EPA Publishes Final Risk Evaluation for 1,2-Dichloroethane
A final risk evaluation published recently by EPA identifies “unreasonable” risks to workers associated with certain conditions of use of the chemical 1,2-dichloroethane, which is primarily used to make vinyl chloride. According to the agency, 1,2-dichloroethane is “a volatile, colorless, and oily liquid with a chloroform-like odor,” and the 15 conditions of use that “significantly contribute to the unreasonable risk to workers” include manufacturing; repackaging, recycling, and other processing operations; industrial uses in adhesives, sealants, lubricants, and greases; commercial use as a laboratory chemical; and disposal. EPA’s findings are based on both non-cancer health effects and cancer risk related to inhalation and dermal exposures to workers. EPA anticipates that occupational non-users will also be exposed to the chemical via inhalation but not the dermal route as this group is not expected to directly handle 1,2-dichloroethane. The chemical’s high vapor pressure contributes to concerns regarding inhalation exposure.
“Workers with the greatest potential for exposure are those who work directly with the chemical in environments where 1,2-dichloroethane is manufactured, processed, or disposed of,” EPA’s risk evaluation states.
As part of the risk evaluation, EPA calculated an existing chemical occupational exposure value for inhalation exposures to 1,2-dichloroethane of 0.014 ppm, or 0.058 mg/m3, as an eight-hour, time-weighted average (TWA). The risk evaluation also includes a 15-minute short-term occupational exposure value (STEV) of 0.46 ppm, or 1.9 mg/m3. A table summarizing different occupational exposure limits for 1,2-dichloroethane states that EPA’s eight-hour TWA value and its STEV are “not considered regulatory limits.”
The 0.014 ppm occupational exposure value is the most sensitive and is based on lifetime cancer inhalation unit risk, EPA explains. The current OSHA permissible exposure limit for 1,2-dichloroethane, adopted in 1979, is 50 ppm as an eight-hour TWA. OSHA acknowledges that many of its PELs are outdated and inadequate for protecting workers. Other eight-hour TWAs for 1,2-dichloroethane are the NIOSH recommended exposure limit, which is set at 1 ppm, and the ACGIH Threshold Limit Value, which is 10 ppm.
The Toxic Substances Control Act (TSCA) requires EPA to develop a rule to protect workers from the risks identified in the risk evaluation. The agency could set exposure limits for 1,2-dichloroethane as part of its risk management rule.
“Any existing chemical exposure limit (ECEL) established for occupational safety risk management purposes could differ from the occupational exposure value presented in [an appendix to this risk evaluation] based on additional consideration of exposures and non-risk factors consistent with TSCA section 6(c),” EPA says.
The final risk evaluation and supporting documents can be found on the agency’s webpage on 1,2-dichloroethane.
Related: A recent Synergist series on TSCA has discussed methodological and practical challenges of TSCA’s occupational exposure assessment approach as well as potential changes to the implementation of TSCA based on litigation, policy changes, and possible legislation. The next article in the series, to be published in the June/July issue, will focus on the importance of engagement among AIHA members on TSCA-related matters.