Pests, Poison, & People

Managing a landscape with or without pesticides is a difficult decision.  What’s so difficult you may ask? Pesticides are created to kill things. They are an inherently dangerous product. This should be an easy decision.  However, the pests they seek to eliminate also bring a danger. There's a reason one of the Four Riders of the Apocalypse was pestilence.  After immersing myself, at the request of a client, in the study of this subject and trying to separate the science from the emotion, I find that the subject is, as in most things, far more nuanced than I initially believed.

I, like most people, initially approached the subject from the aforementioned position that pesticides, herbicides, and fungicides are designed to kill things and therefore must be bad for the environment and bad for human health. I also assumed that organic products, being ‘natural’ would be better. When you are asked to counsel a client on their landscape management plan, you will probably find that it's not quite so simple.

Which are safer?

For instance, let’s look at the assumption the organic products are safer than synthetic products. This is not necessarily true. There are organic alternatives that are, in fact, carcinogenic. There are organics that have a higher toxicity profile than synthetic pesticides. One of the most used synthetic pesticides, Chlorpyrifos, is 2.5 to 20 times less toxic than Copper Sulfate, a commonly used organic alternative.  Copper Sulfate is carcinogenic and mutagenic. The synthetic pesticide is neither.  Copper Sulfate, also, bioaccumulates, which means that its toxicity increases over time.   Chlorpyrifos is eliminated rapidly from the body, usually within 24 hours.  Just like their synthetic brethren, organic pesticides have warning labels and cautions. One synthetic, made by DuPont, is the first synthetic pesticide that carries no signal word – not danger, not warning, not caution. In fact it was found to have no adverse effect up to 10,000 times the recommended effective dose – the highest level tested.

Which are better for the environment?

What about the environment? Surely organic products are better for the environment than man made chemicals? This too is a dangerous assumption.  One recent study in Canada looked at controlling a problematic agricultural pest using an organic regime vs. a synthetic regime.  The results, the organic regime was more ecologically damaging.  The reason that organic products can be more ecologically damaging is that they are often not specific. They have a higher mortality on non target species.  The potential ecological damage also extends to organic fertilizers as well. The reason is that the organic products are often not as efficient. They have to be applied at a higher rate to obtain the desired result. The excess becomes run off.  They often have other undesired components included. Case in point, organic compost often needed for nitrogen, is usually undesirably high in phosphorous – this can lead to water pollution issues.
 

So what are we to do?

 We may be asked to develop a plan for our clients, how do we advise them? First and foremost you will have to consider the client’s needs. You will have to consider the constraints that they are working under.  Is there a regulatory scheme that will guide the decisions? Secondly you will need to educate them. There are three principles at work. The first is the concept that, “chemicals are chemicals”. It does not matter – for the most part – whether they are synthesized by man or occur naturally.  Most aspirin that you take is synthetic, you can also chew on 5 pounds of willow bark. In the end you’re still getting salicylic acid, it’s just the means of delivery that is different.  The second concept is that, “the dose makes the poison”. This is a cornerstone principle of toxicology.  If it’s designed to eliminate plants or pests – it’s a poison- regardless of its origin. The main question is minimizing the dose and this involves choosing the right tool for the job and applying it in the most educated and judicious manner possible. Keep in mind that the right action may be no action at all.  The third concept is something called the precautionary principle. The precautionary principle simple states that, “when an activity poses a threat to human health or the environment, precautionary measures should be taken even when the cause and effect relationship is not fully established scientifically.” This idea is often misinterpreted to mean that “it is better to be safe than sorry”.  What is needed is a balancing of the risks.  What are the risks of using the tool versus the dangers of not using it?  Avoiding the potential “sorry” part of the precautionary principle does not guarantee, in reality, the “safe” part.

 

Take the balanced approach

Integrated Pest Management is part of LEED. It strikes the balance.  Its approach is that one should use the least damaging, ecologically or physiologically, means possible to achieve your desired end. It is a careful progression that balances the twin harms of action and inaction. It requires care and forethought in the actions one contemplates.  It leaves open the ability to use the most effective and efficient tool, provided all other options have been tried.  Clients may wish to use an all organic approach. That may be part of their value set. They must understand the trade offs, in quality, costs, efficacy, toxicity, and environmental benefits. Other clients may value the perception of quality, or want to minimize labor costs, or to maximize safety, or seek to avoid the broken window effect, or view nice grounds a means of attracting or retaining employees or customers.  All clients, I’m confident, wish to avoid liability, the risk of disease, issues with a board of health, or infestation.  Most people want to preserve the investment they have in their property while having the smallest ecological footprint and the healthiest possible site.  That can be done by balancing all options and understanding the entire equation.

Kevin Dufour is an Environmental Scientist with Viridis Advisors. He collaborates with Tom Irwin on creating greener greenscapes. The opinions expressed by member bloggers are their own and not necessarily those of the USGBC Massachusetts Chapter.