The Aftermath

Numerous weblogs have taken up the task of soliciting donations to support relief efforts for victims of the South Asia tsunami. In the midst of this humanitarian crisis, what I can do is to encourage you to turn to one of them and give what you can. Confined Space provides a resource guide for tsunami relief in this post.

The current assessment by the World Health Organization (WHO) paints a grim picture. It is estimated that as many as 5 million people have been directly affected, including those left homeless and those unable to meet basic health needs. WHO notes that groups particularly at risk include women, children and the elderly. Millions of people are threatened by disease outbreaks resulting from damaged water and sanitation systems and sea water contamination. The water-borne disease threats include cholera, typhoid fever, shigellosis, and hepatitis A and E. Vector-borne diseases such as malaria and dengue fever also pose a significant threat. Refugee camps crowded with displaced people increase the risk of outbreaks of measles, influenza and meningitis, acute respiratory infections and tuberculosis transmission. Leptospirosis may also become a risk. The UN (through the United Nations Environmental Program – UNEP) is also getting prepared for addresing human health and ecological risks from chemically-related hazards – chemical spills from facilities and releases of solids and liquid wastes.

I've read accounts of people here expressing surprise and alarm at the increasing death toll just from the flooding (I wonder what they expected - the counting of just the flood victims could go on for weeks). Even with the best response, we can expect that the worst is yet to come.

Though it has been blown out of proportion, as well as being erroneous, the story of a UN official accusing the U.S. of being stingy with relief aid deserves another look. Juan Cole has noted how the U.S. contribution has been small relative to our capability to give, and proportionally smaller than other wealthy countries. This led me to explore the question of how much aid is needed. Assessment of the immediate needs will be ongoing, although WHO has published its strategy for responding over the next 100 days.

The objectives of WHO's 100-day strategy are:

- Monitoring public health to provide early warning of emerging health threats and to enable the timely organization of any necessary response.

- Replacing lost assets, infrastructure, and supplies that are crucial to meeting additional health needs consequent to the disaster, as well as the reactivation of key previously-available health services.

- Providing technical expertise to health authorities to enable key gaps to be filled;

- Establishing and sustaining effective regional, national, and local health coordination arrangements, to enable efficient deployment of assistance resources;

- Ensuring adequate up to date communications on the health situation is available to all local and international stakeholders;

- Refining health needs assessments over the coming period, and facilitating early recovery and rehabilitation.

The strategy is intended to cover 4 million people in the region, including 2 million refugees and 100,000 injured. The priorities for now are providing safe drinking water, set-up or reactivation of communicable disease surveillance and response systems, and beginning to re-establish basic health care systems, including hospitals. The WHO has estimated that the public health response (this does not include anything else needed for disaster relief such as food, water, shelter, emergency generators) over the next 100 days will be approximately US $37 million.

I won’t get in the middle of the argument about whether or not we’re being stingy, though it is a bit small of us as Americans to quibble over the cost at a time like this. Juan Cole cites an article in the Washington Post stating that President Bush missed an important opportunity to reach out to the Muslims of Indonesia with his parsimonious and lackadaisical response to the disaster.

What we need to do is begin to face the magnitude of the costs that will be associated with relief effort, just in the near term. I’ve tried to do some benchmarking with Federal Emergency Management Agency (FEMA) expenditures for hurricane disasters. FEMA’s expenditures alone, not counting other agencies, for the worst hurricane disasters on record, range from $225 million to $2.25 billion. Those expenditures probably covered a lot of needs other than immediate disaster relief, but it provides some realization that relief and recovery from this obviously larger disaster will require billions of dollars, even in just the near term. Being seen as cheap isn’t the issue; not showing leadership in a time of enormous need is.

Environmental Health Tools – TOXMAP

The National Library of Medicine (NLM) announced this month an interactive webmap called TOXMAP, which displays the geographical distribution of toxic chemicals released into the environment in the U.S. TOXMAP is linked to the U.S. Environmental Protection Agency’s Toxic Release Inventory (TRI) as well as the NLM’s TOXNET database. I have found both TOXNET and TRI to be invaluable resources in understanding the occurrence and fate of chemicals in the environment as well as their adverse effects.

Taking TOXMAP out for a spin, I queried it for emissions to the air in 2002 from tetrachloroethylene (synonym: perchloroethylene, or PCE), a chlorinated solvent used for cleaning in manufacturing operations and for dry-cleaning clothes. The queries can be run for a state, city or county in a state, zip code or specific facility (with and ID number you can obtain from EPA’s web site). I ran a query for all PCE emission sources in Ohio, where I reside, which pulled up the 20 facilities in the state reporting PCE emissions (surprising - I guess dry cleaners don’t have to do TRI reporting). The webmap can be centered and scaled appropriately with a few clicks. The emissions sources can be overlain with census tract information, so that you can see population density in relation to emission source strength. Based on the map, you can see an emissions “hotspot” in a relatively densely population area, a few miles southwest of downtown Cleveland. A few more clicks identified that specific facility, and provided its TRI profile. TOXNET can be accessed from the TOXMAP site, for hazard information on PCE.

The NLM press release suggests as an application for this tool, “for example, a family moving to a new city can locate facilities releasing toxic chemicals by entering the city's name and state, generating a map of facilities in that area. For each facility, information, including location and chemicals released, is provided. Information about the health effects of the specific chemicals identified is also provided.” I can also see this being of value to activists, who want to focus on facilities impacting specific communities.

Some of the limitations of the tool are: 1) there is a bit of a learning curve involved. If you are not conversant in chemicals, it could be a bit confusing to use; 2) it can develop maps for only one chemical at a time; and 3) it is important to remember that what TOXMAP is presenting is release information, not information on exposure or potential health hazards.

With air emissions, the magnitude of exposure and locations where significant exposures would occur also take into consideration meteorological conditions and facility characteristics. What would be really cool would be to link TOXMAP with an air dispersion model to provide estimates of potential exposures to chemicals emitted into the air. Maybe that can be for the future – there are a lot of technical challenges to overcome before exposure maps become a reality. For air emissions, EPA has provided something comparable with its National Air Toxics Assessment, which does provide emissions, exposure and health risk information. For example, a NATA exposure map for PCE in air in Ohio looks like this. The associated excess lifetime cancer risk from PCE inhalation exposure looks like this.

The NATA data also has its limitations. For example, with PCE, the predominant source of exposure is indoor exposure from offgassing from freshly dry-cleaned clothes, an emissions source not accounted for either by TOXMAP or NATA. However, these databases make some effort to alert the user to the limitations.

Though the Bush Administration has made significant efforts to limit the public’s right to know about chemical hazards in their communities in the name of homeland security, all hope is not lost yet. There are still substantial environmental health resources available through the internet.

It Isn't About Malaria

The right wing(nuts) use the term “sound science” to bash any research or line of inquiry raising environmental or health concerns, that potentially threatens an entrenched economic interest.

A favorite sound science example goes something like this: some liberal environmentalist, Rachel Carlson or William Ruckelshaus (!?) depending on the story, leads an army of politically-motivated researchers, who find some nitwit problem (something with birds eggs or rats getting cancer) with that all-important crop protection and vector control chemical, DDT. These pernicious individuals and their fellow travelers in the EPA and the United Nations essentially effect a worldwide ban of DDT. The result is a mounting toll of millions of deaths from malaria in Africa, Asia and Latin America (60 million lives, according to Dr. Elizabeth Whelan, of the American Council of Science and Health – ACSH).

Nice story. A lot of people get taken in by it. However, it is largely a folk tale that runs roughshod over the facts. Worse yet, it has nothing to do with malaria, and everything to do with undermining the efforts of individuals concerned about reducing exposures to persistent organic pollutants in general (all those deaths, because some environmentalist wanted to protect some birds or prevent some phantom cancer epidemic). The risk-benefit analysis for DDT is scarcely applicable to other POPs, such as PCBs or dioxins. Also, the industrialized world, which presumably includes the DDT-loving Reason Foundation or ACSH, has at best treated with neglect development and public health initiatives in the Third World, including malaria control.

The real story is much more interesting, providing many teachable moments. A little taste of that story can be found here. Understanding the story of malaria and DDT requires drawing together many threads, including the interaction between land use and tropical diseases, the mechanics of malaria control programs, the reasons for insect disease resistance to pesticides, the science involved with assessing human health and ecological hazards from pesticides use, and the politics of public health in the Third World. Teasing the real story out takes some effort (I’m wading through the literature right now), and unfortunately it will probably never be as punchy a master narrative as the factoids being peddled by the sound scientists. I’ll report back from time to time, as I draw the threads together.

Mercury Rising – The Federal Fish Advisory

In a recent post, I discussed the findings from the Environmental Protection Agency (EPA) stating that 300,000 newborns may have been overexposed to mercury through their mothers’ consumption of fish. Based in part on these concerns, the Food and Drug Administration and EPA recently published a fish advisory for mercury. The advisory recommends eating up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish. Another commonly eaten fish, albacore ("white") tuna has more mercury than canned light tuna. So, when choosing two meals of fish and shellfish, the advisory notes that you may eat up to 6 ounces (one average meal) of albacore tuna per week.

I am registered with an online fitness forum that addresses topics including strength training, diet and cardiovascular exercise. A member recently asked about mercury in tuna; tuna packets are a convenient way to get protein into your diet when you’re on the go. In response, I ran the calculations for estimating the mercury exposure associated with eating 12 ounces/week of tuna (corresponds to 48.5 grams/day). The average concentrations of mercury in tuna (based on the EPA’s Mercury Report to Congress, book 1 and book 2) is:

Albacore – 0.264 ug/g
Skipjack – 0.136 ug/g
Yellowfin – 0.218 ug/g

The daily intake rates from eating 12 ounces/week then look like this:

Albacore – 12.8 ug/day
Skipjack – 6.6 ug/day
Yellowfin – 10.6 ug/day

The NHANES mercury exposure survey published this year notes that the 95th percentile value for mercury intake from fish ingestion for women ages 16 to 49 ranges from 4.5 to 13 ug/day. When normalized for body weight, the intake rates range from 0.09 to 0.19 ug/kg-day (micrograms mercury per kilogram body weight each day).

Using the available data on mercury concentrations in tuna, the fish advisory consumption rates and an assumed body weight of 120 pounds (representing a women of child-bearing age), I get intake rates normalized for body weight ranging from 0.12 to 0.24 ug/kg-day for different tuna species, with skipjack being the lowest and albacore (white) being the highest. So, it looks like the fish advisory was set so that the exposures are kept close to EPA’s Reference Dose (RfD) of 0.1 ug/kg-day for methyl mercury. The RfD is intended to protect newborns and young children from adverse neurodevelopmental effects (more will be said about the RfD in another post).

The advisory attempts to balance the role of fish and shellfish as important parts of a healthy diet with reducing the risks from mercury exposure. Fish and shellfish contain high quality protein, are low in saturated fat and contain omega-3 fatty acids. A well balanced diet that includes a variety of fish and shellfish can contribute to heart health and children's proper growth and development. Thus, the advisory appears to set fish consumption rates as high as feasible without significantly incurring risks of excess mercury exposure.

However, there are a few questions that remain. Is consumption of 12 ounces/week of fish adequate for good nutrition? Also, there are other toxicants potentially associated with neurodevelopmental effects in children (dioxins, PCBs and brominated fire retardants) that are also found in fish. The fish advisory is designed to reduce exposure to mercury. What is not known is whether or not there are additive effects from the combined exposures. If so, the fish advisory may not necessarily protect newborns and young children from neurodevelopmental effects.

Shorter Wingnuttery

Advocates of public health promotion really are fascists because the Nazis had smoking cessation programs.

Bonus shorter wingnuttery from Jacob Sullum at Reason Magazine: even though I wrote it, I didn’t really mean it.

I’m not sure what the problem is. Health promotion is pretty voluntary in this country. Guys, there’s nothing stopping you from smoking tobacco until your lungs catch on fire (as long as you don't subject the sensible people to your emissions), and eating junk food until you resemble beach balls. I just hope your health insurance is paid up, that I don’t share carriers with you so that your lifestyle choices make my premiums go up, and that you promise not to suck up Medicare resources when you’re not only old, but really, really sick.

Thanks to Washington Monthly for drawing attention to this.

Deceit and Denial

I’m reading “Deceit and Denial: The Deadly Politics of Industrial Pollution”, by Gerald Markowitz and David Rosner, published by the University of California Press in 2002. The theme of the book is how U.S. industries attempted to conceal information about adverse health effects from the public and workers, and obstruct or influence actions by the federal government to regulate exposures to toxic substances. They focus on lead and vinyl chloride as case studies. Clearly, their sympathies lie with labor and citizen activists on this issue, but I’ve found it to be fairly well-researched and generally free of the outrage that environmentalists often engage in.

It appears to have gotten under the skin of the chemical industry. From Confined Space, we hear that the Chronicle of Higher Education notes that lawyers representing more than 20 chemical companies have taken the unusual step of issuing subpoenas to the peer reviewers as part of litigation over the alleged health risks of a widely used chemical compound. The civil case involves a former chemical worker who now suffers from cancer against the companies including Dow, Goodrich, Goodyear, Monsanto and Uniroyal. The case is scheduled to go to trial in February in the U.S. District Court in Jackson, MS.

In the book, Markowitz and Rosner present evidence that in the late 1960s and early '70s, chemical-industry leaders failed to inform the government about the results of animal bioassays indicating a relationship between excess incidence of cancers and exposure to vinyl chloride monomer. Mr. Markowitz has agreed to serve as an expert witness for the plaintiffs in several cases against the chemical companies. In the Mississippi case, he was questioned by the defendants' lawyers for five days in a pretrial deposition. The companies’ attorneys argue that the book doesn’t constitute real research and doesn’t speak to the issues of the case. In an attempt to strengthen that assertion, the companies’ attorneys have taken the unusual step of issuing subpoenas to the peer reviewers of the book.

The authors express their shock and dismay at the attacks on their credibility and professionalism, and at the time they need to invest to respond to these attacks. It would seem surprising that they are only now learning the lesson that lawyers can play hardball much better than academics or technologists. However, this one seems to be a new twist in the game between expert witnesses and attorneys.

Why Not Precaution?

I recently followed an exchange on RISKANAL listserver (you can find it off of Riskworld) contrasting the bioterrorist threat to food supply, beef specifically, with the normal microbiological threat associated with the supply chain. The discussion ranged from the various hazards (E.coli in beef and BSE) to the nature of the threat (we probably wouldn’t notice much of a terrorist incident with the beef supply because it’s pretty contaminated anyway. . .) to what can be done about it (cook your hamburgers and close the border to Canadian beef). The one thread I didn’t see taken up was the possible benefits of a precautionary principle approach where you limit your beef consumption, consume only grass-raised, locally grown livestock, or curtail it altogether. You could achieve multiple benefits of improved health and nutrition, coupled with a reduced burden on ecosystem services.

I suspect that the precautionary principle is a topic that secretly scares people in the same manner as endocrine disruptors. I wonder if the disdain for it held by many well-off, conservative pro-business types is a mask for their fears of having to give up their indolent, resource-sucking, pollutant-spewing lifestyles for the sake of the planet and future generations.

Collegium Ramazzini

I found a new resource while reading Effect Measure the other day: Collegium Ramazzini. Founded by Dr. Irving J. Selikoff of the Mount Sinai School of Medicine in New York, one of the foremost authorities on environmental health, the Collegium Ramazzini offers "a bridge between the world of scientific discovery and the social and political centres which must act on these discoveries" to conserve life.

According to their web site:

The Collegium Ramazzini assesses present and future potential for injury or disease attributable to the environment or workplace and transmits its views to policy-making bodies, authorities, agencies and the public. By holding conferences and symposia, by publishing research papers, and publicizing its views, the Collegium seeks to help legislators, regulators and other decision-makers to better understand the public policy implications of scientific findings. Its goal is to work towards possible solutions to occupational and environmental health problems.

The Collegium is a non-profit organization governed by a Council limited to 180 elected Fellows. It includes leading scientists and other people of over 30 countries distinguished by their concern for occupational and environmental health.

It is named for Dr. Bernardino Ramazzini, one of the fathers of environmental health. In 1700, Dr. Ramazzini published the first edition of his most famous book, the De Morbis Artificum Diatriba (Diseases of Workers), the first comprehensive work on occupational diseases, outlining the health hazards of irritating chemicals, dust, metals, and other abrasive agents encountered by workers in 52 occupations

Their web site along with Effects Measure will be fine additions to the blogroll of Impact Analysis.

Dioxin Poisoning of Victor Yushchenko

From the perspective of this blog, there wasn’t a lot to be gained from the news coverage confirming that someone had tried to poison Ukrainian opposition presidential candidate Viktor Yushchenko by putting dioxin in his food. It says something about the priorities of new organizations when the story of one man poisoned with dioxin is given equal weight to the story of 300,000 kids per year potentially losing cognitive function from mercury exposure. The lesson here is that it takes a little drama to get a story related to environmental health intensely into the news. Or into the political blogs, for that matter.

We’ll see if this news can turn into a teachable moment about dioxin. At least people got an opportunity to see what chloracne looks like. Arnold Schechter was interviewed by NPR. Maybe there will even be a story about brominated fire retardants some day.

Mercury Rising - NHANES Mercury Exposure Survey

As we discussed previously, the media has been reporting on the risks associated with exposure to mercury, principally from eating fish. This post takes up the question of “what’s the risk that my child could have been affected by mercury because I’ve eaten fish?” Another way of examining it is asking how uniformly is the risk distributed.

The U.S. Environmental Protection Agency (EPA) has concluded that 300,000 newborns may have been overexposed to mercury through their mothers’ consumption of fish. The study that everyone is interested in reports blood organic mercury (i.e., methyl mercury) in 1,709 women who participated in the National Health and Nutrition Examination Survey (NHANES) in 1999 and 2000. Their fish consumption was estimated using 24 hour recall diaries (keeping a diary of everything eaten in the past 24 hours) and interviews of foods consumed in the past 30 days. The mercury concentrations in fish were based on data in published studies. The consumption and concentration data were then combined to estimate daily mercury intake.

Blood methyl mercury concentrations were lowest among Mexican American women. Blood methyl mercury concentrations were highest among participants who designated themselves in the Other racial/ethnic category, which includes Asians, Native Americans, and Pacific Islanders. Blood methyl mercury concentrations were seven times higher among women who reported eating nine or more fish and/or shellfish meals within the past 30 days when compared with women who reported no fish and/or shellfish consumption in the past 30 days.

The blood mercury concentrations in women were compared with the Reference Dose (RfD) for methyl mercury to assess the potential risks of adverse neurobehavioral effects in newborns. The RfD value corresponds to a blood mercury level of 5.8 ug/L in (micrograms of mercury per liter of blood) in umbilical cord blood, which is the closest representation of potential dose to a fetus. The derivation of this value is a topic for its own post, but some of the key points are:

1. The RfD, developed by the EPA, is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.
The RfD for methyl mercury was derived from blood mercury level of 58 ug/L (developed by the National Research Council) which is the lower 95% confidence interval (CI) on an estimated dose that doubles the prevalence of children with scores on a test of intellectual development that would fall into the clinically subnormal range. The EPA applied a 10-fold uncertainty factor to NRC’s value to obtain the RfD. See now why this topic requires its own post?

2. In the 1999-2000 NHANES survey, 7.8% of women between 16–49 years of age had blood methyl mercury levels of 5.8 µg/L or higher. EPA applied the 7.8% value to the number of newborns in 2000 (4,058,814, according to The National Vital Statistics Reports) to conclude that > 300,000 newborns per year may have had increased risk of adverse neurodevelopmental effects as a result of in utero methyl mercury exposure.

Another recent study examining the ratio between umbilical cord to whole-body blood methyl mercury concentrations indicates that cord blood is, on average, 70% higher in Hg concentration compared with a whole-body blood mercury level (in other words, the mercury concentration in a blood sample collected from a vein in the arm). When corrected for this ratio of 1.7:1.0, the percentage of women with a blood mercury level that might pose an increased risk of adverse neurodevelopmental effects in newborns increases to 15.7 percent. Does this mean there are really ~600,000 newborns/year at risk? That’s not certain, and EPA did not publish that number in their study. I’m not sure it really matters; either number indicates a potential environmental health crisis.

Another limitation to these findings is that mercury is not the only neurobehavioral toxicant that accumulates in fish as potentially poses a risk to newborns. Persistent organic pollutants including PCBs and dioxins, and polybrominated diphenyl ethers - PBDEs (which aren’t called POPs, but should be) may also pose neurobehavioral risks in the same manner as mercury. As yet, noone has done the cumulative risk assessment addressing mercury and POPs. For the moment, there really isn’t an answer to the question of the combined exposures.

There's more coming on this topic later.

Mercury Rising

Mercury is in the news these days, with word is getting around about the NHANES (National Health and Nutrition Examination Survey) study (reported by the EPA) characterizing exposure to organic mercury. It suggests that more than 300,000 newborns in the United States each year may have been exposed to unacceptable levels of mercury from their mothers’ consumption of fish. For those who see this finding as credible, this has led to some painful consideration of the risk comparisons – heart-healthy diet versus your baby’s brain.

For the moment, we’ll glide by the rant, I mean the analysis, of how print and broadcast media fail abjectly to inform people so that they can form their own opinions about this issue. Instead, over the next several weeks, we’ll focus on a series of questions that may be of near-term interest to anyone:

What’s the risk that my child could have been affected? (How uniformly is the risk distributed?)

What are the consequences of being overexposed to mercury? (What kinds of adverse effects are associated with exposure over the safe level?)

How much can I trust the “safe” level of exposure (What kinds of information have been used to evaluate no-effect thresholds)?

Are all kinds of fish equally risky? Under what conditions can we eat fish for a heart-healthy diet?

And, the longer-term questions such as: where is the mercury coming from? What do we have to change or stop doing to reduce the risks? Is this anyone’s fault, and should there be remediation or compensation?

Noone at the Helm

From Confined Space comes news of a new public health blog, Effects Measures, published under the pseudonym “Revere” by a “senior public health scientist and practitioner. His name would be known to many in the public health community and to a few others in his (very specialized) area of scientific research.” It’s quite good, and he pulls no punches. In discussing the need for anonymity, he says:

The choice of a "virtual" rather than a specific identity allows Revere to speak with a distinctive voice and a diction (choice of words) not constrained by the careful words required of public persons. Revere wishes that voice to include the language used daily around lunch tables and water coolers in agencies, health departments and universities when health workers are speaking plainy. Revere's language on Effect Measure can be saltier, more direct and blunter. We need plain speaking at this moment. But that kind of language can also provoke reprisal and retribution. Revere does not wish any program staff, agency or university funding to be jeopardized by his/her/their utterances off the job. Could that happen? This is the Bush Administration, dear Reader. They play rough and by their own rules. We must expect that.

Public health in America is leaderless, rudderless and dispirited. The failure is across-the-board, including the leadership of virtually the whole federal health establishment, our state health departments, our universities and schools of public health, and our labor unions, among others (Revere is an equal opportunity offender). We must not only feel free to Speak Truth to Power, but just as importantly, to Speak Truth to Each Other. That might mean challenging long held "conventional wisdom" in public health. Revere wants the freedom to do this without unintentionally alienating respected friends and colleagues. It is Open Season.

One of Revere's (not so modest) objectives is to jump-start the process of reconstructing and re-invigorating the progressive public health movement in this country and by speaking in a distinctive voice, to advance the conversation. When wrongheaded, Revere will rely on your astuteness and passion for public health to correct, cajole and inspire. We are all in this together.

I was particularly drawn to the thought of public health in America being leaderless, rudderless and dispirited. Investment in public health, in the same manner as investment in education or the arts or workplace safety, is an indicator of an advanced society, and the worrisome thing is that the disinvestment is a sign of us slipping to a lower-tier status.

I wonder what is going to have to befall us for public health to become important once again: have the water and wastewater treatment infrastructure finally collapse from lack of investment, so that it’s no longer safe anywhere to drink from the tap? Have the healthcare infrastructure collapse from treating a substantial fraction of the population suffering with degenerative diseases incurred through poor lifestyle choices? Bacterial or viral epidemics brought on because there’s no profit margin in developing vaccines or antibiotics? Cancer epidemics from exposure to persistent organic pollutants? Worse yet, discovering that we’ve made an entire generation of children cognitively impaired from exposure to POPs, mercury and lead. International terrorism pales in comparison to the woes awaiting us if we fail to reinvest in public health.

Thank you, Revere for sounding the call to arms.

Postscript: I learn from the masthead that Paul Revere was a member of the first local Board of Health in the United States, in Boston, 1799.

Blog Hiatus

I’m back, hopefully, after a dry spell. I’m learning the difficulty in maintaining a blog where the topics require some research, in the face of family needs, a demanding job, other personal and career influences, and the need for some good old down time. For example, I’m a board-certified industrial hygienist, and that has maintenance requirements fulfilled by conference attendance, holding office in local professional organizations, and a variety of courses, include home-study programs. Since I haven’t had time to hold office, and conference attendance is expensive (gotta show the business value in it to get funding support from my employer), I’m a bit behind on certification maintenance points for this year, I’m doing the home-study course – which is another pull on my time.

One of the other lessons I’ve learned is that when your time is limited, you need to pace yourself in blogging – long articles need to be interspaced with short vignettes, news clips, book reviews and so forth.

So, here’s to the return of Impact Analysis. Let’s hope that 2005 postings will be more frequent.

New Findings on Benzene

The New York Times reports today on a study that evaluated decreases in white blood cell counts in Chinese workers exposed to benzene. The results were that changes in white blood cell counts were observed in workers exposed to at or below 1 ppm benzene. 1 ppm is the current Permissible Exposure Limit (PEL) for benzene.

The 1 ppm standard was one of those highly controversial compromises that fundamentally changed the way occupational exposure standards were developed. That’s a story for another time; I used to be familiar with it, but now would have to do the homework to do it justice. A summary of the issue by Peter Infante is here.

The NCI study, "Hematotoxicity in Workers Exposed to Low Levels of Benzene," was published in the December 3, 2004, issue of Science. It reports results from 250 Chinese workers exposed to benzene through the air in their workplace and compares blood cell counts to 140 non-exposed workers. The study included workplace air sampling over the course of a year, to evaluate seasonal changes in workers' exposures.

A team of investigators from the National Cancer Institute (NCI), University of California, Berkeley, the Chinese Center for Disease Control and Prevention (Chinese CDC), University of North Carolina at Chapel Hill, and the New York Blood Center and the New York Blood Center were contributors.

NCI researchers, in collaboration with the Chinese CDC, have been studying industrial workers in China since the mid-1980s. The project grew out of a Chinese national health survey which found worker exposure to benzene to be commonplace. The NCI-funded studies included 75,000 workers exposed to benzene and 35,000 unexposed workers in over 700 factories in 12 cities in China. These studies collected industrial hygiene information on the workers' exposures and surveillance information on adverse effects. These studies suggested that benzene exposure is associated with an increased risk of blood and related disorders at average benzene exposure levels of less than 10 ppm.

About the same time, Dr. Martyn Smith at U.C. Berkeley demonstrated that benzene was metabolically activated to a carcinogen by the enzyme myeloperoxidase (MPO). MPO also was later identified as a enzymatic marker for sensitivity to the adverse effects of benzene exposure. Dr. Stephen Rappaport, also at U.C., Berkeley at the time began to develop methods for biological monitoring of benzene and its urinary metabolites. In the early 1990s, the U.C. Berkeley researchers began to collaborate with NCI and Chinese CDC epidemiologists and industrial hygienists. In 1992, this interdisciplinary team carried out a study of 44 workers exposed to benzene and 44 controls in Shanghai. That study found evidence of lowered blood cell counts among workers exposed to less than 31 ppm benzene, with an average exposure of about 14 ppm in air.

Benzene has been shown to causes leukemia and lowers blood cell counts in people who are exposed to high levels of benzene at work. Historically, adverse effects to blood-forming tissues has been clearly observed with exposures higher than 100 ppm, and are less apparent at 10 ppm in air or lower. As noted by the NCI press release, further work is needed to understand the potential leukemia risks for large groups of workers exposed to low levels of benzene. It has estimated that up to 3 million workers in the U.S. may be exposed to benzene.
This isn’t going to trigger any significant action for awhile yet (especially with a Bush Administration Department of Labor). However, it does reinforce the course of prudence in reducing worker exposures to as low as feasible – in other words, just because the standard is 1 ppm isn’t really a reason to stop there.

Bhopal

Yesterday was the 20th anniversary of the Bhopal disaster, which remains one of the saddest episodes in the sorry history of environmental health. Jordan at Confined Space covers the event very well, and what he’s written is well worth reading. There is little I could add other than to say it is a shame that Bhopal apparently wasn’t able to generate a groundswell of changed thinking in environmental protection, compared with the environmental health crises of previous years – think about DDT and Silent Spring, the Santa Barbara oil spill, the thalidomide disaster, and even Times Beach and Love Canal, all of which enacted major changes in environmental health thinking. PSM, RMP, TRI and the Chemical Hazards and Safety Board, even when they had teeth, just don’t resonate historically the same way as the National Environmental Policy Act or the formation of the EPA.

The political and public affairs blogs haven’t seemed to cover this issue, either.