Unplanned releases and injuries associated with aerial application of chemicals, 1995-2002.

Introduction

Aerial application is an efficient means of targeting chemical application to increase crop production. Aerial-application pilots, however, have a high rate of fatalities compared with pilots in other industries (Centers for Disease Control and Prevention [CDC], 2004; Suarez, 2000). Along with the risk of aircraft crash, there is an added risk of exposure to hazardous substances. Unplanned or uncontrolled releases of pesticides or other hazardous substances may occur during any phase of the aerial-application process, including mixing and loading of chemicals into the aircraft, application of the chemicals, and servicing of the aircraft (Minnesota Department of Agriculture [MDA], 2000; University of Nebraska, 1996). Accidental releases can affect not only agricultural chemical-application workers, but also others entering the area. For this report, data from the Agency for Toxic Substances and Disease Registry's (ATSDR's) Hazardous Substances Emergency Events Surveillance (HSEES) system were analyzed to 1) describe the number and type of unintended acute releases of hazardous substances associated with aerial application during 1995-2002, 2) describe associated human health consequences, and 3) review measures to reduce releases and associated injuries. Data from the National Transportation Safety Board (NTSB) were also reviewed and compared with HSEES data.

Methods

Seventeen state health departments participated in the HSEES system during 1995-2002. Alabama, Colorado, Iowa, Minnesota, Mississippi, Missouri, New York, North Carolina, Oregon, Texas, Washington, and Wisconsin participated for the entire period. Five states participated for part of this period: Louisiana (2001-2002), New Hampshire (1995-1996), New Jersey (2000-2002), Rhode Island (1995-2001), and Utah (2000-2002). Participating states collected data from a variety sources, such as state and local emergency responders, environmental and health agencies, poison control centers, hospitals, and the news media.

An HSEES event is an uncontrolled, illegal, or threatened release of a hazardous substance that requires removal, cleanup, or neutralization according to federal, state, or local law. A hazardous substance is one that can be reasonably expected to cause an adverse health effect. Events involving only a threatened release were included if the threat of release resulted in an action to protect public health, such as evacuation. Events involving petroleum only were excluded. Victims were defined as any person sustaining at least one symptom, such as eye irritation, in conjunction with the hazardous substance release.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Data specifically attributed to aerial-application accidents in the National Transportation Safety Board's (NTSB's) Aviation Accident Database were also reviewed for 1995-2002 for states participating in HSEES. By NTSB definition, these accidents involved substantial damage to the aircraft or injury to those in the aircraft, but did not necessarily involve release of hazardous substances. Reporting of crashes or injuries to NTSB is mandatory.

Results and Discussion

During 1995-2002, 54,090 events were recorded in the HSEES system. Ninety-one events, including one threatened release, involved aerial application. The number of aerial-application events was relatively constant from 1995 to 2000, but the number decreased in 2001 and 2002 (Figure 1). Three hundred and fifty NTSB aerial-application accidents were identified for the corresponding HSEES states. The number of these accidents per year also appears to be decreasing, with 39 to 54 per year for 1995-2000 and 34 to 35 per year in 2001-2002.

Seasonal trends were similar for the HSEES data and the NTSB data (Figure 2, Figure 3). Most HSEES and NTSB events occurred during May to September. Most of the 81 HSEES events for which the time was known occurred in the morning (nine events per hour between 7:00 a.m. and 10:00 a.m.). Most of the 350 NTSB accidents also occurred in the morning, with a peak of 38 events between 9:00 a.m. and 10:00 a.m. (not shown).

HSEES data and NTSB data differed in geographic distribution (Table 1). The highest numbers of HSEES events were in Minnesota and Wisconsin (25 and 14 events, respectively). The highest number of injuries in HSEES events was reported for Washington (16), with the most fatalities in Texas (4) (Table 1). NTSB data showed more aerial-applicator accidents in Texas (108), followed by Mississippi (56). The highest number of injuries in NTSB accidents was in Texas (43), which also had the highest number of related fatalities (14).

Reasons for differences in distribution of events between HSEES and NTSB are not known; differences in reporting may be a factor (NTSB reporting is mandatory, and HSEES reporting is not), as may be differences in case definitions (e.g., NTSB events include all crashes with substantial damage and injuries but may not involve releases, or may involve petroleum-only releases).

[FIGURE 3 OMITTED]

The method of chemical release in HSEES events was most commonly reported as spill (58 spills) or spill with air release (14 spills with air releases). Eighty-nine events involved release of at least one pesticide. Malathion, released in 21 events, was the most commonly released substance; 2,4-Dichlorophenoxyacetic acid (2,4-D) was the second most common (8 events). Altogether, 36 events involved the release of organophosphate cholinesterase inhibitors or n-methyl carbonate cholinesterase inhibitors (carbofuran, carbaryl, methomyl). Aircraft fuel (including diesel, gasoline, kerosene, and unspecified fuel) was released in 13 of the events. Because petroleum releases alone are not included in the HSEES system, releases of aircraft fuel were always reported in conjunction with releases of another agricultural chemical. The quantity released, reported for 77 events, ranged from 1 gallon to 3,000 gallons, with a median of 55 gallons.

Thirty-nine of the 91 HSEES aerial-application events had 56 victims, including 12 fatalities (Table 2). Trauma was reported for all victims with fatal injuries, although two of these victims also had thermal burns. Most injuries were sustained by pilots, often during a crash, but some injuries were received by others on the ground in the application area. In 2002, eight injuries were reported as due to overspray or misapplication, which is more than in 1995-2001 (range: 0 per year to 5 per year). This increase may be due to an increase in the actual number of overspray events, or it could represent better surveillance.

Responders to a crash scene may also be affected by chemicals released during an aerial-application emergency (e.g., police officers, as noted in Table 2). Chemicals spilled or ejected from the aircraft may be dispersed up to several hundred feet away from an actual crash site, injuring people on the ground. Even properly applied chemicals could pose a risk to responders, accident investigators, or others several hours after application if protective equipment is not worn. This possibility is suggested by a report of hospital workers being affected by treating people contaminated with malathion (Horton, Berkowitz, & Kaye, 2003.)

The proportion of injuries from aerial-application releases is higher than for other HSEES transportation-related events. About 5 percent (1,032 of 21,927) of HSEES transportation-related events from 1995-2002 involved victims, while about 45 percent (39 of 86) of aerial-application events involved victims (five of the 91 events were not coded for transportation). Death was more likely to occur in aerial-application events: 28 percent (11 of 39) of HSEES aerial-application events with victims involved fatalities, while 9 percent (95 of 1,032) of all other HSEES transportation-related events with victims involved a fatality.

Aerial application involves a number of potential hazards, including adverse weather conditions, mechanical malfunction, time restrictions, limited space for maneuvering, and flight path obstacles (CDC, 2004; University of Nebraska, 1996). In addition, some studies have suggested that pilot exposure to chemicals, especially those containing nervous-system toxicants, such as organophosphates and carbamate pesticide inhibitors of cholinesterase, has been a factor in aerial-applicator crashes (Driskell, Groce, Hill, & Birky, 1991; Quantick & Perry, 1981; Reich & Berner, 1968; Richter, Gordon, Halamish, & Gribetz, 1981).

This review is limited because reporting to the HSEES system is not mandated by all participating states, a circumstance that may result in underreporting of qualifying events; furthermore, the findings represent only HSEES-participating states and may not accurately reflect events or conditions in nonparticipating states.

Conclusion

Data from 2001 and 2002 suggest that the number of applicator incidents (but not victims) may be declining. Aerial application involves relatively high risks for injury from trauma or chemical exposure for pilots, ground workers, responders, and passers-by. General acceptance and use of safety precautions could reduce accidents and victims. Safety precautions include

* providing showers or other decontamination equipment near application sites.

* providing proper personal protective equipment and training for site workers,

* providing proper equipment and training in pesticide hazards for community first responders or accident investigators,

* posting warnings in areas where pesticide application is occurring to reduce risk to passers-by, and

* limiting pilot exposures to pesticides: Ground crews, not pilots, should mix and load chemicals. Pilots should be protected from pesticides during application by use of closed cockpits or by wearing respirators, and should avoid flying through airborne pesticides (University of Nebraska, 1996). The pilots cholinesterase levels could also be tested before application of organophosphates or carbamates, and levels could be monitored periodically thereafter to identify potential poisoning (Quantick & Perry, 1981; Reich & Berner, 1968), as has been required for agricultural workers in California.

Disclaimer and Acknowledgements: This report is supported by funds from the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) trust fund and the Office of Terrorism Preparedness and Emergency Response of the Centers for Disease Control and Prevention (CDC), provided to the Minnesota Department of Health under a cooperative agreement by the Agency for Toxic Substances and Disease Registry (ATSDR), Public Health Service, U.S. Department of Health and Human Services. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of ATSDR.

The authors would like to thank ATSDR for providing data and support, the Minnesota Duty Officer Program for assisting with data collection, and the Minnesota Department of Agriculture for reviewing the work and providing technical comments.

Corresponding Author: Nancy Rice, MN HSEES Coordinator, Minnesota Department of Health, 625 North Robert Street, P.O. Box 64975, St. Paul, MN 55164. E-mail: [e-mail].

REFERENCES

Centers for Disease Control and Prevention. (2004). Work-Related pilot fatalities in agriculture--United States 1992-2001. Morbidity and Mortality Weekly Report, 53(15), 318-320.

Driskell, W.J., Groce, D.F., Hill, R.H. Jr., & Birky, M.M. (1991). Methomyl in the blood of a pilot who crashed during aerial spraying. Journal of Analytical Toxicology, 15(6), 339-340.

Horton, D.K., Berkowitz, Z., & Kaye, W.E. (2003). Secondary contamination of ED personnel from hazardous materials events, 1995-2001. American Journal of Emergency Medicine, 21(3), 199-204.

Minnesota Department of Agriculture. (2000). Issues of liability and regulation: Aerial applicators--Municipal airports: Legislative report (MINN Doc. No. 00-0126). St. Paul, MN: Author.

Quantick, H.R., & Perry, I.C. (1981). Hazards of chemicals used in agricultural aviation: A review. Aviation, Space and Environmental Medicine, 52(10), 581-588.

Reich, G.A., & Berner, W.H. (1968). Aerial application accidents 1963 to 1966. Archives of Environmental Health, 17(5), 776-784.

Richter, E.D., Gordon, M., Halamish, M., & Gribetz, B. (1981). Death and injury in aerial spraying: Pre-crash, crash, and post-crash prevention strategies. Aviation, Space, and Environmental Medicine, 52(1), 53-56.

Suarez, P. (2000). Flying too high: Worker fatalities in the aeronautics field. Compensation and Working Conditions, 5(1), 39-42.

University of Nebraska, Pesticide Education Office. (1996). Aerial pest control for the commercial/non-commercial pesticide applicator. http://pested.unl.edu/catmans/aerial.skp/aercont.htm (24 July 2004).

Nancy Rice, M.P.H.

Rita Messing, Ph.D.

Larry Souther

Zahava Berkowitz, M.Sc., M.S.P.H.

TABLE 1 Aerial Application Accidents, 1995-2002

                           HSEES    HSEES      HSEES      NTSB
State                      Events  Injuries  Fatalities  Events

Alabama                      5        4          3         27
Colorado                     3        2          1         18
Iowa                         2        1          0          4
Louisiana (2001-2002)        1        0          0         14
Minnesota                   25        8          0         38
Mississippi                 10        3          0         56
Missouri                     0        0          0         13
New Hampshire (1995-1996)    0        0          0          0
New Jersey (2000-2002)       0        0          0          3
New York                     0        0          0          0
North Carolina               1        1          0          9
Oregon                      12       14          3         18
Rhode Island (1995-2001)     0        0          0          0
Texas                       10        5          4        108
Utah (2000-2002)             0        0          0          2
Washington                   8       16          1         32
Wisconsin                   14        2          0          8
Totals                      91       56         12        350

                             NTSB      NTSB
State                      Injuries  Fatalities

Alabama                      15         7
Colorado                      5         4
Iowa                          2         0
Louisiana (2001-2002)         6         3
Minnesota                    14         0
Mississippi                  16         5
Missouri                      3         1
New Hampshire (1995-1996)     0         0
New Jersey (2000-2002)        0         0
New York                      0         0
North Carolina                3         0
Oregon                       11         3
Rhode Island (1995-2001)      0         0
Texas                        43        14
Utah (2000-2002)              0         0
Washington                   14         2
Wisconsin                     1         1
Totals                      133        40

HSEES = Hazardous Substances Emergency Events Surveillance.
NTSB = National Transportation Safety Board.

TABLE 2 Injuries from Aerial Application: Hazardous Substances Emergency
Events Surveillance (HSEES) System, 1995-2002

Variable                                      Number   Percentage

Category of victim*
  Employee                                      49        87.5
  General public                                 4         7.1
  Police officer                                 2         3.6
  Student                                        1         1.8
  Total                                         56       100.0
Severity of injuries
  Death                                         12        21.4
  Treated at hospital--admitted                  9        16.1
  Treated at hospital--not admitted             25        44.6
  Treated on scene                               3         5.4
  Observation at hospital, no treatment          1         1.8
  Adverse health effect experienced within       6        10.7
    24 hours
  Total                                         56       100.0
Symptoms**
  Trauma                                        32        57.1
  Eye irritation                                17        30.4
  Respiratory system problems                   13        23.2
  Dizziness or other CNS problems               13        23.2
  Gastrointestinal problems                     13        23.2
  Headache                                       8        14.3
  Thermal burns                                  4         7.1
  Skin irritation                                4         7.1
  Other                                          3         5.4
  Total symptoms reported                      107        --

*Sex of victims (n = 56): 51 male, 5 female. Age of victims (n = 42):
Median = 41; range = 23-75.
**Victims may have multiple symptoms.