You are here: Home Blog 2011 March 18 New Data Supports Stricter Restrictions on 2,4-D, Chlorothalonil, Diuron

New Data Supports Stricter Restrictions on 2,4-D, Chlorothalonil, Diuron

by Josh Vincent — last modified Mar 18, 2011 04:42 PM
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An evaluation of the National Marine Fisheries Service's (NMFS) fourth Biological Opinion (BiOp) on pesticide risks to threatened and endangered Pacific salmon. Focusing on 2,4-D, diuron, linuron, triclopyr BEE, captan and chlorothalonil.

Earlier this month, the National Marine Fisheries Service (NMFS) released its fourth Biological Opinion (BiOp) appraising the pesticide risks posed to threatened and endangered Pacific salmon from southern California to northern Washington and even into parts of Idaho. This BiOp looks at six commonly used chemicals: the herbicides 2,4-D, diuron, linuron and triclopyr BEE, as well as the two fungicides captan and chlorothalonil. Together they account for almost 100 million pounds of use in American homes, gardens, crops and by industry and government.

This marks the continuation of NMFS’s comprehensive evaluation of 37 different pesticides. So far, twenty-four of the 37 pesticides have been examined, with 19 requiring new restrictions based on the best available scientific data. Evaluation of all 37 pesticides is expected to be complete by the middle of 2012.

To their credit, this latest NMFS evaluation is generally strong. The agency performed a comprehensive evaluation of the risks associated with these six pesticides, looking at effects that  the U.S. Environmental Protection Agency did not consider as a part of the pesticide registration process. First, NMFS documented important concerns associated with habitat degradation and multiple chemical exposures, leading to a conclusion that the use of three of the pesticides -- 2,4-D, chlorothalonil and diuron -- warranted new restrictions on their use.

Second, NMFS based its analysis on both crop and non-crop uses (BiOp at 419), while  EPA’s methods failed to evaluate most non-crop uses of these pesticides. According to the most recent estimates, approximately 11 million pounds of 2,4-D alone are applied annually around the home.

Third, NMFS’s more accurate evaluation considered actual monitoring data showing pesticide contamination at higher levels than EPA’s “worst case scenario” models. NMFS therefore included the monitoring data in its evaluation and refined the EPA model to better reflect actual contamination of salmon habitat (BiOp at 420 and 429).

Unfortunately, NMFS failed to use this scientific anlaysis to recommend more informed guidelines for pesticide use. The Endangered Species Act directs NMFS to evaluate the current legal regulations and the instructions for use that are approved by EPA as stated on pesticide labels. Instead, NMFS in some cases adopted the stance that regulations do not need to be changed because pesticide applicators are claiming that they may already abide by stricter, yet largely voluntary, standards than the labels require. This decision marks a dramatic shift from how NMFS has made previous evaluations, and seems to reveal several glaring oversights.

First, the NMFS decision allows certain pesticide uses to continue even in the face of documented harm to endangered species. NMFS data clearly shows that EPA’s legally allowed uses of triclopyr BEE will harm and even kill groups of salmon (BiOp at 613). Still, NMFS chose to make no revisions to its legal use. In so doing, NMFS is neglecting its duty to determine if established pesticide registrations are protective.

Second, whether or not on-the-ground use meets or exceeds label requirements doesn’t come to bear on what those label requirements should be. The label requirements should be based on the best available scientific data with regard to threatened and endangered salmon. NMFS evaluated the best data in its BiOp. Now that information must be used to draft improvements to the  pesticide regulation.  To the extent that such voluntary use reductions are verifiable and are documented not to harm fish, there should be no objection to making them legally enforceable as label requirements.  

Third, while some applicators take special care in how they use chemicals, there is neither any reason to believe nor any way to know for certain that the majority of applicators using these products are actually holding themselves to a stronger standard than law requires. This notion likely does not reflect reality, it is unquantifiable, and it is traceable to the public relations and lobbying efforts of the pesticide manufacturers. CropLife America alone spent $751,000 to lobby congress in the final quarter of 2010. Furthermore, as it suggests that applicators are already voluntarily doing what new regulations would require them to, the argument is incongruous with previous claims from pesticide manufacturers and applicators about the extra burden of cost and labor they believe new pesticide restrictions might bring.

The next step in this process is to have the U.S. Environmental Protection Agency implement the restrictions prescribed by NMFS. To date EPA has been recalcitrant. It has been over two years since NMFS first required restrictions for several other pesticides and EPA has still not taken any substantial action to implement these much-needed protections for imperiled salmon.

The good news is that you can do something. Public comments are being accepted until April 5th, so please weigh in on this precedent setting evaluation. Allowing harmful uses to remain legal isn’t fair to endangered salmon, other wildlife, or even pesticide applicators.

Suggested Talking Points to NMFS and EPA:

1. Thank NMFS for raising the scientific standard by going beyond industry generated data and evaluating the concerns associated with habitat degradation, exposure to undisclosed inert ingredients, and synergistic effects.

2.  Express support for the proposed protective measures outlined in the draft Biological Opinion. Urge NMFS to maintain and expand upon these protections in the final BiOp.

3. Tell NMFS it is its duty to ensure legal pesticide applications do not harm salmon. Urge NMFS in the final biological opinion to uphold the Endangered Species Act by evaluating the pesticide uses that EPA has legally authorized, rather than relying on unverifiable claims by pesticide manufacturers who insist that  voluntary best practices are the norm.

4. Urge NMFS to utilize any effective and verifiable best management practices of applicators as input for how to best improve EPA’s registration requirements.

5. Urge EPA to act swiftly to implement strong protective measures to keep these pesticides out of our waters.


To submit comments go to the federal rulemaking portal at:

Follow the online instructions to submit comments.

You must identify the docket identification number is EPAHQ-OPP-2008-0654 as well as the pesticides to which the biological opinion pertains :2,4-D, captan, chlorothalonil, diuron, linuron, and ticlopyr BEE.

All comments are public and will be posted on the docket.


The biological opinion can be found at:

The proposed restrictions include:

1. An end to the use of 2,4-D butoxyester ethyl in salmon waterways and riparian zones.

2. An end to the use of all three pesticides when soil moisture is at capacity or a rain event is predicted within 48 hours of the application.

3. A monitoring plan for sensitive habitat to evaluate the efficacy of the restrictions.