Drug positivity rates fall 65% in the last decade
Drug positivity rates fall 65% in the last decade
Marijuana is most commonly found substance
Positive results from workplace drug testing in the United States have declined 65% in the past decade, according to data released recently by a company that provides a large portion of the testing services.
SmithKline Beecham Clinical Laboratories (SBCL) of Collegeville, PA, performed 5.7 million drug tests in 1998. The company reports that 4.8% were positive, down from 5.0% in 1997.
Big decline from 1980s
Those results follow the trend of the past 10 years, with current positivity rates way down from a decade earlier. The positivity rate for 1988, as reported by SmithKline Beecham in its workplace drug testing statistics, was 13.6%.
When broken down by testing reason, the highest positivity rates were in for-cause testing, with 25.3% testing positive in 1998, down from 26.7% in 1997. Those positivity rates are about three times the positivity rates for the next highest categories: random, return-to-duty, and post-accident.
Marijuana was the most commonly detected substance. (See bar graphs illustrating positivity and prevalence rates, at left.)
The results also give some indication of the extent of drug test tampering. More than 1,800 job applicants were reported as positive for the use of nitrites since April 1998, when SBCL initiated adulterant testing as a complement to workplace drug testing.
Nitrites sometimes are used as a masking agent in an attempt to defeat drug tests.
Western and South-eastern states are among the regions of the country with detection rates at or above average for nitrites. (For additional information on test rates, see graphs on positive results by drug category, inserted in this issue.)
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