# SENSITIVITY OF A COMMERCIALLY AVAILABLE QUALITATIVE FIT 

# TEST AGENT (DENATORIUM BENZOATE) IN FULL FACE RESPIRATORS WITH FIXED LEAKS VERIFIED WITH CONTROLLED NEGATIVE PRESSURE QUANTITATIVE FIT TESTING 

A thesis submitted to the

Division of Research and Advanced Studies

of the University of Cincinnati

in partial fulfillment of the

requirements for the degree of

**MASTER OF SCIENCE**

in the Department of Environmental Health

of the College of Medicine

1999

by

Carlos J. Rodriguez

M.D., Universidad de Carabobo, Venezuela 1989

> Committee Chair: Roy McKay, Ph. D.

ABSTRACT

In this research, a solution of Denatorium Benzoate (Bitrex™, Macfarland
Smith Ltd., Montvale, NJ), developed and commercialized by 3M
Corporation for qualitative fit testing (QLFT) of respirators was
evaluated for its ability to be detected in the presence of controlled
fixed leaks in full-face respirators. Prior to inducing leakage, 26
subjects wearing a full-face respirator were evaluated with a Controlled
Negative Pressure fit test system (CNP) to verify a fit factor above
500. Then, a controlled leak was induced by loosening (i.e. turning) the
exhalation valve retainer, without perturbing the respirator's
fundamental fit, until a nominal fit factor between 60 and 100 was
obtained by CNP.

A qualitative fit test using a commercial solution of Bitrex™ was
conducted using a modification to the OSHA protocol. This was
accomplished by substituting the head straight-ahead maneuver for the
entire protocol to prevent additional sources of leakage.

## The data were analyzed to see if they supported the null hypothesis that there is no significant sensitivity in qualitative respirator fit testing as measured by taste of the commercial solution of denatorium benzoate (Bitrex™) for detecting fixed leaks in full face respirators equipped with high efficiency particulate filters and having an average fit factor slightly less than 100 measured with QNFT.

For the test of sensitivity we followed, the ANSI Draft Guidelines
Z88.10 for validation of fit test methodologies that states that those
subjects with a fit factor less than 100 must detect the test agent
greater than 95% of the time.

We found that only 23% of participants were able to taste the Bitrex™
Test Solution through a leaking exhalation valve retainer with a mean
fit factor of 89, a range of 71 to 96, and a mean percent leak of ±
1.123%.

The results reflect a dramatic 77% of False Negatives (accepting an
inadequate fit) when the commercial solution of denatorium benzoate --
Bitrex™ - is used for fit testing in North™ full-face respirators models
7600 with induced leaks and fit factors less than 100.

# Dedication

### 

### To my mother Mrs. Luisa Maria Medina de Rodriguez, in appreciation for her continuous love, spiritual support and for inculcate early in my life constancy and perseverance in all my endeavors. Father, you would have been proud.

### To my wife Sonia, who ease my hard days with her deep love, comprehension, and, encouragement. 

### To my lovely daughters Sonia Maria and Gabriela Alejandra, who have brought endless 

### 

### joy to my life with their love, intelligence and innocence.

To all the persons in Petroleos de Venezuela Inc. (PDVSA) who help me to
capitalize

my educational journey. Special gratefulness to Dr. Sigifredo Rosales
and Dr. Fred

### Añez.

To my friend John Evans and his family, for giving us a sincere
friendship and being

there every time my computer crashed.

Finally, I dedicate this work to the city and people of Cincinnati who
let my family and

me call this beautiful American place "our home town" over the past two
years.

#### Acknowledgments

### I would like to express my sincere appreciation to Dr. Roy McKay for his continued support, guidance and encouragement for the entire duration of my thesis project.

### I wish to express my gratitude to Dr. James Lockey, Dr. Douglas Linz and Dr. Andrew Freeman for their expert advice and consultation during the preparation of this Thesis.

### I want to thanks the Division of Occupational and Environmental Health at the University of Cincinnati School of Medicine for giving me the privilege and opportunity to obtain my Master Degree in this prestigious educational institution.

### The completion of my Master Degree and this work would have been impossible without the financial support from **Petroleos de Venezuela S.A. (PDVSA Inc.).**