August 21, 2006

U.S. Environmental Protection Agency

Office of Pesticide Programs (OPP)

Regulatory Public Docket (7502P)

1200 Pennsylvania Ave NW

Washington, DC 20460-0001

RE: Triazine Cumulative Risk Assessment

Docket EPA-HQ-OPP-2005-0481

Dear Docket:

The American Water Works Association (AWWA) is an international, nonprofit,

scientific and educational society dedicated to the improvement of drinking water quality

and supply. Founded in 1881, the Association is the largest organization of water supply

professionals in the world. Our 57,000-plus members represent the full spectrum of the

drinking water community: treatment plant operators and managers, environmental

advocates, engineers, scientists, academicians, and others who hold a genuine interest in

water supply and public health. Our membership includes more than 4,200 utilities that

supply roughly 80 percent of the nation's drinking water.

AWWA appreciates the opportunity to comment on the Triazine Cumulative Risk

Assessment. AWWA has been closely following the regulatory development process for

atrazine, simazine, and the other triazines since Maximum Contaminant Levels (MCLs)

were promulgated in the early ‘90s. Atrazine and other triazine herbicides have been a

major issue for AWWA and its member utilities for many years, due to the potential for

groundwater and surface water contamination from these herbicides. For more than 20

years, AWWA has written multiple letters to EPA and Congress expressing our concern

with the impacts of agricultural chemicals, including the triazines, on drinking water

supplies. AWWA has written extensive comments on EPA’s proposals as part of the

atrazine reregistration process. AWWA has been concerned with the lack of data for

making informed regulatory decisions, and EPA’s past Interim Reregistration Eligibility

Decions (IREDs) have been a step in the right direction in mandating more monitoring

data paid for by the registrants. These registrant-monitoring requirements should be a

typical component of the reregistration process for those pesticides with significant

drinking water exposure.

Government Affairs Office

1401 New York Avenue

Suite 640

Washington, DC 20005

T 202.628.8303

F 202.628.2846

www.awwa.org

Headquarters Office

6666 W. Quincy Avenue

Denver CO 80235

T 303.794.7711

F 303.347.0804

The Authoritative Resource on Safe Water

SM
Docket EPA-HQ-OPP-2005-0481

August 21, 2006

Page 2

Due to the criticality of the risk assessment issues, AWWA contracted with Dr. Joseph

Cotruvo and Dr. Richard Bull to conduct a detailed review of this risk assessment. Some

comments on broader triazine issues are below, followed by some relevant comments on

this specific cumulative risk assessment. These comments conclude with some general

observations about the risk assessment processes at the Office of Pesticide Programs

(OPP) and the Office of Groundwater and Drinking Water (OGWDW).

AWWA has submitted several sets of comments to EPA OPP throughout the atrazine

special review and triazine reregistration processes. Our past comments have focused on

several issues, but primarily, our main concern is the ongoing additional treatment burden

that our utility members, and ultimately their customers, will have to pay for in order to

comply with the drinking water standards, primarily the current atrazine standard. The

atrazine Maximum Contaminant Level (MCL) was finalized in 1991, and many surface

water utilities installed additional treatment soon thereafter to comply with this new

standard. While the registrant and the growers have made some limited progress in

controlling atrazine at the source, additional regulatory actions (sooner rather than later)

are necessary so that drinking water utilities (and their customers) are not saddled with

additional costs for additional treatment. EPA’s regulatory actions should be geared

towards moving the costs from the utilities’ customers to the atrazine registrants and

users.

In order to better understand triazine occurrence patterns and the relationships between

the parent compounds and their degradation products, the Water Industry Technical

Action Fund (WITAF) funded two extensive research efforts in 2003 and 2004. The

2003 monitoring program was conducted at 38 plants using the EPA-approved

Beacon/Syngenta immunoassay (IMA) analytical method as the primary analytical

method. Dr. Craig Adams of the University of Missouri-Rolla (UMR) developed a GCMS analytical method for the triazine parents and their degradation products. UMR also

conducted treatability studies through separate funding from the Missouri Department of

Natural Resources (DNR). All of the utilities monitored weekly from March to

September by collecting samples and shipping them to the University of ColoradoBoulder (CU) for IMA analysis. A smaller subset, consisting of 14 utilities, conducted

both weekly (IMA at CU) and daily monitoring (IMA onsite). Approximately 10% of the

overall number of samples collected by both the daily and weekly samplers were sent to

UMR for GC-MS analysis. Information on treatment practices and source water quality

were collected at the same time as the samples.

In April 2003, problems with the Beacon/Syngenta IMA analytical method became

apparent. Interferences from chlorine, chloramines, chlorine dioxide, Total Organic

Carbon (TOC), and other compounds were investigated at UMR. Since this project was

not a method validation project, all of the potential interferences were not investigated.

However, it is clear that this IMA method is precise but not accurate, and generally

biased high. The lack of robust IMA method performance was also confirmed by EPA’s

Environmental Technology Verification (ETV) program conducted by Battelle in 2004.

It should be noted that EPA has requested comments on withdrawing approval for this
Docket EPA-HQ-OPP-2005-0481

August 21, 2006

Page 3

analytical method (70 FR 7909) but the final status on that withdrawal is unclear at this

time.

The 2004 monitoring program was conducted at 49 plants. This project was a partnership

between the Water Industry Technical Action Fund (WITAF) and the Awwa Research

Foundation (AwwaRF). Monitoring was again conducted in the March-September

timeframe and analysis was conducted using the Abraxis IMA method at the offices of

McGuire Environmental Consulting (MEC). Again, approximately 10% of the samples

were split and analyzed for triazine parents and their degradation products using GC-MS

at UMR. The 2004 IMA monitoring data show some improvement compared to the 2003

data, with the results being precise but not accurate, and generally biased slightly high.

Monte Carlo analyses were conducted to understand the potential compliance impacts

from different compliance sampling regimes (bi-weekly, monthly, quarterly, etc.), but it

became apparent that more than one year of monitoring data was needed to analyze

potential regulatory compliance monitoring options. A listing of the six peer-reviewed

publications that have resulted from this research effort is enclosed at the end of these

comments.

This year, WITAF has also funded two ongoing research efforts. The first is a carbon

cost survey project, which will use an electronic survey of utilities to assess the extent of

agricultural contamination, such as atrazine and nitrate, and to assess the ongoing costs

incurred by utilities to meet those respective MCLs. This project should be completed in

October 2006. The second project is a statistical analysis of the multiple years of

Syngenta monitoring data. As previously mentioned, it became apparent from the

previous research that more than one year of monitoring data was needed to analyze

potential regulatory compliance monitoring options. Recently, Syngenta has provided

our contractor, Clancy Environmental Consultants, with their monitoring data from 1993

to 2005 in order to conduct a more robust statistical analysis. This project should be

completed by the end of 2006 and the results will be made available to EPA. .

Again, AWWA is pleased to comment on this cumulative risk assessment for atrazine,

simazine, and propazine and their chlorinated degradation products. Atrazine and

simazine are widely used in the US as herbicides, while propazine is not. Their use

patterns and geographic distribution lead to substantial opportunities for seasonal runoff

and entry into source waters and drinking water supplies in those use areas. We believe

that it is incumbent upon OPP in its pesticide registration processes to as much as

possible assure that pesticides are applied in such a way as to minimize contamination of

source waters. If MCLs are exceeded, public water supplies should not be burdened with

the responsibility of adding additional treatment to remove these chemicals to below the

MCL because conventional water treatment is not designed to remove many of these

types of chemicals.

OPP has determined that these triazines and their chlorinated degradation products

constitute a Common Mechanism Group (CMG) that induces common toxic effects in

mammals i.e. in the same organ or tissue by the same sequence of biological events. The
Docket EPA-HQ-OPP-2005-0481

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chemical group includes atrazine, simazine, propazine, desethyl-s-atrazine (DEA),

desisopropyl-s-atrazine (DIA), and diaminochloroatrazine (DACT). Propazine has been

removed from the Cumulative Assessment Group (CAG) because its use patterns differ

from atrazine and simazine, and therefore, limit its potential exposure through drinking

water and home uses. We agree that the triazine CAG is of similar chemical structure and

there is sufficient information to conclude that they operate by a common mechanism of

toxicity.

The data cited in the document strongly support the conclusion that atrazine, simazine,

and their common chlorinated metabolites belong to a common mechanism group and

based on occurrence information should be assessed as a cumulative assessment group.

The most complete database has been developed for atrazine and the six-month study

provides an excellent point of departure that can be finely drawn because of closely

spaced doses. The No-Observed-Adverse-Effects-Level (NOAEL) of 1.8 mg/kg/day and

the endpoint are appropriate given the determination that the mammary tumors observed

in one strain of rats are not likely to be indicative of cancer risk in humans, and an

uncertainty factor of 100 is reasonable for application to the NOAEL for producing a

Reference Dose (RfD).

The weakness in this cumulative risk assessment is that the comparisons in potency

among the different compounds are not precise. A study was conducted (reference

MRID 45471002) in which the effects of atrazine, simazine and DACT on attenuation of

the lutenizing hormone (LH) surge were studied, but the space between the NOAEL and

LOAEL doses was from 5 to 40 mg/kg day

-1

using a four-week treatment period. Some

finer data (i.e. the differences between NOAELs and LOAELs were only a factor of 2

exist for all of the compounds in a study conducted that examined male pubertal

separation (Stoker et al. 2002) over a different developmental period (PND 23-53).

However, it is the attenuation of the lutenizing hormone (LH) surge that is used as the

critical endpoint based on the six-month study. The assumption is made that all

compounds were equipotent with atrazine. It would seem that a comparison of

benchmark doses would be a more appropriate method of comparing the relative

sensitivity to the four compounds. If the benchmark doses are not significantly different,

one is justified in using the atrazine NOAEL from the six-month study for all the

compounds. If they differ significantly, some adjustment of the activity of the other

chemicals in terms of atrazine equivalent doses would be appropriate. This approach has

the advantage of making use of all the available dose-response data, and is much less

dependent upon the spacing of doses to arrive at an objective comparison.

We do not comment on the appropriateness or inappropriateness of use of an additional

Food Quality Protection Act (FQPA) factor of 3 for toxicology uncertainty. However, we

feel that the method that OPP uses to apply FQPA factors that mix exposure and

toxicology uncertainty in one term is confusing and inconsistent with standard toxicology

computations. Therefore, it can cause some misinterpretation when comparing screening

values for the Drinking Water Level of Concern (DWLOC) and toxicology-based values

for risk assessments. We believe that the two FQPA concepts should be separated
Docket EPA-HQ-OPP-2005-0481

August 21, 2006

Page 5

sequentially by first calculating the more traditional toxicology based RfD and MOE

possibly with inclusion of the FQPA toxicology-based uncertainty factor if it is justified,

then separately computing a DWLOC screening value that may or may not involve an

exposure-based uncertainty factor. This rather simple sequential separate approach

would make it much easier for the reader to follow the logic of the need or lack of need to

add the additional exposure uncertainty factor in the screening DWLOC or MOE, and

make it clear that the DWLOC is a hybrid value not necessarily based on uncertainties

arising from the toxicology database.

Shifting to CAG applications to RfDs, technically it would be appropriate to aggregate

the components of the CAG by calculating an RfD for each and prorating them by their

individual molecular weights when their masses are being added. This is a small point

since their molecular weights do not differ greatly, but it could make a difference when

drinking water MCLs are being computed, assuming that the OPP risk assessment

methodology will be used in that determination. Of course, this leads to a logical

conclusion that the future revised MCL could well involve an aggregation of the same

chemicals into one enforceable drinking water standard.

AWWA continues to be concerned with the potential disconnect in risk assessment

approaches between the Office of Pesticide Programs (OPP) and the Office of Water

(OW). AWWA commends OPP for its detailed and mechanistic assessments. AWWA

further commends OPP for explicitly considering drinking water exposure and for its

rigorous analysis of Relative Source Contribution (RSC) so that those assessments can be

used by OGWDW when RSCs are applied in MCLs. AWWA also commends OPP for

considering drinking water source protection as a specific and key control on pesticide

labeling and use.

AWWA’s concerns are two-fold:

1. OPP and the Office of Groundwater and Drinking Water (OGWDW) should

agree on the toxicology and risk assessment and the health based

conclusions, i.e., EPA should have one risk assessment, not two, or at least

they should both be scientifically consistent. Otherwise, EPA runs the risk

of a legal finding of being arbitrary and capricious.

2. Our utility members need assurances that OPP’s registration process and

labeling and use restriction requirements do not place the burden of

removing a pesticide from drinking water on the water utility. If OPP’s

registration process is less restrictive than OGWDW’s MCLG/MCL

philosophy, then water utilities (and their customers) will be responsible to

pay for additional treatment for removal, if OGWDW develops an MCL

using more restrictive assumptions.

The regulatory policies in both OPP and OGWDW must assure that the use patterns of

the pesticides are managed and water supply contamination prevented so that drinking
Docket EPA-HQ-OPP-2005-0481

August 21, 2006

Page 6

water suppliers are not left with the major responsibility to prevent or limit human risks.

The primary control of human exposures and the potential public health impacts of

pesticides and herbicides must reside with the producers, users, and applicators of these

agricultural products.

It is not clear whether OGWDW will follow the risk assessments put forward by OPP, as

there has been a fundamental difference in how the two offices have addressed these

issues. Essentially, OPP must conclude that the likely exposures do not exceed their level

of concern and it approves the uses of the pesticide. In contrast, OGWDW must establish

an MCL. However, when OGWDW issues an MCL, the usual quarterly monitoring of

chemical contaminants in drinking water is not appropriate for this group because of the

application during a limited period of time during the year, and therefore, runoff will

result in contamination in some watersheds during limited times. Seasonal monitoring

may be necessary, and our previously discussed ongoing multi-year statistical analysis

should provide some logical and implementable regulatory options for both monitoring

requirements and the ultimate compliance determination.

It is not completely clear at this time whether OGWDW will develop individual standards

for the parent compound and the degradation products, or develop a combined standard.

EPA needs to clearly articulate how the Agency is going to develop this future standard,

and reconcile the differences in the risk assessment, regulatory development, and

decision policies and processes between OPP and OGWDW.

If you have any questions about these comments, please feel to call Alan Roberson or me

in our Washington Office at 202-628-8303.

Yours Sincerely,

Thomas W. Curtis

Deputy Executive Director

cc: Ben Grumbles—OW

Susan Hazen—OPPTS

Jim Jones—OPP

Brian Mannix—OPEI

Cynthia Dougherty—OGWDW

Pam Barr—OGWDW

Ed Ohanian—OST

Alan Roberson

Steve Via
Docket EPA-HQ-OPP-2005-0481

August 21, 2006

Page 7

Peer-Reviewed Publications Resulting from Triazine Research

• Graziano, N., McGuire, M., Adams, C., Roberson, A., and Blute, N.

National Atrazine Occurrence Monitoring Program (2003) Using the

Beacon ELISA Method (In Press for September 2006 Journal

AWWA).

• Jiang, H., Adams, C., Graziano, N., Roberson, A., McGuire, M., and

Khiari, D. Occurrence and Removal of Chloro-s-Triazines in Water

Treatment Plants. Environmental Science & Technology

(40:11:3609).

• Jiang, H., Adams, C., Graziano, N., Roberson, A., and McGuire, M.

Enzyme Linked Immunoassay Analysis (ELISA) of Atrazine in Raw

and Finished Water. Environmental Engineering Science (23:2:357).

• Graziano, N., McGuire, M., Roberson, A., Adams, C., Jiang, H., and

Blute, N. 2004 National Atrazine Occurrence Monitoring Program

Using the Abraxis ELISA Method. Environmental Science &

Technology (40:4:1163).

• Adams, C., Jiang, H., McGuire, M., Graziano, M., Roberson, A and

Frey, M. Accuracy and Interferences for Enzyme-Linked

Immunoassay Tests for Atrazine. Journal AWWA, 96:12:126

(December, 2004).

• Jiang, H., Adams, C., and Koffskey, W. Determination of Chloro-sTriazines Including Didethylatrazine Using Solid-phase Extraction

Coupled with Gas Chromotography-Mass Spectrometry. JournalChromotography-A, 1064:2:219.

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