by Eileen Senn, MS

The multiple options that OSHA is considering to address their badly outdated rules for chemical hazards were described in my November 17 post. They include updating OSHA Permissible Exposure Limits (PELs) which are erroneously considered to be safe levels for chemicals in workplace air. In reality, it’s wrong to call them “safe” levels. Most PELs are based on toxic ignorance, that is, our lack of sound and complete toxicology data on most chemicals. It is the rare chemical that has been tested for all disease endpoints including cancer and effects on reproductive, endocrine, and immune systems. When new toxicology data becomes available, the need for more protective, lower air levels and exposure limits is invariably demonstrated, but OSHA’s PELs remain stuck in time.

Some OSHA stakeholders, notably the American Industrial Hygiene Association (AIHA), believe that updating PELs should be a high priority for OSHA. A recent AIHA survey of their members determine that updating OSHA PELs is their number one policy priority for 2011-2012, beating out adoption of an OSHA Injury and Illness Prevention (I2P2) rule, which ranked second. AIHA’s 10,000 members work primarily for business and industry but also for government, academia, and labor.

PELs only really help if workers’ exposures are found to exceed them. Those who support updating and lowering PELs, may believe this will make a difference in OSHA’s ability to find PEL violations, issue citations, and thereby protect workers. I am doubtful, however, because new PELs are not likely to be that different from old PELs. I believe for many substances, the PELs would have to be at least a hundred times lower to be truly health-protective. For a brief period of time in 1989 before an OSHA standard with lower PELs was overturned by the U.S. Court of Appeals, inspectors still found high rates of compliance. For example, the PEL for 2-butoxy ethanol was cut in half, from 50 ppm to 25 ppm but the compliance rate remained at 100 percent. The best improvement was for n-hexane where the PEL was cut by a factor of ten from 500 ppm to 50 ppm and the compliance rate dropped from 100 percent to 92.1 percent.

There is a huge difference between using an occupational exposure limit (OEL) as a guideline and using them as a legal limit. When an OEL is used as guideline, it is not meant to distinguish a safe or unsafe level. When used as a legal limit they are. When OSHA turned American Conference of Governmental Industrial Hygienists (ACGIH) guidelines into legal limits in 1972, OSHA did exactly what the ACGIH, creators and marketers of the Threshold Limit Values (TLVs®) consistently warned government agencies not to do. A 1988 ACGIH policy statement says:

It is not appropriate for individuals or organizations to impose on the TLVs® their concepts of what the TLVs® should be or how they should be applied or to transfer regulatory standards requirements to the TLVs® .

By turning guidelines into legal limits, OSHA froze the limits in time and created a false line between safe and unsafe exposures. OSHA and workers have been paying the price ever since. OSHA sampling almost always shows that chemical exposures are perfectly legal. Regrettably, the reporting to workers of “in-compliance” exposure levels is rarely accompanied by an explanation that the “in-compliance” level is not necessarily safe. To paraphrase the new leadership in the House of Representatives, PELs are “worker-killing underegulation” – a license to overexpose workers.

But it is not just their fossilized state that is a problem. Many industrial hygienists both inside and outside of OSHA, misuse the PELs by reducing chemical exposure assessment into just air sampling. Few industrial hygienists use the full spectrum of chemical assessment exposure tools: interviews of workers, wipe sampling to evaluate exposure via skin contact and ingestion, observation and evaluation of existing controls, and evaluation of exposure to chemicals without PELs. Instead, the only thing that counts is whether or not air sampling shows PEL violations. No violations, no citations, no worker protection.

Adding to the problem is the fact that it is extremely easy to manipulate air sampling to avoid finding the worst exposure. In my experience, employers and their consultants do this all the time. And many employers make it difficult for OSHA industrial hygienists to sample the worst exposures. Employers shut down or alter operations so they don’t reflect the typical conditions to which workers are exposed.

To top things off, OSHA has minimal staff and resources in occupational medicine and nursing. As a result, chemical exposure problems are rarely investigated by determining whether affected workers have symptoms or illnesses associated with exposure to the chemical or elevated levels of chemicals in their bodies. This could be changed if the resources currently being squandered in futile efforts to enforce PELs were directed to a more comprehensive enforcement strategy for chemicals.

While I am primarily addressing the PELs listed in Tables Z-1, Z-2, and Z-3 in the OSHA standard on Air Contaminants, 29 CFR, 1910.1000, the PELs for 16 chemicals in 20 OSHA comprehensive standards are nothing to brag about either. OSHA’s statute requires the agency to factor in economic and technological feasibility in setting exposure limits. As a result, many allow high life-time risk of cancer. For example, the most recent OSHA comprehensive standard, for chromium VI, allows a significant excess risk of cancer—at the “safe PEL” exposure limit there is still an estimated 10 to 45 excess cancers per 1,000 workers.

To the extent that OSHA’s comprehensive standards have improved working conditions, it is not clear how much the PELs had to do with it. OSHA has conducted relatively few lookback reviews of their standards. After a recent review, OSHA claimed the PEL was key to the success of the methylene chloride standard. But could it just as well have been, at least in part, the considerable pressure on the affected industries by the standard-setting process and other requirements of the standard such as regulated areas, medical removal, and worker education? For the general industry and construction lead standards, blood lead monitoring has certainly been at least as important to documenting exposure problems and forcing change as PELs.

OSHA should liberate itself from PELs. They drain and damage the agency and will continue to do so until OSHA revokes them. (Doing so administratively would be ideal, since rulemaking to rescind them would be another drain on scarce OSHA resources.) A popular idea at the June 24, 2010 1-day OSHA stakeholder meeting on PELs was for OSHA to issue an annotated list of PELs noting the basis and limitations of each one. That would include what target organ or endpoint was used to set the limit, whether the data was from animals or humans, the quality of the data, the quantity of the data, protection factors used, who paid for the research to produce the data, and most importantly, data gaps. The easiest way for OSHA to do this would be to work with ACGIH to link to the 1971 documentation of the TLVs® from which the PELs were adopted.

OSHA cannot realistically lower PELs to levels that would be protective of health because there is not enough time, money, toxicity data, or political capital to do the job right, even if limits derived through risk assessment are used, for example, those from EPA and California. The European Union’s REACH approach will take decades before even a small percent of chemicals have exposure limits. It remains to be seen if the limits being produced by EU chemical manufacturers are based on good enough science and ethical procedures.

If OSHA stops relying on PELs, it will be a big adjustment for many industrial hygienists. It is impossible to overstate how completely the comparison of air sampling results with Occupational Exposure Limits (OELs) dominates our profession. If they learn nothing else, every industrial hygienist is taught to evaluate workplace chemical exposures by collecting air samples. Lists of OELs for evaluation of sampling results are the iconic tools that no industrial hygienist seems able to live without. The need for air sampling and OELs is rarely questioned, the science behind these practices evaluated, or alternatives sought or practiced.

For nearly 5 decades, no one critically examined the scientific data underlying the TLVs®. It took two non-industrial hygienists to trigger a crises of confidence in the late 1980′s when environmental consultant Barry Castleman, ScD and occupational physician Grace Ziem, MD, DrPH exposed corporate influence and other serious shortcomings in setting TLVs®.

According to ACGIH, the TLVs® are time-weighted-average concentrations for an 8-hour work day and a 40-hour work week to which “nearly all workers may be repeatedly exposed without adverse health effects.” However, in 1990, industrial hygienists Steven Rappaport Ph.D. and the late Stanley Roach, DSc, Ph.D. of the University of California at Berkeley found that TLVs® reflected the levels of exposure which were perceived to be achievable in industry, not health considerations.

ACGIH recovered from these revelations and then a costly 2004 lawsuit that according to ACGIH

“threatens the credibility of the occupational hygiene profession and the ability of occupational hygienists to continue their work”.

ACGIH instituted conflict of interest policies in 2000. Today, their TLV® Committee continues to generate OELs for chemicals, approximately 700 to date. For more than a half-century, ACGIH TLVs® have been exported to numerous other countries. Recently, however, the Netherlands found the underlying toxicological database met their criteria for a health-based OEL for only about 40% of the compounds and revoked the offending TLV®-based limits.

OSHA held a webchat January 5, 2011 on its regulatory agenda. In response to questions about updating PELs, OSHA stated:

Unfortunately, OSHA does not have the statutory authority to simply adopt ACGIH TLVs®. While OSHA was allowed to do this in the first 2 years after OSHA was created in 1971, the agency must now go through rulemaking to set new permissible exposure limits. This process is often quite lengthy.

In order to adopt the ACGIH exposure limits, OSHA would still be required to go through the rulemaking process. It is time to try a different approach to regulating employee exposure to hazardous chemicals. Rather than using formal rulemaking, which has failed in the past, OSHA is considering programmatic approaches to updating the PELs. We are also looking at new way to proceed, and we are currently in the process of selecting 10-15 chemicals to begin targeting through our enforcement efforts.

I’m cautiously optimistic because these answers seem to indicate that OSHA has at last decided to liberate itself and workers from PELs. If this really happens, I predict that workers and the industrial hygiene profession within and outside of OSHA will be far better off for it.

Eileen Senn is an industrial hygienist who has performed occupational health work for government and unions for 40 years. She was an OSHA industrial hygiene inspector in Philadelphia for eight years in the 70s and 80s. She directed an OSHA New Directions training grant from 1979 to 1981. She worked in occupational health surveillance for the state of New Jersey from 1986 to 2002. She has been an Independent consultant for the past eight years. She is perhaps best known for her seminal article, Playing Industrial Hygiene to Win.