Monday, April 27, 2015

More on Gypsy Moth spraying: Toxicity redux

Much as I expected, my post on "the nocebo effect" and spraying for gypsy moths” drew a whirlwind of criticism on Twitter and in my email inbox. The major concern had to do with the fact that in my post I dealt with Btk in general and did not concentrate on the specific formulation used for spraying in Surrey and Delta: Foray 48B. Now Foray 48B is a proprietary formulation of Btk produced by Valent BioSciences and is sold in Canada by Valent’s Canadian Agent: Valent Canada Inc.  Valent’s Canadian page for Foray 48B is here while a more detailed set of documents is available at Valent’s US website. The intent of this post is to address my previous deficiency and in doing so build on my previous series of posts on risk assessment and toxicology since, as many of you know, the intent of this blog is to enhance evidence-driven decision-making in British Columbia and understanding the science is the best way to do that. 

Now as I noted above, I did a series of posts explaining the basics of risk assessment and toxicology in February. Unfortunately, due to the nature of my blogging platform (read free and simple since I am a chemist and not a web designer) it is not terribly easy to figure out what I have written in the past so I will summarize here. The intent of that series of posts was to help me out in situations like this. You see talking about Foray 48B would be very hard if my audience didn’t understand the language of the field. The posts started with “How Big and Small Numbers Influence Science Communication Part 2: Understanding de minimis risk” which explained how the science of risk assessment establishes whether a compound is “toxic” and explained the importance of understanding dose/response relationships. It explained the concept of a de minimis risk. That is a risk that is negligible and too small to be of societal concern (ref). The series continued with “How Big and Small Numbers Influence Science Communication Part 3: Understanding "Acceptable" Risk” which, as the title suggests, explained how to determine whether a risk is “acceptable”. I don’t have the space to recap that post here so feel free to read that post then come back...I will wait here for you...okay I see you are back so let’s continue. I then went on to explain how a risk assessment is actually carried out in “Big and Small Numbers in Science Communication Part 4: the Risk Assessment Process. I finished off the series by pointing out the danger of relying on anecdotes in a post titled: Risk Assessment Epilogue: Have a bad case of Anecdotes? Better call an Epidemiologist.  Now anyone who has read all those previous posts can probably figured out what I am going to write next but that would be less fun for me so I will continue here.

The most common comment was by far the easiest to answer: I was informed “that the compound had an MSDS then it must, by definition, be dangerous”. This is simply incorrect. A Material Safety Data Sheet (MSDS) is a basic requirement of the Workplace Hazardous Materials Information System (WHMIS). Now I agree that WHMIS does indeed have the word “hazardous” right in its title but that doesn’t mean that it only regulates “hazardous” materials. Rather the system provides a consistent method to supply employers and workers with information about chemicals and compounds used in their workplace. WHMIS was developed to provide a uniform system to communicate the risks associated with “controlled products”. So there you have another set of scare quotes. You see the unspoken secret about WHMIS is that it covers pretty much every compound that is used in an industrial setting. The reason for this is that due to the nature of industrial processes almost any chemical can have dangerous properties. MSDSs are available for some of the most terrifying compounds out there from distilled water, to Coca-Cola, to table salt? So you are probably wondering: how can distilled water be considered a hazard? Well let’s look at the MSDS. Distilled water is incompatible with: “Strong reducing agents, acid chlorides, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride”. Moreover, as any first year chemist who loves seeing cool reactions will tell you, when you mix distilled water with sodium metal the reaction can be very entertaining. So to ensure the safety of employees, MSDSs exist for virtually every compound used in an industrial/commercial setting.

The next common comment was: look at the MSDS and all those restrictions on its use. Now while there are standards for use in preparing an MSDS, we live in a litigious society and some companies can be extremely cautious when they write an MSDS. Consider this MSDS for distilled water: it includes a pretty detailed description of the necessary skin protection when encountering distilled water. It is so entertaining I will present it unedited: 

Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm

Now that is some scary stuff! Think about it for a moment, they are warning you not to touch distilled water unless you are wearing gloves. Forget those hospital-issued latex gloves, they aren’t enough to protect you from this dangerous substance, you need to use nitrile gloves. Remember not just any nitrile gloves are enough either, the only safe gloves need a minimum thickness of 0.11 mm. The part I find hardest to figure out is what substance you are expected to use to “wash hands” after exposure to that nasty distilled water! Now not only is that water dangerous to touch, it also has a reported LD50 under the toxicological Information. Specifically rats die when administered an oral dose of >90 ml/Kg. Even more frightening is the fact that distilled water has been “investigated as a mutagen”. According to the Sigma-Aldrich MSDS for distilled water: “To the best of our knowledge, the chemical, physical, and toxicological properties have not been thoroughly investigated” According to the David Gray & Co MSDS: distilled water can be a “very slight eye irritant” and “excessive inhalation may cause drowning”. Based on these MSDSs I would be considered derelict as a father if I put my beautiful daughter in the tub for fear of the potential mutagenic exposure. Can’t let her outside while it is raining as water is an inhalation risk and I will also have to weigh her regularly to ensure I don’t administer too heavy a dose of water through that sippy cup!

Another common complaint was that the compound may not be appropriate for use because according to “A Health Professional Gives Facts about Foray 48B” posted at the No spray zone web site, the material is not even organic. Well while the “certified organic” label is reserved for foodstuffs and is certified by the various appropriate governmental bodies, the Organic Materials Review Institute (OMRI ™) certifies the raw materials and chemicals used in the production of “certified organic” foodstuffs. Unlike normal users of products, the OMRI™ gets to look at the actual chemical composition of a product being considered for certification. As indicated at their Website: Foray 48B has received  certification as for use in certified organic food production. So when “A Health Professional Gives Facts about Foray 48B” the first thing you may want to check is the background information. First and foremost what kind of health professional are you talking about (a toxicologist maybe?). In this case the “Health Professional” is actually an undefined “Mental Health Professional”. So what that means is that the person is apparently not trained in toxicology, epidemiology or other applicable field. Moreover, when this “mental health professional” informs you that “Foray 48B is not "certified organic" you may want to check with the OMRI™ anyways, because well, because. Given an unnamed “mental health professional” on one hand, and the body authorized to certify chemicals as organic by the United Sates Department of Agriculture on the other, you may want to trust the body authorized to certify compounds and formulations as organic.

The final point was that a large percentage of the Foray 48B is made up of mysterious “inert” ingredients. Well as noted OMRI™ got to look under the hood at that list and they still decided to certify the compound as organic.  As for better toxicological data, I have linked to a New Zealand assessment of Foray 48B that includes details of testing up to an including the feeding of Foray 48B to people. Yes they had test subjects take capsules of the stuff daily for five days, they were that confident that it would cause no harm. As described in the document on the use of Foray 48B: 

“Foray’s inert ingredients, which include various carriers, suspension agents, and stabilizers are classified by the Environmental Protection Agency (EPA) as inert ingredients of minimal toxicological concern to non-target organisms and the environment (EPA’s List 4B and 3)”

“All inert ingredients in Foray formulations are included in 40 CFR 180.1001. This list has been designed by the EPA as ‘exempt from the requirements of a residue tolerance on raw agricultural commodities” VBC verifies that none of its Btk formulations contain toxic inert ingredients, such as benzene, xylene, or formaldehyde”

So yes Foray 48B has proprietary compounds that are not on the MSDS, but that compound list is considered to pose an acceptable risk by the EPA , is certified as organic and appropriate for use on organic foodstuffs and is certified to be used up to and on the day of harvest. Yes read that again, you can apply the stuff to plants on harvest day and send them to your local organic market and they will still be considered both safe to eat and organic. 

Honestly at this point I am just banging a drum here folks. The data is pretty overwhelming. The compound has been certified as safe in Canada, the US, New Zealand and every other place where it has been sprayed. It is a certified organic mixture that provides a safe and effective method of controlling a financially devastating pest with a risk that is below the de minimis level. For those people out there complaining about symptoms like sore throat, and difficulty breathing I would direct you to the pollen outlook for the Vancouver because my family has been suffering from the same symptoms described in all the news stories and we are well outside the spray area. We are, however, sitting in the middle of the pollen season and the days suitable for spraying (dry days immediately after a rainfall) are exactly the same days that are most suited for spore dispersal by trees, flowers, grasses, molds and mushrooms. As someone who tracks pollen levels for my work, I can tell you that the best way to avoid waking up with a headache and dry throat is to take a Claritin before you go to bed and if that doesn’t work then sleep with your bedroom windows closed until the end of the pollen season because based on the toxicology that is the most likely culprit for your symptoms.

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