January 28th, 2002
To: Dr. Paul Joe, CDC Re: Worker/population exposure to Organophosphate-based Chemical Warfare Agents
I have just read the Federal Register notice publishing a proposed rule on exposure limits for three organophosphate based chemical formulations. This response questions the appropriateness of suggesting that any exposure limits can be set which would be below the level of harm for all persons within any segment of our society for this class of chemicals. It is certainly not accurate to assume all workers possess equal biochemical protections against these toxicants and it would be profoundly inaccurate to say the general population could withstand such exposures regardless of age or medical condition.
Please forgive my over-simplification of the issues as I am not a scientist. I am a person who was repeatedly exposed to organophosphate and pyrethroid pesticides over the course of my lifetime and am now disabled and brain damaged at the age of 45. My research has led me to have a cursory familiarity with some of the principles involved which must be taken into consideration when exposing workers to these substances.
Organophosphates (OPs) appear to be rendered “harmless” in the body via two avenues of protective enzymes. Firstly, there are the acetylcholinesterases, which prevent the overexcited nerve cells in every organ of the body from excessive firing, leading to cell death following exposure to these nerve agents. AchE is reduced, sometimes to damaging and even fatally low levels in exposed persons. Are baseline levels of AchE (both plasma and RBC levels) taken on all workers? Without this essential baseline information, surveillance procedures which would have to include periodic AchE testing, would have no value until damage of perhaps an irreversible nature had already occurred. Why not have procedures which permit the monitoring of adverse effects prior to appearance of overt symptoms? Suppressed AchE is supposed to regenerate within the space of a month or so yet continued exposures would prevent such a “rebound” and increase the likelihood of permanent effects. Adverse effects of OPs can have insidious onset, unnoticed by the parties being exposed to low levels of the substances on a ongoing basis.
The national levels for “normal” amounts of AchE in the bloodstream (for plasma levels) have been lowered time and again over the past years to some ridiculously low parameters. There is no evidence that the “normative groups” upon which these new levels are based have not experienced OP exposure and subsequent AchE inhibition. In fact, given the ubiquitous presence of OPs in foods and the environment (over 80% of persons tested for chloryrifos metabolites in their urine were positive in some studies), AchE inhibition is likely a very prevalent condition rather than a normal state among Americans.
Workers can only be protected if they are first subject to baseline analysis of their own AchE levels and are scrutinized via the use of questionnaires designed to examine their exposures to OPs in their daily lives. For example, is their diet high in agricultural products where OPs are used routinely? Are the buldings in which they work exterminated with OP based pesticides? Their home use of pesticides must be examined as well for a picture of cumulative expsoures. Workers cannot be assumed to be a homogeneous group at equal risk for AchE inhibition. There are also genetic variations among the cholinesterases for which I lack the education and background to address here. As some of these forms may provide less protection than other types, some analysis would appear to be required on this level. I would refer you to Dr. Lockeridge at the University of Nebraska for such data..
Secondly, the enzyme known as paroxonase or PON 1, has been shown to be essential to the detoxification process of certain OPs as per decades of study by Dr. Clement Furlong and his team at the University of Washington in Seattle. Approximately 16 percent of the population is deficient in this enzyme and at high risk for damage from exposure to those OP agents which are effected by the enzyme. This includes chlorpyrifos, an agent to which I was repeatedly exposed over the course of many years in occupational and residential settings. I have recently learned that I am among the group of PON 1 deficient individuals. The failure of the public to be informed of the connection between pesticide tolerance and PON 1 levels is a crime which has been perpetrated upon all citizens. Apparently, no infants have this enzyme, developing it in later childhood. The awareness on the part of industry and the scientific community of our universal exposures to OP agents is a heinous sin of omission, if such hyperbole can be permitted in the text of public commentary for proposed rules in the federal register.
The test for PON 1, is not commercially available so even physicians, notoriously lacking in toxicological information, can have no knowledge of this risk factor. However, workers handling agents for which this protective enzyme is necessary MUST be screened for it. The segment of the population for whom deficiencies are present is simply too high to ignore, even if one believes in the concept of “acceptable risk” As one of millions who are now statistics within the category of “acceptable risks” benefitting some industry or other, I will refrain from further commentary on the philosophy and practice of this concept under our current economic and regulatory policies.
Lastly, I would like to point out that the Federal Register notice contained the following paragraph:
“There is no indication that the current exposure limits, as implemented by the U.S. Army Program Manager for Chemical Demilitarization, have been less than fully protective of human health. This may be due to rigorous exposure prevention efforts in recent years as well as the conservative implementation of the existing limits. ”
Considering the fact that the population of ill Gulf War Veterans appears to have an unusually high incidence of low PON 1 concentrations according to the work of several researchers, one must wonder what “indications” are being considered. We know many had OP (sarin) exposures as well as exposures to combinations of pesticides of various formulations. A lack of inquiry using appropriate research parameters into this phenomenon is a more likely scenario than a lack of “indications” that harm has been done. A failure to acknowledge the relevance of certain indicators is not the same as an absence of indicators in such investigations where certain findings arise over and over again in both military and civilian populations.
I object to any proposed rule which sets universal exposure guidelines for any population without scrutiny for individual differences in biochemical, immune system functioning. We are a heterogeneous species due to individual genetic differences. We are also exposed to a vast variety of environmental exposures which place some of us at great risk from anticipated occupational exposures to toxicants. The full range of precautionary procedures based upon all current scientific knowledge of human responses to poisons must be implemented if people are to be exposed to harmful chemical agents in the course of their lives. Regardless of the final rule which is implemented, all persons for whom exposures are going to be a requirement of their job descriptions should be issued a warning notice specifying that the state of or knowledge regarding short and long term effects of chemical exposure, is incomplete. We cannot claim to have any complete understanding of such matters given the limitations of scientific knowledge and, most importantly, the restricted pool of data which results from private industry being the responsible party for such inquiries. Until independent studies become the norm, conflicts of interest must render all available data as suspect in terms of its competeness and accuracy when it comes to the health and safety of the public.
Thanks you for your attention.
Barbara Rubin P.O. Box 224 Locust Valley, N.Y. 11560
cc; EPA N.Y.S. Senators Steven Tvedten
[Federal Register: January 8, 2002 (Volume 67, Number 5)]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
Airborne Exposure Limits for Chemical Warfare Agents GA (Tabun),
GB (Sarin), and VX
AGENCY: Centers for Disease Control and Prevention (CDC), Department of
Health and Human Services.
ACTION: Notice of proposed revisions to CDC recommendations for
protection of public health and safety during disposal or transport of
chemical warfare agents GA (tabun), GB (sarin), and VX through revision
of worker and general population airborne exposure limits.