WASHINGTON — Bronx Rep. Ritchie Torres is asking the Drug Enforcement Administration for information after local health officials detected elephant tranquilizer carfentanil and veterinary anesthetic medetomidine in New York City street drugs.

Carfentanil, a more powerful cousin of fentanyl, was found in small quantities in eight samples of local opioids between March and June, including two cases in which the user overdosed, according to the city’s Department of Health and Mental Hygiene.

Medetomidine was found in one Bronx sample in June.

“I am writing to inquire about the actions that the Drug Enforcement Administration (DEA) has taken or will take to disrupt the supply chains that perpetuate the spread of carfentanil in America’s largest city,” Torres (D-NY) wrote to DEA administrator Anne Milgram.

“The spread of carfentanil, even in the barest quantities, would make the deadliest drug crisis far deadlier— by orders of magnitude,” Torres wrote.

“Given the growing presence of carfentanil in NYC and the profound threat it poses to both public safety and public health, I am seeking clarity about the DEA’s law enforcement efforts in relation to combating carfentanil supply chains.”

The composition of street drugs and the risk they pose to users has evolved significantly over time — sending US overdose deaths to an all-time high in 2022.

National and New York state fatalities dipped only slightly last year, according to preliminary data.

The evolving chemical composition of street drugs has created issues for detection and treatment.

New York City health officials warned in a recent alert that carfentanil, an extremely potent synthetic opioid, “was not detected via point-of-care drug-checking technologies” such as fentanyl test strips “due to the technologies’ limitations” and was instead found “through secondary laboratory testing.”

All eight of the samples also contained fentanyl, which can kill in doses as small as about 10 grains of table salt, the local officials said.

The city’s Office of the Chief Medical Examiner says carfentanil was detected in at least seven cases of fatal drug overdoses between January and June 2024 — up from three known instances from 2023.

Medetomidine, meanwhile, was found in late June in a sample that also contained fentanyl, the health officials said.

The presence of medetomidine is potentially troubling because its effects can be similar to opioids, but it cannot be treated with the opioid antidote naloxone.

Medetomidine “is similar to xylazine” — a veterinary painkiller and muscle relaxant commonly cut into street drugs since about 2020 — “but is more potent and causes longer-lasting effects,” city officials said.

Health officials recommend “rescue breathing” if apparent overdose victims do not respond to naloxone due to the possible effects of xylazine and medetomidine.

Xylazine is detected most commonly in the Northeastern US, according to federal data, with reports from 2022 showing particular prevalence in New Jersey, though not New York.

The precise contribution of various compounds to overdoses is muddied by the fact that toxicology reports don’t always test for all potential substances or describe their specific analogs.

Carfentanil’s potential impact has been feared for as long as fentanyl has been prevalent, but it has not eclipsed its better-known relative — though research has shown it has at least contributed significantly to fatal overdoses in some parts of the country.

A study of drug overdoses in Cuyahoga County, Ohio, which includes the city of Cleveland, found that fentanyl was present among 90% of the 543 overdose victims in 2017, with carfentanil present in 35% of cases, often overlapping.

Opioid addicts largely turned to heroin and other street drugs following the tightening controls on OxyContin and related pain medications — which had been aggressively marketed and heavily dispensed legally, hooking Americans through broad dispensation peaking in 2010.

Heroin in turn increasingly became cut with — or entirely supplanted by — fentanyl and related synthetic compounds made largely in China, tripling US opioid overdose deaths over the past decade, with users of unrelated drugs such as cocaine and counterfeit prescriptions also stricken by doses of the cheap import.