FOI request (FOIR-855045787)

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?