associated with the use of mineral spirits;
analyzing the benzene content of numerous soft drink beverages to assess the benzene dose associated with typical and upper-bound soft drink consumption; and
developing an indoor air model to assess vapor accumulation and residential exposure to chlorinated VOCs in groundwater.

ChemRisk^® Publications

Gaffney, S.H., J.M. Panko, K.M. Unice, A.M. Burns, M.L. Kreider, R.H. Gelatt, L.E. Booher, and D.J. Paustenbach. 2009. Occupational exposure to benzene at the ExxonMobil refinery in Baytown, TX (1978-2006). J Exp Sci Env Epidemiol. Advance online publication, October 28, 2009. doi: 10.1038/jes.2009.53.

Panko, J.M., S.H Gaffney., A.M. Burns, K.M. Unice, M.L. Kreider, L.E. Booher, R.H. Gelatt, J.R. Marshall, and D.J. Paustenbach. 2009. Occupational Exposure to Benzene at the ExxonMobil Refinery at Baton Rouge, Louisiana (1977–2005) Journal of Occupational and Environmental Hygiene, 6(9): 517-29.

Gaffney, S.H., E.C. Moody, M.A. McKinley, J.S. Knutsen, A.K. Madl, and D.J. Paustenbach. 2008. Worker exposure to methanol vapors during cleaning of semiconductor wafers in a manufacturing setting. J Occup Environ Hyg. 5:313-24.

Finley, B.L., D.J. Paustenbach, J. Nethercott, and J. Fowler. 1995. Risk assessment of the allergic dermatitis potential of environmental exposure to hexavalent chromium. J Toxicol Environ Health. 44(3):377-383.

Haws, L.C., J.A. Tachovsky, E.S. Williams, L.L.F. Scott, D.J. Paustenbach, and M.A. Harris. 2008. Assessment of potential human health risks posed by benzene in beverages. J Food Sci. 73(4):T33-41.

Madl, A.K. and D.J. Paustenbach. 2002. Airborne concentrations of benzene and mineral spirits (stoddard solvent) during cleaning of a locomotive generator and traction motor. J Toxicol Environ Health A. 65(23):1965-79.

Williams, P.R.D., J.M Panko, K. Unice J.L. Brown, and D.J. Paustenbach. 2008. Occupational exposures associated with petroleum-derived products containing trace levels of benzene. J Occup Environ Hyg. 5(9):565-574.

Williams, P.R.D., K. Robinson, and D.J. Paustenbach. 2005a. Benzene exposures associated with tasks performed on marine vessels (circa 1975 to 2000). J Occup Eviron Hyg. 2(11):586-99.

For Additional information, please contact Ken Unice at kunice@chemrisk.com; (412) 281-6900, ext. 1023.