HEARING TO EXCLUDE POSITIVE MARIJUANA URINE SCREEN
A thirty-four year old male sustained a crushing injury in the course of his employment. A timely urine drug screen was reported as positive for marijuana. Realizing that the urine drug screen did not establish drug-related impairment at the time of the accident, the workers' compensation carrier elected not to deny benefits. After paying very substantial treatment and rehabilitation costs, a charge back to the employer was made. The employer filed suit against the insurance carrier based partially on failure to deny benefits.
PLAINTIFF POSITION: The employee was impaired at the time of the accident. Plaintiff expert, a qualified Medical Review Officer (MROCC) opined the positive screening test for marijuana metabolites exceeding 50 ng/ml of urine established impairment at the time of the accident.
DEFENSE POSITION: The urine drug screen failed to establish, in reasonable medical probability, the existence of impairment at the time of the accident.
DISCUSSION: The issues involved were submitted to binding arbitration at which time the defense expert testified that the urine test should not have been reported as positive without performance of a confirming qualitative test, preferably gas chromatography/mass spectroscopy, with quantitation. Even if confirmed, the results cannot be correlated with impairment but serve only to establish marijuana having been used sometime during the preceding three or more weeks. Appropriate documentation from the scientific literature was submitted to the examiner.
CONCLUSION: Final briefs omitted the urine drug test and resolution was based on other issues.
The common practice of random and post-accident urine drug tests for marijuana and other drugs of abuse was implemented pursuent to Federal Drug Policy to achieve a drug-free society through the ability to detect users of illicit drugs and not for determination of impairment. The only scientifically supportable application when performed in compliance with the National Institute on Drug Abuse recommended procedures is to eliminate any possible involvement of drugs. If positive and quantitated, such tests might establish drug use being so remote in time that an accident occurring only hours prior to urine collection was not influenced by drug use.
NOTES: The subjective high after a single marijuana cigarette peaks at about thirty minutes and disappears within four hours (Hollister, 1981; Chiang, 1984). Marijuana metabolites appear in urine after cessation of use for an average of 13 days with a range of nine to 25 days (Schwartz, 1985). Half life for urinary excretion of metabolites is approximately 50 hours (Hunt, 1980). Urinary persistence of marijuana metabolites is a function of the sensitivity of the analysis. With a cutoff of 20 ng/ml, positive urines may occur for as long as 46 consecutive days. Average excretion time is 27 days (Ellis, 1985). Detection of the carboxylic acid derivative in urine has no relationship to impairment and no quantifiable determination of time of use can be derived from urine tests for metabolites (Morgan, 1988).
Eric G. Comstock, M.A., M.D., DABMT, FACMT, FAACT, FACOEM, expert for the defense (9317)
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BIBLIOGRAPHY:
Chiang C, et al. Marijuana Effect and Delta-9-Tetrahydrocannabinol Plasma Level. Clin Pharmacol Ther 36:234-238, 1984.
Ellis GM Jr., Mann MA, Judson BA, et al. Excretion Patterns of Cannabinoid Metabolites after Last Use in a Group of Chronic Users. Clin Pharmacol Ther 38:572-578, 1985.
Hollister LE, et al. Do Plasma Concentrations of Delta-9-Tetrahydrocannabinol Reflect the Degree of Intoxication? J Clin Pharmacol Rev 23:273-278, 1981.
Hunt CA, et al. Tolerance and Disposition of Tetrahydrocannabinol in Man. J Pharmacol Exp Ther 215:35-44, 1980.
Morgan JP. Marijuana Metabolism in the Context of Urine Testing for Cannabinoid Metabolite. J Psychoactive Drugs 20:107-115, 1988.
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