I have heard the opinion floated several times recently that the research of alternative pest control methods or materials can result in cancellation or limitation of existing pesticides. I'm thinking that while this opinion is sort of understandable I've never found the documented evidence to support it. Furthermore, the bigger thing is the worry that people will end up depriving promising pest management technologies of resources based on this misreading of what is actually going on.
To make my case, I will look at two materials, chlorpyrifos and methomyl, that had their labels eliminated for use in strawberry and a third, malathion, had its use restricted. In all three instances outlined below, the reader will see that regulatory actions proscribing use were independent of the emergence or existence of an alternative to any one of them. Regulatory actions were driven by issues with the materials themselves and in fact, the existence of alternatives to these three materials was never even mentioned in the resulting documentation.
Before continuing on with my thesis, it is important to get some background on what is going on here. The re-registration process for older pesticides (meaning those registered before November 1, 1984 and a group to which all three of our examples correspond) began in 1996 and was completed in 2008. The reason for this re-registration was to ensure that these older chemistries still met with current scientific and regulatory standards.
Based on the findings in these reviews, the US Environmental Protection Agency (US EPA) developed mitigation measures as needed to reduce risks of concern for each individual pesticide. In practice this has meant limiting or eliminating certain uses of the pesticide, requiring buffer zones around areas to be treated, or requiring different protective clothing (PPE) for pesticide handlers.
So let's take a look at how this played out for chlorpyrifos, malathion and methomyl:
Chlorpyrifos: Chlorpyrifos for many years was registered in strawberries, but never used very much. Associated with neurological damage in children, and after many years of review, the EPA canceled the label. I will let the statement of the day of its cancellation of EPA Administrator Micheal Regan suffice since it outlines in full the reasoning behind this action:
“Today EPA is taking an overdue step to protect public health. Ending the use of chlorpyrifos on food will help to ensure children, farmworkers, and all people are protected from the potentially dangerous consequences of this pesticide. After the delays and denials of the prior administration, EPA will follow the science and put health and safety first."
Methomyl: Registered in 1968, and a member of the broad class of carbamate insecticides, methomyl was another candidate for a re-registration review. Because of the EPA's findings and estimates of the drinking water risks in many agricultural settings, the manufacturers agreed to voluntarily cancel certain uses of methomyl, of which strawberry was one.
Malathion: Malathion was registered in 1956 and is an organophosphate insecticide, making it a prime candidate for review by the US EPA. It is an extremely useful material, with low mammalian toxicity and a broad spectrum of control. The limitation of its use here in berries hurt. Nevertheless, malathion had its annual permitted usage amount reduced after the re-registration process of the US EPA. The review of this material, which included the input of grower groups, brought up a whole raft of issues of concern, including drinking water, handler, post-application and ecological risks. All sorts of mitigations were arrived upon from this work, including engineering solutions, modified PPE, longer re-entry intervals and a lower amount permitted to use annually on the label.
Conclusion: In my research in understanding the regulatory actions directed at the three pesticides above, not a once was I able to find any documentation that these actions were driven in any way by the emergence or existence of alternatives to them. The evidence only confirmed that these actions had everything to do with properties of these three materials themselves.