Workplace Environmental Exposure Levels Committee
The mission of the committee is to produce guides on exposure levels when no legal or authoritative limits exist.
Goals and Objectives
Goals:
- Develop Workplace Environmental Exposure Level (WEEL) guides for chemical and physical agents and stresses.
- Disseminate up-to-date WEEL guides and supporting documentation.
Objectives:
- Make appropriate recommendations about exposure levels to standards-setting bodies.
- Update existing WEELs as new information becomes available.
- Disseminate WEELs and supporting documentation through publication by the AIHA national office.
Strategies:
- Assemble and evaluate available information relevant to setting exposure levels.
- Cooperate with the ACGIH TLV® Committee and similar organizations in setting safe exposure levels.
- Identify the agents and stresses being addressed by the WEEL Committee to other authoritative organizations.
2,3,3,3-TETRAFLUOROPROPENE (HFO 1,2,3,4 yf) RATIONALE
The primary point of departure for the WEEL is the mortality seen in the adult rabbits at 5,500 ppm(WIL 2008), although PBPK modeling shows that the rabbit uptake is twice that of humans. There was a clear NOEL at 4,000 ppm, yet this mortality was not seen at these same levels of exposure in rats.(Schuster, 2008) In the 4-hour acute toxicity study, no mortality was seen at 405,800 ppm and in several repeat exposure inhalation studies no treatment related toxicity was seen at the highest level tested, 50,000 ppm.(Huntingdon 2004) However, there were unexplained deaths in rabbits at 10,000 ppm during the reproductive study. This WEEL would also be protective of developmental effects.(TNO 2005)
RECOMMENDED WEEL GUIDE
500 ppm as an 8-hour TWA
References:
AIHA has the disc of all the references for this document that was presented to them in person on October 1, 2008. However, attached are the refs cited in the rationale.