Case Study

740 MMWR August 20, 2004

Brief Report

Illness Associated with Drift of Chloropicrin Soil Fumigant

into a Residential Area — Kern County, California, 2003

Chloropicrin is the fourth most commonly used soil fumi- gant in California. Exposure to chloropicrin causes eye and respiratory tract irritation, vomiting, and diarrhea (1). This repor t describes an investigation by the California Department of Pesticide Regulation (CDPR) and the Kern County Agriculture Commissioner (KCAC) into illnesses associated with the offsite drift of chloropicrin in Kern County. A total of 165 persons experienced symptoms consistent with chloropicrin exposure. The findings underscore health risks associated with fumigants and the usefulness of procedures adopted in California to ensure both prompt identification of exposure events and timely notification of the affected public.

On October 3, 2003, an agricultural pest control service began applying 100% chloropicrin at a concentration of 80 pounds/acre to 34 acres of fallow land in Kern County. Chlo- ropicrin was injected 17–18 inches into the soil; a weighted board was used to compact the soil, treating 18 acres. That evening, residents living one quarter mile west of the applica- tion site experienced irritant symptoms. The Kern County Fire Department (KCFD) was contacted to investigate; how- ever, darkness, distance from the treated field, and absence of chloropicrin odor prevented firefighters from identifying the source of the irritation. Records from a weather station approximately 7 miles southeast of the application site indi- cated low wind speeds and stable atmospheric conditions but also that the wind direction had changed that evening, blow- ing from the field toward the residential dwellings.

The next day, chloropicrin was applied to the remaining 16 acres. A 60-foot, chloropicrin-free buffer was maintained around the perimeter of the field because workers noted a persistent odor when they arrived. Residents one quarter mile west and south of the field complained about irritant symp- toms that evening. Residents notified KCFD; several respond- ing firefighters experienced eye irritation. The wind had changed again that evening and begun blowing from the field toward the residential dwellings. Suspecting a pesticide release, KCFD notified KCAC. The field was recompacted, and the odor ceased.

On October 6, KCAC notified CPDR about the incident. KCAC and CDPR conducted in-person interviews at 35 households located approximately one quarter mile west and

south of the field and at a day care center; additional inter- views were conducted on October 15. The 35 households and day care center had a total of 172 persons present during the exposure period. Representatives from each household and the day care center were interviewed by using a standardized questionnaire (2). In addition, five workers involved with the fumigation were questioned informally, and KCFD records were reviewed to identify affected firefighters.

The investigation determined that 165 persons reported symptoms compatible with illness caused by chloropicrin; median age of the persons was 16 years (range: 3 months–63 years). Nearly all (99%) had irritant symptoms (e.g., eye or upper respiratory) (Table); nine (5%) received medical evalu- ations. Seven had persistent respiratory symptoms when interviewed 11 days after the event. Follow-up medical care was limited because most of the affected persons lacked health insurance.

Exposures were retrospectively estimated by using a stan- dard air dispersion model (3). Estimated 1-hour average chlo- ropicrin air concentrations in areas south and west of the field ranged up to 0.20 parts per million (ppm). Peak-to-mean extrapolations indicated that peak concentrations might have exceeded 1 ppm. The Occupational Safety and Health Administration permissible exposure limit and the National Institute for Occupational Safety and Health (NIOSH)- recommended exposure limit is 0.10 ppm averaged during 8 hours. However, extrapolations from animal studies suggest 0.0044 ppm as a safe level for a 1-hour environmental exposure (4).

According to KCAC, a possible cause of the offsite drift was failure to contain the chloropicrin adequately after applica- tion. After the incident, KCAC imposed new restrictions on chloropicrin applications, including prohibition of applica- tions within one quarter mile of an occupied structure and mandatory use of a heavy-duty tarp or water seal for applica- tions within one half mile of such structures.

The findings in this report are subject to at least two limita- tions. First, this report is limited by an imprecise estimate of reported cases. Some affected persons likely were not inter- viewed, leading to an underestimation. Conversely, false- positive cases cannot be excluded because some self-reported symptoms might not have been related to exposure. Second, environmental measurements were not conducted to confirm chloropicrin exposure.

Adequate chloropicrin containment measures are needed to prevent similar community outbreaks. In addition, when out- breaks occur, measures are needed to prevent the community

Vol. 53 / No. 32 MMWR 741

TABLE. Number* and percentage of persons with acute chloropicrin-related illness, by selected characteristics — Kern County, California, October 2003 Characteristic No. (%)

Age group (yrs) 0–5 22 (13) 6–9 17 (10)

10–14 23 (14) 15–19 15 ( 9) 20–29 18 (11) 30–39 21 (13) 40–64 26 (16) Unknown 23 (14)

Sex Female 77 (47) Male 88 (53)

Severity†

Low 163 (99) Moderate 2 (1)

Date of exposure October 3 9 ( 6) October 4 135 (82) Both dates 22 (14)

Occupation Firefighter 9 (6) Applicator/Grower 4 (2) Day care worker 2 (1) Nonoccupational (community resident) 150 (91)

Symptoms Eye 164 (99)

Lacrimation 125 (82) Pain/Burning 89 (54)

Skin (pruritis or rash) 3 (2) Gastrointestinal 77 (47)

Vomiting 37 (22) Nausea 35 (21) Abdominal pain 10 (6) Diarrhea 5 (3) Hematochezia 1 (1)

Respiratory 85 (51) Cough 53 (32) Dyspnea 27 (16) Upper respiratory irritation 22 (13) Chest pain 8 (5) Asthma exacerbation 6 (4)

Neurologic 40 (24) Headache 39 (25) Dizziness 1 (1) Fatigue 1 (1)

* N = 165. †

Using CDCs severity index for use in state-based surveillance of acute pesticide-related illness and injury. Available at http://www.cdc.gov/niosh/ topics/pesticides/pdfs/pest-sevindexv6.pdf.

distress that arises when government authorities do not pro- vide timely information regarding the emergency response and follow-up investigation findings. In 2003, CDPR developed procedures to respond to incidents involving offsite drift of pesticides (2). This approach might be useful in other juris- dictions where offsite pesticide drift can occur.

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742 MMWR August 20, 2004

Reported by: MA O’Malley, MD, Univ of California, Davis; S Edmiston, D Richmond, M Ibarra, T Barry, M Smith, California Dept of Pesticide Regulation. GM Calvert, MD, Div of Surveillance, Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health, CDC.

References 1. Prentiss AM. Chemicals in War: A Treatise on Chemical Warfare. New

York, New York: McGraw-Hill, 1937. 2. California Department of Pesticide Regulation. Responding to non-

occupational pesticide use-related exposure episodes. Sacramento, Cali- fornia: California Department of Pesticide Regulation, 2003. Available at http://www.cdpr.ca.gov/docs/enfcmpli/penfltrs/penf2003/ 2003044.htm.

3. U.S. Environmental Protection Agency. User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models for Use in the Multimedia, Multipathway and Multireceptor Risk Assessment (3MRA) for HWIRR99, Volume II: Description of Model Algorithms. Washing- ton, DC: U.S. Environmental Protection Agency, 1999. Available at http://www.epa.gov/epaoswer/hazwaste/id/hwirwste/pdf/risk/reports/ s0528.pdf.

4. Alexeeff GV, Budroe JD, Collins JF, et al. Air Toxics Hot Spots Program Risk Assessment Guidelines. Part I. The Determination of Acute Refer- ence Exposure Levels for Airborne Toxicants. Sacramento, California: California Office of Environmental Health Hazard Assessment, 1999. Available at http://oehha.ca.gov/air/pdf/acuterel.pdf.

West Nile Virus Activity — United States, August 11–17, 2004

During August 11–17, a total of 194 cases of human West Nile virus (WNV) illness were reported from 17 states (Alabama, Arizona, California, Colorado, Florida, Illinois, Louisiana, Maryland, Minnesota, Mississippi, Missouri, New Mexico, Ohio, South Dakota, Texas, Utah, and Virginia).

During 2004, a total of 27 states have reported 689 cases of human WNV illness to CDC through ArboNET (Table, Figure). Of these, 291 (42%) cases were reported from Arizona. A total of 386 (56%) of the 689 cases occurred in males; the median age of patients was 50 years (range: 1 month–99 years). Illness onset ranged from April 23 to August 12; a total of 20 cases were fatal.

A total of 55 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET in 2004. Of these, 33 (60%) were reported from Arizona, eight from California, three each from Florida, New Mexico, and South Dakota, two from Colorado, and one each from Iowa, Missouri, and Wisconsin. Of the 55 PVDs, two persons aged 66 and 69 years subsequently had neuroinvasive illness, and 11 persons (median age: 55 years [range: 22–73 years]) subsequently had West Nile fever.

In addition, during 2004, a total of 2,530 dead corvids and 441 other dead birds with WNV infection have been

TABLE. Number of human cases of West Nile virus (WNV) illness, by state — United States, 2004*

West Other Total Neuroinvasive Nile clinical/ reported

State disease† fever§ unspecified¶ to CDC** Deaths

Alabama 4 0 0 4 0 Arizona 112 31 148 291 3 Arkansas 1 2 0 3 0 California 64 74 24 162 5 Colorado 18 104 0 122 1 Florida 9 3 0 12 1 Illinois 3 2 1 6 0 Iowa 1 2 0 3 1 Kentucky 0 1 0 1 0 Louisiana 10 0 0 10 5 Maryland 0 1 0 1 0 Michigan 1 0 0 1 0 Minnesota 4 3 0 7 0 Mississippi 3 1 1 5 1 Missouri 2 1 1 4 0 Nebraska 0 1 0 1 0 Nevada 2 0 0 2 0 New Mexico 5 12 1 18 0 New York 2 1 0 3 0 North Dakota 0 2 0 2 0 Ohio 2 0 0 2 1 Pennsylvania 1 0 0 1 0 South Dakota 2 13 0 15 0 Texas 4 1 0 5 2 Utah 2 2 0 4 0 Virginia 0 0 1 1 0 Wyoming 1 2 0 3 0 Total 253 259 177 689 20

* As of August 17, 2004. † Cases with neurologic manifestations (i.e., West Nile meningitis, West

Nile encephalitis, and West Nile myelitis). § Cases with no evidence of neuroinvasion. ¶ Illnesses for which sufficient clinical information was not provided.

** Total number of cases of human WNV illness reported to CDC through ArboNet by state and local health departments.

FIGURE. Areas reporting West Nile virus (WNV) activity — United States, 2004*

* As of 3 a.m., Mountain Standard Time, August 17, 2004.

Human WNV illness Nonhuman WNV infection only