A: Traditionally, screening for cannabis use in the workplace would test hair or urine samples. These sample types will detect past cannabis use; in the case of urine, this could be up to 30 days, and for hair, up to 90 days. The detection window of urine and hair is too long, which could cause employers difficulty retaining employees in the context of safe recreational or medical use outside of the workplace. Although not yet available, devices using breath collection can only detect use within about 2 hours; this detection window is too short to capture the window of cannabis impairment fully.
Saliva has emerged as the best sample for determining recent cannabis use. By using a 10 ng/mL cut-off for THC, the window of detection in saliva is about 10 hours. This aligns with the window of impairment, which lasts up to 8 to 10 hours or over the typical work day, helping to promote a safe workplace environment.
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