EPA’s Draft Toxicological Review of PCE and (Once Again) What’s Wrong with Risk Assessment?

I wasn’t sure I was going to play in this sandbox again. I’m not really involved with volatile organic compound risk assessments anymore. I’ve expressed the opinion that what we need is not another toxicological assessment, but some action to replace the highest-exposure uses with some implementable alternatives. Outside of the workplace, perc isn’t terribly high on the list of environmental health hazards. But there is a framework in place for replacing it with lower-toxicity substitutes which could be template for other, more hazardous, compounds.

But instead, we have a draft toxicological assessment that is intended to provide toxicity values on EPA’s Integrated Risk Information System, which can then be used for risk assessments.

Just by eyeball, the estimated risks are similar to the last risk assessment conducted, done by Cal-EPA in the late 1990s. So, I’m not sure what’s been gained here – while it seems to be well-written, I’m wondering how this risk assessment is going to help us make faster or better decisions about managing PCE risks, given that it doesn’t say anything terribly different from what we knew a few years ago, and does not put much energy behind PCE risk-based decision making. In fairness, I should note that it’s not intended to be a policy document – its purpose is to make sure that good science and the right values are put up on IRIS.

At a high level, EPA’s assessment says that PCE is “likely to be carcinogenic” in humans by all routes of exposure and that the primary non-cancer toxic effects of PCE exposure in humans occur to the central nervous system, kidneys, liver and developing fetus. On the quantitative side, EPA judges the cancer potency of PCE to be slightly higher compared with its previous risk assessment, conducted in the late 1980s/early 1990s. Also, EPA judges PCE to pose slightly more of a non-cancer health risk, compared with previous assessments.

Once again, I’m wondering how we address what’s broken about risk assessment. I’m apparently not the only one:

However, risk assessment is at a crossroads. Despite advances in the field, risk assessment faces a number of significant challenges including lengthy delays in making complex decisions; lack of data leading to significant uncertainty in risk assessments; and many chemicals in the marketplace that have not been evaluated and emerging agents requiring assessment.

This is from the teaser from a forthcoming book from the National Academy of Sciences, Science and Decisions: Advancing Risk Assessment. This book promises to build off of the original framework for risk assessment, published in the book published in 1983 by the NAS, Risk Assessment in the Federal Government (also known as the Red Book). The Red Book established a framework for much of risk assessment as it is practiced today Science and Decisions, “embeds these concepts within a broader framework for risk-based decision-making.” Maybe it will contribute to “fixing” risk assessment. We’ll see. I’ve ordered a copy and will discuss it in a future post.

The NAS and PCE

I missed this before. The National Academy of Sciences has been asked by the EPA to conduct a scientific review of the EPA’s external review draft "Toxicological Review of Tetrachloroethylene (Perchloroethylene) CAS No. 127-18-4 in Support of Information on the Integrated Risk Information System". I suppose this is a bit of a timesaver that reflects lessons-learned from the review of TCE. If you recall, the EPA released a draft risk assessment for TCE in 2001 which was shelled by stakeholders including the DOD, solvents and aerospace industries, prompting a year-and-a-half NAS review which was completed in July 2006. By the way, what’s happening with TCE these days? The NAS report on it came out seven months ago. Haven’t heard a peep from EPA about revising the risk assessment. . . .

EPA is getting out ahead of matters this time –the toxicological review document isn’t even out in draft yet (EPA’s web site for PCE is here). It was requested by the Office of Air and Radiation, for purposes of evaluating PCE as a hazardous air pollutant. I suppose that makes sense, to have verified toxicity values for conducting residual risk assessments that assess the effectiveness of control technologies for dry cleaner emissions, implemented under the Clean Air Act.

At the same time, it’s worth raising the question of whether or not spending the better part of two years updating the risk assessment for PCE is necessary to help us manage the risks associated with its use in dry cleaning. Maybe California’s model is the way to go for addressing health risks from PCE.

California Phases out Perc for Dry Cleaning

As long time Impact Analysis readers (all five of you) know, I was on a tear for awhile about perchloroethylene used in dry cleaning (see here, here and here). Perc is the backbone of the dry cleaning industry, which is filled with low-income small businesses. Yet at the same time, dry cleaning is a pathway for exposing millions of Americans to low levels of perchloroethylene. Perc is probably carcinogenic in humans, but at the same time, an apparently relatively low potency carcinogen. However, even a low-potency carcinogen that most everyone is exposed to represents an environmental health matter warranting further scrutiny.

The California Air Resources Board has cut through all of the handwringing, and has amended the Dry Cleaning Air Toxics Control Measure to phase out perchloroethylene use by 2023. The phase-out would happen gradually, replacing the older, less efficient machines first. A training program also will be implemented to have trained operators of dry cleaning machines in all shops in the interim.

According to the ARB’s Initial Statement of Rulemaking, the individual risks from perchloroethylene exposure from dry cleaning emissions was not large – the highest estimated lifetime cancer risk was 75 in a million, for someone located 20 meters downwind from a shop with an older, less efficient dry cleaning machine which emitted higher levels of perc (keep in mind that someone generally doesn’t spend their lifetime at this one location). This risk estimate doesn’t include the doses that dry cleaning customers receive through offgassing from bringing home freshly dry cleaned clothes, a source of exposure that’s potentially more significant.

There’s the usual whining about businesses – in this case, small businesses – being hit harder by a perc ban. However, dry cleaners historically have made the shift from flammable petroleum hydrocarbons, to hepatotoxic carbon tetrachloride to perchloroethylene. In addition, the state appears to be making an effort to assist the industry in converting over to other cleaning agents. Some make the argument that the health risks from perchloroethylene are slight and do not warrant a ban on its use. That’s a point that will continue to be debated, but state, federal and international authorities appear satisfied that perchloroethylene is a probable human carcinogen, and there’s evidence that exposure to it is widespread. Eliminating it from dry cleaning can reduce that exposure. There is a more important issue, though. Perchloroethylene (PCE) in dry cleaning is a poster child for the cause of finding alternatives to toxic chemicals in commerce, in today’s market-driven environment. As a society, if we can’t summon the collective will to solve the problem of implementing lower-risk fabric care products in place of PCE, we’re going to have real problems dealing with other widespread substances with health concerns, such as phthalates or bisphenol-A.

So, let’s hear it for the state of California. Once again, it’s an example of a state blazing a trail where the Federal government (particularly under younger Bush) fears to go.

Who Needs PCE?

Perchloroethylene (PCE) in dry cleaning is a poster child for the cause of finding alternatives to toxic chemicals in commerce, in today’s market-driven environment. As a society, if we can’t summon the collective will to solve the problem of implementing lower-risk fabric care products in place of PCE, we’re going to have real problems dealing with other widespread substances with health concerns, such as brominated fire retardants, phthalates or bisphenol-A.

Most stakeholders in the PCE “game” don’t really need it. People who use dry cleaning don’t “need” PCE; what they really need is convenient and affordable fabric care. Clothing manufacturers don’t “need” PCE, they need fabric care products that clean without damaging clothes. Dry cleaners “need” PCE, because many of them cannot afford the retrofits to use PCE alternatives and are afraid that customers, unwilling to risk their clothes on an “unproven” cleaning method, may start going to competitors.

Do chemical manufacturers “need” PCE? Available information suggests that current demand for PCE is around 300 million pounds per year, and is manufactured domestically in three facilities in the U.S. Government statistics report that approximately half of that used for dry cleaning, though a solvents industry statistic estimates that 12 percent is used for dry cleaning. A limited survey suggests that the cost for PCE is around one dollar per pound (or around ten dollars per gallon). Sources are here, here and here. The total annual value of PCE delivered to the dry cleaning industry (something less than $300 million?) would appear to be a small fraction of the total value of deliveries of all petrochemicals ($20.3 billion in 2002). This doesn’t include what users have to pay for emissions controls and waste management – but those aren’t things the chemical manufacturers have to worry about in determining the price for PCE. The point here is that chemical manufacturers might be able to manage without the PCE for dry cleaning market. The real challenges and costs are in helping dry cleaners convert from PCE.

This line of argument implies that I’ve already decided that the risks from PCE warrant finding substitutes, though not everyone would agree with me (see here and here). However, a fair-minded individual would entertain the possibility that having to do this much parsing of the uncertainty in health risks, for a setting involving widespread public and worker exposures, indicates that alternatives to PCE in dry cleaning should be given some consideration.

If we get to this point, the next step is to figure out, based on the risks from PCE exposure, what the alternatives should be. What kinds of risks need to be reduced, and how quickly should risk reduction occur? Can risks be reduced by the application of control technologies, or is substitution for fabric care chemicals needed? What are the relative costs of these various alternatives, and how permanent are they? Are there intermediate steps involved – should dry cleaners invest in PCE emissions controls now and purchase non-PCE-using wet-cleaning machines later, or is the appropriate wet-cleaning technology available now? What encouragement needs to be applied to the garment manufacturers to modify their “dry-cleaning only” labels, so that non-PCE alternatives can be used on clothes? What are the economic impacts of the additional risk reductions? How are these impacts offset for those firms hit the hardest by them?

For some, this sounds too much like risk and cost-benefit analysis, something which in theory is a useful tool for helping make complex decisions affecting different stakeholder groups. However, it’s flawed if not used in a democratic fashion (a discussion on making these kinds of analyses more democratic is here). Cost-benefit analysis enjoyed some brief popularity in the mid-1990s, but rapidly lost favor thanks to the Republicans in Congress, who brought it into disrepute by molding it into a tool for slowing the pace of environmental regulation and reducing regulatory impact to industries.

About the same time, there was active research into alternatives to PCE in dry cleaning – which seem to have tapered off. The work is still on the shelf though, waiting for us to summon the political will to get the process started. By itself, PCE is not the largest chemical or environmental health problem we face. But it could become the template for how we start developing alternatives for higher-hazard chemicals in general, if that’s what we want to do.

What to do About PCE in Dry Cleaning?

In 1997, New York State and New York City adopted regulations to control perchloroethylene (PCE) emissions from dry cleaners located in residential and other buildings. From 2001 to 2003, the New York State Department of Health (NYSDOH) measured indoor air concentrations of PCE in apartments located in buildings in New York City where dry cleaners used PCE on site. While PCE exposures are widespread in the U.S. population, previous studies have shown that the most significant non-occupational exposures occurs in residences located over or adjacent to dry cleaners.

Mean indoor air PCE concentrations have decreased by about 10-fold since 1997, when additional dry cleaner regulations were implemented. Despite these accomplishments, PCE concentrations in several of the sampled apartments still exceeded the NYSDOH residential air guideline of 100 ug/m3. PCE concentrations in a few apartments exceeded the 1,000 ug/m3 action level set by NYSDOH. Moreover, the mean indoor air PCE concentrations in minority neighborhoods (75 ug/m3) were four times higher than in nonminority households (19 ug/m3). The mean PCE concentrations were > 10 times higher in low-income neighborhoods (256 ug/m3) than in higher income neighborhoods (23 ug/m3).

The study concluded that "[f]actors that may be contributing to the elevated perc levels detected, especially in minority and low-income neighborhoods, are being explored".

It doesn't take a lot of looking around to come up with a plausible explanation for why low-income neighborhoods (which would substantially overlap with minority neighborhoods) have higher PCE exposures. Dry cleaning is not a high-margin industry. According to the International Fabricare Institute, most commercial drycleaners are single facility, family-owned operations. An average number of five employees work at a plant. Commercial dry cleaning may not generate large profit with median annual revenues below $250,000. Bureau of Census statistics essentially confirm the industry figure. Bureau of Labor Statistics figures show that mean annual incomes of dry cleaning workers is $8.80 per hour ($18,290 per year). EPA’s draft dry cleaning NESHAP from 1993 cited the capital cost of secondary controls (a refrigerated condenser) at $6,300 with annual costs of $1,000 for process vent controls. The California ARB’s recent report on the dry cleaning industry also cites similar costs for installation of secondary controls.

Even before doing the arithmetic, it appears reasonable that many dry cleaning facilities would find installation of emission controls to be an economic burden, worth the risk of non-compliance. If it’s assumed that the dry cleaners in the lower-income neighborhoods have revenues lower than the median, the burden of emissions controls would be proportionately greater, the proportion of non-compliance greater, hence higher PCE exposures in lower income neighborhoods.

Whether we should continue to use PCE to dry clean clothes involves a balancing of the risks versus the benefits, and balancing competing risks. Beyond that, it involves balancing who is reaping the benefits versus who is being subjected to the risks. How significant are those risks? Are the costs for controlling PCE emissions an economic burden to dry cleaners? Are the risks and costs for control significant enough to warrant finding alternatives to PCE for dry cleaning? A further question is what kinds of alternatives are there to dry cleaning with PCE? Are these more “environmentally friendly”? Do they provide suitable quality in fabric care? What kinds of economic impacts are there to the dry cleaning industry with switching from PCE?

PCE use in dry cleaning is a laboratory experiment for implementation of the precautionary principle. In this case, some harm potentially has been done from PCE exposure (more on this topic later), and more harm may be averted through finding alternatives to PCE in dry cleaning. However, other types of harm such as economic dislocation, unemployment and poverty for some, which have their attendant health risks, might be created by forcing the replacement of PCE as a dry cleaning solvent, indicating the need for a more nuanced view of the precautionary principle than “just don’t use it”. Navigating through this maze and solving the problem of replacing PCE in dry cleaning might provide lessons in toxic substance use reduction that could be applied elsewhere.

More PCE Phase-Out News

Tuxedo rental company Selix Formalwear settled a lawsuit last week with Oakland-based Center for Environmental Health (CEH) requiring the firm to phase out use of PCE at its Hayward, California facility. The settlement resulted from a March 2004 lawsuit that raised concerns about Selix workers being exposed to potentially cancer-causing PCE emissions. According to CEH, Selix has agreed to eliminate one of its two PCE cleaners by mid-2006, and eliminate all PCE emissions from the facility by the end of 2008.

Until that date, the company will place statements warning that PCE is "known to cause cancer" on dry cleaning bags (note: they should have been doing this already – PCE is listed under Proposition 65 - maybe this was a Prop 65 suit; I'm still trying to find the legal opinion), in mailings to neighbors, and at a noticeable location at the Hayward facility.

Selix wasn’t returning calls to the press, which was a bit strange. This would have been a great opportunity for them to reframe this as a forward-looking green move on their part, even if they had to be clubbed into it through litigation.

PCE Substitution Issues

Perchloroethylene (PCE) used in dry cleaning is probably the most significant source of human exposure for this compound. General public exposure to PCE is widespread from people transporting freshly dry-cleaned clothes in their cars and storing them in their homes. Occupational exposures of dry cleaning workers to PCE are more pronounced compared with the general public. PCE is considered by the National Toxicology Program to be reasonably anticipated to be a human carcinogen, based on sufficient evidence in laboratory animals and limited (and somewhat inconclusive) evidence in humans. There is evidence of reproductive abnormalities in drycleaning workers (spontaneous abortions, menstrual irregularities, but again, the studies are as yet inconclusive. PCE has been found as a soil or groundwater contaminant at nearly 800 Superfund sites.

So, there’s sufficient evidence of adverse effects based on laboratory animals, but inconclusive evidence directly from the human experience. Human exposure to PCE is widespread, and the consequences of low-dose carcinogen exposure to very large groups are uncertain. Exposed workers, though smaller in number, are still a sizeable group.

Substitutes for PCE for professional fabric cleaning exist, and for some, it may appear that PCE is a good candidate for exercising the precautionary principle:

When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of an activity, rather than the public, should bear the burden of proof.

(A copy of the full Wingspread Statement can be found here)

However, anyone who is serious about phasing out PCE in dry cleaning needs to be aware of the realities of the fabric care industry. Dry cleaning remains a mom-and-pop type of operation, the kind of small business that is slowly drying up in this age of Wal-Mart. The profit margin on dry cleaning is slim, and many are probably treading water financially. Attitudes of both workers and owners on chemical hazards have been surveyed, and it appears that health and safety, while on workers’ minds, are not their highest concerns (the study doesn’t call it out, but I have to wonder if their biggest concern is making a living). Telling these folks to just give up perc for the sake of the environment or their health will fall on deaf ears.

In some places, government is taking a hand to move the PCE phase-out along. The South Coast Air Quality Management District (SCAQMD) has a pretty fearsome set of dry cleaning regulations, including a PCE phase-out, going on now with a completion date of 2020. Dry cleaners are being offered financial assistance by the district to purchase alternate wet cleaning machines. However, in places where the regulatory agencies aren’t quite as progressive as the SCAQMD, there may be other effective methods, combined with the financial assistance, to enable a PCE phase out. This would require consumer pressure applied elsewhere along the supply chain. Most apparel manufacturers do not label their “dry clean only” garments to allow wet cleaning methods, which might make cleaners reluctant to switch over voluntarily. Many retailers selling apparel pride themselves on their corporate environmental stewardship policies (see here and here). Selling the retailers on the idea of providing “no-perc” product lines and pressuring their suppliers to modify their labeling requirements, as a corporate citizenship activity, could be an alternative to governmental action in phasing out PCE.

It might work better than going to war with the corporations.

TCE and PCE Stories

The persistence in the marketplace of chlorinated solvents such as TCE (trichloroethylene) and PCE (perchloroethylene) is astonishing. One would have thought that the liabilities of soil and groundwater contamination, known health risks to workers, questions about health risks to the general public, burdensome regulations related to hazardous waste, air toxics and ozone depletion and the availability of alternatives, would have been more effective in phasing these chemicals out of the market.

The notable point about TCE and PCE from the viewpoint of environmental health is that their use patterns lead to widespread human exposure. A primary use for TCE and PCE are for solvent cleaning. Half of all PCE use is for dry-cleaning clothes. This means that TCE and PCE uses cut across a large number of industry and workplaces. NIOSH has estimated that approximately 390,000 workers are potentially exposed to TCE nationwide, and that approximately 690,000 workers are potentially exposed to PCE, based on the National Occupational Exposure Survey (NOES). While the NOES was completed over 20 years ago, and there hasn’t been an update, these numbers are likely to be reasonably consistent today. Chlorinated solvent use appears to have declined over time (trends for the U.S. have been hard for me to find – if I uncover more information, I’ll post it), but it is likely that a lot of these solvents are still sold. Occupational exposure is the most significant human health concern with TCE and PCE exposure (a topic for another day – I’ll be writing a number of posts on these chemicals).

Every day, millions of people bring home clothes from the dry cleaners that are off-gassing PCE. Dry-cleaned clothes represent one of the largest sources of exposure to PCE by the general public (see “Everyday Exposure to Toxic Pollutants”, by Wayne Ott and John Roberts, February 1998 Scientific American, downloaded for a price from sciam.com). This is consistent with a wealth of studies (most recently here) indicating that a preponderance of volatile organic compound exposure occurs indoors.

According to the ATSDR, over 1,309 Superfund sites in the U.S. have soil or groundwater that is contaminated with PCE; 1,460 Superfund sites are contaminated with TCE. This does not include thousands of other sites under the jurisdiction of state agencies and undergoing cleanup as part of RCRA Corrective action, which are not listed on the National Priority List. TCE exposure at contaminated sites is of sufficient concern that ATSDR has established a TCE subregistry within its National Exposure Registry.

In many cases, people living near these sites have been exposed to these chemicals in domestic-use water, from ingestion, skin contact or inhaling chemicals that volatilize from water. However, what has become a greater concern is vapor intrusion, a pathway where these chemicals volatilize from soil or groundwater, migrate through soil near building foundations and are drawn into indoor air through egresses in foundations. This issue took regulatory officials a bit by surprise, and has been a growing issue for hazardous waste site cleanups across the U.S. In New York, state officials are going to revisit 400 sites that had cleanup decisions made before 2003 to investigate the potential for indoor exposures to volatile compounds from vapor intrusion (this comes from the TCE Blog, your source for all things related to chlorinated solvents in the environment).

As you can imagine, there’s much more to this story, beyond the fact that TCE and PCE exposures are widespread. Who needs to be concerned about potential exposures? Under what conditions could people be at significant health risks? What can they be doing to reduce their risks? What can other stakeholders, such as governments and industries, be doing to reduce health risks from these chemicals? How do the potential risks from TCE and PCE exposure compare with other chemicals in a person’s environment?

Stay tuned for more posts on this topic. Until then, check out TCE Blog.