Regulations (Preambles to Final Rules) - Table of Contents|
| Record Type:||Occupational Exposure to Methylene Chloride|
| Title:||Section 9 - IX. Environmental Impact|
IX. Environmental Impact
This section analyzes the impact on the environment of changing the standard for methylene chloride (MC) to an eight-hour time weighted average (TWA8) permissible exposure limit (PEL) of 25 parts per million (ppm), with a 125 ppm 15-minute short-term exposure limit (STEL) and ancillary requirements. It is based principally on information collected for OSHA by CONSAD Research Corporation and its subcontractor, PEI Associates Inc., and reported in Economic Analysis of Draft Regulatory Standard for Methylene Chloride, 1990, OSHA Docket, Ex. 15, and also draws upon other materials in the OSHA docket.
Current uses of methylene chloride involve releases to the air through venting of storage tanks or drums and through evaporation of MC during the performance of various activities such as paint stripping and cold cleaning indoors or outdoors. The volume of MC emitted as a percentage of MC used varies greatly among industries. Some processes, such as polyurethane foam manufacturing and paint stripping, typically release 100 percent of the MC to the atmosphere (Ex. 15). Other uses, such as solvent recovery and the manufacture of methylene chloride, involve less than 1 percent of the MC used being emitted to the atmosphere (Ex. 15). In addition, air, water, or solid waste pollution may occur as a result of the disposal of waste residues containing MC. Additional details by application group are presented in CONSAD's report [Ex. 15].
Future environmental releases of methylene chloride resulting from the final standard will largely be a function of how it affects the demand for methylene chloride and for its substitutes. The demand for methylene chloride has been declining (e.g., generally, it is no longer being used in formulating hairsprays). Any regulatory action by OSHA is expected to further reduce the demand for MC and thus the extent of its environmental releases.
Although it is technically possible to substitute chlorofluorocarbons (CFCs) for methylene chloride in electronics and foam blowing, OSHA does not expect the revision of the MC standard to have any such effect. CFC products are significantly more expensive than MC products and are themselves being phased out or banned because of their effects on the environment.
To the extent that firms might have to use greater quantities of substitute chemicals to get the same effects formerly obtained with MC, waste residues and disposal costs would increase. On the other hand, increases in MC leak prevention and recycling would improve the environment.
The Paint Remover Manufacturers Association (PRMA) has charged that the standard would cause "massive amounts" of methylene chloride to be emitted into the atmosphere (Ex. 19-11). In Chapter III, OSHA noted that it could find no convincing argument by PRMA as to why the total amount emitted after installation of exhaust ventilation would differ significantly from the amount now simply leaking into the atmosphere.
At informal public hearings, PRMA stated that "an exposure level of 25 PPM is so low that it brings into the issue the formation of vapor clouds with levels of greater than 25 PPM that could move in and around the neighborhood," allegedly through decomposition of the MC [Tr. 245, 9/17/92]. There is no evidence that this hypothetical situation has ever occurred. PRMA may have confused decomposition with diffusion [Tr. 940-941, 9/21/92]. At Eastman Kodak Company, which currently emits more methylene chloride into the atmosphere than any furniture stripper possibly could, the chemical has diffused so rapidly that no clouds of MC have been formed [Tr. 1237-1238, 9/22/92].
Generally, it is not expected that any significant environmental impact will result from revision of the methylene chloride standard.
- [62 FR 1494, January 10, 1997]
|Regulations (Preambles to Final Rules) - Table of Contents|