Title: The Effectiveness and Safety of Pepper Spray
Series: Research for Practice
Author: National Institute of Justice
Published: April 2003
Subject: Less-than-lethal technologies
13 pages
27,000 bytes

----------------------------

Figures, charts, forms, and tables are not included in this ASCII plain-text file.
To view this document in its entirety, download the Adobe Acrobat graphic file
available from this Web site or order a print copy from NCJRS at 800-851-
3420 (877-712-9279 for TTY users).

----------------------------

U.S. Department of Justice
Office of Justice Programs
National Institute of Justice

Research for Practice
The Effectiveness and Safety of Pepper Spray

APR. 03

----------------------------

U.S. Department of Justice
Office of Justice Programs
810 Seventh Street N.W.
Washington, DC 20531

John Ashcroft
Attorney General

Deborah J. Daniels
Assistant Attorney General

Sarah V. Hart
Director, National Institute of Justice

This and other publications and products of the U.S. Department of Justice,
Office of Justice Programs, National Institute of Justice can be found on the
World Wide Web at the following site:

Office of Justice Programs 
National Institute of Justice
http://www.ojp.usdoj.gov/nij

----------------------------

APR. 03

The Effectiveness and Safety of Pepper Spray

Comments regarding this Research for Practice may be e-mailed to
askost@ojp.usdoj.gov or sent by postal mail to LTL Program Manager,
National Institute of Justice, 810 Seventh Street N.W., Washington, DC
20531.

To learn more about NIJ's less-than-lethal research and development program,
visit http://www.ojp.usdoj.gov/nij/sciencetech/ltl.htm.

Findings and conclusions of the research reported here are those of the authors
and do not reflect the official position or policies of the U.S. Department of
Justice.

The North Carolina study discussed in this report, "An Evaluation of Oleoresin
Capsicum (O.C.) Use by Law Enforcement Agencies: Impact on Injuries to
Officers and Suspects," by J. Michael Bowling and Monica Gaines, was
supported by NIJ under award number 1997-LB-VX-K018.

The in-custody deaths study discussed in this report, "Deaths in Police
Confrontation When Oleoresin Capsicum is Used," by Charles S. Petty, was
supported by NIJ under purchase order number 2001-M7-56.

NCJ 195739

----------------------------

About This report

This report presents the findings from two recent unpublished NIJ-funded
studies that used different methodologies to test pepper spray's safety and
effectiveness. One study looked at officer and suspect injuries in three North
Carolina police jurisdictions before and after pepper spray was introduced. The
other examined the deaths of 63 suspects held in custody after pepper spray
was used in their arrest.

What did the researchers find?

o The North Carolina study found that the number of injuries to police officers
and suspects declined after pepper spray was introduced. Complaints that the
police used excessive force also declined.

o The study of in-custody deaths concluded that pepper spray contributed to
death in two of the 63 cases, both involving people with asthma. In the other
cases, the researcher concluded that death was caused by the arrestee's drug
use, disease, positional asphyxia, or a combination of these factors.

What were the studies' limitations?

o In the North Carolina study, procedures for identifying officer and suspect
injuries differed considerably from agency to agency and within each agency
over time, which limited the extent of the conclusions that could be drawn.

o The number of in-custody deaths in which pepper spray was used in the
arrest process is very low, which makes identification of trends difficult.

o Each arrest situation is unique; it is virtually impossible to collect enough
nearly identical arrest scenarios with and without pepper spray in the field to
conduct a quantitative study.

Who should read these studies?

Law enforcement policymakers and practitioners, defense and prosecution
attorneys involved in pepper spray cases, and medical examiners.

----------------------------

The Effectiveness and Safety of Pepper Spray

Pepper spray, or oleoresin capsicum (OC), is used by law enforcement and
corrections agencies across the United States to help subdue and arrest
dangerous, combative, violent, or uncooperative subjects in a wide variety of
scenarios. Though generally assumed to be safe and effective, the
consequences of the use of OC, as with any use of force, can never be
predicted with certainty. The need for reassurance on these points remains. This
Research for Practice summarizes the results of two unpublished NIJ-funded
studies on the safety and effectiveness of pepper spray in real-life arrests and
compares them with previous studies. The goal: to expand the scope of
knowledge on this complex subject.

One study looked at officer and subject injuries in three North Carolina police
jurisdictions before and after pepper spray was introduced. The other examined
63 incidents nationwide in which people were sprayed with OC in the arrest
process and later died in custody.

The North Carolina study found that the number of injuries to police officers
and suspects decreased after pepper spray was introduced. Complaints that the
police used excessive force also declined.

The study of in-custody deaths, which follows a similar study conducted in
1994,[1] concluded that exposure to pepper spray was a contributing cause of
death in 2 of the 63 fatalities, and both cases involved people with asthma. In
the other 61 cases, death was judged to have resulted from the arrestee's use of
drugs, disease, positional asphyxiation (which may occur when subjects are
placed in a prone position, typically handcuffed behind the back, in which
breathing becomes more difficult), or a combination of these factors.

These findings complement those of another recent experiment that used healthy
volunteers who inhaled pepper spray and were then placed in a sitting position
or handcuffed in a prone position. The volunteers exhibited no breathing
difficulties in either position.

The North Carolina study

Claims of pepper spray's effectiveness were tested in a 2-year study conducted
by a multidisciplinary team of investigators at the University of North Carolina's
Injury Prevention Research Center in Chapel Hill, North Carolina. This
research sought to assess whether the introduction of pepper spray had
reduced the number of 

o Injuries to police officers from assaults.

o Injuries to suspects from police use of force.

o Excessive force complaints against the police.

The records of three North Carolina police departments--the
Charlotte-Mecklenburg Police Department (CMPD), the Winston-Salem
Police Department (WSPD), and the North Carolina State Highway Patrol
(SHP)--were compared for the periods before and after the introduction of
pepper spray by each agency. SHP was the first of the three to introduce
pepper spray in January 1993. WSPD and CMPD followed suit in April 1993
and January 1995, respectively.

Data sources

Officer injuries. All information on the use of force by Charlotte-Mecklenburg
officers (including injuries to officers and suspects) came from the CMPD Use
of Force Database. Information on in-juries to Winston-Salem officers and
suspects was taken from the Injury Database, 1990-1998. Information on
State Highway Patrol officer injuries came from their Worker's Compensation
and Medical Only Claims files. Records in which the injury resulted from a
motor vehicle crash or actions unrelated to an arrest were excluded.
Researchers applied statistical methods to determine whether observed declines
in the number of injuries after the introduction of pepper spray were significant
enough to be attributed to its use.

Injuries to suspects. Suspect injury data were available from the Charlotte-
Mecklenburg and Winston-Salem police departments. No information was
available for injuries to suspects arrested by the State Highway Patrol.

Excessive force complaints. Although data on excessive force complaints were
collected from all sites, only the State Highway Patrol had data going back far
enough to analyze statistically.

Results

Officer injuries. In Charlotte, monthly counts of injured officers declined steadily
from 1991 to 1998 (see exhibit 1). This decline began before pepper spray
was introduced and continued at roughly the same rate afterward. Before
pepper spray was introduced in Winston-Salem, there were two upward trends
in monthly counts of officers injured, the first ending in August 1991 and the
second in December 1992. After pepper spray was introduced, officer injuries
declined, followed by an increase, then a relatively stable period of low counts
beginning in December 1995 (see exhibit 2).

The monthly count of injured State Highway Patrol officers, however, shows a
substantial decline that corresponds with the implementation of pepper spray. In
1992, 87 officers were injured, whereas only 58 were injured in 1993, a 33-
percent decline over a 1-year period (see exhibit 3).

Suspect injuries. Monthly counts of suspects injured by CMPD officers began
falling after the introduction of pepper spray (see exhibit 4). In Winston-Salem,
on the other hand, monthly counts of suspects injured by WSPD officers had
already been declining before pepper spray was introduced (see exhibit 5).

Excessive force complaints. Ninety-four excessive force complaints were filed
against State Highway Patrol officers from 1975 to 1998, peaking in 1992--the
year before pepper spray was issued. Complaints dropped sharply after the
introduction of pepper spray (see exhibit 6).

Thus, the data suggest relationships between the use of pepper spray and
declines in the number of State High-way Patrol officer injuries, suspect injuries
in Charlotte, and excessive use-of-force complaints against SHP officers.
Although pepper spray could have contributed to declines in officer injuries in
Charlotte and Winston-Salem and suspect injuries in Winston-Salem, the
available data were not sufficient to support those claims. A 1998 study,
however, indicated that the introduction of pepper spray reduced the number of
assaults on police significantly in the Baltimore County (Maryland) Police
Department.[2]

Study limitations. Due to differences among the study's data sources, only a
limited number of conclusions could be drawn. The procedure for identifying
officer and suspect injuries differed considerably from agency to agency and
within each agency over time. The availability of data at each site differed,
depending on the level of computer use and the sophistication of programming
and software. The systems in place at the State Highway Patrol and in
Winston-Salem in the early 1990s required officers to describe the
circumstances leading up to injuries. Thus, determination of the number of
injuries depended on the officer's recall of the incident and the degree of detail
in his narrative report.

Moreover, injuries captured in one system might have been overlooked in
others. The State Highway Patrol included only those injuries for which officers
had filed Worker's Compensation claims, whereas cases identified in
Winston-Salem and Charlotte were not limited to those requiring medical
attention or loss of work.

The in-custody deaths study

Early on, as pepper spray use began to spread, questions arose as to its safety,
especially after several exposed arrestees died in custody. A professor of
forensic sciences and pathology at the University of Texas, Southwestern
Medical Center, recently conducted a study of 73 cases of in-custody deaths
following pepper spray use to determine the role, if any, played by pepper
spray.

For each case, the author collected reports from law enforcement sources,
emergency medical technicians, emergency room personnel, coroners and
medical examiners, and toxicologists. Analysis of police reports of the
confrontation was combined with the more quantifiable autopsy findings and,
finally, with numerically precise toxicological data. The author believes that
information from each of these sources is necessary to have the maximum
confidence in the cause of death.

The author did not always agree with the cause of death listed by the autopsy
surgeon or medicolegal officer. In some of these cases, he had more or different
information than was available to the certifying official at the time an opinion
was given on the cause of death.

Classifying the cases

Of the 73 reported cases of in-custody deaths allegedly involving pepper spray,
10 were excluded from the study. Three cases were excluded because
investigation showed that pepper spray had not been used. Another seven were
excluded because insufficient details were included in the case reports.

The remaining 63 cases were broken down into four subsets (see exhibit 7):

o Clear cut--cases in which the cause of death was clear and well-founded.

o Combined effects--cases in which the cause of death could be attributed to
two or more factors working together.

o Outliers--cases that defied categorization.

o Asthma--cases in which compromised air passages to the lungs were found at
autopsy.

Clear-cut cases. In 12 of the 23 cases included in the clear-cut category, drugs
alone were determined to be the cause of death. In another four cases, death
was attributed to drugs and heart disease. In the remaining seven cases, the
author attributed death to positional asphyxia, which can occur when subjects
are placed in a position in which they cannot use the muscles that move air in
and out of their lungs. When a subject is made to lie face down, hands cuffed
behind, pressure on the abdomen forces the abdominal contents up against the
diaphragm, making it harder to breathe. This situation is exacerbated when the
subject is obese. Weights applied to the back, such as an arresting officer
placing his weight on the subject's shoulder-blade area, also interfere with a
suspect's ability to breathe (in one case reported in this study, a sofa was
placed on the subject to help control him). Pepper spray was ruled out as a
direct or contributing cause in all of these deaths.

Combined effects. In these cases, drugs and disease combined with the
confrontational situation to such a degree that it was impossible to isolate a
single cause of death. In 23 cases, death was attributed to a combination of the
confrontational situation and drugs. In five cases, death was attributed to the
confrontational situation and the effects of disease. In another four cases, all
three factors contributed to death. Again, pepper spray was ruled out as a
cause or contributing factor in these deaths.

Outlier cases. Other weapons or health issues were involved in the deaths and
were likely the main cause of death.

Asthma. In the two cases involving asthma, death was attributed to the disease.
In one case, details of the confrontation with law enforcement were not
available, but the autopsy found signs of preexisting asthma, and the medical
examiner certified the death as asthma precipitated by the use of pepper spray.
In the other case, signs of asthma were not found, but the autopsy revealed
airway damage that could have made the subject susceptible to bronchial
spasms triggered by inhaled pepper spray. The autopsy surgeon listed OC and
disease as the cause of death.

Pepper spray was used more times in this case than in any other, but according
to police officers, it was ineffective. The subject, who was obese, was
handcuffed behind his back and placed in a face-down position when being
transported. The difficulty of breathing in this position may have been
compounded by the damage already done to his airways. In this case, the
confrontational situation could have caused or contributed to death.

Was pepper spray the cause of death? 

For pepper spray to cause death, it would have to make breathing difficult by
closing or narrowing the bronchial tubes. The subject would have to struggle to
both inhale and exhale. These effects would be noticeable shortly after the
application of pepper spray. Yet, except for the two cases in which the subjects
were classified as asthmatics, comments regarding breathing (other than
"ceased breathing") were found in only five case reports, none of which referred
to a struggle to breathe. In none of these cases did death immediately follow
pepper spray application. For these reasons, the study concluded that pepper
spray was not the direct or sole cause of death in these five cases.

Lessons and observations

In addition to concluding that pepper spray did not cause or contribute to death
in 61 out of 63 cases, the author viewed pepper spray as a relatively innocuous
force option, ranking at the low end of the "escalation of force" scale. Although
pepper spray was reported by arresting officers to be effective in only 20
percent of the cases studied, all confrontations examined in the present study
were distinguished by the fact that they ended in the subject's death.

A 1999 study that examined 690 incidents of pepper spray use concluded that
pepper spray was effective 85 percent of the time, according to the broadest
definition of the term "effectiveness."[3] None of the arrestees in these incidents
died in custody. Other studies have reported lower and higher effectiveness
rates, but effectiveness is a subjective term and its definition varies across
studies. The 1999 study found that the effectiveness rate reported by officers
was significantly reduced when subjects exposed to pepper spray appeared to
be on drugs (about 13 percent of the incidents). In the in-custody death study,
toxicological data showed that 39 of 63 subjects (62 percent) had some level
of drugs in their body. This apparent large difference in drug use and varying
interpretations of what constitutes effectiveness may explain some of the
differences in effectiveness rates reported in the two studies.

The current study also concluded that, despite some skepticism as to its
existence,[4] positional asphyxia is real and can (and does) cause death.
Although pepper spray was not found to be effective in any of the cases of
positional asphyxia examined in this study, its precise role in these cases could
not be determined. The results of a recent experiment that tested the effect of
pepper spray on drug-free, healthy volunteers, by itself and when combined
with positional restraint, are discussed below.

Pepper spray and positional restraint

In another study, medical researchers at the University of California-San Diego
measured the effects of pepper spray on breathing and other health parameters,
particularly when combined with positional restraint.[5] Subjects (34 recruits
from a law enforcement training academy) were exposed to pepper spray and a
placebo spray and then placed in a sitting position or handcuffed in the "hogtie"
or "hobble" position.

The study found that pepper spray inhalation alone does not pose a significant
risk for respiratory compromise or asphyxiation, even when combined with
positional restraint. Researchers found no evidence that OC exposure resulted
in any additional change in respiratory function in the restraint position. In both
the OC and placebo groups, pulmonary function was restricted in the restraint
position, but measurements remained within the normal range. Moreover, there
were no statistical differences between the OC and placebo groups relative to
these declines.

Pepper spray did, however, result in an increase in blood pressure of 10 to 15
percent, perhaps due to the discomfort and pain associated with it. The clinical
implications of this finding are unknown.

This study had several limitations:

o Conditions that occur in the field are impossible to replicate in the laboratory. 

o The effects of prolonged sprays and repeated exposures were not studied.

o All of the subjects were cadets at the local police academy and were
generally healthy.

o Subjects wore goggles to reduce pepper spray exposure to the eyes, which
causes irritation and pain. (The purpose of the study was to measure acute
effects of inhalation). 

o Restrained subjects were placed on a medical examination table rather than
on a hard surface, as often occurs in the field. 

o The study did not investigate the long-term effects of pepper spray exposure
or the potential for complications from chronic occupational exposure to it.

Practical implications

In-custody deaths occurred before pepper spray was introduced and still occur
today in cases not involving pepper spray. Determining the risks of pepper
spray in arrest situations is complicated by two facts:

o The number of in-custody deaths in which pepper spray was used in the
arrest process is very low.

o Every situation in which a suspect resists arrest is unique; it is impossible to
collect enough useful data on nearly identical documented arrest scenarios with
and without the use of pepper spray.

The studies cited in this report do not and cannot prove that pepper spray will
never be a contributing factor in the death of a subject resisting arrest. In the
in-custody death study summarized here, the evidence led the author to believe
that, except for two cases, the deaths could be explained as being caused by
the struggle with officers and the presence of drugs or alcohol (or both) even if
OC had not been used.

The clinical study of subjects exposed to pepper spray and placed under
positional restraint, even hogtied, strongly indicates that these conditions alone
are unlikely to produce any significant risk to subjects. That study, however,
was performed on healthy subjects who were not on drugs or obese. They had
not fought with officers or subjected themselves to other physiological or
psychological stress that could have compromised their health. These
complicating conditions, often found in the field, cannot be replicated in a
laboratory. Thus, there can be no definitive clinical determination of the risk of
pepper spray use in all arrest circumstances.

The North Carolina study provided results that, in some instances, supported
the general belief that the use of pepper spray will reduce injuries to police
officers and suspects and excessive force complaints against police. Limitations
in the data, however, made it impossible to draw conclusions on all three
effectiveness measures at all three study sites.

The in-custody death study noted that pepper spray was reported to be
effective in only about 20 percent of the incidents. This rate is much lower than
that found in a 1999 study of arrests involving pepper spray, which examined a
large number of incidents in which no deaths occurred. The subjects in the
in-custody death study had a much higher rate of drug use, however, and there
is evidence that pepper spray is less effective on subjects who are on drugs. A
possible implication of these observations is that officers may want to move
quickly to another force option if subjects appear to be on drugs and seem
unaffected by a blast of pepper spray that clearly hit them in the face. Doing so
could reduce risks to officers from continually aggressive subjects.

The results of all studies discussed in this Research for Practice seem to confirm
that pepper spray is a reasonably safe and effective tool for law enforcement
officers to use when confronting uncooperative or combative subjects; they
provide no reason to stop using this important less-than-lethal weapon. Other
studies continue to be conducted on pepper spray, however, and this will not
be the last word on the subject.

Additional reading

Kaminski, Robert J., Steven M. Edwards, and James W. Johnson, "Assessing
the Incapacitative Effects of Pepper Spray During Resistive Encounters With
Police," Policing: An International Journal of Police Strategies and Management
22 (1) (1999): 7-29.

Kaminski, Robert J., Steven M. Edwards, and James W. Johnson, "The
Deterrent Effects of Oleoresin Capsicum on Assaults Against Police: Testing
the Velcro-Effect Hypothesis," Police Quarterly 1 (2) (1998): 1-20.

National Law Enforcement Technology Center, "Positional Asphyxia--Sudden
Death," National Law Enforcement Technology Center Bulletin, Washington,
DC: U.S. Department of Justice, National Institute of Justice, June 1995.

Notes

1. Granfield, John, Jami Onnen, and Charles S. Petty, "Pepper Spray and
In-Custody Deaths," Executive Brief: Science and Technology, International
Association of Chiefs of Police and National Institute of Justice, March 1994.

2. Kaminski, Robert J., Steven M. Edwards, and James W. Johnson, "The
Deterrent Effects of Oleoresin Capsicum on Assaults Against Police: Testing
the Velcro-Effect Hypothesis," Police Quarterly 1 (2) (1998): 1-20.

3. Kaminski, Robert J., Steven M. Edwards, and James W. Johnson,
"Assessing the Incapacitative Effects of Pepper Spray During Resistive
Encounters With Police," Policing: An International Journal of Police Strategies
and Management 22 (1) (1999): 7-29.

4. Much of this skepticism resulted from a case in which a forensic pathologist
answered that he could not prove, in the case in question, that death resulted
from positional asphyxia. (See Price v. County of San Diego 990F Supp 130.)

5. More information on this study can be found in Chan, Theodore C., et al.,
Pepper Spray's Effects on a Suspect's Ability to Breathe, Research in Brief,
Washington, DC: U.S. Department of Justice, National Institute of Justice,
December 2001, NCJ 188069.

----------------------------

The National Institute of Justice is the research, development, and evaluation
agency of the U.S. Department of Justice. NIJ provides objective, independent, 
nonpartisan, evidence-based knowledge and tools to enhance the 
administration of justice and public safety.

NIJ is a component of the Office of Justice Programs, which also includes the
Bureau of Justice Assistance, the Bureau of Justice Statistics, the Office of
Juvenile Justice and Delinquency Prevention, and the Office for Victims of
Crime.

----------------------------

NCJ 195739