2 tables omitted
Ground and aerial applications of insecticides are used to control populations
of adult mosquitoes, which spread such diseases as West Nile virus–related
illness, eastern equine encephalitis, and dengue fever.1 This
report summarizes investigations of illnesses associated with exposures to
insecticides used during 1999-2002 to control mosquito populations in nine
states (Arizona, California, Florida, Louisiana, Michigan, New York, Oregon,
Texas, and Washington) (estimated 2000 population: 118 million). The findings
indicate that application of certain insecticides posed a low risk for acute,
temporary health effects among persons in areas that were sprayed and among
workers handling and applying insecticides. To reduce the risk for negative
health effects, public health authorities should (1) provide public notice
of application times and locations and appropriate advice about preventing
exposures, (2) ensure that insecticide handlers and applicators meet state-mandated
training and experience requirements to prevent insecticide exposure to themselves
and the public, and (3) implement integrated pest management control strategies
that emphasize mosquito larval control, reduction of mosquito breeding sites,
and judicious use of insecticides to control adult mosquito populations.
Staff in state-based pesticide poisoning surveillance programs identified
patients who had been exposed to insecticides used in mosquito-control efforts
in nine states during April 1999–September 2002. Information was gathered
on persons who had illnesses consistent with the national case definition
for pesticide poisoning, which requires the collection of data on pesticide
exposure, health effects, and toxicologic evidence supporting an association
between exposure and effect.2,3 Cases of insecticide-related illness
or injury were classified as either definite, probable, or possible, depending
on the certainty of exposure and whether health effects were signs observed
by a health-care provider or symptoms reported by a patient.2,3
Of the 133 cases of acute insecticide-related illness associated with
mosquito control that were identified, two (1.5%) were classified as definite,
25 (18.8%) as probable, and 106 (79.7%) as possible. Of the 132 cases for
which work-relatedness could be assessed, 36 (27.3%) were work-related and
96 (72.7%) were not work-related; 31 (86.1%) of the 36 work-related cases
occurred among males, and 66 (68.8%) of the 96 cases that were not work-related
occurred among females.
Of the 49 cases identified in 2001, a total of 29 (59.2%) were related
to a single event at a softball game in which workers operating a mosquito-control
truck inadvertently sprayed 29 persons (16 spectators, 12 players, and one
coach) with Fyfanon ULV®, which contains malathion. All 29 persons were
treated in emergency departments (EDs).
Of the 133 persons with acute insecticide-related illness associated
with mosquito control, 35 (26.3%) were identified from monitoring media reports
(including 34 reported subsequently by health-care providers), 32 (24.1%)
were reported by poison-control centers, 27 (20.3%) were self-reported, and
seven (5.3%) were reported by state health departments. Physicians and EDs
were responsible for initial reporting of five and three cases, respectively.
The remaining cases were reported initially by friends or relatives (n = seven),
government agencies (n = five), employers (n = four), laboratories (n = two),
and other sources (n = six).
Of the 85 persons with reported illness who were known to have sought
medical care, 45 (52.9%) were treated in EDs, 35 (41.2%) were treated in physicians'
offices, four (4.7%) were treated in employee health centers, and one (1.2%)
was hospitalized. An additional 16 persons received advice from a poison-control
center, and 15 did not seek medical care; information about medical treatment
was not available for 17 persons.
Of the 133 reported cases of pesticide-related illness, 95 (71.4%) cases
were associated with organophosphates, primarily malathion. Malathion alone
was associated with 64 (67.4%) of the 95 cases; 37 (27.8%) cases were associated
with pyrethoids, primarily sumithrin (24 cases) and resmethrin (10 cases).
Illness severity was categorized for all cases.4 One exposure
was associated with illness of high severity. When her neighborhood was sprayed,
a woman aged 54 years was exposed to sumithrin, which passed through operating
window fans and a window air conditioner. She had exacerbation of her asthma
and chronic obstructive pulmonary disease. The majority of the remaining cases
were of low (65.4%) or moderate (33.8%) severity.
The majority of cases were associated either with respiratory (66.2%)
or neurologic (60.9%) dysfunction. Other systems affected were gastrointestinal
(45.1%), ocular (36.1%), dermal (27.1%), cardiovascular (12.0%), renal-genitourinary
(3.0%), and miscellaneous (28.6%).
Of 36 persons who were exposed at their workplaces, 14 (38.9%) were
insecticide applicators, and 22 (61.1%) were performing tasks that did not
involve pesticide application. Seven (50.0%) of 14 applicators were exposed
to sumithrin; of the other 22 workers, 11 (50%) were exposed to malathion,
and five (22.7%) were exposed to resmethrin. Illness of moderate severity
was more frequent among applicators (42.9%) than nonapplicators (27.3%).
MP Mauer, DO, New York State Dept of Health. R Rosales, J Sievert, M
Propeck, Texas Dept of Health. A Becker, MPH, Florida Dept of Health. E Arvizu,
M Hadzizanovic, MD, Arizona Dept of Health Svcs. L Mehler, MD, California
Dept of Pesticide Regulation. D Profant, PhD, C Thomsen, MPH, Oregon Dept
of Human Svcs. L Baum, Washington State Dept of Health. M Lackovic, MPH, Louisiana
Dept of Health and Hospitals. J Granger, MPH, Michigan Dept of Community Health.
GM Calvert, MD, Div of Surveillance, Hazard Evaluations and Field Studies,
National Institute for Occupational Safety and Health; WA Alarcon, MD, EIS
The findings in this report indicate that serious adverse outcomes potentially
related to public health insecticide application were uncommon. When administered
properly in a mosquito-control program, insecticides pose a low risk for acute,
temporary health effects among persons in areas that are being sprayed and
among workers handling and applying insecticides. In this analysis, adverse
health effects were identified in a small percentage of the population in
the nine states. Data about the actual number of persons potentially or actually
exposed were not available because insecticide applications were conducted
only in certain areas of participating states, and the boundaries of these
areas were not available.
Malathion, naled, sumithrin, and resmethrin were associated with the
majority of reported cases of acute insecticide-related illness. Malathion
is an organophosphate insecticide that is classified as an acute toxicity
category III compound.* Although it is less acutely toxic than many other
organophosphates, adverse health effects have been reported by exposed persons.5 Naled is an acute toxicity level I organophosphate. When combined
with piperonyl butoxide, resmethrin and sumithrin are highly effective insecticides
that are of low-order toxicity to mammals, including humans; these pyrethroid
products are classified as acute toxicity category III compounds and have
been associated with adverse health effects in humans.6,7
These insecticide formulations are registered by the U.S. Environmental
Protection Agency for use in urban areas for mosquito control and benefit
the public by controlling populations of mosquitoes that transmit diseases
that affect humans. Reported symptoms associated with these insecticides were
temporary and included dermal, ocular, and upper and lower respiratory tract
irritation and exacerbation of conditions such as asthma. These health effects
might represent irritant or allergic responses, to either the insecticide
or its carrier.5,7,8 Anxiety about insecticide use for mosquito
control also might have been responsible for symptoms in some persons.
The findings in this report are subject to at least three limitations.
First, the number of reported cases is probably an underestimate of the true
magnitude of illnesses associated with mosquito-control efforts. Affected
persons who did not seek medical care or whose symptoms were not reported
to a surveillance system could not be identified; even if these persons had
sought medical care, their illness might not have been recognized as insecticide-related,
and even if they had received a proper diagnosis, their cases might not have
been reported. Second, only nine states have pesticide poisoning surveillance
systems, and the data in this report might not be representative of the 41
states without such surveillance systems. Finally, although all cases were
consistent with case definition criteria, the possibility of false positives
cannot be excluded. Because clinical findings of pesticide poisoning are nonspecific,
especially when of mild severity, and no standard diagnostic test exists,
some illnesses related temporally to insecticide exposures might be coincidental
and not caused by the exposures.
To reduce potential risks from insecticide exposure, CDC recommends
the use of integrated pest management strategies for mosquito-control programs
that emphasize mosquito larval control, reduction of breeding sites (e.g.,
human-made collections of stagnant water such as unchlorinated swimming pools,
discarded tires or other containers, and bird baths), and judicious use of
insecticides to control adult mosquito populations when quantitative measures
suggest an elevated risk for human infection or in community settings when
extensive immature mosquito larval habitats cannot be controlled.9,10 When insecticides are used, public health agencies should inform the
public when and where spraying will occur and communicate how to reduce the
likelihood of exposure. To avoid direct exposure from passing spray trucks,
public health agencies should ensure that visible and audible warnings are
made before spraying. Persons with exposure-related health concerns should
consult their health-care providers. To prevent exposures from improper application
methods, insecticide handlers and applicators should be trained in proper
insecticide handling and application methods and in the use of appropriate
personal protective equipment.
References: 10 available
*The U.S. Environmental Protection Agency classifies pesticide products
into one of four acute toxicity categories on the basis of certain criteria,
with category I comprising pesticides with the greatest toxicity and category
IV those with the least toxicity.
Surveillance for Acute Insecticide-Related Illness Associated With Mosquito-Control Efforts—Nine States, 1999-2002. JAMA. 2003;290(5):591-592. doi:10.1001/jama.290.5.591