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 as 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.