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April 13, 2010 

Ms. Joan Harrigan-Farrelly 

Joan Harrigan-Farrelly, Director 

USEPA Headquarters 

Antimicrobials Division 

Ariel Rios Building 

1200 Pennsylvania Ave. NW 

Mail Code: 7510P 

Washington, DC 20460 

Subject: EPA should Ignore Ashland’s Untimely Attempt to Distort the Science Underlying 

Nalco’s Use of Bleach plus Halogen Stabilizers 

Dear Ms. Harrigan-Farrelly: 

I am writing on behalf of Nalco in response to the March 25, 2010 letter from Dr. Donald Penner 

that was submitted by Ashland. First, it is important to point out that Dr. Penner is not an expert in the 

area of chlorine chemistry, or in the application of such chemistry to industrial or similar systems. 

Instead, Dr. Penner’s expertise is in the area of weed science, including the reaction between glyphosate 

and products such as ammonium sulfate that result in a chemical change to the glyphosate molecule. 

Dr. Penner asserts that Nalco’s use of stabilizers is not analogous to the agricultural use of 

adjuvants because Nalco’s system involves a “reaction vessel” instead of tank mixing. However, this is 

simply incorrect. First, contrary to Dr. Penner’s assertion, there is no “reaction tank” involved in the 

application process for halogens in pulp and paper systems. The registered sodium hypochlorite is 

directly into the process, along with a stabilizer and pH adujster. All mixing occurs in-line. 

An agricultural spray tank typically serves to dilute the pesticide(s) and other materials being 

applied and to allow any reaction between adjuvants and pesticides to occur. A mix tank therefore 

contains a significant amount of water, and the chemicals are mixed in the tank prior to application. The 
Ms. Joan Harrigan-Farrelly 

April 13, 2010 

Page 2 

additional water is needed to ensure adequate and appropriate dilution, and therefore adequate coverage 

with the mixture over a large area. When chemicals are added to water based systems such as pulp and 

paper, however, there is no need for extra water to ensure coverage. The water itself is what is being 

treated, and there is a single in-line point at which chemicals are introduced to the system to be treated. 

Thus, as Nalco explained at the meeting on February 16, there is no “reaction tank” in Nalco’s system. 

In Nalco’s applications that utilize ammonium sulfate and urea, these stabilizers are added to the 

feedline that is used to deliver EPA-registered sodium hypochlorite to paper mill process for the purpose 

of microbial control. The in-line blending uses a static mixer or tee-mixer to ensure adequate mixing. 

However, there is no reaction tank and no way to distinguish that the Nalco approach is fundamentally 

different from the tank mix (i.e. spray tank) used to apply stabilized pesticides to crops. 

Second, Dr. Penner’s focus on “tank mixing” is misplaced. EPA has never stated that adjuvants 

are limited to those products that are mixed in a tank prior to application. The ASTM definition cited by 

Dr. Penner is not referenced in any EPA regulation or guidance. ASTM E 1519-05 simply defines an 

adjuvant as ‘a material added to a tank mix to aid or modify the action of an agrichemical, or the 

physical characteristics of the mixture’. While the ASTM standard was developed specifically for 

agricultural adjuvants, Nalco’s use of ammonium sulfate and urea are consistent with this definition. 

The ammonium sulfate and urea modify the action the sodium hypochlorite, so that it is less reactive to 

allow the chlorine residual to persist longer in the treated water system. Increased chlorine persistence 

allows the chlorine to provide the intended level of control of microbial growth and deposit formation 

This is similar to the definition of “extender” in the ASTM standard, where extended is defined as “a 

material that increases the effective life of an agrichemical after application.”. 

Third, contrary to Dr. Penner’s comments, reactions do take place in the spray tank equipment 

used to apply conventional chemicals. If reactions did not take place in the spray tank, there would be 

no reason to use the ‘water conditioners’ with post emergence herbicides. The ASTM definition for 

‘water conditioning agent’ as used with agicultural chemicals specifically identifies that it is to reduce or 

eliminate antagonism in the water used for application, i.e., in the spray tank. Moreover, Dr. Penner 

provides no support for his assertion that “Adjuvants by definition do not undergo [] reactions.” Letter 

at p. 2. There is no regulatory definition for adjuvants, and the available standard for agrichemical 

adjuvants neither includes nor excludes such reactions. 

Fourth, Dr. Penner’s focus on the formation of “covalent bonds” is misplaced. ASTM E 1519-

05 defines an adjuvant as ‘a material added to a tank mix to aid or modify the action of an agrichemical, 

or the physical characteristics of the mixture’. In this definition there is no exclusion of specific 

reactions or chemical bonds. The well-known, well-understood, and long practiced use of nitrogen to 

stabilize halogen chemistry in water treatment depends upon ensuring that the majority of the halogen is 

in the combined form. That is the intent of the use of stabilizers, to prevent the degradation or 

conversion of the highly reactive halogen into unreactive forms. Free halogen can and is quickly 

consumed in systems, which can result in the need for significantly higher amounts that would need to 

be applied to ensure adequate microbial control before the free halogen is consumed (i.e., converted to 

forms that have no activity against microorganisms). However, the extent of stabilization has never 
Ms. Joan Harrigan-Farrelly 

April 13, 2010 

Page 3 

been a basis for determining whether separately added non-biocidal components are or are not pesticides 

requiring registration 

Furthermore, Dr. Penner is inaccurate when he states that the reaction of ammonium sulfate/urea 

with chlorine is an irreversible reaction. While covalent bonds do form between chlorine and ammonia 

or urea, resulting in the formation of monochloramine and chlorourea, these are not permanent covalent 

bonds and hydrolysis is well documented.1 In fact, Ashland acknowledged and documented dissociation 

constants in their February 16, 2010 presentation to EPA. Hydrolysis constants are dependent not only 

on the source of the nitrogen, but also on the concentration of the chlorinated-nitrogen compound, the 

ratio of chlorine:nitrogen, pH, and temperature.1

 Hydrolysis of monochloramine to HOCl increases in 

weak solutions.2

 In the case of chlorourea, free residuals are minimal allowing for enhanced 

compatibility with functional chemicals used in the papermaking process and enhanced persistence of 

the chlorine residual. Hydrolysis of chlorourea and the role of HOCl in disinfection are indicated based 

on the observation of overstabilization of chlorourea in the presence of excess stabilizer according to the 

principle of Le Chatelier.3

 

Finally, the regulatory and policy issues raised by Nalco in its December 2007 petition and 

reiterated since that time are not specific to Nalco’s products. Dr. Penner clearly was not been made 

aware of the materials presented at the February 16 meeting, the scope of the issues, the regulatory 

background, history and implications, and the set of issues that Nalco has presented. Dr. Penner’s paper 

therefore should not be given any weight by EPA. 

Sincerely, 

Elizabeth Anne Brown, Ph.D. 

Sr. Technical and Regulatory Analyst 

 1

 Morris, J.D. “Kinetics of reactions between aqueous chlorine and nitrogen compounds”, in “Principles 

and Applications of Water Chemistry”’ Faust, S.D., Hunter, J.V., Eds.; John Wiley and Sons, New York (1967). 

2

 White, G.C. “Handbook of Chlorination”; John Wiley and Sons, New York. 1999. 

3

 Williams, D.E., E.D. Elder, and S.D. Worley. Is free halogen necessary for disinfection? Appl. 

Environ. Microbiol. 54:2583-2585.