Response 4045584

Response to request for information

Reference

4045584

Response date

7 July 2026

Request

I am writing as a follow-up to my recent Freedom of Information request regarding drug testing safeguards in substance misuse services commissioned or operated by your authority.

Since submitting that request, I have become aware of additional published evidence regarding the known limitations of immunoassay-based drug screening — the type of point-of-care test routinely used in workplace and service settings across the UK.

Specifically, peer-reviewed literature confirms that lawful, everyday substances can produce false positive results on these devices.
Documented sources of cross-reactivity include poppy seeds, over-the-counter CBD products, prescribed medications (including codeine, tramadol, gabapentin, and certain antidepressants), tonic water, bananas, passive or environmental exposure to cannabis smoke, and certain antihistamines — among others.

These are not theoretical risks. They are reproducible, documented in clinical and forensic toxicology literature, and well known to laboratory professionals.

In light of this, I am requesting the following additional information under the Freedom of Information Act 2000:

1. Is your authority (and/or its commissioned substance misuse service provider) aware of the cross-reactivity risks identified above? Has any assessment been made of the likelihood of false positive results from lawful sources when using immunoassay screening?
2. Does the applicable drug and alcohol testing policy require that all positive screening results are confirmed by a second, independent analytical method — specifically GC-MS or LC-MS/MS — before any disciplinary, safeguarding, or service-access decision is made?
3. If confirmatory testing is not routinely carried out, on what basis are positive screening results treated as definitive?
4. Has your authority (and/or its provider) received any complaints, grievances, or representations from individuals who attributed a positive drug test result to any of the lawful sources listed above?

If so, how many in the last three years, and what was the outcome?

5. What guidance, if any, has been issued to staff involved in drug testing about the possibility of false positives from lawful substances, and the appropriate steps to take before acting on a screening result?

Response

1. Is your authority (and/or its commissioned substance misuse service provider) aware of the cross-reactivity risks identified above? Has any assessment been made of the likelihood of false positive results from lawful sources when using immunoassay screening?
   • Yes, both ourselves and our provider are aware of the cross-reactivity risks. Our drugs and alcohol testing are undertaken by Synlab UK who will have their own safeguards and processes in place.
2. Does the applicable drug and alcohol testing policy require that all positive screening results are confirmed by a second, independent analytical method — specifically GC-MS or LC-MS/MS — before any disciplinary, safeguarding, or service-access decision is made?
   • The Council has a Alcohol and Substance Misuse Policy. Should an employee provide a non negative result from a “saliva / sweat” drugs test we use an external company to carry out a urine trust within two hours. The urine sample obtained by the external company will remain under the chain of custody conditions (this means the sample will be dealt with securely and that it cannot be tampered with). Once the urine sample is collected it will then be taken to a laboratory at Synlab UK for analysis.
3. If confirmatory testing is not routinely carried out, on what basis are positive screening results treated as definitive?
   • Not applicable, our non-negative drugs and alcohol test results are always followed up with a urine sample taken to a laboratory at Synlab UK for analysis.
4. Has your authority (and / or its provider) received any complaints, grievances, or representations from individuals who attributed a positive drug test result to any of the lawful sources listed above?
   • The Council have received two complaints within the last three years in relation to a drugs and alcohol confirmed laboratory result, these were confirmed by Synlab and an explanation provided to the employee.

If so, how many in the last three years, and what was the outcome?

5. What guidance, if any, has been issued to staff involved in drug testing about the possibility of false positives from lawful substances, and the appropriate steps to take before acting on a screening result?
   • The Council’s a Alcohol and Substance Misuse Policy and random and with cause drugs testing in our safety critical roles are covered in our tool box talks. The employees who carry out drug testing are also aware of the importance of stressing that the initial wipe test can come back as a non-negative and no results are confirmed as a positive until we receive the laboratory analysis.