National Toxicology Program

The NTP is coordinating an effort between NIEHS/NIH and NIOSH/CDC to better characterize worker exposures, educate workers, and identify occupational health research gaps. Current efforts are addressing worker exposure to asphalt fumes and 1-bromopropane and future initiatives are proposed for occupational mixtures such as welding fumes, abrasive blasting compounds, and metal working fluids. An industry consortium has petitioned the EPA to list 1-bromopropane as an alternative for ozone-depleting solvents for general metals, precision, and electronics cleaning, aerosols, and adhesives. If this occurs, there is the potential for a vast increase in the exposure of workers and the public to this compound. Currently an appropriate occupational exposure limit for 1-bromopropane is not available. Asphalt fumes generated during road paving have been linked to acute irritation of mucous membranes and skin, but to date no cancer risk has been established. A study is underway to characterize asphalt fume composition including polycyclic aromatic hydrocarbons, develop a bioanalytical method that can be used to characterize exposure in laboratory inhalation studies, and assay gene expression response to asphalt fume exposure.