Sunday, June 29, 2008

We Knew That

I just picked up an abstract from the open access journal Environmental Health which presents a review of cancer epidemiology studies at hazardous waste sites. Epidemiology is the science and art that attempts to identify the relationships between disease and environmental factors. Some of the most painstaking investigative work in science occurs in epidemiological investigations. A classic example is the investigation of occurrence of cholera in London, conducted by John Snow As a part of this investigation, Snow mapped the locations where cholera cases occurred along with the locations of the local water pumps, thus creating the story of “the pump handle”.

The conclusion from this study was that epidemiological investigations generally did not provide a lot of information about whether communities near hazardous waste sites experienced an increased cancer risk or not. Limitations in the study design and limited information regarding levels of exposure were cited as support for this conclusion.

This study was funded by the City of New York. Why the City of New York is interested in drawing attention to the limitations of hazardous waste epidemiology isn’t made clear. However, it isn’t really news that hazardous waste epidemiology is grossly imperfect. We knew that already back as 1991. What is surprising is how little appears to have changed in the intervening years.

Most of the studies reviewed in this recent paper were identified as ecological studies, which examine rates of diseases between different groups (i.e. a community using contaminated groundwater compared with a community using an uncontaminated supply). Detailed information on the health status of individuals or detailed exposure information generally is not part of an ecological study. An ecological study is most useful for generating hypotheses and scoping more detailed epidemiological studies. Limited modeling or sampling data were incorporated into these studies, particularly measurements at the locations where individuals were most likely to come into contact with hazardous waste contaminants.

There’s a whole litany of things that could be done better here. We’ve known about these for a long time, but haven’t bestirred ourselves to deal with them.

The exposure data for assessing hazardous waste site contaminants is very limited, but we can’t all be tobacco epidemiologists who get to work with human populations who dose themselves like they were laboratory animals. There hasn’t been enough emphasis on community-based participatory methods for increasing community cooperation with exposure studies, as well as not enough emphasis on risk communication to help explain that simply looking for exposure doesn’t necessarily mean there’s a significant risk. From personal experience, I am aware that residents get understandably edgy when you want to come in to collect air samples from inside their homes or soil samples from their yards. They naturally run to the conclusion that there must be a problem (if there wasn’t, we wouldn't be looking, right?). However, because risk assessors are unable to discuss exposure and health risk in simple English, decision makers really don’t have a clue about what’s really going on, and everyone is afraid to speak up without a bunch of hedging and qualifying when the lawyers are in earshot, the people who have the biggest need to understand what’s going on – the neighbors to a hazardous waste site – routinely don’t get a straight story.

There’s the two-part problem of the lack of conclusiveness of epidemiology, coupled with the extremely sensitive perceptions of risks, both of which contribute to the sense of anxiety and uncertainty in the neighbors of hazardous waste sites. Both parts, the relative risk of 2.0 as evidence of causation, and the excess lifetime cancer risk of 1 in 1,000,000 as a threshold of acceptable risk, do not appear to be grounded in any sort of public health reality. It’s an obscure point, which is the topic for another post (because this one’s getting too long. . .).

We don’t seem to have learned anything from epidemiology to better inform hazardous waste decision making. Therefore, we fall back on making cleanup decisions using the crudest of risk assessment methods, which either don’t address real and significant health risks, or are a wasteful expenditure of resources in relation to the amount of risk reduction that occurs.

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Sunday, June 22, 2008

The Sad State of Environmental Health Policy Today, Redux

My first essay on this topic is posted here.

Keeping to my New Year’s resolution to blog more has been difficult. I moved our household across the country in preparation for a new job, and for the past several weeks, I was busy studying for my examination for recertification as an industrial hygienist (update: I took the test last month – and just received notice that I passed, so I’m still a CIH). I’ve also felt pretty played out on the blogging front, so I took a vacation from it.

Not that there haven’t been things to blog about. Revere weighed in on EPA’s “streamlining” of its Integrated Risk Information System (IRIS), a data warehouse of focused toxicity profiles and values for use in quantitative risk assessment. That post is spot-on in terms of how the Bush Administration is tinkering with transparency and accountability with yet another environmental health system. Where I differ with Revere is in the overall value of IRIS, which was characterized as:

Considered authoritative by many states and countries, its judgments have become the basis for official standards. It's been around since the start of Reagan's second term (1985) so there is no claim it is some kind of fringe environmentalist fantasy. It's not the Last Word but it's a loud voice and taken seriously by anyone tasked with protecting the public from toxic hazards.

Having been an IRIS power-user for many years, I would argue that IRIS wasn’t that even in its heyday. It’s true that the usability has been further reduced from the slowdown of profiles being posted on it. However, IRIS profiles for several of the highest profile chemicals have lagged for years, sometimes predating the first Bush Administration. Hundreds of other profiles aren’t consistent with the most current data or risk assessment methods (which is actually less of a problem than you’d imagine – I would argue that many of these aren’t significant environmental regulatory drivers anyway). We don’t just have a problem with politically meddling in regulatory science, but a problem with how toxicity assessments get done. Actually, we have a problem in general with how risk assessments are getting done these days (see here, here and here), but I’d rather not get into that now, because I’ll just start to rant incomprehensibly. . . .

IRIS isn’t the real travesty in health standards. That honor is reserved for OSHA’s Permissible Exposure Limits (PELs). Twenty years ago, OSHA published a final airborne contaminants rule amending the PELs, making values more protective for 212 chemicals, and promulgating values for 164 more, the first widespread update of the PELs since the OSH Act was enacted in 1970. At the time, there was a lot of hand-wringing about this streamlined approach for developing standards for nearly 400 chemicals, particularly in relying on TLVs. Ziem and Castleman have been prominent critics of TLVs – a summary of their arguments along with a historical perspective on the airborne contaminants rulemaking is presented in Chapter 7 of Illness and the Environment: A Reader in Contested Medicine. That rule was overturned in court in 1992 [AFL-CIO v. OSHA, 965 F.2d. 962], with the court concluding that OSHA needed to do an independent risk analysis on nearly 400 chemicals. So, currently, the PELs in force are based on the TLVs from the late 1960s. The exceptions are PELs that have been promulgated more recently as part of chemical-specific standards, such as benzene, vinyl chloride or hexavalent chromium. OSHA hasn’t attempted to promulgate new standards, and Congress apparently hasn’t seen fit to act in this matter either. This is just another example of how occupational and environmental health is important enough for the public to wring their hands over, but not important enough to deal with effectively.

An aside: what is interesting to me is how their reputation has been somewhat rehabilitated, since anti-regulatory critics have aimed their sights at TLVs. Celeste Monforton summarizes that controversy on Defendingscience.org.

You could run down the list of standards, advisory values, criteria and find similar situations. EPA’s Ambient Water Quality Criteria were created in the 1970s and early 1980s, and have not been updated in the intervening years, which ties in with the fact that most of the IRIS profiles haven’t been updated either. Same story for the drinking water standards, or Maximum Contaminant Levels (MCLs), most of which were last updated in the mid and late 1980s. National Ambient Air Quality Standards are updated at a glacial pace.

I’ve wondered why environmental regulations don’t keep pace with the emerging science. My current speculations go like this: the methods for toxicity and risk assessment have become more complex. Thus, the analyses take more time, and perhaps provide more opportunities for criticism by stakeholders such as industry groups and federal agencies such as DOD. Rulemaking processes are adversarial, which provides further scope for criticism and manufactured uncertainty. Public desires for no uncertainty regarding understanding of health effects, along with assurances of zero risks push us to the very margins of what laboratory studies can provide in terms of prediction of adverse effects (bisphenol-A is a good example of what science can and cannot say about adverse effects).

It seems that the regulated industries have articulated a strategy (including slowing regulatory processes with doubt and backing the winning horse politically) for how to address environmental and health hazards from chemical contaminants, which these days appears to routinely outmaneuver environmentalist and other progressive stakeholders. With a political sea-change in the offing, it will be interesting to see environmentalists will make some progress in altering how chemical hazards are managed.

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