February 17, 2010 

Tim Leighton 

Office of Pesticide Programs 

U.S. Environmental Protection Agency 

One Potomac Yard (South Building) 

2777 South Crystal Drive 

Arlington, VA 22202 

Dear Tim: 

The AEATF has reviewed the December 16, 2009 HSRB final report of October 20-21, 2009 

meeting. A revised protocol in track changes that incorporates EPA and HSRB comments at the 

meeting and summary of changes to the protocol are attached. The AEATF also has reviewed 

the final HSRB report and provides the below responses to the comments on the aerosol study 

protocol. 

 

The Board raised the concerns highlighted in italics below. Our response/clarification follows. 

1. Use of the Results: EPA plans to use the data generated from the proposed aerosol study 

generically to estimate dermal and inhalation exposures and risks for other antimicrobial 

ingredients where the product is packaged in a pressurized aerosol spray can. However, 

other variables can affect rates of exposure, including different nozzle sizes, spray and 

ejection rates, the size of the particles generated, and the generation of nonvolatile active 

ingredients. Inhalation versus dermal exposure may also vary with these variables. 

It is also unclear if occupational handler exposure can be used to estimate exposure of nonprofessionals using similar consumer products. However, for risk assessment purposes it 

was felt that exposure among occupational users is likely to exceed that of consumers; the 

higher frequency of exposures among occupational users is likely to exceed a plausibly 

higher individual but less frequent exposure among nonprofessional users. 

Response: We agree that dermal and inhalation exposure risks to antimicrobial ingredients 

delivered using a pressurized aerosol spray can will be impacted by different nozzle sizes, 

spray and ejection rates, the size of the particles generated and the generation of nonvolatile 

active ingredients. The aerosol products represented by the AEATF II have been divided 

into four major use categories: 

1. Hard-surface disinfectant fine sprays 

2. Foaming aerosol products 

3. Soft surface disinfectants 

4. Air fresheners 
Mr. Tim Leighton 

February 17, 2010 

Page 2 

Prior to selecting a product that represents the four major use categories, keeping in mind that 

we wanted to select a product that represents an inhalation exposure worst-case situation, a 

non-human pilot study was conducted. In that study, one representative and commercially 

available product was selected from each category. The study design and results of the pilot 

study were presented in Appendix A of the Aerosol Application Scenario: Rationale for 

Study Design. The results of the pilot study clearly show that the hard-surface fine spray and 

the air freshener used generated the most inhalation and/or dermal exposure potential. The 

total mass of the active ingredient dispensed per unit time for the hard-surface fine spray is 

more than double the air freshener; based on that information, inhalation and dermal 

exposure will likely be higher for the hard surface fine spray. Additionally, the hard-surface 

spray product will be used to a much greater extent in a day, especially in commercial use, 

than the air freshener. Based on the available data, the hard-surface fine spray would 

represent a high and conservative choice for exposure monitoring studies. The selected 

product should also meet objectives of the study and test material selection criteria, i.e.: 

• Serve as surrogate for most aerosol use categories 

• Use pattern represents high-end exposure – a conservative scenario 

• Use scenario covers most influential variables of exposure 

o Highest percentage of active ingredient 

o Nozzle size of majority of aerosol products 

o Particle size distribution representative of fine spray 

o Used for hard surface and confined spaces 

• Having stable active ingredient 

• Results can be extrapolated to most products on the market 

Since the goal of this study is to select one surrogate for most aerosol use categories, the 

product selected for this study was a hard-surface disinfectant fine spray, the “Clorox 

Disinfection Spray.” 

We agree with the HSRB regarding occupational handler exposure and non-professional 

exposure. 

2. Sample Size and Analysis: Raw and descriptive data will be provided, but no statistical 

analyses have been planned. Sample size adequacy cannot be judged without a statistical 

analysis plan. Placing 18 subjects into three clusters of six each requires consideration of 

cluster effects and may complicate analysis of the results. Assumed constants related to 

exposure to the active ingredient may also prove to be incorrect, and additional subjects may 

need to be enrolled. 
Mr. Tim Leighton 

February 17, 2010 

Page 3 

Response: If the benchmark accuracy goal (i.e., K=3) is not met once the data are collected 

and analyzed, the AEATF II will, in consultation with regulatory agencies, determine the best 

course of action to take. This may mean the development of guidance for the use of these 

data that takes the increased imprecision of the estimates into account. It is possible that 

collection of additional clusters might be considered. 

3. Application of Spray: The target number of cans sprayed in each location by each worker 

on each day could be specified better within the protocol. For example, does a worker need 

to continue spraying a room if the target application is met before completion of that room? 

Additional protocol clarifications needed include: addressing the issue of the interval 

between sampling at different sites (currently, it appears that no two monitoring events can 

occur within the same building within one week); clarifying the issue of using empty 

apartments rather than motel rooms; and clarifying the effect of exhaust vent effects on 

exposure, which could be different than indicated in the protocol. 

Response: We will clarify in the protocol the target numbers of cans sprayed in each 

location by each worker on each day. Workers will be given full cans as well as half full 

cans, as specified in the protocol. A worker does NOT need to continue spraying a room if 

the target application is met. Two monitoring events can occur within the same building, but 

not the same room within ONE DAY. The next day the same room could be used. 

Regarding the use of apartments rather than motel rooms, we have surveyed the Fresno area 

and have found a number of motels with full kitchens. We will be using hotels/motels 

exclusively for the study and will not be using apartments. 

4. Quality Assurance and Control (QA/QC): QA/QC can be improved by: 

a. Determining likely differences in the air sampling results depending on the method used 

(e.g., depending on the air sampling equipment used, differences in the orifice diameters 

and air flow sampling rates could affect aerosol collection efficiencies and effects). 

b. Setting the minimal spike to two to four times that of the limit of quantitation (LOQ; cf. 

AEATF II 2009b: 42, 46). 

c. Considering other variables that may influence the measurement of exposure, including 

whether the surface being treated is dry or wet at the time of the next spray application, 

and whether the applicant accidentally wiped the surface after spraying. Data 

accumulated during gross deviations from the protocol should also be excluded. Finally, 

the protocol should indicate that there will be a maximum of two workers on any given 

day in the same location. 
Mr. Tim Leighton 

February 17, 2010 

Page 4 

Response: 

a. The determination of differences in air sampling results based on the difference in the 

orifice diameter, etc., would imply comparing different products. This is not in the scope 

of this study since we will be using one product. In this study, we will be using the same 

sampling equipment for all subjects. The equipment will be calibrated daily for air flow 

sampling rate. 

b. The LOQ for field fortification will be corrected. The minimum spike of four times the 

LOQ will be incorporated in the protocol. 

c. At the time of application, all treated surfaces will be dry. The same room will be treated 

three times on three separate days. The goal is to have two ME/day/locations, and complete 

the application of the product to different rooms. Back-up workers will also be available in 

case the primary worker does not show up. 

If you have any questions, please contact me at (703) 741-5637 or via email at 

has_shah@americanchemistry.com. 

Sincerely, 

Hasmukh Shah 

Manager, AEATF 

Cc: John Carley 

 Kelly Sherman