Estimating the Risk of Exposure to Fentanyl in New York City: Testing Drug Residue in Used Syringes

Abstract

Objectives. To estimate the risk of exposure to fentanyl among syringe exchange program (SEP) participants in New York City.

Methods. We recruited a convenience sample from 11 SEPs in New York City between March and June 2017. Consenting participants (n = 434) received a labeled syringe for their next injection. We tested collected syringes with gas chromatography–mass spectrometry and liquid chromatography–quadrupole–time-of-flight mass spectrometry. Fentanyl or fentanyl analogs detected in quantities greater than 10% of the residue mass were reported.

Results. The final analysis included 271 syringes; 46 (17.0%) contained fentanyl or a fentanyl analog. Fentanyl was the most frequently identified fentanyl compound, identified in 36 (13.3%) syringes. Furanylfentanyl was detected in 10 (3.7%) syringes, and 4-fluoroisobutyryl fentanyl was detected in 5 (1.8%) syringes.

Conclusions. The risk of exposure to fentanyl in syringes used by SEP participants was significantly lower significantly lower than the amount of fentanyls identified among overdose decedents in New York City. Further research is needed to understand how people who use drugs have adapted to fentanyl in the drug market. Understanding the risk of exposure to fentanyls is critical to development of targeted public health messaging.

Since 2010, rates of unintentional drug poisoning (overdose) deaths have increased steadily in New York City. In 2016, there were 1425 overdose deaths compared with 942 in 2015, an increase of 483 deaths (51%).¹ Fentanyl was involved in 16% of the overdose deaths in 2015, whereas fentanyl contributed to 44% of the overdose deaths in 2016.² Nationally, fentanyl is involved in a growing number of overdose deaths and seizures of illicit drugs.^3–5 New York City data mirror the Centers for Disease Control reports showing that the rate of overdose deaths involving synthetic opioids doubled in a single year.^6,7 In New York City, law enforcement seizures provided evidence that nonpharmaceutical fentanyl is present in heroin, cocaine, and methamphetamine.⁸

Despite evidence from mortality data that fentanyl is increasingly associated with overdose deaths and evidence from drug seizure data that fentanyl is present in the drug supply, the risk of exposure to fentanyl among people who use drugs is not known. Research also shows that many individuals are not aware of their risk for fentanyl exposure,⁹ further increasing overdose risk and highlighting the importance of estimating risk of exposure to fentanyl.

To estimate the risk of exposure to fentanyl among people who use drugs, we tested drug residue in syringes used by syringe exchange participants in New York City. Several previous studies have tested used syringes^10–12; however, to our knowledge, no comparable study has been conducted in the United States.

METHODS

We recruited a convenience sample from 11 syringe exchange programs (SEPs) in New York City from March to June 2017. Sample size calculations suggested that 300 individuals needed to be recruited to maintain a margin of error less than 0.05. Estimating that 20% of participants would be lost to follow-up, we aimed to recruit 380 individuals. Individuals were eligible if they were actively enrolled in the SEP, were current injection drug users, and were at least 18 years old. Participants were recruited from both mobile and storefront sites during regular exchange hours. Participants provided verbal informed consent to protect confidentiality.

Participants received a single study-specific, coded syringe and a roundtrip MetroCard to encourage return of the syringe the same or next day. On returning the used syringe, participants received an honorarium of $20. Interviewers were on site for data collection.

Drug residue in collected syringes was first tested at NMS Labs, a clinical and forensic toxicology laboratory, by rinsing the syringe barrels with a methanol wash that was used to perform an acid-base extraction to clean and concentrate the samples. The acid-base extracts were first tested with gas chromatography–mass spectrometry, at an expense of $391 per syringe. A portion of the acid-base extracts were transferred to the Center for Forensic Science Research and Education for analysis with liquid chromatography–quadrupole–time-of-flight mass spectrometry. A standard drug testing panel used liquid chromatography–quadrupole–time-of-flight mass spectrometry to test for 1790 substances such as pharmaceuticals, steroids, and illicit drugs, including fentanyl and 35 fentanyl analogs. Per expert recommendation, substances in quantities of 10% or more of the residue mass were reported to avoid reporting substances present in blood residue.

RESULTS

We recruited 434 participants into the study. A total of 359 syringes were returned and corresponded to a unique individual. Syringes from 2 participants who were not active SEP participants were excluded because of failure to meet inclusion criteria, resulting in 357 syringes sent for testing. One syringe was lost in transport and not tested.

Of the 356 syringes tested, 80 (22.5%) had no compounds detected, and 5 (1.4%) syringes contained only nonscheduled psychoactive compounds, such as caffeine and nicotine, leaving a total of 271 syringes in the final analysis (Table 1). Of the 271 syringes, 46 (17.0%) contained fentanyl or a fentanyl analog (“fentanyls”). Fentanyl was the most frequently identified fentanyl compound, identified in 36 (13.3%) of the tested syringes and 78.3% of the syringes containing fentanyl compounds. Other fentanyl analogs included furanylfentanyl in 10 (3.7%) syringes (21.7% of the syringes containing fentanyl compounds) and 4-fluoroisobutyryl fentanyl in 5 (1.8%) syringes (10.9% of the syringes containing fentanyl compounds). No other fentanyl analogs were detected. Syringes containing fentanyls were identified in all 5 New York City boroughs.

TABLE 1—

Drug Residue Testing Results From Syringes Used by Syringe Exchange Program Participants: New York City, March–June 2017

	Syringes, No. (%)
Syringes tested for toxicology	356 (100)
No compound detected	80 (22)
No controlled substance detected	5 (1)
Controlled substance detected	271 (76)
Syringes positive for controlled substances	271 (100)
Other psychoactive substance detected	225 (83)
Fentanyl or fentanyl analogs detected	46 (17)
Fentanyl or fentanyl analoga	46 (100)
Fentanyl	36 (78)
Furanylfentanyl	10 (22)
4-Fluoroisobutyryl fentanyl	5 (11)

^aSum of values will not equal total, because categories are not mutually exclusive.

DISCUSSION

In this study, the risk of exposure to fentanyls in syringes used by SEP participants was significantly lower than fentanyls identified among overdose decedents in New York City. Nonetheless, fentanyls pose an ongoing risk to people who use drugs.

Our findings are not directly comparable to those of previous studies that tested drug residue in syringes, because studies in other countries did not focus on fentanyl testing.^10–12 This may be the result of differences in drug markets in New York City and the United States compared with those in European countries and the influx of illicit fentanyls in the United States in recent years. To our knowledge, this study is the first of its kind in the United States to test drug residue in used syringes, as well as to focus on identifying fentanyls.

These findings have important implications for public health in the current opioid epidemic. Residue testing of syringes can estimate the risk of exposure to fentanyls in a particular population. Specifically, syringe testing complements drug seizure analysis to quantify the presence of fentanyls in the drug market. Health departments can request law enforcement testing data, specifying street-level purchases, to approximate what individuals who use drugs would be likely to use. Understanding the risk of exposure to fentanyls is critical to the development of targeted public health messaging. This is particularly urgent when people are unaware that fentanyls might be mixed into their drugs and unaware of the risk of overdose with fentanyls. Toxicology testing of syringes is expensive, so jurisdictions should consider collaborating with local law enforcement to obtain drug seizure data before embarking on a similar study.

Our study had several limitations. While obtaining consent, we informed participants that the study’s main purpose was to test for the presence of fentanyls; therefore, people who suspected that their drugs contained fentanyls may have been more likely to participate. We also recruited a convenience sample of SEP participants, limiting the generalizability of the sample. Although the laboratory screening panel tested for the most common fentanyl analogs, not all fentanyl analogs were included in the panel. Consequently, our results may have underreported the risk of exposure to fentanyls. Results also only indicate whether fentanyls were detectable in a syringe, not concentration or purity. Almost one quarter of tested syringes had no findings, limiting the precision of our estimates. Finally, results reflect exposure to fentanyls at a single point in time and may not mirror the rapidly changing drug market.

Although fentanyls were detected in approximately half of the New York City overdose decedents in 2016,² we found that 17% of used syringes tested at SEPs contained fentanyls. Although we cannot draw conclusions about SEP participants’ risk reduction practices, this population has been exposed to education on fentanyl, overdose prevention education, and risk reduction messaging. Thus, they may have adopted risk reduction practices. Further knowledge is needed to understand how people who use drugs are adapting to the presence of fentanyls in the drug supply, and universal risk reduction practices should be encouraged for people who use drugs.