Re: Fwd: Re: Chlrorform

["Thomas J Savin " <tjsav@LYCOS.COM>]

Here is the total article - I do not think the attachment was successfully sent out last message.  Sorry for the inconveince - Tom

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Tom Savin



Stirring controversy over cancer guidelines



EPA ADDRESSES KIDS ISSUES IN FIRST-TIME CHLOROFORM RISK FINDING



_______________________________________________



Date: November 12, 2001 -  







EPA has released a precedent-setting risk value for chloroform that for the first time finds that a non-pesticide carcinogenic compound can have a “safe” level of exposure. 







While industry sources are applauding the move, some EPA officials and other health experts are criticizing a key section on children's risk and faulting the agency for failing to have it peer reviewed. The need to have outside reviewers scrutinize children's risk characterizations is particularly important, they say, because addressing kids' risk was part of a key compromise reached with respect to the agency's controversial draft cancer guidelines that allowed the draft to move forward after challenges from children's advocates stalled their progress last year. 







“The chloroform characterization of children's risk is neither cogent nor biologically based,” according to one prominent developmental health expert at a major university. 







But industry experts disagree, with one noting that “EPA did a very good job of describing the rich toxicological database on chloroform and made well thought-out conclusions based on that information.” 







The chloroform risk file was released on the agency's Integrated Risk Information System (IRIS) Oct. 21 following an agency-wide consensus process. IRIS is a database containing a compendium of chemical risk values used widely by state and regional risk assessors and regulators. An EPA source says that the chloroform characterization is the “first time under the IRIS program where the agency concluded a compound has a nonlinear dose response curve.” Although the listing updates estimates solely for the oral, and not the inhalation, pathway, sources agree that it is an important acknowledgement that there is sufficient toxicological evidence to move away from the agency's standard “linear” or protective assumption in calculating cancer risks for a chemical. 







Industry experts are praising the agency's evaluation of chloroform's risk, noting that it follows a byzantine sequence of expert panel reviews, scientific evaluations, agency science policy reversals, litigation and a major precedent-setting case in the U.S. Court of Appeals for the D.C. Circuit in which a panel of three judges found that a threshold for a compound can exist and still protect human health (Risk Policy Report, April 18, 2000, p5). An industry scientist says that “EPA did an excellent and credible job of explaining the issues regarding chloroform risks and why children are not at higher risk than adults appear to be. I'm not sure there's much controversy here.” 







But some EPA and other federal health officials are raising strong concerns about how the risks to children are presented in the chloroform risk file. These sources argue that some of the scientific reasoning in the section addressing children's issues is weak and that that particular language should have been peer reviewed before it was placed on IRIS given the lack of data on children's response to chloroform exposure. 







According to the IRIS file, “there is no suggestion from available studies of chloroform to indicate that children or fetuses would be qualitatively more sensitive to its effects than adults. The developing organism would not be expected to be particularly sensitive to cytotoxic agents . . .” which sources say is a precursor to cancer processes. 







Sources agree that the children's section has implications for future chemical evaluations under the agency's draft 1999 cancer risk assessment guidelines because it is the first time such issues have been specifically addressed under a new provision in the 1999 version of the guide. 







The language addressing children is important because environmentalists had intensely criticized the draft guidelines over the last three years for not considering children's unique physiology and developmental processes when evaluating chemical risks. Several sources say their opposition led then-EPA Administrator Carol Browner to hold up the guidelines because “she didn't want them finalized on her watch,” according to one EPA source. 







As part of an effort last year to break a logjam over the handling of children's risk issues in the guidelines, EPA science policy officials agreed to require specific children's language. Having to address why specific biochemical sequences that appear to apply to adults are also relevant to the young would obviate the need for more protective assumptions. The specific language required is called a “cogent biological rationale” (CBR) for why toxicological mechanisms that apply to adults are likely to apply to children as well. But if the rationale is not considered adequate, research would have to be conducted on immature animals to see if the biochemical impacts were the same as those affecting adults or if more conservative approaches should be taken to protect children. The CBR for chloroform is available on our web site, InsideEPA.com. 







One federal health scientist says that the chloroform CBR is directed at the critical public health issue of in utero and perinatal exposures, but faults the rationale for being “as much policy derived as it is informed by science. It is misleading at best given that there may be another metabolic pathway such as glutathione transferase that could participate in the cancer process.” This source says that the CBR “is not a very defensible rationale. It reads like assumptions based on assumptions. The science isn't there and they recognize that it's a judgment call.” 







Several EPA scientists are raising alarms by pointing out that the CBR has not been externally peer reviewed. Although children's risk issues were addressed during a Science Advisory Board (SAB) review of chloroform more than a year ago, the specific language of the CBR was not crafted until this past summer. According to one EPA source, “complete risk assessments in the future will be fully peer reviewed,” before appearing on IRIS. 







Industry sources agree that peer review of all agency technical products should be a priority, but one source notes that “this portion of the IRIS file will receive attention in the preamble to the Stage 2 microbial/disinfection byproduct discussion for setting health goals.” 







Another EPA scientist takes issue with a section in the chloroform CBR that addresses lifetime dose estimates. According to the IRIS file, “It can be noted that if data indicated that it were appropriate to apply a linear approach to part of a lifetime, such as the first 3 first years of life, the resulting risk would be represented by a small increment of the total dose per body weight over a lifetime since most of a 70 year life is at an adult body weight. When this total is divided by 70 years to derive the lifetime average daily dose, the small increment of early dose does not significantly increase risk.” This scientist says that making such a conclusion is impossible without actually calculating it. “I don't know you can make a blanket statement that every three years of exposure is insignificant. What if such an assumption would be applied to Superfund sites? There's some loose thinking here.” But other EPA scientists are comfortable with the CBR, claiming it is a good !

s

ummary of a complex dataset. 







Industry sources, however, are praising the language, with one noting that “this is all about the public health benefits associated with chlorination of drinking water and preventing cholera.” This source adds that EPA has taken a “balanced and reasoned” approach to crafting the chloroform CBR. 







Sources within and outside of the agency agree that the language is precedent-setting not just for the cancer guidelines but because it addresses enzymes that metabolize common environmental chemicals such as trichlorethylene and butadiene, in addition to chloroform. “This is not a trivial mechanism. It bears on a number of compounds and mode of action hypotheses in the current literature,” explains one EPA source. 







Another EPA source adds, “I hope the precedent would be that we would have more information and discuss the issues in a more rigorous manner. In reviewing the statements on maternal toxicity and the assumed linkage with fetal effects when in fact these could be separate mechanisms, this CBR as it stands raises more questions than it answers,” this source says. 







One problem with the CBR approach is that what is considered “cogent” is still a judgment call that different scientists in the agency may differ on, according to one source. “In that sense, it just postpones controversy, instead of contributing to its resolution,” this source explains. Another EPA source adds that attention to crafting CBRs in the future should be a priority. “A framework for what needs to be in a cogent biological rationale is a key part of what needs to be addressed in the final version of the guidelines to bring consistency to decision-making,” this source says. 



>DATE: Mon, 17 Dec 2001 15:15:25

>From: "Steve Gibb" <steve.gibb@iwpnews.com>

>To: <tjsav@lycos.com>

>

>Dr. Savin: thank you for you request. Although we do not usually provide

>electronic access to our articles for non-subscribers to our website

>InsideEPA.com, I will make an exception in this case. Thank you for your

>interest in our publication -

>

>Cheers,

>

>Steve Gibb

>Managing Editor

>Inside EPA's Risk Policy Report

>Tel: 703-416-8578

>Fax: 703-416-8543

>"For scientists interested in environmental policymaking

>and policymakers interested in science"

>----- Original Message -----

>From: Thomas J Savin <tjsav@lycos.com>

>To: <riskpolicy@iwpnews.com>

>Sent: Monday, December 17, 2001 12:08 PM

>Subject: Chlrorform

>

>

>> Greetings,

>>

>> I have the November 12, 2001 VOL 8, Number 11 Risk Policy Report in front

>of me - my company is a subscriber.  Is there anyway I could receive an

>electronic copy of pages 3 and 4 - "EPA addresses kids issues in First-Time

>Chloroform Risk Finding" I know of a few people who would be very interested

>in reading this.

>>

>> I would consider it a grest favor, Thanks, Tom Savin

>>

>>

>>

>>

>>

>>

>

>

>





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