In June 2024, drug checking programs in Portland and Philadelphia found something in the local fentanyl supply that nobody expected. It wasn’t a new synthetic opioid or a veterinary sedative. It was a plastics additive, an industrial chemical used to keep patio furniture and vinyl siding from breaking down in sunlight. Within two months it had spread across the country.
The chemical is BTMPS, and its arrival marks a genuinely strange turn in the drug supply. Adulterants usually make some sense: they’re cheaper drugs, bulking agents, or compounds that mimic the effect of the real thing. A UV light stabilizer for plastics fits none of those categories, and researchers are still working out why it’s there. What’s clear is that people using street opioids are now inhaling and injecting a substance that was never intended for human contact in any amount.
Key Takeaways
- BTMPS is a hindered amine light stabilizer sold commercially as Tinuvin 770, used to protect plastics and coatings from ultraviolet damage.
- It first appeared in the illicit drug supply in June 2024 and has since been detected in at least 22 states and all regions of the country.
- One forensic laboratory has found it in more than 600 tested drug materials.
- BTMPS is not approved for human or animal use, is not a scheduled substance, and has never been studied for human safety.
- Its presence has since been linked to the appearance of entirely new fentanyl-related substances in the supply.
What BTMPS Actually Is
The full chemical name is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate. According to the Department of Homeland Security’s fact sheet on BTMPS, it’s a hindered amine light stabilizer, often sold commercially as Tinuvin 770, and it’s used primarily in exterior industrial applications as a UV light stabilizer in plastics, adhesives, films, and coatings.
In its pure form, it’s a white crystalline solid with a melting point between 82 and 85 degrees Celsius. It’s largely insoluble in water. The version showing up in the drug supply is often the dihydrochloride salt, which dissolves more readily, a detail that matters because it makes the compound easier to mix into a product meant to be injected or smoked.
People who encounter it describe a distinctive and unpleasant sensory signature. DHS documented accounts from drug users describing a strong, pervasive odor resembling bug spray or plastic, along with rubbery, synthetic, or fishy smells. That description has become one of the informal warning signs circulating in harm reduction circles.
How Fast It Spread
The speed is what alarmed researchers. Researchers first detected BTMPS in June 2024 in Portland and Philadelphia. DHS reports it has since been observed in at least 22 states, including Illinois, North Carolina, New York, Wisconsin, Maine, Florida, Michigan, Oregon, Pennsylvania, Colorado, California, New Mexico, Virginia, Washington, and Ohio.
A May 2025 public alert from the Center for Forensic Science Research and Education, developed with the Drug Enforcement Administration, summarized the scale bluntly: BTMPS has been detected in all regions across the United States, demonstrating vast prevalence, and has appeared in more than 600 drug materials tested by that laboratory alone.
For a substance that didn’t exist in the drug supply before mid-2024, national saturation inside a year is an extraordinary trajectory. It suggests the contamination is happening upstream, at the manufacturing or wholesale level, rather than through local dealers adding something on their own.
Why Would Anyone Add It
Nobody knows for certain. Forensic scientists have been candid that the early detections were baffling, and several explanations remain under consideration.
- A bulking or cutting agent. The simplest theory. It’s cheap, available in industrial quantities, and adds weight.
- A perceived effect enhancer. Some have suggested it’s added because of a belief that it strengthens or extends fentanyl’s effects.
- A byproduct of synthesis. This theory gained ground. The CFSRE alert notes that BTMPS contains substituted piperidine rings, a core structural feature it shares with fentanyl.
That last point turned out to matter enormously. In early to mid-2025, forensic laboratories began detecting substances chemically linked to BTMPS, including tetramethyl-4-piperidinol, followed by compounds tied to fentanyl itself, including 4-AP and norfentanyl variants. CFSRE concluded that the emergence of these substances, combined with intelligence information, indicates the manufacture of fentanyl-related precursors, byproducts, and perceived intermediates from BTMPS.
In plain terms: clandestine manufacturers appear to be using BTMPS as a starting material to make fentanyl-like compounds. The chemical isn’t just being mixed in. It may be part of how the drug is now being made.
What It Does to the Body
Here’s the most uncomfortable part. DHS states directly that too few published studies are available to make human toxicity estimates. Meaningful human safety data don’t exist because no one ever imagined the need for it.
What exists comes from animal and laboratory work:
- The oral lethal dose in rats is 3,700 mg/kg, and the dermal lethal dose exceeds 3,170 mg/kg.
- The inhalation lethal concentration in rats is 500 mg per cubic meter over four hours.
- In one inhalation study at lower concentrations, no deaths occurred, but animals showed salivation, watering eyes, and changes in activity.
- Applied undiluted to skin, Tinuvin 770 acted as a primary irritant, and sensitization was seen in two of 50 human subjects tested.
The finding with the clearest relevance to overdose risk is pharmacological. DHS notes that BTMPS acts as an L-type calcium channel blocker. Calcium channel blockers affect heart rhythm and blood vessel tone, which is why they’re used as blood pressure medications. Introducing an unmeasured, unregulated calcium channel blocker alongside a potent respiratory depressant creates a combination with real cardiac potential, and one that nobody can dose or predict.
Recommended handling for BTMPS in industrial settings gives some sense of how it’s regarded outside the drug context: tightly fitting safety goggles, impervious gloves, protective clothing, and respiratory filtration.
Policy analysts have reached similar conclusions about the information gap. A fact sheet on BTMPS as an industrial chemical adulterant notes that it is not approved for use in humans or animals and is not a scheduled or regulated substance in the United States, which means there is no regulatory mechanism tracking it and no framework requiring anyone to study what it does to people who consume it.
There’s also a thermal question specific to how many people use these drugs. BTMPS loses mass when heated, with measurable decomposition beginning well below the temperatures reached when a substance is smoked. What that decomposition produces, and what someone inhales as a result, has not been characterized. Smoking an adulterated product is therefore not the same exposure as injecting it, and neither has been studied.
What This Means Practically
For anyone using street opioids, BTMPS adds another layer to a supply that was already unpredictable. It joins xylazine in the fentanyl supply and the arrival of nitazenes, which are more potent than fentanyl, as substances a person cannot see, taste reliably, or dose around.
Some practical realities worth being direct about:
- Naloxone still works on the opioid component of an overdose. It does not reverse BTMPS, xylazine, or any non-opioid adulterant, so a person may not fully wake up even after naloxone reverses respiratory depression. Call 911 regardless.
- Fentanyl test strips detect fentanyl. They do not detect BTMPS.
- The chemical smell people report is a signal worth taking seriously, though its absence proves nothing.
- Drug checking services, where available, can identify adulterants that individual testing cannot.
None of this makes ongoing use safe. It shows the supply has moved beyond what anyone can manage through caution. Recognizing the signs of an overdose in progress and having naloxone on hand are the immediate priorities for anyone still using or living with someone who is.
Why This Strengthens the Case for Medical Detox
The steady arrival of new adulterants has changed what withdrawal management involves. A person entering detox today may have been exposed to fentanyl analogs, xylazine, BTMPS, and compounds that haven’t been named yet, in unknown combinations and quantities. That affects the clinical picture in ways we are still mapping.
Supervised care handles that uncertainty in ways self-managed withdrawal cannot:
- Medical assessment can identify complications from adulterants, including the wounds associated with xylazine and cardiac irregularities that may relate to compounds like BTMPS.
- Continuous monitoring catches problems that don’t follow the textbook opioid withdrawal pattern.
- Withdrawal from an unknown mixture can involve more than one syndrome at once, which requires more than one treatment approach.
- Cardiac monitoring is available if it’s needed, which it may be more often as calcium channel blocking agents circulate.
The broader lesson from BTMPS is that the illicit supply is now shaped by industrial chemistry rather than by anything resembling a drug market with consistent products. Each new detection reinforces the same conclusion: the gap between what people think they’re taking and what they’re actually taking keeps widening, and the only way to close it is to stop taking it under medical supervision.
References
- BTMPS: An Industrial Additive in the Illicit Drug Supply – U.S. Department of Homeland Security, Science and Technology Directorate
- An Update on the Presence of BTMPS in the Drug Supply and the Discovery of Tetramethylfentanyl-Related Substances – Center for Forensic Science Research and Education
- Fentanyl – National Institute on Drug Abuse
- BTMPS: An Industrial Chemical Adulterant in the Illicit Drug Supply – Legislative Analysis and Public Policy Association
FAQs
Can a Fentanyl Test Strip Detect BTMPS?
No. Fentanyl test strips are designed to detect fentanyl and some of its analogs. They give no information about BTMPS, xylazine, or other adulterants. A strip that reads positive for fentanyl tells you nothing about what else is present.
Does Naloxone Reverse a BTMPS Overdose?
Naloxone reverses opioid effects only. It will not counteract BTMPS or any non-opioid adulterant, so someone may remain sedated or unresponsive after naloxone has restored breathing. Give naloxone anyway, since the opioid is usually what stops respiration, and call 911 every time.
How Would Someone Know if Their Supply Contains It?
Usually they wouldn’t. The most commonly reported clue is a strong chemical odor resembling bug spray, plastic, or something rubbery or fishy. That smell is a reason for concern, but its absence is not reassurance. Only laboratory drug checking can identify it reliably.
Is BTMPS Illegal?
BTMPS itself is not a scheduled or regulated controlled substance in the United States. It’s a legal industrial chemical sold for manufacturing use. Adding it to a controlled substance doesn’t change the legal status of the drug it’s mixed into.
Are There Long-Term Health Effects From Exposure?
Unknown, and that’s the concerning part. No human safety studies exist because the compound was never intended for human exposure. Animal data show adverse effects at high doses, including cardiac toxicity, and its activity as a calcium channel blocker raises questions about cardiovascular effects that have not been studied in people.
