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Jennifer McPartland, Ph.D., is a Health Scientist.
Common sense tells us it’s impossible to evaluate the safety of a chemical without any data. We’ve repeatedly highlighted the scarcity of information available on the safety of chemicals found all around us (see for example, here and here). Much of this problem can be attributed to our broken chemicals law, the Toxic Substances Control Act of 1976 (TSCA).
But even for those chemicals that have been studied, sometimes for decades, like formaldehyde and phthalates, debate persists about what the scientific data tell us about their specific hazards and risks. Obtaining data on a chemical is clearly a necessary step for its evaluation, but interpreting and drawing conclusions from the data are equally critical steps – and arguably even more complicated and controversial.
How should we evaluate the quality of data in a study? How should we compare data from one study relative to other studies? How should we handle discordant results across similar studies? How should we integrate data across different study designs (e.g., a human epidemiological study and a fruit fly study)? These are just a few examples of key questions that must be grappled with when determining the toxicity or risks of a chemical. And they lie at the heart of the controversy and criticism surrounding chemical assessment programs such as EPA’s Integrated Risk Information System (IRIS).
Recently, a number of efforts have been made to systematize the process of study evaluation, with the goal of creating a standardized approach for unbiased and objective identification, evaluation, and integration of available data on a chemical. These approaches go by the name of systematic review.
Groups like the National Toxicology Program’s Office of Health Assessment and Translation (OHAT) and the UCSF-led Navigation Guide collaboration have been working to adapt systematic review methodologies from the medical field for application to environmental chemicals. IRIS has also begun an effort to integrate systematic review into its human health assessments.
Recently a paper in Environmental Health Perspectives (EHP) by Krauth et al. systematically identified and reviewed tools currently in use to evaluate the quality of toxicology studies conducted in laboratory animals. The authors found significant variability across the tools; this finding has significant consequences when reviewing the evidence for chemical hazard or risk, as we pointed out in our subsequent commentary (“A Valuable Contribution toward Adopting Systematic Review in Environmental Health,” Dec 2013).
EDF applauds these and other efforts to adopt systematic review in the evaluation of chemical safety. Further elaboration of EDF’s perspective on systematic review can be found here.
Richard Denison, Ph.D., is a Senior Scientist.
[UPDATE 1/28/14: See updates at several places in this post regarding a 2011 Eastman safety data sheet on crude MCHM – which, though more recent than the 2005 version initally circulated, still does not reference the additional oral toxicity studies conducted by Eastman in the 1990s.]
Little more than two weeks after the January 9, 2014, spill of multiple chemicals into West Virginia’s Elk River, it’s becoming increasingly clear that the private and public sectors at all levels failed miserably with regard to protecting the public’s health. There is plenty of blame to go around.
Our focus in the blogging we’ve done about this terrible incident has been and remains on the lack of reliable information available on the chemicals involved in the spill, the failure to promptly share what was available with the public, and the shaky science upon which decisions and public communications as to the critical safety questions were based. In this post, I revisit several aspects of the initial and ongoing information gaps to add some additional perspective.
I discuss in some detail below two major problems that I believe demand close examination in the Chemical Safety Board’s and others’ investigations into the causes and consequences of the spill:
I end by briefly describing some of the implications of this tragic incident that need to be addressed going forward.
One caveat: Because information on this incident has emerged in a piecemeal and haphazard manner, I cannot vouch for the accuracy of every detail provided in this post. I have strived to the best of my ability to accurately describe the sequence and nature of events based on the available information. (more…)
Richard Denison, Ph.D., is a Senior Scientist.
Well, this story is rapidly evolving! Even since my last blog post this morning, new information has come to light as to the identity of the “new” chemical that was present in the leaking tank that led to contamination of the drinking water in Charleston, WV.
The Charleston Gazette has now reported that Freedom Industries, the owner of the leaking tank, has told government officials that the “new” chemical is actually a mixture of two chemical products, both of them made by The Dow Chemical Company. One of those is in fact the “DOWANOLTM PPh Glycol Ether” I discussed in my last post. The second is a closely related Dow product called “DOWANOLTM DiPPh Glycol Ether.” (These links are to Dow’s Material Safety Data Sheets (MSDSs) for the two products.)
The first product consists almost entirely (>99.5%) of propylene glycol phenyl ether (CAS no. 770-35-4). The second is a mixture (see its MSDS), the main component of which (≥60%) is di-propylene glycol phenyl ether (CAS no. 51730-94-0) – a closely related chemical.
My earlier post indicated that a Dow contact had told me this morning it does not make a “stripped” version of its PPh product, and hence did not believe it was the supplier of the material to Freedom Industries. As I noted in that post, use of the “stripped” designation to describe the “proprietary” chemical listed in the MSDS supplied yesterday by Freedom Industries for the “new” chemical had suggested the substance had somehow been further distilled.
But the latest article in the Charleston Gazette helps to clarify the situation. It cites State officials indicating that Freedom Industries’ “PPH, stripped” is in fact a mixture of the two Dow products.
Interestingly, the MSDSs for the two Dow products reference a considerably larger amount of toxicity data than does Freedom Industries’ MSDS. It appears, therefore, that there may be more data for officials to go on to assess potential risks associated with this “new” chemical.
Dow’s Technical Data Sheet and Product Safety Assessment for “DOWANOLTM PPh Glycol Ether” list several uses for the product, none of which appear to explain why Freedom Industries would have added the product to the tank of MCHM, which is used to wash coal.
There appear to be some disconnects between Dow’s knowledge of how its own chemicals are being used and by whom, and also between the intended uses of such chemicals and their actual use. These disconnects point to flaws in our current chemical safety policies: chemical manufacturers often don’t have a full picture of how their chemicals are actually used, and downstream users may not have a clear picture of which uses of a chemical are appropriate or not.
The number of lessons to be drawn from this West Virginia chemical spill appears to be growing by the day.
Richard Denison, Ph.D., is a Senior Scientist.
[PLEASE SEE UPDATE TO THE INFORMATION BELOW IN MY MORE RECENT BLOG POST.]
I blogged last night that the Charleston Gazette had reported that a “new” chemical that was revealed to have been present in the tank in Charleston, WV, that began leaking into the Elk River on January 9 and contaminated the drinking water supply for 300,000 residents.
Two alert readers recognized the acronym “PPH” and the description of the chemical in Freedom Industries’ Material Safety Data Sheet (MSDS) for “PPH, stripped”, to which I had linked, and suggested the identity of the chemical might be a grade or form of propylene glycol phenyl ether (CAS no. 770-35-4).
I’ve not been able to find further references to or information on “PPH, stripped,” but with the help of those alert readers I have found information on what appears to be a similar but not identical product made by The Dow Chemical Company, under the trade name “DOWANOLTM PPh Glycol Ether” – see Dow’s Technical Data Sheet and its Product Safety Assessment. Among the names Dow lists for its product are both “propylene glycol phenyl ether” and “PPh.”
I’ve compared information available on the Dow and Freedom Industries products. Physical-chemical properties are similar but not identical for the two materials. For example, the boiling point for “PPH, stripped” is 247°C, and for DOWANOLTM it’s 241°C. (This is consistent with the process of “stripping,” by which more volatile components of a mixture are distilled out, which would raise the boiling point of the remaining more concentrated higher molecular weight components of the mixture.) The liquid densities of the two products also match: 1.06 grams per cubic centimeter.
Both products are indicated as being eye and skin irritants, but of low acute oral toxicity.
I contacted Dow this morning, and asked if the Freedom Industries’ “PPH, stripped” material was supplied by Dow or is the same material. My Dow contact answered no to each question. There are quite a few suppliers of this chemical globally.
[PLEASE SEE UPDATE TO THE ABOVE INFORMATION IN MY MORE RECENT BLOG POST.]
It thus appears likely that the “new” chemical in the West Virginia spill is a form of propylene glycol phenyl ether. But questions remain as to who made the “stripped” version, who supplied it to Freedom Industries, why its specific chemical identity is being claimed proprietary, and what information beyond that in the company’s MSDS is available regarding its hazard properties.
Richard Denison, Ph.D., is a Senior Scientist.
Just when you thought this story couldn’t get any weirder or worse, it has just been revealed that another chemical substance was present alongside the crude MCHM mixture that leaked into the Elk River and contaminated the drinking water of 300,000 West Virginia residents.
A story published late today in the Charleston Gazette by Ken Ward, Jr., reports that the U.S. Environmental Protection Agency (EPA) has told officials that a chemical identified as “PPH, stripped” was present in the leaking tank at a level of 5.6%. A Material Safety Data Sheet (MSDS) for the substance, provided by the Gazette, describes the substance as consisting of 100% “polyglycol ethers” – but withholds the substance’s specific chemical identity as “proprietary.”
And while the scant toxicity data provided on the substance in the MSDS suggest it has lower acute oral toxicity than the crude MCHM mixture – at least for what is called the “majority component” (suggesting that this substance, too, is a mixture) – the MSDS notes that “PPH, stripped” is a “serious eye irritant” and a skin irritant.
It has already been reported by the Charleston Gazette that some residents making hospital visits did so because of rashes or other skin irritation; other reports indicate eye irritation among residents as well. It should be noted that the MSDS for crude MCHM reports that it is also a skin and eye irritant.
Some quick searches I’ve done tonight for “PPH” and “PPH, stripped” – including one using ChemIDPlus, a large chemical database maintained by the National Library of Medicine, have not yielded further information.
All this means yet more questions and more uncertainty for West Virginia residents. A few:
– How did EPA learn of the presence of this new chemical in the spilled material? So far, EPA’s not talking.
– Why did it take 12 days for this information to come out? And then, not from the company, Freedom Industries, that owns and operates the leaking tank?
– Has this chemical been monitored for in the river and drinking water samples? (Presumably not, since its presence was just revealed.)
– Who makes PPH, and will they now reveal its identity given the massive human exposure that has occurred?
– Or will EPA exercise its rarely used authority under the Toxic Substances Control Act (TSCA) to compel disclosure of the identity of PPH? Section 14(a)(3) of TSCA provides that confidential business information “shall be disclosed if the [EPA] Administrator determines it necessary to protect health or the environment against an unreasonable risk of injury to health or the environment.”
Surely, this is such a case.
Richard Denison, Ph.D., is a Senior Scientist. Jennifer McPartland, Ph.D., is a Health Scientist.
Slowly but surely, like the movement downstream of the spill’s plume, we are learning more about how government officials derived the 1 ppm “safe” level in the drinking water for the chemical MCHM that was spilled into West Virginia’s Elk River late last week.
A few more slivers of light were cast today onto what has been a remarkably opaque procedure used by CDC and other officials to set the 1 ppm level, which got even more confused with last night’s issuance of a “Water Advisory for Pregnant Women” by the West Virginia State Department of Health.
The slivers come from a story today in the Charleston Gazette by Ken Ward, Jr. and David Gutman reporting on their conversation with an official from the Centers for Disease Control (CDC), and a media call today with the same official.
CDC finally gave a fuller description of their methodology, and while it appears to have more closely followed standard practice than the methodology they initially described, many questions remain about the study used as the starting point. Release of these studies, therefore, is essential. [UPDATE: EVENING OF 1/16/14: Late today, Eastman finally made its studies public: they are available here.]
We discuss the details further below. But first:
CDC’s erroneous claim that its “safe” level is “highly conservative”
CDC’s claim that the 1 ppm level is “highly conservative” is not warranted on scientific grounds. This claim is based on its use of three 10-fold adjustments, referred to by CDC as “uncertainty factors,” to extrapolate from a dose identified in an animal study to a level in drinking water consumed by people.
The CDC official referred to these adjustments as “safety factors” – implying they provide for a large margin of safety. This is FALSE. These are REALITY FACTORS.
Each of these accounts for known circumstances with regard to the effects of chemical exposures on people in the real world. There are plenty of examples of chemicals where:
Don’t take our word for it, but rather the National Academy of Sciences, in a seminal 2009 report titled Science and Decisions: Advancing Risk Assessment (p. 132, emphases in original):
Another problem … is that the term uncertainty factors is applied to the adjustments made to calculate the RfD [reference dose, derived from, e.g., a no-effect level] to address species differences, human variability, data gaps, study duration, and other issues. The term engenders misunderstanding: groups unfamiliar with the underlying logic and science of RfD derivation can take it to mean that the factors are simply added on for safety or because of a lack of knowledge or confidence in the process. That may lead some to think that the true behavior of the phenomenon being described may be best reflected in the unadjusted value and that these factors create an RfD that is highly conservative. But the factors are used to adjust for differences in individual human sensitivities, for humans’ generally greater sensitivity than test animals’ on a milligrams-per-kilogram basis, for the fact that chemicals typically induce harm at lower doses with longer exposures, and so on. At times, the factors have been termed safety factors, which is especially problematic given that they cover variability and uncertainty and are not meant as a guarantee of safety.
CDC’s Methodology Revealed
Until yesterday, all indications were that the 1 ppm level was derived from a single oral lethality study in rats that is not publicly available but reported a median lethal dose value (LD50). Yesterday, CDC referred to “additional animal studies” that were under review. In today’s Charleston Gazette story and this afternoon’s call, the CDC official indicated for the first time that CDC used a second study – also not publicly available – as the starting point for the calculations. This second study was stated as identifying a “No Observable Adverse Effects Level (NOAEL)” for MCHM of 100 milligrams per kilogram of body weight per day (mg/kg/day).
[UPDATE 1/17/14: This study, finally made available late yesterday, was performed using “pure MCHM” (97.3%) rather than the “crude MCHM” mixture that was the material actually spilled. This adds some additional uncertainty; if other components besides MCHM present in the crude mixture are more or less toxic than MCHM, the mixture’s toxicity would differ from that found for the pure material.]
Numerous questions about this study remain unanswered that bear on its relevance for the purpose to which it has been put. Just a couple key ones:
But at least we now know how CDC made the calculation that led to the 1 ppm level:
Welcome to the wild and woolly world of risk assessment, folks. More to come, we’re sure.
