Topic
Scientific Approaches for Group(s)
Discussion
 

Health Effects

CLOSED DISCUSSION

How should EPA determine that groups of contaminants may have adverse health effects? How should EPA establish the health based values (Health Reference Levels or Maximum Contaminant Level Goals) for groups of contaminants?

Good Morning 2 Replies New
Facilitator Gail Bingham
7/29/10 05:41 AM
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Welcome to Day Two of this web dialogue, “Drinking Water Strategy: A New Framework for Addressing Contaminants as Group(s).” Thank you all for the detailed, thoughtful comments you offered yesterday, and for the technical information shared. Highlights of yesterday’s dialogue will be posted and you can go back to each separate discussion for the details at any time.

Today we move forward, building on yesterday’s discussion. Specifically, our topics for today are: 1) how to make scientific and technical findings for groups of contaminants as part of the regulatory decision-making process under the Safe Drinking Water Act and 2) implementation issues, including issues of cost-effectiveness, implications for small systems, and communicating what this means with the public.

Please take a moment to review the discussion questions for all the topics before posting. Yesterday, most ideas were posted in one discussion area, which was a little .like a workshop where topics planned for the afternoon get mixed into the morning’s agenda. This can mean that good ideas may not be responded to and elaborated by others as much as they might have been – although nothing will get lost.

Also, I noticed that some of you found the “I agree” option. It’s informal, and not intended to be the basis for making choices, but please feel free to use that feature if you like.

I look forward to today’s conversation. Gail
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Active Panelist Jennifer Sass
7/29/10 07:45 AM
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I agree option
where is it?
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Facilitator Gail Bingham
7/29/10 08:03 AM
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Location of I agree choice
It's close to the "Reply" option -- but panelists and facilitators don't see it, only "participants." Sorry!
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Active Panelist Eric Burneson
7/29/10 05:59 AM
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Health effects are a critical driver in the risk management frame work established under the Safe Drinking Water Act. To regulate contaminants under the Safe Drinking Water Act, EPA must determine the contaminant 1) may have adverse health effects, 2) occurs or is substantially likely to occur in public water systems at a frequency and levels of health concern and 3) presents a meaningful opportunity for health risk reduction through regulation. EPA has used Health Reference Levels (HRLs) as health based values in making past regulatory determinations on individual contaminant candidates. EPA derives these HRLs using methodologies similar to those used for establishing Maximum Contaminant Level Goals (MCLG) The MCLG is the level at which no known or anticipated adverse effects on the health of persons occur and which allows an adequate margin of safety. The MCLG is the health based value that drives the establishment of the enforceable Maximum Contaminant Level (MCL) which is set as close as feasible to the MCLG or Treatment Technique. In this discussion topic, we are seeking input on how the agency should determine that groups of contaminants may have adverse health effects. We are also seeking your thoughts on how we should establish the health based values (Health Reference Levels or Maximum Contaminant Level Goals) for groups of contaminants. Please consult the Draft Discussion Paper under item 2 in the Library. Section 4 of the discussion paper presents ideas for how the Agency might derive health based values. We welcome your thoughts on these ideas as well as any other suggested approaches you might have.
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John Gaston
7/29/10 06:24 AM
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MCLG Conundrum
I may be having yet another early morning senior moment, but isn't it required that MCLG's for carcinogens be set at "zero"? If my recollection is correct, is this a statutory requirement or an Agency decision. Wouldn't it be more valuable to have an actual value for the MCLG rather than "0"?
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Active Panelist Eric Burneson
7/29/10 06:55 AM
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MCLGs
John
MCLGs must be set at the level at which no known or anticipated adverse effects on the health of persons occur which allows an adequate margin of safety. For carcinogens, EPA has typically established MCLGs of zero, because there is no data to demonstrate a dose that is without risk of cancer. The exception would be when there is sufficient scientific data available to demonsrate a dose threshold that without risk of cancer. While MCLGs are established at zero for most carcinogens EPA uses the cancer slope factors for these contaminants to estimate the cancer risk for various exposure levels (i.e, potential MCLs) to inform the health risk reduction cost analysis in developing the regulation.
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John Gaston
7/29/10 08:04 AM
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How to deal with groups?
So it is fair then to assume that if compound "X" is a carcinogen the MCLG is going to be zero, and furthermore if compound "X" is included in a group the MCLG for that group will have to be zero. Will it be possible then to set a MCL for the group based upon some analysis of the group? if we chose an easy and existing small group, such as TCE & PCE, would the MCL be 10 ppb to reflect the sum of the existing MCL's?
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Larry Ladd
7/29/10 10:17 AM
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TCE/PCE group mcl
"if we chose an easy and existing small group, such as TCE & PCE, would the MCL be 10 ppb to reflect the sum of the existing MCL's?"


With the layman's assumption that TCE and PCE toxicity are very similar and roughly equivalent, I would hope that if the federal MCLs for TCE and PCE have to remain at 5 ppb, then the joint MCL for both solvents combined would ALSO be 5 ppb. Otherwise, why bother to regulate them as a group?
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Active Panelist Eric Burneson
7/29/10 09:08 AM
[jump to parent] in reply to John G.
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How to deal with Groups
John: This concept is discussed in the Discussion Paper (available in the Library under section 2). It could be possible to establish an MCLG of zero for a group of contaminants that includes contaminants for which there is no known exposure that is without risk of adverse health effect. The MCL for the group would be set at the level that is as close as feasible to the MCLG of zero. EPA would have to evaluate whether a combined group MCL or individual MCLs for the contaminants in the group would provide the greatest health protection considering benetits and costs. The feasibility analysis is being discussed under the treatment technique section of this discussion.
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Inactive Panelist Tom Grubbs
7/29/10 08:01 AM
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Non-zero MCLG
EPA set a non-zero MCLG for chloroform based on threshold.
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Paul Ponturo
7/29/10 06:53 AM
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MCLGs Set at Zero
I believe you are correct. It is a SDWA requirement based on the EPA Administrator's human carcinogenicity decision. From the perspective of anyone trying to explain risk to the public at large, the "zero" concept will always be a challenge. Any detection will imply risk, but is the detection reproducable, and is the risk significant relative to exposures of the same contaminant via other media? Improved lab capabilities will likley be at the heart of the current 6-Year Review for Tetrachloroethylene (PCE) and Trichloroethylene (TCE)
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Mohammad Habibian
7/29/10 08:06 AM
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Health effects
You have raised a very important issue and this is relative risk consideration. As an example, we are exposed to many chemicals via food we eat, personal care products we use, etc. Often the exposures via these routes are far beyond the exposure via drinking water. This is another reason why a program such as EU REACH program is a much better tool for addressing contaminants in the environment. My comments on this issue were posted yesterday and I am copying it here.

Regulation by groups is not an optimum solution to ever increasing numbers of chemicals in the environment. The current program is now well established. Its slowness can be addressed by new toxicology methods such as Tox21. It will take many years to develop and mature the group method. It will slow down the progress in innovative and very rapid methods for toxicological analysis. More importantly, it keeps the responsibility for assessing chemical safety on the government, rather than the manufacturers, as is envisioned in one of the key speeches by the EPA Administrator, and as practiced for about 8 years in EU. Also, The TT for each group could impact other TTs in a negative manner, similar to lead-copper rule and the DBP rule. The resolution of such conflicts could take years. We would be much better off with considering a program such as REACH adopted by the EU.
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Nicholas Anastas
7/29/10 08:21 AM
[jump to parent] in reply to Mohammad H.
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REACH and health effects
Mohammad-What are the central features of the REACH approach that you feel are important for EPA and others to consider in setting standards?
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Mohammad Habibian
7/29/10 09:47 AM
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Health efects
Here is the major Points of the EU New Regulation for Control of 30,000 Chemicals:
The main goal. Chemicals bring about benefits on which modern society is entirely dependent, On the other hand, certain chemicals have caused serious damage to human health resulting in suffering and premature death and to the environment EU chemicals policy must ensure a high level of protection of human health and the environment for the present generation and future generations while also ensuring the efficient functioning of the internal market and the competitiveness of the chemical industry .
The Concerns and the framework. The lack of knowledge about the impact of many chemicals on human health and the environment is a cause for concern. EU chemicals policy pursues a high level of protection of human health and the environment. Fundamental to achieving these objectives is the Precautionary Principle.
The current framework and its major shortcoming. The present system for general industrial chemicals distinguishes between "existing substances" i.e. all chemicals declared to be on the market in September 1981, and "new substances" i.e. those placed on the market since that date. There are some 2,700 new substances. Testing and assessing their risks to human health and the environment according to Directive 67/548 are required before marketing in volumes above 10 kg. For higher volumes more in-depth testing focusing on long-term and chronic effects has to be provided. In contrast, existing substances amount to more than 99% of the total volume of all substances on the market, and are not subject to the same testing requirements.
Inappropriate allocation of responsibilities. There is a general lack of knowledge about the properties and the uses of existing substances. The allocation of responsibilities is inappropriate because authorities are responsible for the assessment instead of enterprises-which produce, import or use the substances. Furthermore, current legislation only requires the manufacturers and importers of substances to provide information, but not the downstream users (industrial users and formulators).
Increased transparency. Another limitation of the current system is its lack of transparency. Consumers need access to information on chemicals to enable them to make informed decisions about the substances that they use and enterprises need to understand the regulatory process.
Setting deadlines: The Commission proposes to implement a step by step process to address the ‘burden of the past’ and develop adequate knowledge for existing substance that industry wants to continue marketing. Given the vast number of existing substances on the market, the Commission proposes that first priority is given to substances that lead to a high exposure or cause concern by their known or suspected dangerous properties -physical, chemical, toxicological or ecotoxicological.
Making industry responsible for safety: Responsibility to generate knowledge about chemicals should be placed on industry. Industry should also ensure that only chemicals that are safe for the intended uses are produced and/or placed on the market
Substitution of hazardous chemicals: Another important objective is to encourage the substitution of dangerous chemicals by less dangerous substances where suitable alternatives are available.
Action 3C: Exposure-triggered testing: The current testing regime for new substances has been criticized for not taking sufficiently into account the differences in the exposure to chemicals. (Please note that this is similar to the idea of bioaccumulation and biomagnifications that I have raised)
Endocrine disrupters: The majority of the endocrine disrupting chemicals would have to undergo authorization in the REACH system. Serious human health effects which have so far been associated with endocrine disrupting chemicals are testicular cancer, breast cancer, prostate cancer, decrease in sperm concentration and semen volume, cryptorchidism, hypospadia and impaired development of the immune system and the nervous system. All these effects would qualify a substance either to be classified as carcinogenic or as toxic for reproduction and so would trigger its submission to authorization. Furthermore, adverse effects on the endocrine system of wildlife species have been causally linked to certain POPs, which will be subject to authorization.
Pro-active requirement for industry: The current approach requires authorities to provide convincing arguments, usually in the context of a risk assessment, before restriction measures are taken. Their task is further complicated because the current system does not encourage industry to support the assessment. On the contrary, delaying the process is "rewarded" with an extended marketing period. Industry has usually provided data when such data were deemed suitable to avoid the restrictions under consideration. An apparent lack of data aggravates the situation and often leads to a risk assessment conclusion that ‘further information is required’ before an informed decision on risk management can be taken. Other delays are caused in cases where analytical methods must be developed to check compliance with a potential restriction. Authorities have to carry the main burden of the development of the analytical methodology. Su Such an approach is not amenable to attaining a high level of safety. Authorization, in contrast, requires industry to take a pro-active role in the evaluation process. If analytical tools need to be developed to control exposure, their availability should be a prerequisite for authorization.
Establishment of a central entity: The Commission proposes at this stage to establish a central entity (an expanded European Chemicals Bureau) for the administration of the REACH-system and the provision of technical and scientific support.
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paul schorr
7/29/10 12:35 PM
[jump to parent] in reply to Mohammad H.
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health effects and the EU approach - how does mass flux get considered?
How if at all would the mass flux of a contaminant or group be considered in determining 'health effects'. The best available science for occurrence should include calculation or estimation of the "loading" This requires that the mass flux within and between media is understood qualitatively or quantitatively. At each step of the evaluation, and especially at the beginning in defining occurrence, of a group or of a contaminant, the flow rate should be multiplied by the concentration. This will help define the nature of the source, the strategy for regulation and if necessary the exposure, control or treatment - Regulation of a group or chemical that is measured at one millionth of a pound in the environment might better occur at the source for example

EPA has published many documents that dealt with fluxes, indirectly. Contact me if you want a pdf version of the following EPA documents.
One- Wastewater in Receiving Waters at Water Supply Abstraction Points, EPA-600/2-80-044 by SCS Engineers, Inc. - Two - Guidance for Planning the Location of Water Supply Intakes Downstream from Municipal Wastewater Treatment Facilities, PB84 157247 (accession no.) by Culp,Wesner, Culp.

Both publications document issues throughout the USA that described a possible EPA approach toward "occurrence" of wastewater, groups and individual contaminants. The perspective of 30 years from when these documents were published highlights how national legislation bifurcated wastewater from the water supply issue and how regulation can reduce one contaminant but result in the formation of another - the conversion of ammonia to nitrate is an example.
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Inactive Panelist Lloyd Wilson
7/29/10 06:50 AM
[jump to parent] in reply to John G.
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MCLG
The following is copied from the attached EPA document, Six Year Review Chemical Contaminants Health Effect June 2003. Reading through this document suggests to me it is EPA policy to set the MCLG to zero. I have attached the document too so you can see Table 1 on Page 10

EPA also used the six alphanumeric categories (A, B1, B2, C, D, E) of the 1986 cancer guidelines (USEPA, 1986) in establishing the MCLG. The six-group classification system is
often equated to the three-category system in the NPDWR Federal Register announcements.
Table 1 describes the three categories and, with few exceptions (e.g., beryllium), their usual 3
equivalent alphanumeric classification. If a chemical is a known or probable human carcinogen
(Category I, generally Group A or B), the MCLG is generally set at zero because it is assumed,
in the absence of other data, that there is no known threshold for carcinogenicity. If a chemical
falls in Group C, a RfD approach along with an additional safety factor is used in deriving the
MCLG. The methodology used for establishing MCLGs for chemicals with varying degrees of
evidence of carcinogenicity is briefly described in Table 1.
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Uncertainty 10 Replies New
Active Panelist Eileen Murphy
7/29/10 06:07 AM
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How should EPA address the issue of uncertainty here? For many of the contamiants that have been detected in water samples, there simply is no health effects information. How should this be addressed? What are some other areas of uncertainty that we should consider?
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David Lipsky
7/29/10 11:44 AM
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uncertainty
Perhaps we should flip this around and speak of certainty rather than uncertainty. Speaking as a manager for an unfiltered system, I would hate to spend billions of dollars on a treatment system to remove trace contaminants that are now being measured individually in the ppt-ppq range, based on too great a belief in the robustness of our risk assessment methods, our cherry-picking risk issues from one group of contaminants d'jour to the next group, and with too much (or rather too early) reliance on the precautionary principle; unless there was a high degree of certainty that there would be a significant (and ideally measurable) public health benefit. If there is not adequate health effects information, then the contaminants should not be grouped for MCLG or MCL purposes; though they could be grouped for analytical and treatment technique purposes. We should be very cautious about using the precautionary principle to add uncertainty factors (when as Steve Via points out we have too little data so we add more factors).
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Inactive Panelist Rebecca Head
7/29/10 07:16 AM
[jump to parent] in reply to Eileen M.
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Uncertainty Approach
When referring to "no health effects" does that mean no human and no animal test data/results exist? In any case, going to structure -activity comparisons may be useful - though only as a screen. So another question - why focus on these contaminants? They are suspect because...?

If any are components of a group that is being tested & removed (as with a contaminant group) that would serve to eliminate. Can an example of this (i.e., a contaminant for which no health effect data exist that would be removed when a contaminant group is removed) - be provided?
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Steve Via
7/29/10 07:10 AM
[jump to parent] in reply to Eileen M.
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EPA Draft Discussion Paper
Eric's initial question pointed discussion toward the draft discussion paper and in particular to section 4 (starting on page 10). In the examples provided, uncertainty is embedded in each approach prior to the analytical process described for creating a group. In effect higher uncertainty leads to more conservative health reference levels (HRLs) which are then subsequently considered to be of equal validity with HRLs based on more complete data in crafting the group and subsequent regulatory management tool (MCLs, treatment technique, etc.) for the group. It would seem that large uncertainties in the public health relevance of a contaminant should lead to that contaminant playing a lesser role in shaping a contaminant group and associated regulatory requirements.
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Inactive Panelist Rebecca Head
7/29/10 07:21 AM
[jump to parent] in reply to Steve V.
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Public Health Effects & Uncertainty
Steve - you are correct that often lack of health data/relevance of a contaminant leads to that contaminant playing a lesser role. However, public health is based on prevention - so waiting for the effects to show is not necessarily a sound public health approach. Our regulatory approach, on the other hand, depends on exhibiting the data to show an effect.
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Bruce Macler
7/29/10 08:53 AM
[jump to parent] in reply to Rebecca H.
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SDWA theory
While some NPDWRs are proactively preventative (Surface Water Treatment Rules) and some are reactively corrective (Groundwater Rule, Total Coliform Rule), all require that there is a problem to address. If we don't know that a water constituent is problematical, why would it be a sound public health approach to control it?
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Active Panelist Shane Snyder
7/29/10 09:14 AM
[jump to parent] in reply to Bruce M.
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Good Question
There are many forums here that overlap, so I feel a bit repetitive. However, I believe it is critical to consider relative source contribution for the groups and to consider the energy requirement for the "group treatment technologies". On the latter, there are simply not that many tools in the tool box that are not already being employed to meet the current regulations. Short of GAC and RO/NF, I fail to see any large gains in trying to remove unknown groups.
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Steve Via
7/29/10 07:42 AM
[jump to parent] in reply to Rebecca H.
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Being a bit clearer
In the current regulatory process and the examples outlined in the Draft Discussion Paper we have HRLs based on assumptions and HRLs based on data. Where we lack data we tend to make very conservative assumptions. For example the presumption with many chemicals that are believed to have a cancer endpoint, is that the MCLG is 0. Similar but less extreme examples exist in the multipliers used in developing the RfD or surrogate measures of toxicity.

At present, if the risk assessment for chemical x incorporates a 10,000x safety factor and chemical y which has a stronger basis in the scientific literature has an embedded safety factor of 10, they are both treated as being of equivalent concern.
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Bruce Macler
7/29/10 09:56 AM
[jump to parent] in reply to Steve V.
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uncertainty solutions
Steve, your point is important and long-debated within the regulatory risk assessment community. One problem is that the methods used by many for these assessments are driven to get to a value that is of minimal risk, without considering the many physiological and biochemical systems that humans have to protect them from these insults. California's Office of Environmental Health Hazard Assessment does this deliberately, for example, based on their understanding of legislative requirements. As has been noted, we consider uncharacterized carcinogens as risky at any level, although the accumulated data clearly show that very low levels are either without risk or protective. Oral ingestion of hexavalent chromium, a carcinogen, results in rapid orders-of-magnitude reduction to trivalent chromium, a nutrient, but such detoxification is seldom included. The 1000x or 10,000x uncertainty factors are applied largely to generate a number for risk management purposes, without regard to reality.
So, what can be done? If the driver is strictly the interpretation of the statutory language or risk goals, then a discussion on the interpretation is warranted. If not, it might be appropriate to have a "laugh test" panel of public health professionals (as distinct from peer review by other risk assessors) consider the plausibility of these assessments.
However, it just may be that we have no better approach at this time and will just have to muddle along.
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Facilitator Gail Bingham
7/29/10 08:08 AM
[jump to parent] in reply to Steve V.
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implications of this?
What are your thoughts about the implications of this in a group(s) context?
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Steve Via
7/29/10 08:19 AM
[jump to parent] in reply to Gail B.
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Implications
Relying on the treatment of uncertainty in the HRL alone is inadequte when developing groups of contaminants.

A transparent, deliberative process for addressing uncertainty will need to be incorporated into:

1. selecting contaminants to include in a group
2. determining which contaminants are the basis for risk reduction benefits within the group
3. assigning regulatory monitoring requirements for the group,
4. setting expectations for treatment to remove the group of contaminants.
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John Gaston
7/29/10 06:18 AM
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In determining a group contaminants of similar toxicity must be "lumped". As an example, suppose we determine there are five currently regulated contaminants that we wish to form into a group.
Contaminant MCL
A x mg/L
B 3x mg/L
C 3x mg/L
D 4x mg/L
E 5x mg/L
It might be possible to set a limit (MCL) for the combination of B, C, D & E, but because of the lower value assigned to A it would have to be regulated separately or any "combined" number set would exceed the acceptable value for A. Also there will have to be a dual standard such as: "B-E combined not to exceed 10x mg/L with no single contaminant to exceed 3x mg/L".
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Bruce Macler
7/29/10 09:34 AM
[jump to parent] in reply to John G.
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grouping by health effects
Our current approach to risk is based on toxicology, not public health as practiced by the medical community. Physicians look at toxic exposures much differently than do toxicologists and, especially, regulatory risk assessors. The regulatory risk assessor/toxicologist approach is designed to identify a bright line, below which virtually nothing adverse is expected to happen. Physicians are looking at what actually happens, which is almost always orders of magnitude above that bright line. I think we'd benefit from having a panel of appropriately-trained physicians look over the contaminants we regulate and the water constituents we have identified, and offer their opinions on which might be worthy of control. I would expect that they would naturally group these by health effect. We could also expect that some (arsenic, uranium) would appear in more than one grouping.
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Active Panelist Shane Snyder
7/29/10 08:46 AM
[jump to parent] in reply to John G.
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"Similar Toxicity"
John: I have made this point in other forums, but I will share my concern here as well. While substances with a common mode of action have certainly been shown to be additive in some cases, what concerns me is the inconsistency in the animal models used for the development of RfD's. As we know, even within a species, there can be great diversity in terms of response. There are many examples of this variability among and especially between speicies. It seems to me that grouping makes more sense when a common assay is applied and the data are comparable. Otherwise, I do not see how the mathamatics realistically works out.
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Mohammad Habibian
7/29/10 10:02 AM
[jump to parent] in reply to Shane S.
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Similar Toxicity"
Dr. Snyder has done great work on ECs. He has shown that often our exposure to ECs via drinking water is close to none when compared with our exposure via other routes. This raises the question about focusing on drinking water in isolation from other exposure routes such as food, etc. We would be much better off to establish a program similar to EU REACH program. Please see my comments under question related to the science
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Nancy Swan
7/29/10 02:23 PM
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Grouping of chemicals or toxins seems efficient to help the public and health personnel assess toxicity. However, the EPA needs to assess toxicity and contaminates by its grouping of people. Contaminates that are not rated by the EPA to be at levels not toxic to adults, can be deadly to young children, immune deficient and other vulnerable populations.

I was seriously injured by methyl isocyanate and toluene di-isocyanate from fumes and contact with product when wet form roof was applied to Long Beach Junior High in Mississippi. http://www.nancyswan.com/toxic-j...

The public needs to be informed that any group contaminate toxicity is only for adults. Perhaps the EPA needs to lower the toxicity level for children and other vulnerable groups.
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Facilitator Gail Bingham
7/29/10 02:40 PM
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Thank you to everyone for your participation in this web dialogue -- and for the questions, ideas and technical information you shared. In the end, we had over 260 people registered -- and many more could have read the posts as well. This web dialogue will close shortly, but your comments will remain online for you and others to read in the future.

Warm regards, Gail Bingham
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