December 2014

PELs demystified

By Ellis Brasch

On Oct. 9, federal OSHA announced "a national dialog with stakeholders" for dealing with worker exposures to hazardous chemicals. The announcement came in the form of a request for information from the public on the best approaches for managing hazardous chemical exposures and updating the agency's outdated permissible exposure limits.

If you are an industrial hygienist, you are familiar with the term, permissible exposure limit – more commonly known by its acronym, PEL. But if you do not know what a PEL is, you are not alone. Many, if not most, employers and employees have no idea what a PEL is, let alone how to manage chemical exposures.

What are PELs and why should you be concerned about them?

PELs are OSHA's mandatory limits for air contaminants above which workers must not be exposed. PELs generally refer to how long a worker can be exposed to a hazardous substance. They are expressed three ways:

1. Time weighted averages (PEL-TWA), which establish average limits for eight-hour exposures; it is usually expressed as an average exposure over an eight-hour workday for a 40-hour workweek.

2. Short-term limits (PEL-STEL), which establish limits for short term exposures for a continuous 15-minute period.

3. Ceiling limits (PEL-C), which are never-to-be-exceeded maximum exposure levels.

Currently, there are PELs for about 470 substances that OSHA lists in tables (referred to as "Z-tables") in Subpart Z of its general industry, construction, and maritime rules.

OSHA is calling for a national dialogue on PELs because the agency has been unable to successfully update them since 1971, when they were adopted from federal health standards originally set by the Department of Labor through the Walsh-Healy Act. OSHA's PELs are still based on research performed during the 1950s and 1960s and do not take into consideration newer research on chronic health effects occurring at lower occupational exposures. The agency acknowledges that the limits do not adequately protect workers.

OSHA's unsuccessful attempts to update PELs stem from legal challenges, objections from industry and labor leaders, and the requirements imposed by the OSH Act.

Compounding the problem with PELs is that no one knows how many chemicals are in commence now (the American Chemistry Council estimates there are approximately 8,300 chemicals in commerce in significant amounts) or how many of those chemicals are hazardous.

Are there alternatives to OSHA's PELs?

OSHA PELs are part of a broader class of exposure limits – called occupational exposure limits or OELs – that also establish how long a worker can be exposed to a hazardous substance. What is important to remember is that the OSHA PELs are mandatory – employers have to comply with them even though they are out of date. The alternatives to OSHA PELs are guidelines, but they are generally considered to be more protective than OSHA PELs.

Here are examples of alternative OELs and the organizations that established them:
OEL What it is Who established it
TLV (Threshold limit value) Airborne concentrations of chemical substances under which it is believed that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse health effects. ACGIH (American Conference of Governmental Industrial Hygienists)
REL (Recommended exposure limits) Exposure limits recommended by NIOSH as being protective of worker health and safety over a working lifetime. NIOSH (National Institute for Occupational Safety and Health)
CAL/OSHA PEL Permissible exposure limits enforced under California OSHA's jurisdiction. California OSHA
BEI (Biological exposure index) Procedure for estimating the amount of material contained in the human body by measuring it in tissue, body fluids, or exhaled air. ACGIH (American Conference of Governmental Industrial Hygienists)

In 2013, OSHA annotated its existing Z-Tables with the occupational exposure limits established by Cal/OSHA, NIOSH, and the ACGIH. The agency maintained that its own PELs were still mandatory but recommended that "employers should consider using the alternative occupational exposure limits because the agency believes that exposures above some of these alternative occupational exposure limits may be hazardous to workers, even when the exposure levels are in compliance with the relevant PELs." Later that year, OSHA also offered employers a step-by-step toolkit that offered information, methods, tools, and guidance on using safer chemicals in their workplaces.

While the annotated tables gave employers the option to consider using "safer" OELs, some employer organizations wondered if OSHA was attempting to impose more stringent requirements on employers and enforce them through the agency's General Duty Clause.

Are Oregon OSHA's PELs the same as federal OSHAs?

Generally, Oregon OSHA's PELs are identical to federal OSHA's PELs. There are some exceptions, however. They are identified in bold print in Oregon's rules for air contaminants in general industry (437-002-0382), construction (437-003-1000), and agriculture (437-004-9000).

Non-OEL controls

OELs will always be an essential part of controlling workplace chemical exposures, but there are other control strategies that do not rely solely on the precise targets set by PELs and other occupational exposure limits.

These so-called non-OEL approaches focus more on determining types of controls necessary to reduce exposures rather than specific quantitative requirements. They may offer promise for the future of chemical management if they are technically and economically viable. Here are six examples:

1. Informed substitution to safer chemicals and processes: Uses the most current information on hazardous chemicals to inform employers about safer substances and non-chemical alternatives.

2. Hazard Communication and GHS: Uses the HazCom 2012 classification system as a tool for determining hazard classes and controls.

3. Health hazard banding: Organizes chemicals with similar toxicities into hazard groups, or bands. Hazard banding combined with information on worker exposures may be a useful risk assessment tool when toxicity data are not available.

4. Occupational exposure banding: A method proposed by NIOSH for assessing chemicals; the method sorts chemicals into five bands, with each band representing a different hazard level.

5. Control Banding: Uses hazard statements from labels and safety data sheets as guidelines for establishing chemical controls.

6. Task-based exposure assessment and control: Categorizes job tasks in terms of exposure potential and implements controls to reduce exposures to safe levels. End

If you want to receive the Resource Newsletter, sign up for future issues here.

Reprinting, excerpting, or plagiarizing any part of this publication is fine with us. Please send us a copy of your publication or inform the Resource editor as a courtesy. If you have questions about the information in Resource, please call 503-378-3272.

For general information, technical answers, or information about Oregon OSHA services, please call 503-378-3272 or toll-free within Oregon, 800-922-2689.