Atrazine: Potential MOA Revisions 

Discussion with Technical Registrants 

November 3, 2009 

2:00 – 4:00 p.m. EDT 

Conference Call Requested By: EPA Office of Pesticide Programs

Participants: 

 

Office of Pesticide Programs, EPA – Richard Keigwin, Robert McNally, Eric Olson, Melanie 

Biscoe, Mary Frankenberry 

Atrazine Technical Registrants – 

SYNGENTA 

Janis McFarland 

Dan Campbell 

AGAN CHEM MFG, LTD 

MAKHTESHIM-AGAN OF NORTH AMERICA INC 

Kris Venkatesh 

DREXEL CHEMICAL COMPANY 

Roy Olson 

OXON ITALIA S.P.A. 

Maria Ciccotelli 

SIPCAM AGRO USA, INC 

Joe Burley 

Meeting Notes 

 

Introductions

Meeting participants introduced themselves. EPA indicated that the meeting notes would be 

placed in the atrazine Special Review docket within 10 days of the call, and that any CBI should 

be noted during the meeting. 

Discussion of Potential MOA Modifications:

1. Monitoring to capture peak, single-day exposures in Community Water Systems. 

Syngenta said that it is trying to think of data that can be pulled together to address EPA’s 

concerns in a timely manner. Syngenta indicated that with the total weight-of-evidence from 

Syngenta’s database (nearly a quarter-million samples) as well as other databases, the likelihood 
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of missing peak concentrations is quite low. Syngenta has recently developed a trend report that 

looks at the variability of all the data within surface water systems, and proposed that Syngenta 

and EPA scientists meet to examine and discuss the data. Syngenta indicated that the primary 

data sets that can be provided to the Agency for the purpose of knowing if we are capturing 

peaks are the Peri-reservoir databases that include daily sampling, the Heidelberg data that 

include flow-based sampling, and the ecological monitoring data set that includes daily sampling 

as well as flow data (within the ecological monitoring program, there are approximately 11 sites 

that have daily monitoring). Syngenta indicated that these three data sets would represent a 

worst-case scenario, as they include data on systems with “flashier” data than typical drinking 

water systems. Syngenta would like to do a bootstrap analysis on these data sets to determine if 

peaks are actually being captured. 

Syngenta also said that AWWA may also have daily drinking water data. 

EPA asked Syngenta to clarify whether it just has the data sources available or whether it has 

already evaluated the data from those sources. 

Syngenta indicated that it has recently submitted a frequency of monitoring report which 

includes information on different types of watersheds and the vulnerability at different sites. 

(EPA confirmed that it received that report). Syngenta said that AWWA has also done its own 

analysis, but that their approach is geared toward annual averages. 

Syngenta stated that it has, in its database, searched for the highest atrazine concentrations and 

know what the highest concentrations would be in any of the different types of sites sampled. 

EPA asked Syngenta whether its data is for atrazine-only or whether it is for metabolites and/or 

TCT. 

Syngenta said that metabolites and TCT data are available for the 2009 ecological monitoring 

systems. 

EPA wanted to clarify whether these data will be submitted for EPA to evaluate in preparation 

for the April SAP, or whether Syngenta will undertake analyses themselves. EPA wanted a 

sense of who would do what, when. 

Syngenta indicated that it wants to conduct analyses in a way that makes sense and then provide 

those analyses to EPA in a timely and efficient way. 

EPA summarized that Syngenta currently has information that meets the Agency’s needs, and 

that we all want to make sure that the Agency can look at it and meet with Syngenta’s scientists 

in a timely manner. At that meeting where Syngenta and Agency scientists examine the data, 

any need for additional monitoring could be addressed at that time. 

Syngenta agreed with EPA that there is time to look at all the data and act, if needed, by the 2010 

growing season. 
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EPA and Syngenta agreed that a face-to-face meeting of scientists in the following two weeks 

could work. Syngenta added that a year-to-year analysis would be interesting to pursue. 

Syngenta expressed its confidence that it has data that will make everyone feel comfortable. 

EPA noted that it should check with OW and USDA concerning any additional daily atrazine 

monitoring data that may be available. 

2. Providing drinking water monitoring data to the public more quickly. 

Registrants discussed how there is a long public record of notifying CWSs and the public of the 

MCL exceedences in terms of not causing fear in people. 

Registrants stated that there are short term MCLs that aren’t monitored for very often. They also 

state that there is a public notification handbook used to determine which situations require 

public notification so that public fear isn’t generated, and that the precedent of requiring 

additional notification as EPA proposed in this meeting is inconsistent with these other 

notification guidelines. 

Registrants asserted that CWSs work under rules of what is reportable, and when and none of the 

data fall under those rules, the data are not reported to the public. 

EPA summarized that on its web page all the monitoring data is available. The web page also 

puts the data into context. 

Registrants stated that the OPP web page should explain what the data mean in terms of EPA’s 

levels of concern. With regards to the data themselves, the registrants would prefer that data 

released reference data by county instead of by specific CWS. The registrants assert that they 

would need to figure out how to keep CWSs in the program if EPA releases data specified for 

each CWS. 

The registrants asked why the data need to be put out for the public when the level of concern is 

not exceeded. EPA discussed the desire to be more transparent with the data. 

3. Prohibiting atrazine use in the watershed after one exceedance of the 37.5 ppb 90-day rolling 

average. 

Registrants stated that prohibiting atrazine use in the watershed after one exceedance of the 37.5 

ppb 90-day rolling average in raw water would go against precedence 

Registrants indicated that they would like to have a meeting with EPA scientists to discuss why 

EPA scientists feel that there is uncertainty around the endpoint that would warrant prohibiting 

atrazine use in the watershed after one exceedance of the 37.5 ppb 90-day rolling average in raw 

water. 

EPA asked if registrants would agree to prohibiting atrazine use in the watershed after one 

exceedance of the 37.5 ppb 90-day rolling average in finished water. Registrants stated that this 
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would go against precedence. Registrants added that the MCL is not mitigated in that fashion – 

specifically, people still drink their water when the MCL is exceeded. Registrants indicated that 

they would like to meet with EPA to discuss uncertainty with the endpoint. 

4. Establishing a performance standard for the 298 ppb one-day drinking water level of concern 

established in the Atrazine RED. 

Registrants stated that there is no precedence for regulating on the acute endpoint. EPA stated 

that this endpoint is in the RED and there is a perception issue surrounding the Agency not 

regulating on this acute endpoint. 

Meeting Notes Prepared by: Melanie Biscoe and Eric Olson