Occupational Health Perspectives and History

In June of 2011, at the AIHA Conference, Dr. Michaels, the head of OSHA, stated “Our existing PEL (personal exposure limit) is not protective,” said Michaels. “To say it is outdated is generous. To that end, OSHA would be issuing a proposal for a new silica standard in the next few months, said Michaels, adding that the agency was also thinking about a comprehensive health standard for crystalline silica. During the question-and-answer session Michaels was also asked about another preventable workplace hazard for which a standard of increased stringency is long overdue: noise. Earlier this year, OSHA withdrew a proposed interpretation of its noise standard. To the question, “When is OSHA going to review its hearing conservation standard?” Michaels responded by saying, “That is an area of great frustration and sadness.” There are reasonable and inexpensive ways to prevent noise and hearing loss, said Michaels, pointing out that not having a more protective hearing standard was actually a competitive disadvantage for the U.S. “If a U.S manufacturer wants a quieter machine it will likely buy one from Europe. European machines are quieter than American machines because they have to be.”

Dr. Michaels goals 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 determined 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.

Liz Borkowski is a Research Associate at the George Washington University School of Public Health’s Department of Environmental and Occupational Health who believes 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 statementsays:

• 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 the OSHA 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.

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.

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.

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.

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.

Threshold Limit Values (TLVs)

Threshold Limit Values (TLVs) are air pollution limits for the workplace. Since 1946, TLVs have been devised and published by a private organization called the American Conference of Governmental Industrial Hygienists (ACGIH), a private group composed of industrial hygienists from state and local governments, plus academics and industry consultants. ACGIH clearly wants its audience to believe that TLVs are health-based standards. The preface to ACGIH’s annual TLV list says TLVs "are health-based recommendations derived from assessment of the available published scientific information from studies in exposed humans and from studies in experimental animals." Furthermore the preface says TLVs are airborne concentrations "to which nearly all workers may be exposed for 8 hours per day, 40 hours per week for a working lifetime without adverse effect" [1].

In 1970 Congress created the Occupational Safety and Health Administration (OSHA) to protect workers from injury and from toxic chemicals. In 1971, OSHA adopted the ACGIH’s 1968 TLVs as official workplace standards called PELs (permissible exposure limits). The rationale at the time was that the Occupational Safety and Health Act (OSH Act) required OSHA to adopt standards quickly and there was no time to develop independent standards. However, the OSH Act created a new process for OSHA to follow in establishing future PELs, and it created a National Institute for Occupational Safety and Health (NIOSH) with official responsibility for providing scientific advice to OSHA. During the next 20 years, NIOSH developed and published Recommended Exposure Limits, or RELs, for 160 chemicals. However, OSHA ignored the bulk of NIOSH’s recommendations and adopted only 12 new PELs during the 20-year period.

During the 20 years that OSHA spent setting 12 new PELs, the ACGIH TLV Committee revised 234 TLVs downward, making them more protective (and stricter than the corresponding PELs which had been adopted in 1970 but never revised), and adopted 168 new TLVs for which there were no PELs. By 1987, official PELs were lagging badly behind the development in TLVs, and this was a source of embarrassment to OSHA. In the spring of 1987 OSHA began a formal procedure to adopt a new Air Contaminants Standard. OSHA proposed to adopt, once again, all of the ACGIH’s TLVs (in their 1987 revision) [2].

During the next 2 years, TLVs came under close scrutiny. In 1988, two occupational hygienists, Barry Castleman and Grace Ziem, examined the official documentation that ACGIH said it had relied upon in setting TLVs. Castleman and Ziem reported that at least 104 of the TLVs were based on nothing more than unpublished allegations, often made to the TLV committee by industry scientists whose employers had a direct financial interest in the particular substance being considered[3].

Despite this information, OSHA continued proposing to adopt all TLVs as official PELs.

During public hearings on the proposed Air Contaminants Standard in 1988, NIOSH placed 4000 pages of testimony in the record. They offered evidence that at least 98 of the 400 proposed PELS would not protect the health of workers. For 50 of the 98 substances, NIOSH had already published Recommended Exposure Limits (RELs). NIOSH’s average (mean) REL was 71 times lower (more protective) than the corresponding TLV.

During the public hearings, the New Jersey State Department of Health (NJSDOH) placed in the record a study that it had conducted of existing and proposed PELs, using EPA’s Integrated Risk Information System (IRIS) database [4].

The IRIS database was created by EPA to collect and systematically review human and animal toxicity data on particular chemicals. The IRIS database in 1990 contained reviews of 370 chemicals. The purpose of the IRIS system is to support EPA and other governmental regulators in their efforts to protect public health.

NJSDOH researchers randomly selected 43 existing and proposed PELs. Using widely-accepted risk assessment methods to extrapolate from reference doses and unit risks in the IRIS database, the NJSDOH researchers calculated health-based occupational guidelines. For the 43 chemicals, the average (mean) existing PEL was 9.5 mg/m3; the average (mean) proposed PEL was 7.5 mg/m3; and the average (mean) health-based guideline calculated by NJSDOH was 0.004 mg/m3. Thus average existing PELs exceeded NJSDOH’s health-based guidelines by a factor of 2375 and proposed PELs exceeded NJSDOH’s health-based guidelines by a factor of 1875, on average. The New Jersey State Department of Health concluded that OSHA’s proposed PELs were based on outdated information and weak methodology and would not protect worker health.

Despite these compelling criticisms, OSHA formally adopted all of ACGIH’s TLVs as enforceable PELs in January 1989. As a practical matter, this astonishing decision had the effect of making ACGIH’s TLV Committee the de facto workplace-standards-setting body in the U.S. Since the TLV Committee operates behind closed doors without peer review of its methods or conclusions, this transfer of authority from OSHA to ACGIH effectively gutted the OSH Act, which had established a public process for setting occupational standards. (In July 1992, a court declared the new PELs illegal, thus re-establishing the 1971 PELs, based on the 1968 TLVs, as official U.S. standards; the Clinton administration did not appeal that court ruling[5].

Although they are called THRESHOLD limit values, implying that they are set at a level that would PREVENT disease, in many cases they have been set at or above levels at which disease is known to occur in humans.

For example, 7 of 14 workers exposed to chlorodiphenyl at 10% of the TLV suffered chloracne; 10 out of 10 volunteers exposed to ethyl ether suffered upper respiratory tract irritation at 75% of the TLV; and 5 out of 5 volunteers exposed to 2-nitropropane suffered central nervous system effects such as headaches, nausea, and vomiting at 80% to 180% of the TLV. In the Air Contaminants Standard, OSHA set the PEL for these three substances at the same level as the TLV [6].

Today the ACGIH and its TLVs are being subjected to a continuous stream of criticism from knowledgeable authorities as not being stringent enough. For example, a well-known industrial hygienist in New Jersey recently said, "The reality is that for the vast majority of chemicals, we have little or no chronic toxicity data. Even when we do, we usually don’t know the chemical’s effects on lung function, nervous system function, immune or endocrine system function, reproductive function, or other vital bodily functions. Without such data, claims that we know what exposures are permissible and will not harm workers are false. Exposure limits are theoretically helpful to workers. However, if we don’t get the numbers right, and it looks like ACGIH and OSHA usually have not, then they are harmful" [4].

As recently as the BP Oil Spill in the Gulf of Mexico, the consensus among all professionals (i.e. OSHA, legal, and IH’s) was to have the data presented with the lowest limit published for all workers to understand the level of exposure.

In 1993, a researcher recalled a 1956 criticism of TLVs: "In the introduction to its 1956 list... the Committee on Threshold Limits says, ‘Values are given... for the maximum average atmospheric concentrations of contaminants to which workers may be exposed... without injury to health.’ Careful study of the data which support the currently accepted values suggests that no such description can be truthfully attached to most of them" [7].

A July 1994 analysis of TLVs finds that 229 of the approximately 600 current TLVs have been criticized, in one technical forum or another, as inadequate to protect workers’ health [8].

What then is the purpose of TLVs, if not to protect the health of workers-—this criticism makes no sense.

Though TLVs often may not protect the health of workers, they do provide what is now commonly known as the "TLV defense" when a company is sued for harming workers by exposing them to toxic chemicals. The typical TLV defense quotes the ACGIH saying TLVs are "thought to be safe for workers—based on the best available information."

Fact: 50,000 to 70,000 workers who die each year from diseases they developed after exposure on the job, and the estimated 350,000 workers who develop new cases of occupational disease each year from toxic chemical exposures.

References

[1] TLV documents quoted in Ernest Mastromatteo, "TLVs: Changes in Philosophy," APPLIED INDUSTRIAL HYGIENE Vol. 3, No.3 (March 1988), pgs. F12-F16. In 1988, Mastromatteo was head of ACGIH’s TLV Committee.

[2] James C. Robinson and others, "Implications of OSHA’s Reliance on TLVs in Developing the Air Contaminants Standard," AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 19, No. 1 (January 1991), pgs. 3-13.

[3] Barry I. Castleman and Grace E. Ziem, "Corporate Influence on Threshold Limit Values," AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 13, No. 5 (1988), pgs. 531-559.

[4]Eileen Senn Tarlau, "Guest Editorial; Industrial Hygiene With No Limits," AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL Vol. 51, No. 1 (January 1990), pg. A9-A10.

[5]Frank Swoboda, "Some Toxic-Substance Rules Being Dropped; Administration Did Not Appeal Court Decision," WASHINGTON POST, March 23, 1993, pg. D1.

[6]S.A. Roach and S.M. Rappaport, "But They Are Not Thresholds: A Critical Analysis of the Documentation of Threshold Limit Values," AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 17, No. 6 (1990), pgs. 727-753.

[7]Henry Smyth Jr., 1956, quoted in S.M. Rappaport, "Threshold Limit Values, Permissible Exposure Limits, and Feasibility: The Bases for Exposure Limits in the United States," AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 23, No. 5 (May 1993), pgs. 683-694.

[8]Barry I. Castleman and Grace E. Ziem, "American Conference of Governmental Industrial Hygienists: Low Threshold of Credibility,"" AMERICAN JOURNAL OF INDUSTRIAL MEDICINE Vol. 26, No. 1 (July 1994), pgs. 133-143.

Unusual work schedules are getting increasingly common that differ from the typical 8-hour-per-day, 5-day-per-week routine. However, most occupational exposure limits assume a typical work schedule. Thus, exposure concentrations for workers with unusual work schedules should be compared to occupational exposure limits (OELs) tailored to each worker's actual work schedule.

ACGIH Position on Unusual Work Schedules

The following appears in the 2011 TLVs® and BEIs® from ACGIH:

"Application of TLVs® to work schedules markedly different from the conventional 8-hour day, 40-hour workweek requires particular judgment to provide protection for these workers equal to that provided to workers on conventional work shifts. Short workweeks can allow workers to have more than one job, perhaps with similar exposures, and may result in overexposure, even if neither job by itself entails overexposure.

"Numerous mathematical models to adjust for unusual work schedules have been described. In terms of toxicologic principles, their general objective is to identify a dose that ensures that the daily peak body burden or weekly peak body burden does not exceed that which occurs during a normal 8-hour/day, 5-day/week shift. A comprehensive review of the approaches to adjusting occupational exposure limits for unusual work schedules is provided in Patty's Industrial Hygiene (Paustenbach, 2000). Other selected readings on this topic include Lapare et al. (2003), Brodeur et al. (2001), Caldwell et al. (2001), Eide (2000), Verma (2000), Rouch (1978), and Hickey and Reist (1977).

"Another model that addresses unusual work schedules is the Brief and Scala model (1986), which is explained in detail in Patty's Industrial Hygiene (Paustenbach, 2000). This model reduces the TLV® proportionately for both increased exposure time and reduced recovery (i.e., non-exposure) time, and is generally intended to apply to work schedules longer than 8 hours/day or 40 hours/week. The model should not be used to justify very high exposures as 'allowable' where the exposure periods are short (e.g., exposure to 8 times the TLV–TWA for 1 hour and zero exposure during the remainder of the shift). In this respect, the general limitations on TLV–TWA excursions and TLV–STELs should be applied to avoid inappropriate use of the model with very short exposure periods or shifts.

"The Brief and Scala model is easier to use than some of the more complex models based on pharmacokinetic actions. The application of such models usually requires knowledge of the biological half-life of each substance, and some models require additional data. Another model developed by the University of Montreal and the Institute de Recherche en Sante et en Securite du Travail (IRSST) uses the Haber method to calculate adjusted exposure limits (Brodeur et al., 2001). This method generates values close to those obtained from physiologically based pharmacokinetic (PBPK) models.

"Because adjusted TLVs® do not have the benefit of historical use and long-time observation, medical supervision during initial use of adjusted TLVs® is advised. Unnecessary exposure of workers should be avoided, even if a model shows such exposures to be "allowable." Mathematical models should not be used to justify higher-than-necessary exposures."

Strategies for Adjusting OELs

Please also see the following presentation for more information about strategies for adjusting OELs to better apply to unusual work schedules.

Please see the attached message from our president and other attachments:

• Message from the President
• CEM Accreditations
• AIHA Certificate
• VPP Government Letter
• Leader Magazine Article
• ISNetWorld RAVS Update
• Historical OEL Limits Maintained by CEM