Pesticide Bans

With spring rolling in and people turning their attention to gardens (at least here in the Great White North – further south I imagine people hit their gardens earlier), now seems like a good time to talk about pesticides and the efforts by a lot of groups and municipalities to ban them.

Should pesticides be banned, either totally or for cosmetic uses? Personally, I think that a “yes or no” answer is far too simplistic. The term “pesticide” refers to a very wide range of products with different chemical compositions, different uses, and different toxicity to humans and animals. They include herbicides for dealing with plants, insecticides (and insect repellents), fungicides and rodenticides. They range from naturally occurring chemicals such as pyrethrins (from chrysanthemum flowers) to modern synthetic chemicals. Obviously it is important to ensure that human health is protected, including those using the pesticides, as well as others in the community who may potentially be exposed. It is also worthwhile to protect the environment, including unintended receptors (e.g. local wildlife) and nearby water bodies. Can we do this and still allow the use of pesticides?

In Canada, pesticides are evaluated by the Pest Management Regulatory Agency. Among other things, they review data on the toxicity of pesticides, determine the potential for exposure, and decide whether adverse effects are likely. They also determine what the maximum amount of a pesticide that can be present on various foods is. Certainly some people will argue that the only acceptable exposure to a potentially “toxic” substance is zero, but the reality is for most substances there are safe amounts to which you can be exposed. In fact, many plants produce their own pesticides, and asĀ  result even completely organic fruit and vegetables will have toxic substances in it – the important thing is that the amount is less than the maximum safe dose. The possible exception is genotoxic carcinogens (carcinogens that react with DNA) – I have no problem with banning cosmetic use of genotoxic carcinogens.

The other side is whether there is any benefit to using pesticides. A lot of arguments for banning pesticides talk about dandelions – really, unless there’s a severe infestation or you’re dealing with a large area, there’s no need to use pesticides for dandelions. You’re probably better off pulling them out. However, there are other noxious weeds that aren’t readily dealt with by pulling them out. Insect infestations are another issue often requiring some sort of pesticide – I’m not talking about normal insects which are often beneficial, but rather severe infestations of harmful insects that are killing plants.

My personal view is that we should focus on what want to accomplish before deciding what action (e.g ban pesticides) to take. I suggest the following:

  • Protection of human health
  • Protection of wildlife
  • Protection of other ecological receptors, including nearby surface water
  • Control of pests (undesirable and/or harmful plants, insects etc.)

Can we accomplish all of these? I think we can.

When a proper evaluation is conducted by PMRA (or by the United States Environmental Protection Agency), toxicologists and other experts determine whether human health or ecological effects are likely to occur if the pesticide is used as directed (a fairly key point). In the past perhaps some of the testing hasn’t considered possible effects such as endocrine disruption, but this is changing and existing pesticides are continually being re-evaluated. There is also a margin of safety included in these evaluations to account for uncertainty in the toxicity database or particularly sensitive individuals. In general, I believe that a pesticide with a recent evaluation can be considered safe when used as directed. The problem comes when people don’t use them as directed, and this is where some form of control may be necessary. Rather than assume people will use them as directed, why don’t we make sure it’s difficult to use them in a potentially harmful way? This could include only allowing sale to individuals in very small containers, not allowing the sale of concentrated forms that require dilution, and not allowing the sale of “weed and feed” products.

To me, a logical strategy would include:

  • Education about alternatives to pesticide use, and encouraging pesticides to be a last resort.
  • Ensuring that not only are the pesticides available for residential safe when used as directed, but that it is difficult to use them unsafely.
  • Requiring a license (with appropriate training/testing) for the purchase of bulk pesticides or concentrated forms (e.g. by commercial applicators).
  • Perhaps taxing pesticides to artificially increase their price, discouraging frivolous use.

In summary, I don’t believe an all-out pesticide ban is warranted. Not all pesticides are the same, and modern pesticides for residential use are not the same as some of the toxic (to humans) chemicals used historically. We also have to consider possible future developments – with advancements in biochemistry and genetics, it is conceivable that pesticides that only affect a particular target and are harmless to everything else could be developed in the future.

7 Responses to Pesticide Bans

  1. Everett Williams says:

    It is very clear that a great number of variables are not being tested in our use of pesticides. We have limits on the toxic levels of various pesticides, but no combined limits nor even many studies on the side effects of combined usage. It is also very clear that some of the most commonly used commercial pesticides in use are active hormone mimics, producing drastic changes in simpler organisms at very low levels, and of unknown toxicity in human exposure. Add that to the hormone mimics in various plastics we are commonly exposed to and the amount of hormones in our water from birth control compounds, and it is clear to me that there are possibly disastrous side effects already out there. Unfortunately, the tests spoken of in this article may be only a very poor indicator of the root of the problem. A more appropriate subject group would be pregnant women and their husbands. Then, survey their offspring over time for overall health. We have only scratched the surface. It is my opinion that all hormone mimics that can be should be eliminated from use in ways that can cause human exposure. Waiting until effects occur on those or any other compounds, especially those with long term or late occurring effects seems an invitation to disaster.

    • ashartus says:

      I agree that are testing needs to be improved, particularly with respect to hormone mimicry and effects of mixtures – though not all pesticides are likely to have hormone effects. A lot of pesticides are currently being re-evaluated with at least some of these factors being considered. Despite that, I think painting all pesticides with the same brush is a gross oversimplification, and it’s also important to consider the benefits as well a the risks (I’m planning a post this weekend that will highlight an example of that).

  2. Everett Williams says:

    I understand the need for sufficient pesticides to allow for the level of mass production of food essential to a society as large as our own, but we need to get the horse back in front of the cart. We are starting to be able to track both chemicals and metabolites at very fine levels, and we need to do this before we deploy a chemical rather than after. What is happening at the moment is that pesticide companies merely shift away from those current chemicals identified as having short and/or long term effects to newer ones without a track record. By the time they have a track record, much damage is done, especially since the newer compounds are more and more sophisticated in their targeting and their content. We need to get away from the idea that we need to be fair to the companies. These compounds are used supposedly to provide us with healthy and plentiful food. If they are going to have serious side effects, we need to at least know what the risks are before we approve the use. Systemics that get into the content of what we eat are the worst, as no amount of washing will get rid of them. Maybe we need to have a requirement that any new pesticide residue be removed in processing or reduced to levels well below any known or suspected toxicity, with a method provided by the manufacturer of the chemical. The cleaning method could not be made proprietary, and must be available to any who process the food for free, with the cost buried in the cost of the pesticide. That way, there would be little incentive not to apply the cleaning. Like our problems with fossil fuels, the only way to change the ethos is to apply the true costs. If even a reasonable amount of the costs of the Iraq war along with other indirect expenses were applied to the cost of petroleum products, we would be a lot further along in a changeover to other forms of energy.

    • ashartus says:

      Good points, and I am in general agreement with you. I’m certainly not opposed to strict regulation of pesticides, including controls on which ones are available and how they’re used; it’s just blanket bans on anything considered a pesticide without looking at the individual chemical and potential for toxic effects (based on sound science rather than emotion) that I’m against.

  3. Everett Williams says:

    Here’s the problem with using “sound science”. We don’t always have it, and we certainly do not spend the money up front to fully and properly test a new pesticide before it goes into production and use. I think that there should be a minimum of five years of testing before a pesticide is even considered for commercial use, and ten before general use. Those numbers are rather arbitrary, but I think they are on the conservative side. Only a fairly small percentage of the population take any drug, but almost all of us are exposed to almost every pesticide in commercial use. To me, this means that pesticides should be even more thoroughly tested than drugs. I realize that this is against the conventional wisdom, but it is good sound science. This is the level of blanket precaution that should be in place. Then, classes of drugs that are known hormone mimics or that mimic other human proteins should have even more thorough testing. The problem with the finer effects in the human body is that they are largely based on shape and very, very subtle chemistry, and we are just now able to work out the actual shape of more complex molecules and understand the locks into which they fit. Shape, unfortunately cuts across chemical classes, making the understanding of effects more than a bit difficult. The mathematics of protein folding are horrendous, and we are just now getting into a computational regime that is capable of solving the problem for candidate shapes that then must be actually tested. Full simulation is not even understood, much less calculable. I’d say that we are ten to twenty years away from a more facile handling of this problem. In the mean time, the only safe testing is long term testing or testing that is reliably accelerated. Right now, we are the guinea pigs for industry, and that just is not right. Industry will have to be forced into more thorough and longer term testing, as it certainly is not in their commercial interests. That is why systemics should almost be banned outright, while external poisons should be removed and destroyed at levels far below the current. Right now, a great deal of what is washed off the produce ends up in downstream water supplies. That is the type of blanket that I would like to throw over the chemical industry in general, and the pesticide industry in particular.

  4. ashartus says:

    Saying a minimum of five years (or ten) seems a bit arbitrary; I’d rather see minimum data requirements. I can’t see a proper testing program done in less than five years though.

    Also note the post was solely about small-scale residential use; commercial use of pesticides on food crops is a whole other topic and requires different safety data. Any pesticide persistent and mobile enough to be getting into water bodies shouldn’t be used for residential purposes in my opinion; we should be sticking to pesticides that stay where you put them and break down within a few days.

    Also, while we want our pesticides to be safe, at the same time the residues remaining with current standards are almost negligible compared to the pesticides produced by the plants themselves, most of which we know almost nothing about (though they do include known carcinogens, and I don’t see any reason why they wouldn’t include endocrine disrupters).

  5. Everett Williams says:

    I did say it was arbitrary, but the point is that the only defense against poisoning ourselves in the absence of causal science, is time. It must be noted that even unbelievably tiny amounts of hormone mimic can trigger major effects if the exposure is at the right time in the reproductive cycle. We see fish and amphibians with absolutely major hormonal related effects from parts per billion. Since we, at heart, are them, ontogeny recapitulates phylogeny and all that, we are certainly vulnerable. Except for those recently inculcated by our designs, we have had millenia and possibly millions of years to acclimate ourselves to those poisons, where modern pesticides have no such advantage for us. And if there were significant endocrine disruptors, our testing methods are sufficiently sophisticated to have detected that. That does not mean that natural poisons are any less potent than human made ones, but it does mean that we are either aware of or acclomated to most of them. Your blog on aflatoxin is an excellent case in point, and I shall shift to that for further comment on it.

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