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Date: September 27, 2011

Subject: Response to Comments on Registration Review for Chlorpropham (CIPC)

To: Eric Meiderhoff, Chemical Review Manager

Office of Pesticide Programs

Regulatory Public Document (7502P)

USA EPA

1200 Pennsylvania Ave. NW

Washington, DC 20460-0001

From: William "Bill" A. Keim

604 Bell Mawr Place

Barberton, Ohio 44203

Dear Mr. Meiderhoff,

From the information available on the EPA website, it appears that possibly some 

clarification can be helpful. It is not possible to address every item due to the lengthiness 

of the explanations.

INTRODUCTION

My practical chemistry began with the application (practice) of academic chemistry and 

mathematics when I joined PPG Industries as a Research Chemist in 1963. PPG was 

having some small success with its Sprout Nip product which is based on CIPC. Because 

of my hazard evaluation experience, I was asked to look at flame arrestors to control 

torching which can occur in the generation of the CIPC aerosol process. Physical 

chemistry soon showed this would not work in a reasonable way. In late 1970s I was 

given a "cold CIPC aerosol fogging project" which had been underway for some years. 

Cold fogging failed because the aerosol particles were too large (high residues in the 

bottom of the pile). This project let me see a commercial CIPC thermal aerosol 

application, the control experiment. Several things were obvious. First, the aerosol fog 

was very stable most of the time. Second, very large amounts of aerosol were being 

displaced from the storage bin that was being treated (2x or double treatments were 

standard). Third, it was amazing how well CIPC inhibited sprouting when so little was 

known about what was going on in the application process. Once again the miracle of 

workable chemistry was demonstrated for me.

The observation of an aerosol treatment during the period of Jan 5-9, 1981 led to my

development of the Sprout Nip 7A formulation which was field tested in April 1982. 

Subsequent significant activities included:

1) I obtained an understanding of potato storage distribution plugging by Sprout Nip 

application with Balivi, Boise, ID, in Jan 1985. I then instructed all of the 
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applicators to control the air velocity used in the internal air handling system in 

order to improve the application process.

2) I carried out potato storage evaluation and recommended treatment procedures

with Wilbur-Ellis, Pasco, WA. to improve uniformity of the CIPC application.

3) I instructed the applicators on the use of reduced air flow planning for storage 

treatments beginning with Fred Reeve, Riverhead, Long Island, NY, in July 1986.

4) I confirmed the correctness of my guidance provided to Wilbur-Ellis and Fred 

Reeve which resulted in me writing differential equations for a mathematical 

model which very accurately represents the CIPC aerosol application process. To 

date, this math represents the best engineering analysis for the potato storage 

treatment.

5) I unplugged Blad Farms potato storages and successfully treated the potatoes

with CIPC aerosol using a very low air flow procedure in Dec 1987. The normal 

CIPC treatment procedure that was used at this time had plugged the storage's air 

recirculation system. No air could be recirculated through the potato pile. 

Immediate action was required. The duct system had been re-designed by a 

major potato storage supplier. The CIPC applicator had not been told about 

redesign. 

Papers on my 7A formulation development and the aerosol treatment process 

mathematical model are published in ASTM STP 1312, 1996. These papers published by

ASTM ARE PEER REVIEWED prior to publishing. Over the years, potato storages 

were visited and evaluated with Sprout Nip applicators in much of the USA and Canada. 

I wrote the CIPC Product Chemistry which was part of PPG's re-registration effort with 

EPA on CIPC in the 1980s. PPG sold the Sprout Nip business about 1987. 

Subsequent contact with the potato industry has confirmed that the technology that I

introduced did exactly what was expected of it. Significant aerosol application variables 

had been identified and some changes made. Significantly higher uniformly distributed 

CIPC residues were obtained from the use of my innovations in the CIPC application 

science. The risk of failure of the sprout inhibition was significantly reduced which was 

the focus at the time. There was, as expected, still copious amounts of CIPC displaced to 

the environment.

As a result of a potato storage fire at Mountain King potato storage in Monte Vista, CO 

on 11/26/2000, Bill Keim was once again involved with CIPC aerosol application. I was 

amazed at how little progress in the commercial aerosol application process there had 

been in the time that I was away (actually it looked like some significant backsliding 

was occurring).

Discussions with my sons resulted in our patent application of June 28, 2004 for using 

potato storage air in the aerosol generation process to control displacement. U. S. Patent 

7,635,665 for this technology was issued Dec 22, 2009 and is currently under 

reexamination by the patent office. The reexamination challenge filed for Aceto by

attorneys indicates that the technology must really have some importance to the 

potato industry otherwise the patent would be ignored. The patent is needed to get 
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financial support to implement this technology which has significant public benefits. 

Alternately, the EPA can support the implementation of this technology and/or any other 

technology that KEEPS THE CIPC INSIDE THE COMMERCIAL STORAGE, 

PRIMARILY DURING THE CIPC INTRODUCTION PHASE for the CIPC aerosol 

application process to stored potatoes. So far any work on this technology has only

generated expenses. 

Environmental Fate and Effects Division (EFED) Response 04/14/11

The Aerobic Soil Metabolism data can also be helpful to assess the fate of CIPC in potato 

storages and the potato samples taken for analysis. Residual soil life of CIPC for weed 

control is poor. Please make details of the work available to the public. 

Thanks for recognizing the need to "minimize the escape of the compound". However, 

after normal housekeeping for a treatment, the majority of displacement is caused by the 

air pump (typically 140 cubic feet per minute) that is part of the aerosol generation 

equipment. Aerosol generation/introduction times are generally an hour or longer, and 

most displacement occurs during aerosol introduction to the potato storage. The aerosol 

hopefully persists as visible smoke in the air space of the storage for one or more hours 

after introduction. Potato air re-circulation should be maintained at a low rate during the 

period of deposition of visible aerosol. Deposition is over when a visible aerosol is no 

longer present (see the applicable physical chemistry). 

I worked continuously with the applicators, particularly after 1980. PPG's label was 

adjusted to reflect technology improvements and to help control how the applicator did 

his job so that it was performed properly. The use of application equipment was 

monitored. Still, the independence of the applicator provided some surprises. After PPG 

sold the CIPC business unit, there were label changes made that actually eliminated most 

of the controls that PPG put in place. Today’s CIPC label essentially lets the applicator 

do whatever he wants when applying the CIPC as it has little if any controls on it that 

should be in place to protect the human population and the environment. 

If displacement does not provide the answer for "where is the missing CIPC?" then 

degradation is a likely candidate. I once obtained a residue of CIPC from a fan shroud in 

a potato storage that contained about 10% of the urea, di-(3-chlorophenyl) urea. Other 

expected degradates can be expected to remain in vapor state. Some of these vapors will 

of course dissolve in the potatoes.

Health Effects Division (HED) Response 17-May-2011

First Paragraph of the letter response on page 3-4: Large amounts of CIPC are displaced 

because of the air pump used with typical aerosol generation equipment to pump outside 

air into the storage. Directions for use on the label do not address this air flow rate or the 

feed rate of CIPC for the aerosol generation equipment. Directions for use of many 
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pesticides provide guidance on the amount of water to be used in the applied spray. 

What is the difference?

Fourth Paragraph under CIPC Application: There seems to be some confusion with 

respect to the residue data being discussed. Our concern is with residues used to evaluate 

a treatment with CIPC which are used to approve registration. We think that our 

comments with respect to these data are valid. Data for residues on potatoes as actually

consumed are also important to the registration process, but are not the subject of our 

comments.

Fifth Paragraph under CIPC Application and First, Second and Third Paragraphs under 

Sampling: Does the residue information used address the concerns that were expressed 

about handling potato samples? Data available to me does not appear acceptably useful 

to do mass balances on the application process. As a chemist, we are trained that you can 

track where everything goes in a chemical reaction using a MASS BALANCE. The use 

of a mass balance is critical to evaluating the CIPC process and the CIPC registration 

process. EPA needs to require all of its registered CIPC label holders to submit a 

mass balance for the CIPC used during their respective application processes in 

order to know where the CIPC goes. Then it needs to check to make sure that this 

process was performed properly.

Sixth Paragraph under CIPC Application: It would be nice to think that the temperatures 

used for melting CIPC are kept reasonably low and the exposure times short. 

Temperatures exceeding 180 oF have been observed. This time at elevated temperature 

can last many hours.

Seventh Paragraph under CIPC Application: Does OSHA have the ability to stop use of 

an EPA approved labeled product? 

Technologies Sciences Group (TSG), Inc. Response Feb 18, 2011

Aerosol Application Process as described by TSG: "The chlorpropham is applied from 

outside the building through a small tube into the building's ventilation ducts, using a 

sealed thermal fogging delivery system. During this application process, chlorpropham is 

not released into the environment."

Clearly the exact equipment described by TSG should be that required for applications of 

CIPC and its specification required by EPA on the product label. All Leco and Tifa 

based equipment use must be prohibited if they use an air pump to put outside air into the 

potato storage during aerosol generation which causes CIPC displacement. TSG implies 

that they don’t use any air pumps to pump outside air into the storage (if they did there 

would be gross displacement of CIPC from the storage). If so, then TSG please share 

the necessary identification of this aerosol generation equipment with the EPA so 

that it can be specified on the label.

Letter of Joel Micka, JMC Enterprises, Inc., of March 31, 2011
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I think that I am aware of the aerosol generation equipment of JMC from discussions 

with Dr. Gale Kleinkopf. I do not know specific details for the equipment. If I were to 

observe applications with JMC equipment, I expect that I could assess its capability and 

evaluate the total process (think total quality). From the claim for "virtually NO escape 

of CIPC during a potato storage thermal fogging treatment with our application 

technology" in the letter one would expect that the EPA would also want to have this 

equipment for application on CIPC specified on the product label along with TSG 

specified equipment.

Letter Michael D. Lewis of April 1, 2011

Lewis knows about the air pumps on Leco and Tifa based aerosol generation equipment

and the displacement of CIPC. He also can be expected to know about JMC equipment. 

Surely some applicator has given him a copy of my Sprout Nip Aerosol Application Field 

Handbook, issued in April 1987. Copies should also be available through records of 

some potato storage fire lawsuits. I worked with lawyers of a legal firm who understand 

the Handbook very well. I cannot understand the scientific basis for most of the Lewis 

comments. Possibly EPA needs to have both of us (or others equally qualified) as 

consultants to get a good understanding of CIPC application.

I too think that CIPC is very critical to the potato industry. We just need to clean up 

displacement. We are going to have to accept some degradation. It is Mother Nature's 

way. She really is the one who makes the rules.

Letter Dale E. Nelson, Nelson's Vegetable Storage Systems Inc., of April 2, 2011

Nelson's History:

The 3 lb ai per gallon CIPC product was the Emulsifiable Product for water spray

application to fresh market potatoes.

The methanol containing product was Sprout Nip 7A, formulated by me. PPG chose 

7A over the solid material for the formulation as it is essentially the same but is more 

easily handled as a liquid. I now recognize that some degradation is much easier to 

control with 7A versus the 4A. Methanol replaced isopropanol and propylene glycol in a 

4A product. Using methanol, a Leco machine can process 42 lbs of CIPC per hour versus 

20 lbs of CIPC per hour with 4A. A Tifa machine can process about 63 lbs of CIPC 

versus 20 lbs of CIPC per hour with 4A.

Comments:

Bill Keim started in 1986 the use of the necessary air velocity control in a potato storage 

which occurs when fan speed is reduced.
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A realistic understanding of the autoignition process in CIPC aerosol generation process 

was developed. If the food grade adjuvant used by Nelson is clove oil, then Nelson can 

have more risk of autoignition.

I would expect that Nelson, who started as an applicator in Idaho in 1979, should know 

me from my visits to PPG Idaho applicators. 

It is very easy to lose a lot of CIPC and still get a successful treatment. CIPC is amazing

for potato sprout inhibition in spite of our application technology ignorance.

If I knew the details of NVSS application process, then I think that I could provide a 

reasonably detailed scientific explanation for its success. It can be expected to be 

explained by reasonable physical chemistry. Part of BP's gulf oil release problem was 

due to the poor use of physical chemistry.

The remaining major area for improvement in CIPC use on potatoes appears to me to be

how much to use in the application (the use rate) and the identification of potato and/or 

potato storage variables significant to the application with appropriate recommendations. 

Problems with understanding the application process and implementing the changes 

needed have made progress on these other issues practically non-existent. The use rate of 

CIPC can be expected to get much lower. The unnecessary requests for higher use rates 

are still being made. The goal needs to be to get to the use rate amounts necessary to get 

the necessary sprout inhibition while minimizing any excess amounts.

CONCLUSION

Can the need for EPA to "Hire knowledgeable consulting guidance on CIPC aerosol 

technology for potatoes." be more apparent?

Sincerely,

William A. Keim

Keim Aerosol Technologies

604 Bell Mawr Place

Barberton, OH 44203

330-805-6453