Green Tobacco Sickness in Tobacco Harvesters -- Kentucky, 1992

Green tobacco sickness (GTS) is an illness resulting from dermal exposure to dissolved nicotine from wet tobacco leaves; it is characterized by nausea, vomiting, weakness, and dizziness and sometimes fluctuations in blood pressure or heart rate (1-3). On September 14, 1992, the Occupational Health Nurses in Agricultural Communities (OHNAC) project of Kentucky * received reports of 27 cases of GTS. The cases occurred among tobacco harvesters who had sought treatment in several hospital emergency departments in south-central Kentucky during the preceding 2 weeks. This report summarizes the findings of the investigation of these cases.

On September 15, OHNAC staff initiated a review of inpatient and emergency department medical records from May 1 through October 2 at five hospitals in the Bowling Green and Elizabethtown areas. The review identified 55 persons in whom GTS, nicotine poisoning, or other illnesses compatible with GTS symptomatology had been diagnosed. On September 25, industrial hygienists from CDC's National Institute for Occupational Safety and Health (NIOSH) observed the tobacco-harvesting process. Worker's hands, forearms, thighs, and backs received the most dermal exposure to wet tobacco. Dew from tobacco leaves often saturated workers' clothing within minutes of beginning field work.

To evaluate possible risk factors associated with GTS, NIOSH investigators and occupational health nurses from the OHNAC project conducted a case-control study. A case was defined as an emergency department diagnosis of GTS or nicotine poisoning in a person whose recorded work history included tobacco harvesting at the time of illness. Forty-nine persons met the case definition, with episodes occurring from July 25 through September 19, 1992; two cases were subsequently excluded from analysis because illness onset coincided with exposure to pesticides (which can induce similar symptoms). Median age of the 47 case-patients was 29 years (range: 14-54 years); 41 (87%) were male. Controls were 83 asymptomatic tobacco harvesters referred by case-patients or local agricultural extension agents. Their median age was 39 years (range: 16-70 years); 72 (87%) were male.

Twelve (26%) case-patients were hospitalized for 1-2 days; of these, two (4%) required intensive-care treatment for hypotension and bradycardia. All case-patients were initially treated in emergency departments with antiemetic drugs, and 35 (74%) received intravenous fluids.

Forty of 47 case-patients and 83 controls were administered a questionnaire by telephone. Respondents were asked about the types of jobs performed during the tobacco growing season, use of protective clothing, exposure to wet tobacco leaves, work in wet clothing, work duration, and personal tobacco use.

Among the 40 case-patients who completed interviews, the median time from starting work to onset of illness was 10 hours (range: 3-17 hours); most frequently reported symptoms included weakness (100%), nausea (98%), vomiting (91%), dizziness (91%), abdominal cramps (70%), headache (60%), and difficulty breathing (60%). The mean duration of illness was 2.4 days. Thirty-six (90%) had previous work experience with tobacco. Of these, 14 (39%) had previously sought medical care for symptoms suggestive of GTS. Seventeen (85%) of 20 case-patients aged greater than or equal to 30 years attributed their illness to working in wet tobacco, compared with 12 (60%) case-patients aged less than 30 years.

Age less than 30 years was a risk factor for illness (odds ratio {OR}=3.1; 95% confidence interval {CI}=1.4-7.0). All case-patients and 69 (83%) controls had worked in fields of wet tobacco where their clothes became wet (OR=infinite; lower confidence limit=1.8). Current use of personal tobacco products (i.e., cigarettes, snuff, chewing tobacco, pipe, or cigars) appeared to be weakly protective, but the estimate was not statistically significant (OR=0.7; 95% CI=0.3-1.5). Sex and work duration (i.e., number of hours per day or number of days per week) were not associated with illness. The reported use of protective clothing was similar for case-patients and controls; for case-patients and controls combined, reported use of protective items worn at least once during the growing season was 5% for waterproof clothing and 32% for gloves.

Representative hospital costs were calculated for three levels of care received by 31 case-patients treated at two participating hospitals. Fees averaged $250 for outpatient treatment, $566 for hospital admission, and $2041 for intensive-care treatment.

Reported By: B Boylan, MS, Lincoln Trail District Health Dept, Elizabethtown; V Brandt, Barren River District Health Dept, Bowling Green; J Muehlbauer, Buffalo Trace District Health Dept, Maysville; M Auslander, DVM, C Spurlock, PhD, Injury Epidemiology Section; R Finger, MD, State Epidemiologist, Kentucky Dept for Health Svcs. Hazard Evaluations and Technical Assistance Br, and Surveillance Br, Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Before 1992, no cases of GTS had been reported to Kentucky public health agencies. Increased surveillance of adverse health events in persons working in agriculture and increased awareness of the condition may explain the reports in Kentucky during this harvest season (i.e., late summer). Before the NIOSH investigation was initiated, OHNAC occupational health nurses had supplied emergency department physicians with literature about GTS. In addition, rainfall during the 1992 season was uncharacteristically heavy, potentially increasing exposure to wet tobacco and incidence of GTS.

The lower risk for GTS among older workers may result from work practices developed over time that reduce contact with wet tobacco. In addition, workers likely to develop symptoms of GTS may leave this work force at a young age. One potential limitation to these findings is that the age distribution of controls may not reflect the local population of tobacco workers.

Personal use of tobacco products may be weakly protective, probably because of development of tolerance to the effects of nicotine among regular tobacco users. Tolerance may not be protective if dermal absorption substantially exceeds the user's customary nicotine intake (4), which may have occurred in this outbreak because of heavier than usual rains.

Approximately 60,000 persons harvest tobacco annually in Kentucky at least part-time (5). The estimated crude 2-month incidence rate of hospital-treated GTS among tobacco workers in the five-county study area was 10 per 1000 workers.** Statewide extrapolation of this incidence rate suggests as many as 600 persons in Kentucky could have sought emergency department care for the condition. However, this figure may underestimate the true incidence of GTS because many affected persons may not seek hospital treatment (2).

Use of protective clothing (e.g., water-resistant clothing and rubber gloves) reduces the amount of nicotine absorbed by workers in contact with green tobacco (6,7). Tobacco farm owners should inform their employees of the hazards associated with harvesting wet tobacco and the importance of safe work practices in preventing GTS; discuss routes of exposure and symptoms associated with the disease; advise workers to change into clean, dry clothing and boots during the work day if these become wet; and allow flexible work hours to avoid work during or immediately after a rainfall. Health-care providers in areas where tobacco is harvested should consider GTS in workers who present with symptoms similar to those reported here.

To determine whether GTS regularly occurs or whether this outbreak was due to an unusually wet growing season, the OHNAC project of Kentucky will continue active surveillance for GTS in local hospitals and clinics during tobacco growing seasons. The Kentucky Department for Health Services will disseminate information on GTS to health-care professionals and institutions statewide. Workers will be informed about the condition and preventive measures through the Cooperative Extension Service and through press releases to community newspapers.

References

1. Gehlbach SH, Williams WA, Perry LD, Woodall JS. Green tobacco

sickness: an illness of tobacco harvesters. JAMA 1974;229:1880-3.

2. Ghosh SK, Parikh JR, Gokani VN, Kashyap SK, Chatterjee SK. Studies on occupational health problems during agricultural operation of Indian tobacco workers. J Occup Health 1979;21:45-7.

3. Gehlbach SH, Perry LD, Williams WA, et al. Nicotine absorption by workers harvesting green tobacco. Lancet 1975;1:478-80.

4. Goodman AG, Rall TW, Nies AS, Taylor P, eds. Goodman and Gilman's -- the pharmacological basis of therapeutics. New York: Pergamon Press, 1975:548.

5. United States Department of Agriculture/Kentucky Department of Agriculture. Kentucky agricultural statistics, 1991-1992. Frankfort, Kentucky: Kentucky Department of Agriculture, 1992.

6. Gehlbach SH, Williams WA, Freeman JI. Protective clothing as a means of reducing nicotine absorption in tobacco harvesters. Arch Environ Health 1979;34:111-4.

7. Ghosh SK, Gokani VN, Doctor PB, Parikh JR, Kashyap SK. Intervention studies against "green symptoms" among Indian tobacco harvesters. Arch Environ Health 1991;46:316-7.

• OHNAC is a national surveillance program conducted by CDC's National Institute for Occupational Safety and Health (NIOSH) that has placed public health nurses in rural communities and hospitals in 10 states (California, Georgia, Iowa, Kentucky, Maine, Minnesota, New York, North Carolina, North Dakota, and Ohio) to conduct surveillance of agriculture-related illnesses and injuries that occur among farmers and their family members. These surveillance data are used to reduce the risk for occupational illness and injury in agricultural populations. ** The denominator for this rate is based on an estimate of 78.8 person-hours worked per acre during tobacco harvest, the number of acres planted with tobacco, and an estimate of 256 harvest-hours worked annually per worker (the median value reported in the Kentucky GTS case-control study). These figures generated an estimate of 4730 tobacco-harvest workers in the five affected counties, of whom 47 sought medical treatment at local hospitals.

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