Comparison Between OSHA PELs and EH40 Occupational Exposure Limits

Here in the US we are used to thinking about OSHA and permissible exposure limits (PELs), but every industrialized country has their own occupational exposure limits. Many countries or provinces either base their exposure limits on the ACGIH TLVs or reference them exactly.

The European Union has developed its own set of occupational exposure levels which are implemented in each EU country. The UK workplace exposure levels (WELs) are summarized in a document called EH40. The EH40 document is regularly updated and the last version was published in 2011 and is available from the UK’s Health and Safety Executive (analogous to OSHA) for £15 paper copy or free download . The EH40 also has a lot of useful information, such as how exposure limits are calculated etc.

It is interesting to make a comparison between the EH40 exposure values and the OSHA PELs in 29 CFR 1910.1000 and other OSHA standards for a few select compounds relevant to disinfection and sterilization in food and healthcare. In general the exposure limits are similar, which is to be expected since published research reports relevant to the effect of chemical occupational exposure are available world wide and neither standard is developed in a regulatory vacuum.

Ethylene Oxide:
OSHA 1 ppm 8hr TWA, 5 ppm 15 min TWA
EH40 5 ppm 8 Hr TWA

OSHA 0.75 ppm 8 Hr TWA, 2 ppm 15 min TWA
EH40 2 ppm 8 Hr TWA, 2 PPM 15 min TWA

OSHA n/a
EH40 0.05 ppm 8 Hr TWA, 0.05 ppm 15 min TWA

Hydrogen Peroxide:
OSHA 1 ppm 8 Hr TWA
EH40 1 ppm 8 Hr TWA, 2 ppm 15 min TWA

OSHA 0.1 ppm 8 hr TWA
EH40 0.2 ppm 15 min TWA

This limited comparison shows that the OSHA standard is more stringent for ethylene oxide and formaldehyde (both fairly recent standards). Glutaraldehyde is not listed by OSHA, though OSHA recognizes the harmful effects of glutaraldehyde and provides guidance for its safe use. Unlike the EH40 values which are periodically updated, the OSHA PELs are still largely the same as they were when first promulgated in 1972. OSHA is aware of the senior status of its PELs and is planning to update them.

One notable difference is the short term exposure limit (STEL) for hydrogen peroxide in the EH40. Hydrogen peroxide is widely used in healthcare and food processing for sterilization and disinfection and the STEL emphasizes the importance of avoiding even short term exposure to low ppm concentrations of hydrogen peroxide vapor.

While the EH40 WELs have no legal standing in the US, they can be used to provide an industry standard for what constitutes a safe level, in a similar manner, industry standards such as the ACGIH’s threshold limit values (TLVs); and are particularly useful for those compounds for which there are no OSHA PELs or for which the OSHA PELs are particularly obsolete.

However, several new compounds finding use in healthcare and the food industry such as peracetic acid and o-phthalaldehyde are listed in neither the OSHA PELs nor the EH40. While the EH40 is updated more regularly than the OSHA PELs, as with any government action, the regulatory wheels move slowly. Users should therefore consult other reliable sources to find appropriate safety information. The ACGIH had led the development of occupational exposure standards for over five decades and continues to lead today for example with its proposed STEL for PAA of 0.2 ppm (15 min TWA).

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