More on Gypsy Moth Spraying: Bioaerosols and Medical Symptomatology

 I had really hoped that after my first and then second posts on gypsy moth spraying that I could get off the topic and move on to more interesting discussions, but the topic is like the bad guy in a horror movie: you think you have dealt it a death blow only to have it re-emerge for another fight. Like my last post, this one is going to be a bit shambolic as I will attempt to cover several topics that have been raised since the last blog posting.

On being a paid “shill”:

As my regular readers know, I have previously discussed the “shill gambit” in my post “On “Bullies”, “shills” and using labels to shut down legitimate debate”. In that post I was talking about other scientists being called shills, but I wasn’t fooling myself. I knew full well that as I continued to blog about evidence-based decision making, it was only time before I was labelled a “shill”. Now admittedly, I have been called it a couple times on the topic of pipelines, but if pipelines get people excited then spraying for gypsy moths turns it up to an eleven. In the last week I have been called any number of names from “shill” to “unethical” with a few people pointing out that my work as a government scientist, and the owner of a money-making blog, puts me in position of a conflict of interest. I’m afraid to say that both my employer and my wife would be a bit surprised by that line of reasoning. My employer because they didn’t realize that I had left my job to go work for the government and my wife because she knows nothing about the slew of slush money apparently coming my way from unknown “corporate interests”. To put this all to rest, let’s start with the obvious. I do not work for the government. I work in the private sector. I do not get paid to blog, and since my blog site has no ads I derive no income from my blog. I blog on my own time, and never on the company dime, as I enjoy my real job far too much to put myself in any conflict of interest on that front. It goes without saying that since I blog on my own time, the opinions expressed here are entirely my own. For those of you wondering, some friends at work read my blog but my wife does not.

On Bioaerosols and Inhalation Risk:

A number of people have directed me to a Facebook page: StopGypsyMothSpraying. At the site is a prominent link to an undated New Zealand TV article on Btk spraying (ref) which I believe refers to spraying conducted in New Zealand in May 1999. The story features a very likable epidemiologist Dr Simon Hales from the University of Otago in Wellington, New Zealand. Dr. Hales brings up some very important points about spraying programmes. Specifically he points out that at the time of the spraying, in May 1999, very little was known about the science of bioaerosol dispersion of this particular compound. For those of you not familiar with the term a bioaerosol is simply a suspension of airborne particles that contain living organisms. The Foray 48B spray is a bioaerosol made up of Btk (a biological organism) in a liquid suspension. Most of the “inert” compounds discussed in my previous posts relate to the liquid suspension. To explain, you can’t simply spray raw bacteria into the air. The sprayed material consists of an active agent (the Btk) in a liquid. If designed correctly, the suspension will not clump and when sprayed correctly will produce uniform droplet sizes which will disperse in a manner that effectively covers the area being sprayed. The chemistry of these suspensions is very tricky and most of the suspensions are the result of years of study (and are thus patented and not shared with competitors). As I discuss in my previous post, the components are known to regulators but are not shared openly to protect all the work invested in producing the recipes. You need the right particle size to get effective coverage and to ensure that the compound hits and stays on the target. For the keeners out there I include a reference that details particle sizes and how they relate to the effectiveness of sprays (ref).

In the clip from the television programme, Dr. Hales points out that not a lot was known about this topic at the time. That being said, a lot of research has been carried out and many of Dr. Hales’ concerns have been addressed. An example of this is a report titled: “Bioaerosol Health Effects and Exposure Assessment: Progress and Prospects” (2003). It indicated that in some cases, under the wrong wind/humidity conditions, droplet sizes can vary from designated parameters and respirable particles can result in both allergic and non-allergic responses in sensitive populations. The Annals of Occupational Hygiene did a major issue on the topic in 2014. I have attached a copy of the feature editorial which discusses the state of the art in the field (Advancing the Science of Bioaerosols’ Exposure Assessment 2014 ref). The literature indicates that for endpoints like cancer there exists no identified mechanism to elicit the response and thus the likelihood of cancer as a result of the spraying is extremely low (below the de minimis risk level). Moreover, the research indicates, when sprayed under the correct environmental conditions, only a very, very small percentage of the spray actually reaches respirable size. Specifically, Foray 48B spray droplet size is calibrated for ~120 μm. This is far larger than the maximum respirable size of <10μm. In the testing, approximately 0.17% of the volume of spray was determined to be <14 μm in size in bench tests (ref). So while it is clear that the possibility exists that respirable particles will be produced by the spraying, the recent literature dismisses the likelihood that it serves as a significant health risk for the typical community. The language used was pretty certain:

  • Some people may experience minor eye, nose, throat and respiratory irritation. The HRAs [health risk assessments] raised the possibility of asthma aggravation of asthma [sic], which was considered biologically plausible, although epidemiological research and surveillance from the WSTM [white spotted tussock moth] operation did not support this.
  • Some people would find the odour of F48B unpleasant. Some people may experience nausea, headache or other symptoms if exposed to unpleasant smells.
  • Available evidence does not support any effects during pregnancy on either mother or fetus, or effects on prematurity, miscarriage rates, birth weights, congenital abnormalities.

On Hospitalization and Asthmatics:

In keeping with the sensationalization of the topic, nothing beats the headline from The Province Newspaper on Tuesday: “Two hospitalized as spraying continues in Surrey and Delta against the gypsy moths”. Reading that headline, I thought it might be time to set up the barricades to protect us from the hoards of people rushing to escape Cloverdale for the kinder, gentler world of Langley. Upon reading the article I discovered that The Province was being a bit liberal with the use of the term “hospitalized”. The story describes two individuals who went to the Surrey Memorial Hospital Emergency Room after encountering the spray. Based on my reading of the story, neither “patient” was admitted but rather as a representative of the Health Service noted: “they were fine and they were released”. Now my understanding is that the definition of “hospitalize” includes the requirement for “treatment”. The simple act of walking into an ER and asking to see a doctor really doesn’t count as being “hospitalized” in my books…unless you are trying to drive readers to your online article…

Regarding asthmatics, here we have a group that clearly represents an “at-risk” population that was specifically described the earlier risk assessments. That being said this population has not been ignored in the research and the risk to them has been studied. Specifically, during the 1999 spraying in Victoria, a matched-pair cohort study was carried out to establish the risk to this population (The effects of aerial spraying with Bacillus thuringiensis Kurstaki on children with asthma). The result was reassuring. There were no differences in asthma symptom scores between subjects exposed to the spray and control subjects located outside of the spray zone. Moreover a larger study conducted at the same time (Human Health Surveillance during the aerial spraying for control of North American Gypsy Moth on Vancouver Island, British Columbia) had a similar conclusion:

Results to date show no apparent relationship between aggravation of asthma in children and aerial spraying of Foray 48B. As well, no short-term health effects were detected in the general adult population nor in hospital emergency room visits.

So when people claim that no studies have been done on this topic, the correct response is “balderdash”. Surrey and Delta are not the first places this spray has been used. It has been in use for almost two decades in a large number of jurisdictions and each and every one did a risk assessment prior to the spraying and all have found the spray to be safe. Of note, I keep reading a comment that Foray 48B was “banned in New Zealand” but I have yet to find any support for this statement and attribute it to an unsubstantiated urban myth.

The Big Conspiracy:

The strangest set of comments have dealt with some unspecified conspiracy between government agencies around the world to ignore the few enlightened individuals on this topic. As I mentioned previously, I have been informed that I am either a witting member of the conspiracy or simply an unwitting dupe. I’m not sure which version I prefer, but do not believe either case. As I mentioned in an earlier post: “Public Sector Compensation – You Get What You Pay for” most of the civil servants in the technical end are underpaid with respect to their private sector peers and many work in the public sector out of a sense of public duty. I cannot believe that every one of these people has been bought out by the dark forces. I think it more likely that if such a conspiracy existed we’d have read about it on WikiLeaks or through some other journalistic enterprise. As for the peer-reviewed literature, it is categorical in that researchers have been unable to demonstrate links to any effects beyond minor discomfort associated with ingesting the spray. The particles, when applied according to specifications, are not respirable and thus would not cause effects in non-sensitized populations. Given the number of exposures necessary to sensitize the population, only the most highly susceptible would appear to even have a chance of having issues. For the vast majority of the population symptoms are limited to minor headaches, a minor odor and a bad taste in the mouth. It is possible that the suspension solution may have food additives that may result in minor reactions but given the minute quantities ingested these symptoms would be expected to disappear shortly after exposure ceased. That being said all studies repeat the same warning: most negative reactions in affected communities will be linked to adverse effects promoted by expectation, otherwise known as “the nocebo effect”.

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3 Responses to More on Gypsy Moth Spraying: Bioaerosols and Medical Symptomatology

  1. TCM says:

    Having slogged my way thru all of the references linked to, (without the help of my chemistry & biology partners of decades long past) I will simply state I am glad the Particle Size and Pathogenicity in the Respiratory Tract reference did not have click-able links. 😉


  2. Mark says:

    Also omitted from the “anti-” camp is just how are we to remove unwanted foreign pests if spraying is not permitted.

    At a certain point the risks of spraying — thought with good reason to be low — are outweighed by the known risks of not spraying. Just as I will get into a car to go to work, despite the risk of bodily injury in a car crash, in order to keep an income.

    People opposed to spraying could reasonably be labelled as people who are for imported foreign pests. Because that's what you get without the spraying.


  3. j burns says:

    Foray 48B
    Btk Overview
    A Short Introduction to Bt and How It Works as an Insecticide
    Detailed Btk Health Information
    Link to Journal of Pesticide Reform Informal Survey Article on Bt
    Plyac (ethoxylated alcohols)
    BIT (1,2-benzisothiazolin-3-one)
    Foray 48B

    Foray 48B is an insecticide used to selectively kill the larval stage of
    family Lepidoterae (butterflies and moths). It is composed of an active
    ingredient, a bacteria called Btk (see below) and mostly “inert”
    ingredients. It is produced currently by Valent Biosciences. Foray 48B
    often used as the pesticide of choice to eliminate gypsy moths, tussock
    moths, painted apple moths, and others all over the world.

    While there are no studies that show more than a handful of serious
    effects from spraying Foray 48B, no really comprehensive studies have
    been conducted. The label states that Foray 48B cannot be used on any
    crops, and that workers should stay out of the spray area for 4 hours.

    The MSDS (Material Safety Data Sheet) for Foray 48B states that the
    carcinogenicity, mutagenicity, and other effects are essentially unknown
    untested. The majority of Foray 48B is made up of “inert” ingredients,
    are not available to the public but could be made up of materials even
    toxic than the active ingredient.

    Recently, scientists at the University of British Columbia “reverse
    engineered” a batch of Foray 48B to see what might actually be in it,
    presented the results in this study (PDF format). They analyzed both
    volatile and non-volatile compounds in Foray 48B. Without more
    they were unable to identify the non-volatile compounds, some of which
    probably were the active ingredients. However, they did manage to
    with a fair amount of confidence compounds in the following list. It
    be that some of these chemicals are the result of decomposition of other

    compounds or byproducts of cellular processes, so the actual number of
    inerts added could be less. Even so, it is startling that there are many

    more than the half-dozen or so inert ingredients that Valent claims are
    Foray 48B.

    The inerts are listed by chemical name and CAS number. In addition, if
    are on the EPA’s lists of inert ingredients, their classification is
    in the third column. List “3” are “inerts of unknown toxicity”; List
    are “inerts generally considered to be safe for use in pesticides.” [An
    aside – the way an inert gets on List 4B is that a company asks for it
    to be
    put there. No testing is actually performed.] Notice that most of these
    compounds are not listed with the EPA as permissible inert ingredients.
    significance of this is unknown. This analysis was performed on a batch
    Foray 48B prior to a possible reformulation, so the composition now may
    slightly different.

    Analysis – Our guess is that BIT was added after 1999 as a preservative.

    The siloxane (organosilicone) compounds are probably added as
    (wetting agents) or anti-foaming agents, or may be indicative that
    used an organosilicone-based methylated vegetable oil as a
    agent. The butylated hydroxy toluene (BHT) likely slows oxidation of the

    vegetable oil carrier. Acetic acid and benzoic acids may have been used
    stabilize the pH of the mixture. Sydnone may be a dye used to color the
    product. Galacticol, 2-hydroxy pyridine and trimethyl phosphine are
    products of fermentation or decay of the bacteria or growth medium.

    Table of Probable Volatile Inerts in Foray 48B from 1999:


    Formula CAS Number EPA Inerts Designation
    1,5-hexanediene-3,4-diol, 2,5-dimethyl 4723-10-8
    1-propanesulfonyl chloride 10147-36-1
    2 methyl-2,3-pentanediol 7795-80-44
    2,4-hexadienedioic acid 505-70-4
    2-butanone, 4-acetyloxy 10150-87-5
    2-heptanone, 3-hydroxy-3-methyl 13757-91-0
    5-hexene-2-one, 5-methyl 3240-09-3
    2-hydroxy pyridine 142-08-5
    acetic acid, 2-propenyl ester 591-87-7
    acetic acid, anhydride 108-24-7 4B
    acetic acid, mercapto -,methyl ester 236-48-2
    benzoic acid 65-85-0 4B
    benzoic acid, siloxane derivative 10586-16-0
    benzoic acid, 2-hydroxy-,phenyl ester 118-55-8
    butylated hydroxy toluene 128-37-0 3
    cyclohexasiloxane, dodecamethyl 540-97-6
    cyclopentasiloxane, decamethyl 541-02-6 3
    cyclotetrasiloxane, octamethyl 556-67-2 3
    cyclotrisiloxane, hexamethyl 541-05-9
    disiloxane derivative 1438-82-0
    disiloxane derivative 18420-09-2
    ethanol, 2-(1methylethoxy)- 109-59-1
    ethanol, 1-methoxy-,acetate 4382-77-8
    ether, sec-butyl isopropyl 18641-81-1
    ethylene diamine 107-15-3 3
    galacticol 608-66-2
    penta siloxane, dodecamethyl 141-63-9 –
    phenyl amine R silane derivative 10538-85-9
    phosphine, trimethyl 594-09-2
    sydnone, 3-(phenylmethyl) 16844-42-1
    thietane 287-27-4
    trisiloxane 3555-47-3 3


    During aerial spraying, the concentration of these products (just the
    volatile compounds) was not detectable down to the limit of the
    used. This is in the parts per million (how many parts is not clear).

    You can see more about inert ingredients at NCAP’s Inerts Page. There is
    good report you can view at the bottom of their page. Also, see the
    information on this page for BIT.


    Bacillus thuringiensis var kurstaki or Btk is a bacteria that is related
    a natural bacteria (Bt) found in soil at extremely low concentrations.
    strains in Foray 48B are not commonly found in soil. Researchers found a

    mutant strain of Btk, generically called an HD-1 type, in a sample and
    selectively bred it for maximum activity against caterpillars. Btk
    used in commercial pesticides are not found in any significant quantity
    their present form (yet!) in nature and may be genetically modified;
    have been patented (it is not possible to patent a natural life form).
    For a
    better understanding of how Btk works, see our short Bt primer.

    All subspecies of Bt produce a substance, called a protoxin, that
    poisonous when it is ingested by target insects (caterpillars for Btk).
    only reason we are not poisoned is that the acid in our digestive tract
    deactivates the protoxin. However, this might not be completely true if
    inhale Btk protoxin. Btk is also toxic in its own right; in the lab it
    been observed to destroy cell walls in animal tissue.

    It is claimed that Btk is a natural insecticide that is found in the
    and is used on organic crops. This is only partly true. While Btk is
    somewhat today as an organic pest control, there is increasing awareness
    the organic farming community that Btk could be a genetically modifed
    organism and probably should be avoided. When we eat vegetables or
    sprayed with Btk, we only swallow a tiny amount of it. During a
    spraying one would expect to inhale more Btk spores in a single breath
    would be consumed in a year’s worth of food. In addition, Btk is
    to some extent by injesting it, but it spores may germinate and
    colonize the human respiratory tract after sprayings. Btk insecticidal
    strains produce protoxin at a level higher than that of the organisms
    commonly found in soil. The protoxin itself is isolated as a chemical
    (called crystalline protoxin or parasporal inclusion bodies) and mixed
    the Btk in Foray 48B.

    No Spray Zone maintains an active survey of health literature on Btk
    is found on our Btk Information Page. There are also exhaustive web
    about alternative Btk information at the Praxis website, and the Journal
    Pesticide Reform.


    Plyac is the trade name of the chemical nonyl phenoxy ethoxylate, which
    in a group of synthetic surfactants called “alkyl phenoxy polyethoxy
    ethanols” or “ethoxylated alcohols.” Surfactants are chemicals that
    the surface tension of water and allow a substance to spread thinner and

    farther when it is applied. Surfactants are used in detergents,
    cleaners, and hard surface cleaners. Alkyl phenoxy polyethoxy ethanols
    slow to biodegrade in the environment and have been implicated in
    health problems. Researchers in England have found that in trace amounts

    they activate estrogen receptors in cells, which in turn alters the
    of certain genes. For example, in experiments they have been found to
    stimulate the growth of breast cancer cells and feminize male fish. One
    member of this family of chemicals (nonoxynol-9) is used as a common
    spermicide as well as an industrial floor cleaner, indicating the
    level of high biological toxicity associated with these compounds.

    Ethoxylated alcohols routinely contain the contaminants ethylene oxide
    1,4 dioxane (not dioxin), both well-known carcinogens.
    Poly(oxy-1,2-ethanediyl),a-isooctadecyl-w-hydroxyl, an ethoxylated
    used in a surfactant larvacide, can contain up to 0.002% 1,4 dioxane.
    is no data on the inhalation risk of these compounds.

    The March 2002 issue of the Washington Free Press has a very good
    article on
    the pervasive effects of endocrine disrupting chemicals in the
    and mentions specifically “alkylphenols”, a synonym for alkyl phenoxy
    polyethoxy ethanols.

    Plyac is mixed with Foray 48B to help spread the pesticide evenly on
    surfaces and make it stick better. Plyac or a similar compound is almost

    certainly one of the “inert” ingredients of Foray 48B.

    BIT (1,2-benzisothiazolin-3-one)

    BIT has been positively revealed to be one of the “inert” ingredients in

    Foray 48B. BIT is a “biocide” (a disinfectant) that is used as an
    to paints, for example, to prevent the growth of unwanted bacteria,
    or molds. It probably is being used in Foray 48B to prevent growth of
    organisms other than Btk while the material is being shipped and stored.

    BIT was banned in 2001 from being discharged into the environment in the

    Netherlands because it is toxic to aquatic life and because there are
    troubling issues with human interactions. A conclusion from their
    government health ministry report: “Refined risk assessment shows that
    (1,2-benzisothiazolin-3-one) is a very hazardous substance.” You can
    the full report here (see pages 31-32).

    The US EPA has listed BIT as a probable immunotoxicant – not a good
    thing to
    spray around people or any other life form for that matter. Small
    amounts of
    BIT might be expected to cause sensitization or allergic reactions after

    exposure. The EPA also has no data as to the inhalation risk.

    Back To NSZ Home…

    Download MSN Messenger @ – talk to
    and friends overseas!
    13 years ago
    Raw Message
    Post by Alex
    We are attempting to post here the latest information on pesticides used
    Washington State to eradicate gypsy moths.
    Is this the same stuff used in NZ?
    And why copy an entire news article, and not post a link to it?
    Also, it came off as a little to conversational/sensationalist for my 100%
    truth detector, maybe get some links to scientific studies or something.
    13 years ago
    Raw Message
    Post by T.N.O.
    Post by Alex
    We are attempting to post here the latest information on pesticides used
    Washington State to eradicate gypsy moths.
    Is this the same stuff used in NZ?
    And why copy an entire news article, and not post a link to it?
    Also, it came off as a little to conversational/sensationalist for my 100%
    truth detector, maybe get some links to scientific studies or something.
    MAf have put in place 700 pheromone traps in and around Hamilton – Brilliant
    MAF have not found any sign of a Gypsy Moth infestation – only 1 male moth
    caught to date – this would suggest a VERY low population (perhaps

    Click to access sharov_et_al_2002.pdf

    this report shows that pheromone trapping/ mating disruption is AS
    EFFECTIVE as aerial spraying in LOW populations of Gypsy moth.

    WE know that IF there really is a Gypsy moth population it will be very
    small – MAF don’t even know if they are spraying the right area.
    700 extra traps should have the threat fenced in. This was the approach used
    in Auckland for the Tussock moth problem and it worked. The original
    infestation there never got past the traps and was successfully eradicated.

    The lessons used in the Tussock moth eradication programme were ignored for
    the Painted Apple Moth – look at what happened.

    MAF have panicked over the Threat of a Gypsy Moth infestation and this
    aerial spray campaign is a knee jerk reaction to that. There is no immediate
    threat to the country. There is time to see if there is a population of
    Gypsy moth that does really pose a threat to NZ. There is the possibility
    that due to the very low numbers (maybe none) of caterpillars out there that
    they will NOT even successfully establish themselves.

    I certainly do not agree with the need for aerial spraying right now but if
    MAF were to show me that a very real and present danger existed then I would
    have to accept the need for it. Right now I do not believe that the threat
    exists as MAF would have us believe that it does and therefor the risk to
    peoples health posed by the spray should not be accepted.
    Aerial Spraying is an important tool in MAFs arsenal against foreign pests.
    It should not be used as a first measure in urban areas however. MAF have
    lost the confidence of a lot of West Auckland’s and now West Hamiltonians
    (watch this space for Mount Wellington) and that could be the biggest loss
    of all.
    13 years ago
    Raw Message
    sorry I don’t know how to do that yet as I am that internet savy yet. And
    yes it is the same stuff MAF is using in NZ. As for your truth detector, it
    might need a bit of fine tuning.

    Kind regards
    Post by T.N.O.
    Is this the same stuff used in NZ?
    And why copy an entire news article, and not post a link to it?
    Also, it came off as a little to conversational/sensationalist for my 100%
    truth detector, maybe get some links to scientific studies or something.
    13 years ago
    Raw Message

    Click to access sharov_et_al_2002.pdf
    Post by Alex
    sorry I don’t know how to do that yet as I am that internet savy yet. And
    yes it is the same stuff MAF is using in NZ. As for your truth detector, it
    might need a bit of fine tuning.
    Kind regards
    Post by T.N.O.
    Is this the same stuff used in NZ?
    And why copy an entire news article, and not post a link to it?
    Also, it came off as a little to conversational/sensationalist for my 100%
    truth detector, maybe get some links to scientific studies or something.
    13 years ago
    Raw Message
    Post by cp1c

    Click to access sharov_et_al_2002.pdf
    apart from the first one, they are all “anti-fan” sites… two sides to
    every story remember.
    neil neil orange peel
    13 years ago
    Raw Message
    simple solution. hold your breath when the plane flies over.

    and what a cool job it would be actually flying those aircraft 200 knots at
    200 feet.

    I agree with TNO on the article. it doesnt seem very objective. but all the
    same a little concerning.
    If this were true of the substance, however, then i would be a very nervous
    CEO of Valent Bioscience in terms of future lawsuits. And i would say that
    the secrecy of the makeup of Foray 48B is for intellectual property reasons,
    not because that they know they are spraying a carcinogenic pesticide all
    over us. You cant get away with that anymore especially in the States where
    they are already using it.




    13 years ago
    Raw Message
    Post by neil neil orange peel
    simple solution. hold your breath when the plane flies over.
    for four hours… maybe oxygen masks/tanks could be handy.
    Post by neil neil orange peel
    and what a cool job it would be actually flying those aircraft 200 knots at
    200 feet.
    True, you cant beat low flying at high speed.
    Post by neil neil orange peel
    I agree with TNO on the article. it doesnt seem very objective. but all the
    same a little concerning.
    I didnt mean to come across as “pro the spray”, Im most definately not,
    infact if they were to spray my area, I’d move(I rent, so no biggy).

    I do however think that it is interesting that no-one complains about the
    smog levels in Auckland, since moving there I have not had one sinus
    problem, tight chest, brown sneeze, but while living there, I had the lot.
    7 Replies
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