Sunday, 21 October 2012

EPA human testing and the toxicity of PM2.5

I've just added this site to the sidebar. The video introduces the lawsuit:

As the video says, The Environmental Protection Agency is being sued for exposing human subjects to levels that greatly exceed its own daily exposure limits in a number of experiments, in which the subjects are exposed to   – and not just any subjects but those who are particularly at risk. This has come to light since the hospitalisation of one of the subjects led to a FOI request that exposed data concerning many others. Those participating in the tests were not notified that the EPA considered that PM2.5 was something for which (just like secondary smoke) there is 'no safe level of exposure'. 'Particulate matter causes premature death. It doesn’t make you sick. It’s directly causal to you dying sooner than you should', says Lisa Jackson of the EPA (see video).

This whole scenario puts the EPA on a sticky wicket. They are lying about the PM2.5 being toxic, or they are lying to test participants by not revealing the full scale of the risks involve in taking part in the tests. They are also expected to explain the necessity for the tests, since PM2.5 is already regulated.

The condemnation of PM2.5 ('no safe level') is based on particle size, but it seems to stretch credibility to state that just because something is microscopic, it is necessarily more dangerous than something with a larger particles – particle size is only one factor in assessing toxicity. (In the EPA experiments, it is alleged that diesel exhaust was used.) I am not a chemist and cannot assess whether it is an important factor. I can understand finding small particles a particular danger as they are more easily absorbed into the body, but not how the EPA can exclude a reckoning of actual toxicity when reaching the conclusion that there is no safe level of something. It is indeed tempting to conclude that the EPA, in declaring that there is no safe level of  exposure to PM2.5, is searching for excuses to regulate. (This discussion covers this assumption over about the first twenty minutes.)

My question is, if there is no safe level of PM2.5, how is there any justification of outdoor smoking bans, if all the background particulates are also so dangerous?

I look forward to more developments on this.

1 comment:

Anonymous said...

The US Department of Energy wired up restaurant and bar workers with air sampling devices to get a better picture of worker exposure to ETS. Their conclusions, published in "Exposure to Environmental Tobacco Smoke in Sixteen Cities in the United States As Determined by Personal Breathing Zone Air Sampling", appearing in the Journal of Exposure Analysis and Environmental Epidemiology, were that inhalation exposure to ETS was so low as to render health hazards negligible to improbable. The study showed that typical exposure rates taken for granted by anti-ETS lobbyists are 2 to 5 times the actual exposure rate, over an 8 hour exposure period. Respirable suspended particulate matter exposure was 1/4 the threshold level OSHA considers significant. These findings were later replicated by the Oak Ridge National Laboratories in ""Determination of Exposure to Environmental Tobacco Smoke in Restaurants and Tavern Workers in One U.S. City" in 2000. Additional studies suggest that, in opposition to the anti-smoking forces' claim that bartenders involuntarily inhale half a pack a day of cigarette smoke, bartenders annual exposure to smoke rises, at most, to the equivalent of 6 cigarettes/year. The question must be asked, then: if exposure to environmental tobacco smoke was so low for individuals working eight-hour shifts in restaurants and bars, how much lower would be the exposure to individuals exposed only during the course of a meal?

The 2006 standards tighten the 24-hour fine particle standard from 65 micrograms per cubic meter (µg/m3) to 35 µg/m3, and retain the current annual fine particle standard at 15 µg/m3.

EPA has decided to retain the existing 24-hour PM10 standard of 150 µg/m3. Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the Agency has revoked the annual PM10 standard.

The Agency selected the levels for the final standards after reviewing thousands of peer-reviewed scientific studies about the effects of particle pollution on public health and welfare. External scientific advisors and the public examined EPA's science and policy review documents. The Agency also carefully considered public comments on the proposed standards. EPA held three public hearings and received over 120,000 written comments.

While EPA provisionally assessed new, peer-reviewed studies about particulate matter and health (including some studies received during the comment period), these studies were not the basis for the final decision. EPA will consider those studies during the next review of the PM standards.