As we have discussed on this blog before, peracetic acid, also known as peroxyacetic acid (PAA), can be quite hazardous if workers are exposed to even a small concentration of the gas. Research has confirmed that PAA is a primary irritant and a known tumorigen, as well as a possible animal carcinogen. Exposure to the gas can be severely irritating to the eyes, nose, throat, and lungs as well as cause circulatory collapse. For these reasons and more, we feel strongly that OSHA should develop a permissible exposure limit (PEL) for PAA.
The current PEL for hydrogen peroxide (H2O2) is 1ppm, due to its classification as an oxidizer. However, PAA is a stronger oxidizer than H2O2 and the effects of exposure to H2O2 are mitigated by the action of the catalase enzyme in the body, which helps to decompose the compound into hydrogen and water. In light of this, the PEL for PAA should certainly be lower than that of H2O2, hence, less than 1ppm.
The Environmental Protection Agency sets Acute Exposure Level Guidelines (AEGL’s) for hazardous gases like PAA. The first AEGL is similar to an 8 hour PEL that OSHA uses in that it represents the “airborne concentration…of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects.” For PAA, the EPA sets the 8hr AEGL 1 at 0.17ppm. Furthermore, a 2001 study published by the British Occupational Hygiene Society recommended a Threshold Limit Value (TLV) of 0.2ppm, based on effects researchers observed in mice after exposure to PAA. Lastly, Solvay, a large manufacturer of PAA, recommends a time weighted average of 0.15ppm as the exposure limit.
In light of this evidence, it seems fitting to establish an OSHA PEL for PAA somewhere between 0.1 and 0.2 ppm. This would help to increase worker awareness and safety in facilities that utilize high concentrations of this potentially hazardous gas.