The ACGIH has recently set a Threshold Limit Value (TLV) Short Term Exposure Limit (STEL) for Peracetic Acid (PAA) of 0.4 ppm, calculated as a 15 minute time weighted average (TWA). This article discusses the legal significance of a TLV compared to an OSHA Permissible Exposure Limit (PEL).

If OSHA issues a PEL, it is a legal requirement. “Thou shalt not expose thine employees to more than 1 ppm ethylene oxide , calculated as an 8 hour TWA.” Currently, there is no PEL for PAA.

The ACGIH is a private organization and TLVs are not legal requirements. Some jurisdictions, including some Canadian provinces directly reference the ACGIH TLVs and so in those areas the TLC’s are law; but the legal authority is coming from the local legislature, not the ACGIH.

In the US, the ACGIH TLVs are important for two reasons. The first is that an employer using PAA knows there is PAA vapor in the air, may even have measured the concentration, but does not know what concentration is safe. Even if the employer finds a research paper that recommends an exposure level of 0.2 ppm, it does not mean that the employer has to believe that is the safe level. There may be other papers out there with different recommended exposure values.

The ACGIH on the other hand is pre-eminent in the world of industrial hygiene and if the ACGIH sets a TLV, people can rely on it. Conscientious employers, who want to do the right thing, can use the TLV to determine what is a safe work environment.

The other argument is more legal. Suppose OSHA wanted to prosecute an employer using the general duty clause , for having a dangerous work environment for which there was no specific PEL (e.g. PAA), or an individual wanted to sue the employer for negligence because of over exposure; what elements would they have to show?  

1) harm or injury

2) cause, i.e. the injury was caused by the exposure

3) there is a relevant standard of exposure

4) the employer failed to meet that standard.

A published paper does not constitute a recognized standard; but an ACGIH TLV normally does. If OSHA or the plaintiff can show that someone was exposed to PAA greater than the TLV, that they suffered an injury and the injury was caused by the exposure, then they probably have a case.

Note: TLV is a registered trademark of the ACGIH.

This blog is intended to give general advice not related to any specific case; consult a lawyer if you have specific legal questions.