I bring you the thoughts of one of the most distinguished experts in the field of pesticides—Keith Solomon!
by Art Drysdale
November 13, 2011
Currently, here in British Columbia, a special all-party committee of the Legislature is examining the very controversial topic of the use of so-called Cosmetic Pesticides. The public was invited to submit presentations, or complete a questionnaire and thousands of the expected non-scientific anti-pesticide people did so.
But so did some highly respected scientists—some who have worked in this area for four or more decades. One of these scientists is Keith Solomon, who was a regular guest on my garden programmes I did both at Toronto’s CFRB Newstalk, and more recently at AM740, also in Toronto. In my opinion, no one presented or presents the real facts on this topic as well as Keith.
For that reason, I was pleased to see that he made a significant submission to the British Columbia all-party committee.
Before I present to you a large number of quotes from his presentation, allow me to document just who he is, as follows:
Professor Keith Solomon is Professor Emeritus and Associate Graduate Faculty in the School of Environmental Sciences at the University of Guelph. He is also Director of the Centre for Toxicology.
Professor Solomon continues to teach courses in toxicology and pesticides at the University of Guelph and to advise graduate students. He directs an active program of research into the fate and effects of pesticides and other substances in the environment, exposure of humans to pesticides and industrial chemicals, and risk assessment. He has, and continues to serve on several advisory committees on matters related to environmental toxicology and pesticides in Canada, the USA, and internationally. He is a member of the Society of Environ-mental Toxicology and Chemistry, the American Chemistry Society (Agrochemistry and Environmental Chemistry), and the American Association for the Advancement of Science. He is the recipient of the 1993 Society for Environmental Toxicology and Chemistry-ABC Laboratories award for Environmental Education, was elected as a Fellow of the Academy of Toxicological Sciences in December 1999, and is recipient of the 2002 American Chemical Society International Award for Research in Agrochemicals. In 2006, he was awarded the SETAC Europe Environmental Education Award and the Society for Environmental Toxicology and Chemistry Founders Award.
He graduated from Rhodes University with a BSc (Hons) in Chemistry and Zoology and holds MSc degrees from Rhodes University and the University of Illinois as well as a PhD from Illinois. He has more than 40 years of experience in research and teaching in pesticide science and toxicology and has contributed to more than 350 scientific publications and reports (more than 240 in the peer-reviewed literature) in the fields of pesticides, environmental toxicology, and risk assessment. To date, he has advised or co-advised eight Post-Doctoral Fellows, 45 Masters Students, and 26 Doctoral Students. Many of these students are currently employed in regulatory positions at the Provincial or Federal level in Canada and several Doctoral students have gone on to faculty positions at Universities.
Herewith, selected and adapted excerpts from Dr. Keith Solomon’s presentation. I hope you’ll not only learn from some of these points, but that you will also be impressed by his admonitions in the final four paragraphs.
“Pests can do very significant damage to our aesthetic spaces, our own gardens and public spaces. You can see damage to lawns [and ornamentals]. There is some Birch Leaf Miner, which will do damage to birch trees, and fungus, skunk damage, and Chinch Bug. All of these cause damage that is difficult to prevent other than with the use of pest control products.
“You can replace the grass, or you can use some other techniques, but pest control products are often more effective.
“By law, anything that controls a pest is defined as a pest control product, but within the class of chemical pest control products, there is a vast range of substances which have very, very different biological and physical properties.
“You probably have not thought about it, but the disinfectant that you use in your toilet bowl is in fact a pest control product that kills bacteria and is actually registered as a pest control product. So we still use these routinely in our houses, even in places that have enacted bans.
“They obviously cause effects in the target organism. Otherwise, you would not use them. It would be a waste of money.
“Some pest control products are fairly toxic to non–target organisms, and some are basically, essentially, in-nocuous, so there is a range here, and that’s the important point. Not every pest control product is highly toxic. Not every pest control product is highly dangerous.
“To be used in Canada, pest control products must be registered. In order to register a pest control product in Canada, you have to take to the Pest Management Regulatory Agency in Ottawa a large amount of data that shows that the product, if used as written on the label, will not cause any adverse effects or risks to either the environment or to humans. This is basically the same process that is used in other countries, such as the United States, the European Union member countries, and then also in many other international jurisdictions who often use the auspices of the World Health Organization for their risk assessments.
“This data is reviewed and is current, including historical data, and it is regularly updated. The review of 2,4–D herbicide, just as an example, was recently completed, in 2007, which was a re–review of a product that had been looked at for many years over and over again. 2,4–D herbicide is still registered here in Canada.
“An important point about these studies is that all of them must be done now under what is called good laboratory practice guidelines, which means, basically, that they are done according to standard protocols and that there is a quality assurance and auditing process in place that actually ensures that what people say was done in these studies was, in fact, done.
“Just to remind you, Health Canada, which is the mother agency for the Pest Management Regulatory Agency, is also the agency that approves the use of pharmaceuticals in Canada.
“Rats are often used as surrogates for mammals, and for environment, they might use birds, such as the Bob White Quail. There are many, many studies that are done with these, and this data is then used in assessing the risk of the pest control product.
“Fish are also used in toxicity testing for chemicals. This kind of data is used, then, to assess impacts or potential impacts on organisms in the environment.
“The focus at Pest Management Regulatory Agency in Ottawa is both environmental and human health, to make sure there is protection in both of these areas. The testing data is reviewed by the regulators.
“Pest Management Regulatory Agency, and other agencies in other parts of the world, use what I call the pre-cautionary approach to set guidelines for exposures for humans. They use safety or what we like to, in the sciences, call uncertainty factors. If you find that a chemical has no effect at a certain concentration in a rat, then you would say, ‘for humans, we will only allow an exposure to one–tenth that concentration’, because, obviously, humans are not rats.
“We will add another uncertainty factor or safety factor of ten times because we know that some humans are different from other humans. So, the sort of basic safety factor that you see for exposure to pest control products is 100–fold from the most sensitive animal tested, the most sensitive end point. Then, in addition to that, there may be additional factors added, up to ten, so you multiply these together, and it's a 1,000–fold safety factor.
“This would be in relation to exposure, say, for children, who might be deemed to be more sensitive. From all of this and an application of these uncertainty factors, the acceptable daily intakes are calculated here in Canada. In the United States, they use a different term for that, which is reference dose. In the United States, they also develop environmental exposure guidelines.
“At least in home and garden use, most pest control products are actually very non-persistent. They only have short-term effects on target organisms. That’s the reason why they often have to be used more than once in a season, and why you get rapid re-invasion by weeds and insects.
“Certainly, for herbicides, these generally have very low toxicity to non–target animals, because they are basically designed to control plants. Of course, they will damage plants if they are deliberately spread on them, but that’s the reason why you might use a herbicide.
“When we look at hazards from chemicals, we're really looking at two issues; one is toxicity, and the other one is exposure. The larger the exposure, the larger the hazard. The larger the toxicity, the larger the hazard. We use toxicity data and we use exposure data to assess risks from pest control products.
“The toxicity of 2,4–D is not very high when compared to something, perhaps, that you're all familiar with–table salt. Table salt would be lethal at 300 milligrams per kilogram. Pest control products are less toxic than table salt. I’m not suggesting you use them on your fish and chips, but just to put it into some sort of perspective. Natural does not necessarily mean it is safe. If you look at the natural product, which is indole butyric acid, it is the hormone that some herbicides mimic. Indole butyric acid is found naturally in plants. We are exposed to it when we eat plants. Indole butyric acid is actually several times more toxic. We need less to achieve an LD50 for this product than we would for the synthetic products.
“Then, this is across the board. Some of the fatty acid products that are now recommended as substitutes for herbicides are in fact much more toxic to frogs than the herbicides that they’re replacing. We don’t necessarily always move in the correct direction. There have been a number of exposure studies done.
They are required for registration by applicators such as farmers or professional applicators. There’s a require-ment for food monitoring and a requirement for water monitoring in Canada for pest control product residues.
“We’ve done some work in our own labs at Guelph where we’ve looked at exposures to herbicides sprayed on turf. The people involved in this exposed themselves to treated turf after it had been sprayed to measure the amounts that get into the body in that process. These are the conclusions.
“In none of these cases did we see any numbers that would be of concern. In addition, the re-entry periods of 24 to 48 hours basically reduced exposure to negligible amounts. These were re-entry periods that were in use in Ontario at the time this research was done.
“A report by the Ontario College of Physicians made some conclusions about linkages between pest control product exposure and diseases in humans. There are some issues with this report, which was not very well done. First of all, it was based only on epidemiology. Many studies were omitted from their report. It did not consider the toxicity data that Health Canada and other agencies use. It did not consider the exposures, and it did not consider the published regulatory reviews from Health Canada and the U.S. Environmental Protection Agency and other agencies.
“Epidemiology is the study of diseases in humans. Humans are good organisms to study, but humans are extremely difficult to work with because we don’t always say what we do. Epidemiology studies are really based only on correlation and suggested links, and they cannot establish causality on their own. I’ve told you that the Ontario College of Family Physicians report was not very well done.
“Others have said the same thing. These people are not even from Canada. So I don’t think there’s any axe to grind here at all. But the United Kingdom Advisory Committee on Pesticides basically said that this report did not raise any new concerns. The Advisory Committee on Pesticides also said there was no reason for additional regulatory action in the United Kingdom.
“There was another opinion on this report from the Royal Commission on Environmental Pollution. According to them, strong conclusions were being drawn from evidence that was of very weak quality.
“There are other opinions on pest control products and cancer from the International Agency for Research on Cancer. There is really a lack of evidence linking pest control product exposure to human risks of cancer.
“In Canada, age-adjusted cancer incidence rates have remained constant or decreased for most forms of cancer.
“Breast and prostate cancer have increased; some of this is because of lifestyle issues, the other part is better diagnosis.
“There is no evidence of any causal link between pesticide use and cancer.
“Childhood cancers have not increased in Canada over the last 20 or 30 years.
“Should domestic and landscape use of pest control products be banned? As a scientist and speaking as a toxicologist, there are no toxicological or health reasons for this. If you want to do it for political reasons, that’s fine. That's within your mandate. But if you do that, you should be honest enough to admit that you’re actually doing that. Consider the countervailing risks.
“There are certainly increased costs related to either the actual cost of the alternatives, or the lack of efficacy of many of these, which means they have to be applied more often, and this increases costs as well.
“The alternatives are not all themselves without risk. I have mentioned the issues with fatty acids and being lethal to frogs.
“Obviously, if we use pest control products, we should use them properly. The best way to do that, I think, is something that British Columbia pioneered over the years, which was to ensure that integrated pest management was used to make sure that all the options that are available are used.”