Happy Anniversary, WHOPES!

1 07 2010

The World Health Organization’s Pesticide Evaluation Scheme (WHOPES) was established 50 years ago. WHOPES, since it’s establishment, has become the standard reference for different countries in setting up practices for public health pesticide use and pesticide life-cycle management. WHOPES collects and analyzes data on the safety, efficacy, and acceptability of different pesticides for public-health purposes and creates guidelines for quality control, pesticide management, and program evaluation.

uhh, what?

The category of illnesses known as “vector-borne diseases” refers to diseases that are caused by bacteria,parasites, or virus– just like all diseases–but are transmitted to humans not through human-human contact, or through the air or water, but via insect “vectors”.  This category includes malaria, dengue fever, west nile virus, and yellow fever which are transmitted by mosquitoes; lyme disease, rocky mountain spotted fever, and tularemia transmitted by ticks, and the infamous “black death” plague that we all learned about in history classes, transmitted from rats to humans via a vector, a tiny flea.

Currently, the most popular method to prevent vector-borne diseases is through targeting the vector–which is often a more realistic option than targeting the pathogen itself. For example, the fight against malaria is largely fought using insecticide-treated nets, insecticide spraying, and larvaciding of waterways to repel and kill the mosquitoes and even kill the mosquito larvae. Think of the mosquito as the middleman between the malaria parasites and the humans: eliminate the middleman here, and the system falls apart. Much effort has been directed towards creating vaccines against the malaria parasite, but the biology behind it is so complicated that it has proven unsuccessful over and over again. Stopping the mosquitoes is something we have the technology to do.

Yup, technology.  Those cans of bug spray we all use on buggy summer nights, and the more fancy but same concept compounds that we treat bednets with and spray on the walls of buildings in malaria regions, contain a type of chemical technology that was very carefully designed to have the ability to kill. There is a famous old saying in the field of toxicology, “All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” (Paracelsus, early 1500s…I told you its an old saying). There is a lot of smart people out there chemically engineering our insecticides to be just right: kill the mosquitoes, and kill them all not just half and not just make them sick but still able to live, so that resistance does not build in the population and render our compound ineffective. Kill the mosquitoes, but don’t kill the bees and the moths that we need to pollinate our crops. And most certainly don’t kill the birds and the wildlife and the people…don’t even come close to making them sick or unhealthy in any way whatsoever. Once you’ve got that compound, now make it into a form that is practical to use and manage, so that we can say it is safe. Oye, what a task. There is so much room for mistakes and unintended consequences. And like we said, all things are poisonous its just the dose that matters…so in reality, while we call these compounds safe for humans, we label them as toxic and put warnings on the bottles for a reason: it can harm you just like it harms the mosquitoes, its designed to kill. Lucky for us, mosquitoes are 1 bajillionth of our size (I did the math myself), and so it takes a much higher concentration, and a much bigger dose, to harm us than it does to harm them.

So once that compound is made and known to be effective and we start using it, we need to make sure that we are monitoring how its used, how its managed, how it is stored and disposed of, so that the exposure to the people stays low that its not poisoning us all. And of course, there are questions over how low is low enough (hence my project.) When we plan to use insecticides large scale to help prevent vector-borne diseases, these aspects of creating management plans and ensuring safety can be very expensive– as are all the tests and evaluation of the product and its use along the way.  The countries which most need these vector-control insecticides for public health reasons (mainly in the tropics–sub-Saharan Africa, India, Central America–because the amount and diversity of insects here is highest– for the ecological explanation of why this is ask me!) simply don’t have the financial resources to do it all, never mind do it AND provide the the prevention options at a price their citizens can afford. And given the financial status of the people who need the products, its not exactly the type of market that a chemical company will make money off of.

The World Health Organization’s Pesticide Evaluation Scheme, over the last 60 years, has taken leaps and bounds at tackling that problem– they supply incentives for development of safer, cheaper chemicals and chemical products that will serve to improve public health by preventing vector-borne disease, and they work with these products to develop guidelines and policies for safe management, help develop strategies for targeted use and monitor safety and quality of compounds, and monitor and evaluate the products once in the field to ensure continued efficacy and cost-effectiveness. Because of their work, it is possible for lower-income countries to tackle large-scale public health problems like vector-borne diseases in ways that are more affordable and safer.

I say “more affordable” and “safer”- not simply affordable and safe. Unfortunately, there is still much work to be done. But for now, happy anniversary to the WHOPES program. They have done great things in 50 years, and I hope they will only continue to improve the quality of environmental chemistry and public health as they go on.

For more information: http://www.who.int/whopes/en/

– Kristen Pfau



2 responses

6 07 2010

Hi Kristen,

(It’s not about hamburg(er) this time!)

I gave the Townsends’ granddaughter, Kile, this address so she can read your reports. Kile has finished her first year at UNH as a biology major.

Keep away from the mosquitoes. Hope you get a lot done in July.

2 08 2010
Lin Xizhi

Hello Mr. Kristen,
We are a long-lasting insecticidal net producer in China. We are looking for a way to have our products approved by WHOPES. We are sending our e-mails to WHOPES, but no reply from WHOPES. We are eager to know how to deal with it. We are highly appreciated if you could give us some suggestions.
Thank you a lot.

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