October 24, 2016
Peracetic acid or peroxyacetic acid (PAA) is a strong oxidant and is widely used in food processing, healthcare and other industries as a very effective biocide and bleaching agent. Exposure to high concentrations of PAA vapor can have adverse health effects and the ACGIH issued a STEL TLV® of 0.4 ppm for PAA in 2015.
The National Institute of Occupational Safety and Health (NIOSH) recognized the need for an Immediately Dangerous to Life and Health (IDLH) level and back in May 2015, NIOSH published a proposed IDLH of 0.64 ppm for peracetic acid (PAA). However, it was a small part of a larger notice that no-one outside of NIOSH noticed, and consequently there were no comments.
NIOSH had a very difficult task. It needed to develop an IDLH for PAA, but there is almost no published literature relating PAA exposure to symptoms in humans. In the end NIOSH primarily relied on an unpublished report from 1986 which studied PAA fogging at a poultry plant. This unpublished report was also relied on by the ACGIH in developing their STEL TLV for PAA and the US-EPA in developing the Acute Exposure Guideline Levels for PAA.
ChemDAQ is a founding member of the Aseptic and Antimicrobial Processing and Packaging Association (AAPPA), an industry association concerned with the safe use of PAA and other chemicals in food processing. Earlier this year after petitioning by the AAPPA and the Peroxy Compounds Task Force (PCTF), another industry group, NIOSH reopened the comment period for another 60 days.
Both the AAPPA and PCTF offered complementary comments. The PCTF’s arguments were based on the process and standards that NIOSH had employed in developing the IDLH, whereas the AAPPA’s comments, critiqued the literature that NIOSH relied on and offered additional data on the relationship between the exposure to PAA and symptoms experienced. ChemDAQ worked closely with other members of the AAPPA in developing these comments.
In brief summary, the Fraser-Thorbinson report was for a fogging application and the symptoms experienced were largely due to the PAA/hydrogen peroxide aerosol rather than the vapor and so the data was not applicable to an IDLH for PAA vapor. In addition, other data was presented which recommended that the PAA IDLH be set at least 2 ppm.
At the time of writing this blog, the comment period has closed and NIOSH is considering the responses. If anyone has additional data that would be useful to NIOSH, I would like to encourage them to submit the data to NIOSH anyhow, even though the comment period has closed, since NIOSH would like all the information they can get.
 Fraser, JAL, Thorbinson A. Fogging trials with Tenneco Organics Ltd., at Collards farm. 30 June 1986.
Note TLV is a registered trademark of the ACGIH.