Drug Testing on the Job

Failed, diluted, or cancelled drug tests are on the rise in the workplace.

By Alexandra Walsh

There has been a recent trend of increasing rates of failed, diluted, or cancelled drug tests, particularly in workplace settings.

At the same time, the percentage of U.S. workers testing positive for marijuana continues to climb as more states legalize the drug for medical and recreational use. The number of workers cheating on these screens is also increasing.

Marijuana positivity in the general U.S. workforce (not including regulated, safety-sensitive positions) increased to 4.5% in 2023—up from 4.3% in 2022 and 3.1% in 2019—according to annual drug testing results compiled by Quest Diagnostics.

The percentage of U.S. workers testing positive for any illicit drug was 4.6%, the same as the previous three years and down precipitously from 13.6% in 1988, when workplace drug testing programs were initiated.

Changing Laws May Lead to More Use

While overall drug use as evidenced by workplace testing has remained flat, positive tests for marijuana continue to increase. After marijuana, workers most often test positive for amphetamines; opiates, which are on a downward trend over the last five years; and cocaine.

The increasing rates of tampered specimens and overall drug positivity may be linked to the growing societal acceptance and legalization of marijuana. Workers may be more likely to use marijuana and then attempt to conceal their drug use through tampering. This trend has been observed in both the general workforce and in safety-sensitive industries.

Currently, in the United States, cannabis is legal in 39 of 50 states for medical use and 24 states and Washington, D.C., allow for recreational marijuana use, according to the National Conference of State Legislatures. Marijuana remains a federally designated Schedule I drug, despite the Biden administration’s efforts to reclassify it as a less-dangerous Schedule III drug.

The rate of positive marijuana tests in states where the drug is legal under state law continues to outpace states where the drug remains illegal. States that have legalized recreational marijuana have seen the largest increases in positive tests. Among the regulated, safety-sensitive workforce, marijuana positivity decreased nationally from 0.98% in 2022 to 0.95% in 2023.

Cheating on the Rise

The significant rise in tampering with workplace drug tests typically takes one of two forms:

1. Replacing urine specimens with someone else’s urine or synthetic samples found online.
2. Submitting invalid specimens, suggesting they have been mixed with an additive.

About 6000 urine samples out of about 5.5 million collected from the general U.S. workforce in 2023 were classified as substituted. That was more than six times the rate from the previous year and was the highest rate ever recorded by Quest Diagnostics.

About 25,000 drug tests were classified as invalid, which could indicate that someone mixed a urine sample with an additive—which can be bought online—designed to hide drug use. Invalid tests were up 45% in 2023 compared with the prior year, marking the highest rate ever reported.

Choose secure collection sites that minimize the possibility of tampering or substitution.

Rethinking Drug Testing

Employers are rethinking their drug testing policies to navigate laws that vary from state to state. They are still drug testing, but there is a trend toward moving away from testing for marijuana, especially for pre-employment and random tests.

Experts contend rescheduling marijuana to Schedule III will not clear up the questions and challenges that employers face when enforcing their drug testing policies. That’s because if the rule is finalized, marijuana would likely be available for medical use with a prescription but still not legalized at the federal level.

It may take a long time for the U.S. Food and Drug Administration (FDA) to regulate marijuana. In the meantime, employees are already obtaining it under state laws at state-approved dispensaries.

Marijuana would most likely be regulated like a prescription drug. Employers can test for prescription medication if they are not penalizing people for lawful medication use. If someone is using a prescription drug without a prescription, employers can take an adverse action. Additionally, making marijuana a Schedule III drug still leaves a conflict with state recreational marijuana laws that permit use of marijuana without a medical prescription.

Implications for Employers

The rise in failed and tampered drug tests poses challenges for employers in maintaining a drug-free workplace. It also raises concerns about workplace safety and productivity.

To prevent tampered drug tests, employers should implement several key responsibilities and best practices:

1. Develop and implement a clear drug testing policy.

• Create a detailed, written drug-free workplace policy that outlines testing procedures, substances tested for, consequences for policy violations, and employee rights.
• Make sure all employees receive and understand the policy, potentially requiring written acknowledgment.
• Check that the policy and procedures comply with federal, state, and local laws.

2. Confirm proper specimen collection procedures.

• Use trained and certified specimen collectors who are knowledgeable about proper collection techniques and the chain of custody.
• Choose secure collection sites that minimize the possibility of tampering or substitution.
• In specific situations (return-to-duty, follow-up, suspected tampering), direct observation of the specimen collection might be required or warranted, according to the Department of Transportation.
• Implement and strictly adhere to chain-of-custody procedures to track the specimen from collection to the lab.
• Ensure proper sealing and labeling of specimens to prevent undetected tampering during transport.

3. Choose reputable and certified testing laboratories.

• Use laboratories certified by the Department of Health and Human Services.
• Select a lab with a proven track record of accurate and reliable drug testing results.

4. Involve a Medical Review Officer.

• Engage a qualified MRO to interpret test results and verify positive findings.
• Specify that the MRO maintains confidentiality and handles test results in accordance with legal and ethical guidelines.

5. Implement random drug testing.

• Random drug testing can serve as a deterrent to drug use and attempts to tamper with drug tests.
• Ensure random selection is truly random using a reliable, unbiased method.
• Determine appropriate random testing rates based on industry and company needs.

6. Train supervisors and employees.

• Train supervisors to recognize signs and symptoms of potential drug use and to understand the drug testing process.
• Educate employees on the company’s drug-free workplace policy and the consequences of violating it.

7. Maintain confidentiality and records.

• Secure confidentiality of drug test results and other related information.
• Maintain accurate and secure records of the drug testing process, including the chain-of-custody forms and test results.

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The increase in failed, diluted, or cancelled drug tests is a complex issue that in turn requires a versatile approach from employers and policymakers to address.

By implementing these practices, employers can minimize the risk of drug test tampering and maintain a safe and drug-free workplace.

Alexandra Walsh is the vice president of Association Vision, a Washington, D.C.–area communications company. She has extensive experience in management positions with a range of organizations.