Employee Drug Testing: Addressing Environmental Exposure Claims

June 23, 2021, 8:00 AM

Legalization of marijuana use has rapidly increased over the last decade. Since 2012, 16 states have legalized the use of recreational marijuana, and all but two states (Idaho and Nebraska) have legalized marijuana or its derivatives (e.g., CBD or THC) in some form. It is no surprise perhaps that over that same period, employment drug-test positivity rates have rapidly increased as well.

In data recently released by Quest Diagnostics, the drug-test positivity rate for THC has increased every year since 2016, with rates surging in states that have legalized recreational use of marijuana. Over that same period, positivity rates for amphetamines have also steadily increased.

Any drug that is smoked (primarily marijuana but also cocaine, methamphetamine, etc.) triggers questions of whether secondhand smoke can cause a drug-testing positive. Hair drug testing must deal with the question of environmental contamination since hair (unlike urine) is exposed to the environment. Confronted with rising drug-test positivity rates, employers can expect more secondhand smoke and environmental contamination claims from workers who test positive for drugs.

How can employers sort through claims of secondhand smoke and environmental contamination raised by individuals who dispute their positive test result?

To help discern between positive test results caused by intentional drug use versus those that arise from secondhand smoke and environmental exposure, employers can rely on several helpful tools such as Medical Review Officers (MRO) and sophisticated techniques used by reputable drug testing labs.

Medical Review Officers

An MRO is typically a licensed and board-certified physician responsible for receiving and reviewing non-negative test results generated by an employer’s drug testing program. MROs act as helpful intermediaries—contacting drug test-takers and providing them an opportunity to explain the non-negative drug test result. Under 49 C.F.R. § 40.137(a)-(b), MROs must " offer the employee an opportunity to present a legitimate medical explanation in all cases.”

For example, if an individual believes that his/her prescription medication was responsible for their drug test results, it is the MRO who will address such claims. MROs can also help debunk claims that a non-negative result could have been from secondhand smoke or alleged environmental factors.

Section 4.2(1) of the Medical Review Officer Guidance Manual for Federal Workplace Drug Testing Programs reads that: “If the donor does not admit to illicit use of a drug consistent with the test results…ask the donor if there is any possible explanation for the test result[.]” In most situations, it is impossible for secondhand smoke or environmental factors to have caused a positive drug test given the cutoffs used by reputable drug testing laboratories.

Relying on an MRO’s independent judgment and expertise can provide employers with an invaluable resource to determine whether positive test results arise from environmental factors.

Separately, MROs can protect employers from inadvertently learning about private health conditions of prospective or current employees, which might trigger affirmative legal duties, such as engaging in interactive process as required by the Americans with Disabilities Act (ADA).

Reputable Lab Techniques

Besides utilizing an MRO, employers should utilize reputable drug-testing labs to reduce any realistic claim that secondhand smoke or environmental factors triggered a “false positive.”

First, reputable labs will use industry-standard cutoffs to ensure that any drug testing positive is from intentional ingestion rather than secondhand smoke or environmental contamination. For instance, reputable urine testing labs typically use a cutoff concentration of 50 nanograms per milliliter (ng/mL) for marijuana.

If an individual has been exposed to secondhand marijuana smoke before taking a drug test, the test will likely yield a marijuana concentration that falls significantly below that cutoff level, and therefore reported as “negative.” Reputable hair drug testing labs also use washing techniques to address any environmental drug contamination.

Legal Response to Positive Test Results

Important to note here that medical or recreational marijuana use is intentional. As such, medical or recreational marijuana use will likely trigger a positive drug test since such intentional use will almost certainly yield results over the laboratory cutoff. The legal response to that positive test will depend on controlling state law.

For example, some states mandate certain accommodations for medical and even recreational marijuana use while others do not. An employer’s obligations may depend on whether the marijuana use was on or off the job, whether the employee possessed marijuana at work, was intoxicated by marijuana at work, whether the job at issue is safety-sensitive, etc.

As access to recreational drugs increases, so too will positive drug test results and claims that positive results arise not from intentional, but from environmental exposure. While employers cannot eliminate those types of claims, they can rely on reputable lab testing procedure and MROs to minimize the likelihood that a prospective or current employee can falsely claim environmental factors caused a positive test result.

This column does not necessarily reflect the opinion of The Bureau of National Affairs, Inc. or its owners.

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Author Information

Michael Clarkson, shareholder in Ogletree Deakins’ Boston office and co-chair of the firm’s Drug Testing Practice Group, is a leading voice on critical drug testing issues. He drafts compliant drug testing policies, advises on drug testing issues, and defends employers against “false positive” drug testing claims.

Ryan Mangum, associate in Ogletree Deakins’ Phoenix office, focuses primarily on employment law and litigation and represents employers in a broad range of matters including harassment, discrimination, and contractual disputes.

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