0151-2817-MTDC: Wildland Firefighter Health & Safety Report No. 3

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Wildland Firefighter Health & Safety Report

Spring 2001 MTDC No. 3

Risk Management

During the 80 years from
1910 to 1990, there were
four recorded deaths of
wildland firefighters
attributed to heat stroke.
Over the following decade,
from 1991 to 2000, three
firefighters died from heat
stroke, two on fires and one
during training.

Obesity and Heat Stress

Obese individuals have a lowered tolerance to heat. The excess weight compromises cardiac function by raising the work and metabolic heat, and by lowering fitness per unit of body weight. Heart rate at rest and during exercise is higher than in lean individuals. Obese individuals have a lower surface-area to body-mass ratio, which diminishes the body's ability to lose heat to the environment. In addition, there is an inverse relationship between sweat gland density and percentage of body fat, compromising the body's ability to lose heat by evaporative cooling. For a given heat load, the elevation in tissue temperature of obese persons is likely to be higher, increasing the likelihood of heat disorders. In a related report, workers were advised to maintain a body-mass index below 28 for work in the heat (Donoghue, A.; Bates, G. 2000. Occupational Medicine). Other factors associated with heat intoler-ance are low aerobic fitness, lack of acclimatization, heavy clothing, illness, and drugs.

Epstein, Y. 1990. Heat intol-erance: predisposing factor or residual injury? Medicine and Science in Sports and Exercise. 22: 29–35.

Drugs and Heat Intolerance

A number of therapeutic agents and drugs of abuse have been associated with heat intoler-ance. Alcoholism and the use of certain drugs are among the 10 major risk factors for heat illness in the general population. Amphetamines are among the most widely used drugs among active, healthy individuals. High body temperature and fatal heat stroke are relatively common occurrences in cases of acute amphetamine overdose.

Therapeutic agents include over-the-counter and prescription drugs such as: diuretics, laxatives, antihistamines, beta-blockers, tricyclic antidepressants, vasoconstrictors, and others.

Drugs of abuse include: amphetamines, cocaine, LSD, cannabinoids, opiates, and alcohol.

A number of pharmacologic agents interfere with the body's ability to maintain normal body temperature during work or under conditions of environmental heat stress. Life-threatening elevation of body temperature may occur. Workers using therapeutic agents or drugs of abuse should consult a physician or pharmacist before they return to work as wildland firefighters.

Vassallo, S.; Delaney, K. 1989. Pharmacologic effects on thermo-regulation: mechanisms of drug-related heatstroke. Clinical Toxicology. 27: 199–224.

Water Intoxication

Several reports have described hyponatremia (abnormally low concentration of sodium in the blood) as a result of excessive water intake during endurance races, due to a desire to prevent heat injury. The military has adopted hydration guidelines to maintain performance and minimize the risks of heat casualties. As military personnel increase their fluid intake, the risk of hypona-tremia as a result of water overload increases. Garigan's and Ristedt's paper reports the first known death of an Army trainee as a result of acute water intoxication. The misdiagnosis of his symptoms as those of dehydration and heat injury led to continued efforts at oral hydration until catastrophic cerebral and pulmonary edema developed.

Garigan, T.; Ristedt, D. 1999. Death from hyponatremia as a result of acute water intoxication in an Army basic trainee. Military Medicine 164: 234–238.

Note: Wildland firefighters require about 1 L of fluid per hour, which is consistent with the revised military hydration guidelines.

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T&D > T&D Pubs > Wildland Firefighter Health & Safety Reports > 0151-2817-MTDC: Wildland Firefighter Health & Safety Report No. 3 Table of Contents Back \| Next \| Cover Page Spring 2001 MTDC No. 3 Risk Management During the 80 years from 1910 to 1990, there were four recorded deaths of wildland firefighters attributed to heat stroke. Over the following decade, from 1991 to 2000, three firefighters died from heat stroke, two on fires and one during training. Obesity and Heat Stress Obese individuals have a lowered tolerance to heat. The excess weight compromises cardiac function by raising the work and metabolic heat, and by lowering fitness per unit of body weight. Heart rate at rest and during exercise is higher than in lean individuals. Obese individuals have a lower surface-area to body-mass ratio, which diminishes the body's ability to lose heat to the environment. In addition, there is an inverse relationship between sweat gland density and percentage of body fat, compromising the body's ability to lose heat by evaporative cooling. For a given heat load, the elevation in tissue temperature of obese persons is likely to be higher, increasing the likelihood of heat disorders. In a related report, workers were advised to maintain a body-mass index below 28 for work in the heat (Donoghue, A.; Bates, G. 2000. Occupational Medicine). Other factors associated with heat intoler-ance are low aerobic fitness, lack of acclimatization, heavy clothing, illness, and drugs. Epstein, Y. 1990. Heat intol-erance: predisposing factor or residual injury? Medicine and Science in Sports and Exercise. 22: 29–35. Drugs and Heat Intolerance A number of therapeutic agents and drugs of abuse have been associated with heat intoler-ance. Alcoholism and the use of certain drugs are among the 10 major risk factors for heat illness in the general population. Amphetamines are among the most widely used drugs among active, healthy individuals. High body temperature and fatal heat stroke are relatively common occurrences in cases of acute amphetamine overdose. Therapeutic agents include over-the-counter and prescription drugs such as: diuretics, laxatives, antihistamines, beta-blockers, tricyclic antidepressants, vasoconstrictors, and others. Drugs of abuse include: amphetamines, cocaine, LSD, cannabinoids, opiates, and alcohol. A number of pharmacologic agents interfere with the body's ability to maintain normal body temperature during work or under conditions of environmental heat stress. Life-threatening elevation of body temperature may occur. Workers using therapeutic agents or drugs of abuse should consult a physician or pharmacist before they return to work as wildland firefighters. Vassallo, S.; Delaney, K. 1989. Pharmacologic effects on thermo-regulation: mechanisms of drug-related heatstroke. Clinical Toxicology. 27: 199–224. Water Intoxication Several reports have described hyponatremia (abnormally low concentration of sodium in the blood) as a result of excessive water intake during endurance races, due to a desire to prevent heat injury. The military has adopted hydration guidelines to maintain performance and minimize the risks of heat casualties. As military personnel increase their fluid intake, the risk of hypona-tremia as a result of water overload increases. Garigan's and Ristedt's paper reports the first known death of an Army trainee as a result of acute water intoxication. The misdiagnosis of his symptoms as those of dehydration and heat injury led to continued efforts at oral hydration until catastrophic cerebral and pulmonary edema developed. Garigan, T.; Ristedt, D. 1999. Death from hyponatremia as a result of acute water intoxication in an Army basic trainee. Military Medicine 164: 234–238. Note: Wildland firefighters require about 1 L of fluid per hour, which is consistent with the revised military hydration guidelines. Top Back \| Next \| Cover Page
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