Comments on Diazinon Ecological Risk Assessment

G. Fred Lee & Associates
27298 E. El Macero Dr.
El Macero, California 95618-1005
Tel. (530) 753-9630 Fax (530) 753-9956
web site:
Please note the new area code for telephone and fax has been changed to 530

October 22, 1997

Dennis Kelly
Novartis Crop Protection
1380 Lead Hill Drive; Ste 201
Roseville, CA 95661

Dear Dennis:

I wish to follow up on the Novartis diazinon meeting to indicate that I found that the meeting was of value with respect to reviewing some of the issues that need to be addressed in evaluating whether diazinon, as currently used, represents a significant threat to environmental quality. It was useful to hear Novartis and its consultants discuss these issues. It is unfortunate, however, that much of the information presented by Novartis on these issues with respect to the current information on ambient water toxicity and its association with organophosphate pesticides in the Sacramento River system is significantly out-of-date. While I cannot speak for the attendees, I believe that this meeting did not significantly change the overall positions of those who are concerned about diazinon, chlorpyrifos and other pesticides in ag and urban stormwater runoff as well as domestic wastewaters. The overall approach that has been used by Novartis is appropriate as far as it goes with respect to stormwater runoff problems. The problem is that there are a number of inadequately addressed issues that have to be resolved before it can be concluded that the dormant spray pulses of diazinon that pass through the Delta each year are not adverse to the beneficial uses of the Delta and therefore require control to eliminate the ambient water toxicity. Further, as discussed in my Upper Newport Bay Evaluation Monitoring Demonstration Project Phase 1 report that I recently sent you, the issues of the water quality significance of diazinon, chlorpyrifos and other pesticides present in urban stormwater runoff has not yet been addressed by Novartis or others.

It is my recommendation that a series of meetings be organized where key people in the group could work out the details of what needs to be done to develop the information that will have to be developed if it can be appropriately concluded that the diazinon pulses associated with the use of this pesticide as a dormant spray as well as in urban areas are not in some way adverse to the beneficial uses of the Sacramento River, its tributaries, the Delta and San Francisco Bay as well as other waterbodies in California.

I have been involved in water quality evaluation and management issues since 1960. Frequently my work has involved incorporating science and engineering into public policy development and implementation. It is my assessment that Novartis' attempts to use the information available to justify not exerting far greater control of the use of diazinon in orchards as a dormant spray pesticide than that currently recommended by Novartis in their "Best Management Practices for Protecting Water Quality in California-Dormant Spray Management Practices" booklet distributed at the meeting, will result in the water quality regulatory agencies justifiably concluding that there are too many unknowns, i.e. unanswered questions, to support the position that the diazinon pulses are not adverse to key fish food organisms within the Delta and therefore must be controlled. The way to resolve this situation is to develop an active line of communication with those who are concerned about the adequacy of the information so that the issues that need to be addressed are, in fact, adequately addressed before the regulatory agencies are put in the position of having to make a decision on the curtailment of the use of diazinon as an orchard dormant spray. To the extent that there is interest, I would be willing to work with those interested to facilitate developing the structure necessary to address these issues in a meaningful way.

As you have seen from my work in Orange County, for many years I have been a strong proponent of determining what Ceriodaphnia toxicity means to ecosystem functioning and water quality. We will never fully understand that situation. However, those who wish to continue to use diazinon as they have been in the past have the burden of proof of showing that it can be used with a high degree of certainty without adverse impacts on the designated beneficial uses of California's waters. A key aspect of this situation is the proposal by the State Water Resources Control Board staff that the Regional Board's Basin Plan objectives be revised so they will allow toxicity in waters, provided this toxicity is not causing a significant adverse impact on the beneficial uses of the waterbody. This proposal is part of the California Toxics Rule "implementation plan" that is currently under review in draft form. If this proposal is adopted, then the issue of no toxics in waters will become mute and there will be a shift in focus to defining what represents sufficient toxicity to be adverse to the beneficial use of a waterbody.

The work with the what I propose to call Toxicity Impact Assessment Group consisting of those concerned about these issues within the state, could develop the kind of guidelines that need to be developed to evaluate on a site-specific basis, such as for the Delta and urban stream or any other location, how regulatory agencies should evaluate to a reasonable degree whether the toxicity associated with pulses of chemicals that are only toxic to a restricted type of organism, such as diazinon, are potentially significant to the beneficial uses of a waterbody of concern. I have the responsibility of addressing this issue together with the technical stakeholders concerned about water quality in Upper Newport Bay in Orange County, California. These activities should be expanded to address this issue on a broader basis than just Upper Newport Bay.

With respect to the Novartis work on diazinon occurrence, toxicity and treatability in POTWs as presented at the meeting and in the August 1997 report Executive Summary, I have found this work significantly deficient in addressing the issues that will have to be addressed to understand the magnitude of POTW effluent toxicity due to diazinon and other pesticides in domestic wastewaters. I have extensive experience with ambient water toxicity issues associated with POTW effluents. Far more definitive studies need to be done on this issue before reliable conclusions can be developed. I am confident that water quality regulatory agencies will find that the Novartis-sponsored studies did not properly address the issues that must be addressed to understand, much less control, the organophosphate pesticide problem in domestic wastewaters.

After the meeting, I suggested to Dennis Tierney that a possible, readily implementable method of managing the wastes associated with the use of diazinon, which evidently now is being dumped, in part, into the sanitary sewer system leading to domestic wastewater toxicity, is through the addition of chlorine bleach. From the information provided in the Novartis POTW studies, it appears that chlorine is an effective reactant for diazinon. I conducted my PhD dissertation on chlorination chemistry and could, if there is interest, work with Novartis in evaluating whether the addition of household bleach to the wastewaters associated with home or commercial use of diazinon could be a means of readily converting the diazinon to non-toxic forms. A number of issues such as contact time, chlorine dose and influence of pH need to be evaluated. If there is interest in exploring having me become involved in such studies, please let me know.

If you, Dennis Tierney or others have questions on these comments or wish further information on any aspect of them, please contact me. Thanks again for organizing the diazinon meeting.

Sincerely yours,

G. Fred Lee, PhD, DEE

Copy to: D. Tierney


References as:"Lee, G.F., 'Comments on Diazinon Ecological Risk Assessment,' letter to D. Kelly, Novartis Crop Protection, Roseville, CA (1997)."

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