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Why The Low Application Rate of the LBAM Spray Is Not Reassuring

by John Thielking
We are told by the CDFA and even the Santa Cruz County Health Dept that the application rate of the Checkmate pesticide sprayed in November 2007 was too low to cause significant health impacts. This article breaks down the details of why that might not be true.
These are my EIR scoping comments concerning the CDFA program to eradicate the Light Brown Apple Moth, as submitted to Jim Rains of the CDFA on March 20, 2008 by e-mail. A similar document was submitted to the USDA for the Environmental Assessment for the LBAM eradication program. This document is not a CASS consensus document. It is entirely my own work, except for the references of course, and except for some help/critique of some of the math that I received from my good friend and Chemistry Professor Dr. Roger Terrill (San Jose State Univ).
Note that the new estimate of 18 kg/acre of spray applied makes it plausible to explain the vast amounts of foam found after the spray by people such as Roy Upton and Ed Porter.

Jim Rains, Staff Environmental Scientist
CA Department of Food and Agriculture
Plant Health and Pest Prevention Services
1220 N Street, Room A-316
Sacramento, CA 95814

Dear Jim Rains:

I am writing to you to present my comments concerning the Environmental Impact of the program to eradicate the LBAM in California.
It has now been documented by a researcher at UCSC who traveled recently to New Zealand that LBAM will likely be controlled by
natural predators if toxic pesticides that interfere with natural predators are not used in an attempt to control LBAM.

The LBAM “emergency” is therefore mostly an emergency that exists on paper and affects trade, more than it is an emergency
concerning possible crop damage caused by LBAM. Please stop funding eradication of LBAM that uses the questionable methods
of ground and aerial spraying of potentially toxic materials.
Thank you.


John Thielking
1346 The Alameda
Suite 7-318
San Jose, CA 95126

Investigation of correlation between possible concentration of Methyl Trioctyl Ammonium Chloride (MTAC) at ground level during spraying to control LBAM in Santa Cruz, CA on Nov 8-9, 2007 and appropriate exposure limits
By John Thielking
BA Physics

John Thielking
1346 The Alameda, Suite 7-318
San Jose, CA 95126

Summary Statement:

It is unacceptable that the actual concentrations of the methyl trioctyl ammonium chloride (MTAC) and other inerts in the Checkmate aerial spray used over Santa Cruz on Nov 8-Nov 9, 2007 were not fully disclosed. Disclosing the concentrations would make it possible to evaluate weather or not reported health effects could be due to the chemicals in question. Although the proposed DOE TEEL’s for MTAC may be high enough to seemingly rule out such a possibility, the way in which the TEEL’s themselves are derived(4) leaves open some rather large uncertainties in what minimal level of toxic exposure may produce health effects in some people. Between the spray being applied unevenly, as documented by the drift cards which had only 1/10 of the expected amount of capsules on them, and the uncertainties involved in converting an LD50 or LC50 to an appropriate TLV, the total uncertainty in what intended application rates will produce what type of health effect could be off by +/- a factor of 800 or more. In layman’s terms, It is quite possible that MTAC is more toxic than the DOE estimated, by up to a factor of 82, and it is also possible that the spray was applied unevenly, such that certain areas received up to 10 times more spray than was intended. Although this latter point is not documented on drift cards, the actual number of drift cards in the treatment zones was small enough that this could have been overlooked. Also we have some anecdotal reports that when people were affected by the spray, sometimes whole families in one household got sick, which lends credibility to the unevenly applied spray hypothesis.

Please completely disclose the concentrations of the inerts and also provide data on how much total chemical was applied by each aircraft in each treatment area. Only in this way can we get a good handle on what the peak concentrations of the spray might be for 1%-5% of the population and also define what the possible health effects might be.

The concentration of the MTAC in the spray was not fully disclosed. All we know for sure is that it is a component of the spray that was applied on Nov 8 and Nov 9, 2007 in the Santa Cruz area and that it is less than 3% by weight of the entire mixture. We also know that the MTAC was used as a surfactant and so was likely a component of the water portion of the mixture, not part of the capsules. If we make the reasonable assumption that the MTAC is in fact 1% of the mix, then we can derive the following argument:

The active ingredient (pheromone) was intended to be applied at a rate of no more than 20 grams per acre. This was supposed to be 25% of the total mix.
This implies that no more than 80 grams per acre of Checkmate LBAM spray was intended to be applied on Nov 8 and Nov 9, 2007. 1% of this total is 0.8 grams per acre. An acre has about 43,500 sq ft, which implies that no more than 0.0000183 grams (0.0183 mg) per sq foot of MTAC would have been applied. If this MTAC were uniformly dispersed in a cloud 10 ft high right on top of the ground, this would imply a concentration of MTAC no more than 0.0183/10= 0.00183 mg/cu ft. Multiplying by 27 to convert from mg/cu ft to mg/m3 gives 0.049 mg/m3.

The Dept of Energy (DOE) has published proposed Temporary Emergency Exposure Limits (TEELs) for MTAC. (1) The TEEL-0 is 0.75 mg/m3, while the TEEL-1 is 2.5 mg/m3. The TEEL-0 is defined as “The threshold concentration below which most people will experience no appreciable risk of health effects.”(4) The TEEL-1 limit is “The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor.”(4) I guess “nearly all” or “most people” does not include the 643 people who reported health complaints in Santa Cruz and Monterey after the Checkmate aerial spraying there (5). Note that TEEL-1 is normally considered to be a 1 hour exposure limit, although ref (4) suggests using 15 minute TWA’s for some reason. How people are expected to breathe residual concentrations of chemicals that remain in the environment 24/7/365 is not explained.

Since the only toxicity information available for MTAC on the corresponding MSDS is for oral LD50 for rats, there may be grounds for saying that there is significant uncertainty in the values of the DOE TEEL’s. In a Japanese paper ( 2 ) an equation is derived for converting LD50 to TLV. However, in order for the linear regression to work, both this paper and one other similar paper (3) concede that the LD50 and TLV numbers have to be plotted on a log-log plot. Otherwise the regression coefficients are not within acceptable ranges. In layman’s terms, what this means is that while the correlations on a log-log plot are good, the possible real world variations in the final answers are so big that they will only fit within the boundaries of a sheet of graph paper if a log-log plot is used. Log-log plots show results plotted in increasing factors of 10, ie 10, 100, 1000, 10,000 etc, corresponding to what would be 1, 2, 3, 4, etc on a linear plot.

What the Japanese paper in effect says is that the available toxicity data for MTAC (oral LD50 for Rat) uses the testing method that has the lowest correlation between LC50 or LD50 and TLV of any of the estimating methods used in the paper. In the real world, what that means is that if the DOE only used oral LD50 for the rat to derive the TEEL’s, those TEEL’s could be either too high or too low. If they are too high, you could reasonably divide the numbers by 57. If they are too low, you could reasonably multiply the numbers by 57. Those two possible answers would be within the range of three standard deviations of the average or what is otherwise known as the 95% confidence interval. That is also assuming that the correlation between LD50 and TEEL/TLV is improved since the units are kept the same between the two values (mg/kg or mg/m3 in this case compared to mmole/kg vs ppm in air which gave a better correlation of LD50 to TLV in the Japanese paper). If the correlation is not as good, then dividing by 82 would be appropriate.

What this means in practical terms for people exposed to MTAC after the spraying is that any concentration higher than 0.75mg/m3 divided by 57 (= 0.013 mg/m3) or even possibly as low as 0.75 mg/m3 divided by 82 (= 0.009 mg/m3) could reasonably be expected to possibly cause a noticeable health effect in some portion of the general population.

There is also the possibility that LD50’s correlate better with short term exposure limits than these numbers suggest. While LC50’s were shown to correlate better with short term exposure limits in the Japanese paper, LD50 correlations of this type were not discussed at all for some reason.

Note that the proposed TEEL-1 for MTAC of 2.5 mg/m3 divided by 57 is only 0.043 mg/m3, which is just under the estimate of 0.049 mg/m3, which leaves open the possibility that the govt could officially concede that classical, mild, reversible health effects could be experienced by the general population if MTAC were in fact 1% of the mix sprayed on Nov 8 and Nov 9, 2007. This requires no hypothesis of Multiple Chemical Sensitivity, at least not for the initial one hour of exposure.

All of these numbers assume of course that the spray was uniformly dispersed and the MTAC completely evaporated, condensing in a heavier than air cloud near the ground. The actual experience is more varied than that. The concentration of pheromone capsules captured at official recording stations was on average only about 1/10 of the expected amount. Unofficial reports say that the spray mixture actually came down in giant globs, some of which slimed entire fence stakes (but only 2 fence stakes out of a whole set). Plus, the planes flew in an overlapping grid pattern that could have caused some areas to get sprayed more than once. Obviously, when there is a big negative deviation (1/10 of expected concentration) in one place, there should also be a big positive deviation (higher than expected concentration) somewhere else. Throwing these additional factors of 10 into the equation for what is the minimum concentration of MTAC expected to produce a health effect in some portion of the general population opens up the possibilities even more.

In addition, the recent reaffirmation by Robert Leavitt that the average droplet size of a water droplet incasing a typical pheromone capsule is on the order of 1000 microns in diameter during the spraying process(6) completely obliterates the estimate that only 80 grams of total spray mixture was applied over each acre. If you do the math, a maximum 800 capsules applied per sq ft as estimated at one of the hearings on the issue(7) implies that up to a whopping 30 kilograms of spray [correction: this should be 18 kg] would have been applied per acre if the 1000 micron droplet size estimate is accurate. How much of this additional water component has surfactant such as MTAC in it is not clear.

Because of these uncertainties in the possible concentrations of MTAC and the possible concentrations of MTAC required to produce health effects, it is
essential that the following steps be taken to ascertain more completely the scope of these variables:

1) The total amount of aerial spray applied in Santa Cruz and Monterey Counties should be disclosed, broken down by individual aircraft, specific areas and specific dates.

2) The actual concentrations of all of the ingredients in the spray should be disclosed.

Only in this way can better defined limits be placed on what inert ingredients if any may be contributing to the reported health effects due to the spray.

Notes on other chemicals that are proposed to be used in ground spraying to control LBAM :

Permethrin is planned to be used in concentrations of 6%(8). This chemical is highly toxic to house cats. A few drops of 45%-60% concentration of the flea control products normally used on dogs can be fatal to cats.(9) For this reason, pet experts recommend using flea control products for cats that have 0.1% or less Permethrin concentration.(9) The animal testing of Permethrin has apparently not included house cats in the analysis, and so gives a false sense of safety for that chemical.(10) Cats are notorious for climbing trees and fences and so they will likely be exposed to Permethrin, especially if the clay-like substance used to contain the Permethrin is not fully dried. It may not wash off in the rain, but it will likely transfer to the exposed skin on the bottoms of cats’ paws.

The use of Bt is also problematic, as some of the strains used are genetically engineered and therefore may not fit the definition of “organic” as well as being closely related to and under some circumstances indistinguishable from bacteria known to cause food poisoning in humans. (11)

1) DOE Rev 19 TEEL’s (2003)
Note that DOE has not included MTAC in subsequent TEEL Revs for some reason, nor is MTAC included in the PAC REV 23 Online Data base at

2) The Contribution of Acute Toxicity in Animals to Occupational Exposure Limits of Chemical Substances

3) Regression method to estimate provisional TLV/WEEL-equivalents for non-carcinogens

4) Derivation of Temporary Emergency Exposure Limits (TEELs)

5)Appendix to CASS Health Complaint Letter

6)Robert Leavitt March 13, 2008 Letter To CDFA


8) USDA APHIS Document on EA of LBAM Eradication Program

9) Cat Fanciers’ Association: Health Committee -- Cats and Flea Control Products

10) Roy Upton “Permethrin – Safety Review” 2-5-08

11) Roy Upton “Bacillus thuringiensis – Safety Review” 3-6-08

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John Thielking
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