Evidence and Research

Evidence and Research

Research Supporting Need-Based Syringe Exchange

The IRA provides services using a need-based, negotiated syringe exchange model.

Research has proven that 1-for-1 needle exchange does not have any effect on safe disposal of needles when compared to need based syringe access. Research also shows that 1-for-1 needle exchange results in increased sharing and reuse of needles when compared to need based syringe access. (SAP Study 1 SAP Study 2 SAP Study 3)

Research Concerning SAP Effectiveness

1. (Federal Research on Syringe Exchange Programs Proves Effectiveness) Between 1991 and 1997, the US Government funded seven reports on clean needle programs for persons who inject drugs. The reports are unanimous in their conclusions that clean needle programs reduce HIV transmission, and none found that clean needle programs caused rates of drug use to increase. The federal Department of Health and Human Services currently maintains a webpage on the effectiveness of syringe exchange programs is at http://www.samhsa.gov/ssp/, last accessed September 17, 2016.
National Commission on AIDS, The Twin Epidemics of Substance Abuse and HIV (Washington DC: National Commission on AIDS, 1991); General Accounting Office, Needle Exchange Programs: Research Suggests Promise as an AIDS Prevention Strategy (Washington DC: US Government Printing Office, 1993); Lurie, P. & Reingold, A.L., et al., The Public Health Impact of Needle Exchange Programs in the United States and Abroad (San Francisco, CA: University of California, 1993); Satcher, David, MD, (Note to Jo Ivey Bouffard), The Clinton Administration’s Internal Reviews of Research on Needle Exchange Programs (Atlanta, GA: Centers for Disease Control, December 10, 1993); National Research Council and Institute of Medicine, Normand, J., Vlahov, D. & Moses, L. (eds.), Preventing HIV Transmission: The Role of Sterile Needles and Bleach (Washington DC: National Academy Press, 1995); Office of Technology Assessment of the U.S. Congress, The Effectiveness of AIDS Prevention Efforts (Springfield, VA: National Technology Information Service, 1995); National Institutes of Health Consensus Panel, Interventions to Prevent HIV Risk Behaviors (Kensington, MD: National Institutes of Health Consensus Program Information Center, February 1997).

2. In 1998, Donna Shalala, then Secretary of Health and Human Services in the Clinton Administration, stated: “A meticulous scientific review has now proven that needle exchange programs can reduce the transmission of HIV and save lives without losing ground in the battle against illegal drugs.”
Shalala, D.E., Secretary, Department of Health and Human Services, Press release from Department of Health and Human Services (April 20, 1998).
http://archive.hhs.gov/news/press/1998pres/980420a.html

3. (NIDA Director Nora Volkow Endorses Effectiveness of Syringe Exchange in Reducing Risk of HIV Infection) “While it is not feasible to do a randomized controlled trial of the effectiveness of needle or syringe exchange programs (NEPs/SEPs) in reducing HIV incidence, the majority of studies have shown that NEPs/SEPs are strongly associated with reductions in the spread of HIV when used as a component of comprehensive approach to HIV prevention. NEPs/SEPs increase the availability of sterile syringes and other injection equipment, and for exchange participants, this decreases the fraction of needles in circulation that are contaminated. This lower fraction of contaminated needles reduces the risk of injection with a contaminated needle and lowers the risk of HIV transmission.
“In addition to decreasing HIV infected needles in circulation through the physical exchange of syringes, most NEPs/SEPs are part of a comprehensive HIV prevention effort that may include education on risk reduction, and referral to drug addiction treatment, job or other social services, and these interventions may be responsible for a significant part of the overall effectiveness of NEPs/SEPs. NEPs/SEPs also provide an opportunity to reach out to populations that are often difficult to engage in treatment.”
Nora Volkow, Director, US National Institute on Drug Abuse, correspondence with Allan Clear, “NIH Response on Harm Reduction and Needle Exchange,” Aug. 4, 2004.
http://proxy.baremetal.com/csdp.org/research/re_souderzerhou.pdf
http://hepcproject.typepad.com/hep_c_project/2004/09/re_souderzerhou.htm…

4. (US Surgeon General’s Determination of Effectiveness of Syringe Exchange Programs, 2011) “The Surgeon General of the United States Public Health Service, VADM Regina Benjamin, M.D., M.B.A., has determined that a demonstration needle exchange program (or more appropriately called syringe services program or SSP) would be effective in reducing drug abuse and the risk of infection with the etiologic agent for acquired immune deficiency syndrome. This determination reflects the scientific evidence supporting the important public health benefit of SSPs, and is necessary to meet the statutory requirement permitting the expenditure of Substance Abuse Prevention and Treatment (SAPT) Block Grant funds for SSPs.”
Sebelius, Kathleen, Secretary of Health and Human Services, “Determination That a Demonstration Needle Exchange Program Would be Effective in Reducing Drug Abuse and the Risk of Acquired Immune Deficiency Syndrome Infection Among Intravenous Drug Users,” Federal Register, February 23, 2011, Vol. 76, No. 36, p. 10038.
https://www.federalregister.gov/articles/2011/02/23/2011-3990/determinat…
http://www.gpo.gov/fdsys/pkg/FR-2011-02-23/pdf/2011-3990.pdf

5. (Centers for Disease Control on Syringe Exchange) “The basic service offered by SSPs [Syringe Services Programs] allows PWID [People Who Inject Drugs] to exchange used needles and syringes for new, sterile needles and syringes. Providing sterile needles and syringes and establishing appropriate disposal procedures substantially reduces the chances that PWID will share injection equipment and removes potentially HIV- and HCV-contaminated syringes from the community. Many SSPs have become multiservice organizations, providing various health and social services to their participants (8). HIV and HCV testing and linkage to care and treatment for substance use disorders are among the most important of these other services. The availability of new and highly effective curative therapy for HCV infection increases the benefits of integrating testing and linkage to care among the services provided by SSPs.”
Don C. Des Jarlais PhD, Ann Nugent, Alisa Solberg MPA, Jonathan Feelemyer MS, Jonathan Mermin MD, and Deborah Holtzman PhD. “Syringe Service Programs for Persons Who Inject Drugs in Urban, Suburban, and Rural Areas – United States, 2013,” Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report (MMWR) 2015;64:1337-1341.
http://www.cdc.gov/mmwr/pdf/wk/mm6448.pdf
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6448a3.htm

6. (Participation in Syringe Exchange Program and Entry Into Drug Treatment) According to a 1997 statement by the National Institutes of Health, “individuals in areas with needle exchange programs have an increased likelihood of entering drug treatment programs.”
National Institutes of Health Consensus Panel, Interventions to Prevent HIV Risk Behaviors (Kensington, MD: NIH Consensus Program Information Center, February 1997), p. 6.
http://consensus.nih.gov/1997/1997PreventHIVRisk104html.htm

7. (US Surgeon General’s Determination of Effectiveness of Syringe Exchange Programs) “After reviewing all of the research to date, the senior scientists of the Department and I have unanimously agreed that there is conclusive scientific evidence that syringe exchange programs, as part of a comprehensive HIV prevention strategy, are an effective public health intervention that reduces the transmission of HIV and does not encourage the use of illegal drugs.”
US Surgeon General Dr. David Satcher, Department of Health and Human Services, “Evidence-Based Findings on the Efficacy of Syringe Exchange Programs: An Analysis from the Assistant Secretary for Health and Surgeon General of the Scientific Research Completed Since April 1998,” (Washington, DC: Dept. of Health and Human Services, 2000), p. 11.
http://home.mchsi.com/~apclc/8fedstudies2.pdf

8. (How Syringe Exchanges Work) “Syringe exchange programs (SEPs) provide free sterile syringes and collect used syringes from injection-drug users (IDUs) to reduce transmission of bloodborne pathogens, including human immunodeficiency virus (HIV), hepatitis B virus, and hepatitis C virus (HCV).”
“Syringe Exchange Programs – United States, 2008,” Morbidity and Mortality Weekly Report (Atlanta, GA: US Centers for Disease Control, Nov. 19, 2010), Vol. 59, No. 45, p. 1488.
http://www.cdc.gov/mmwr/pdf/wk/mm5945.pdf

9. (Legal Access to Syringes) “Studies on behalf of the US government conducted by the National Commission on AIDS, the University of California and the Centers for Disease Control and Prevention, the National Academy of Science, and the Office of Technology Assessment all concluded that syringe prescription and drug paraphernalia laws should be overturned or modified to allow IDUs to purchase, possess, and exchange sterile syringes.”
Diebert, Ryan J., MPH, Goldbaum, Gary, MD, MPH, Parker, Theodore R., MPH, Hagan, Holly, PhD, Marks, Robert, MEd, Hanrahan, Michael, BA, and Thiede, Hanne, DVM, MPH, “Increased Access to Unrestricted Pharmacy Sales of Syringe in Seattle-King County, Washington: Structural and Individual-Level Changes, 1996 Versus 2003,” American Journal of Public Health, Vol. 96, No. 8, Aug. 2006, p. 1352.
http://ajph.aphapublications.org/cgi/reprint/96/8/1347.pdf

10. (Pediatrician Advocacy for Syringe & Needle Exchanges) “Pediatricians should advocate for unencumbered access to sterile syringes and improved knowledge about decontamination of injection equipment. Physicians should be knowledgeable about their states’ statutes regarding possession of syringes and needles and available mechanisms for procurement. These programs should be encouraged, expanded, and linked to drug treatment and other HIV-1 risk-reduction education. It is important that these programs be conducted within the context of continuing research to document effectiveness and clarify factors that seem linked to desired outcomes.”
“Policy Statement: Reducing the Risk of HIV Infection Associated With Illicit Drug Use,” Committee on Pediatric AIDS, Pediatrics, Vol. 117, No. 2, Feb. 2006 (Chicago, IL: American Academy of Pediatrics), p. 569.
http://pediatrics.aappublications.org/content/117/2/566.full.pdf

Research Concerning Basic SAP Data

11. (Services Offered by Syringe Services Programs / Syringe Exchange Programs) “Despite differences in program size, operating budgets, and staffing among SSPs [Syringe Services Programs] in rural, suburban, and urban locations, there were similarities in on-site services (Table 3). Most SSPs offered HIV counseling and testing (87% among rural SSPs, 71% among suburban SSPs, and 90% among urban SSPs) and HCV testing (67% among rural SSPs, 79% among suburban SSPs, and 78% among urban SSPs). A minority of SSPs reported having referral tracking systems for HCV-related care and treatment (33% of rural SSPs, 43% of suburban SSPs, and 44% of urban SSPs). Rural SSPs were less likely to provide naloxone (for reversing opioid overdoses) (37%) compared with suburban (57%) and urban (61%) programs that provided this service.”
Don C. Des Jarlais PhD, Ann Nugent, Alisa Solberg MPA, Jonathan Feelemyer MS, Jonathan Mermin MD, and Deborah Holtzman PhD. “Syringe Service Programs for Persons Who Inject Drugs in Urban, Suburban, and Rural Areas – United States, 2013,” Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report (MMWR) 2015;64:1337-1341.
http://www.cdc.gov/mmwr/pdf/wk/mm6448.pdf
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6448a3.htm

12. (Other Services Offered by SEPs) “In addition to exchanging syringes, SEPs provided various supplies, services, and referrals in 2008; the percentage of programs providing each type of service was similar for the period 2005–2008 (Table 3). In 2008, all SEPs provided alcohol pads, and nearly all (98%) provided male condoms. Most (89%) provided referrals to substance abuse treatment. Other services also offered by SEPs included counseling and testing for HIV (87%) and HCV (65%), and screening for sexually transmitted diseases (55%) and tuberculosis (31%). Vaccinations for hepatitis A and B were provided by nearly half the programs (47% and 49%, respectively).”
“Syringe Exchange Programs — United States, 2008,” Morbidity and Mortality Weekly Report (Atlanta, GA: Centers for Disease Control, November 19, 2010) Vol. 59, No. 45, p. 1489.
http://www.cdc.gov/mmwr/pdf/wk/mm5945.pdf

13. (OTC Availability of Clean Syringes) “Anti-OTC laws [laws against the over-the-counter sale or purchase of syringes without prescriptions] are not associated with lower population proportions of IDUs. Laws restricting syringe access are statistically associated with HIV transmission and should be repealed.
Friedman, Samuel R. PhD, Theresa Perlis, PhD, and Don C. Des Jarlais, PhD, “Laws Prohibiting Over-the-Counter Syringe Sales to Injection Drug Users: Relations to Population Density, HIV Prevalence, and HIV Incidence,” American Journal of Public Health (Washington, DC: American Public Health Association, May 2001), Vol. 91, No. 5, p. 793.
http://ajph.aphapublications.org/cgi/reprint/91/5/791.pdf

14. (Syringe Need and Availability) “Respondents reported injecting a median of 60 times per month, visiting the syringe exchange program a median of 4 times per month, and obtaining a median of 10 syringes per transaction; more than one in four reported reusing syringes. Fifty-four percent of participants reported receiving fewer syringes than their number of injections per month. Receiving an inadequate number of syringes was more frequently reported by younger and homeless injectors, and by those who reported public injecting in the past month.
Daliah I Heller, Denise Paone, Anne Siegler and Adam Karpati, “The syringe gap: an assessment of sterile syringe need and acquisition among syringe exchange program participants in New York City,” Harm Reduction Journal (London, United Kingdom: January 2009), p. 1.
http://www.harmreductionjournal.com/content/pdf/1477-7517-6-1.pdf

15. (SEP Program Components) “For injecting drug users who cannot gain access to treatment or are not ready to consider it, multi-component HIV prevention programs that include sterile needle and syringe access reduce drug-related HIV risk behavior, including self-reported sharing of needles and syringes, unsafe injecting and disposal practices, and frequency of injection. Sterile needle and syringe access may include needle and syringe exchange (NSE) or the legal, accessible, and economical sale of needles and syringes through pharmacies, voucher schemes, and physician prescription programs. Other components of multi-component HIV prevention programs may include outreach, education in risk reduction, HIV voluntary counseling and testing, condom distribution, distribution of bleach and education on needle disinfection, and referrals to substance abuse treatment and other health and social services.”
Committee on the Prevention of HIV Infection among Injecting Drug Users in High-Risk Countries, Institute of Medicine, National Academy of Sciences, “Preventing HIV Infection among Injecting Drug Users in High Risk Countries: An Assessment of the Evidence” (Washington, DC: National Academy Press, 2006), p. 175.
http://www.nap.edu/openbook.php?record_id=11731

Research Concerning Laws & Policies

(Modification and Partial Lifting of the Federal Ban on Funding of Syringe Exchange Programs, 2016) “SEC. 520. Notwithstanding any other provision of this Act, no funds appropriated in this Act shall be used to purchase sterile needles or syringes for the hypodermic injection of any illegal drug: Provided, That such limitation does not apply to the use of funds for elements of a program other than making such purchases if the relevant State or local health department, in consultation with the Centers for Disease Control and Prevention, determines that the State or local jurisdiction, as applicable, is experiencing, or is at risk for, a significant increase in hepatitis infections or an HIV outbreak due to injection drug use, and such program is operating in accordance with State and local law.
HR2029, “Consolidated Appropriations Act, 2016,” Passed by 114th Congress and Signed Into Law on December 18, 2015.
https://www.congress.gov/bill/114th-congress/house-bill/2029/text
https://www.congress.gov/114/bills/hr2029/BILLS-114hr2029enr.pdf

16. (Laws Restricting Syringe Availability) “Programs that provide access to sterile syringes have been proven time and again to reduce HIV transmission without either encouraging drug use or increasing drug related crime. Syringe exchange, as well as similar measures such as nonprescription pharmacy sale of syringes, is an effective and life-saving health intervention. Yet syringe exchange is banned in much of the United States and, where it is allowed, is obstructed by laws forbidding the possession of drug paraphernalia. Other modes of syringe access, such as nonprescription pharmacy sale of syringes, are as of this writing forbidden in five states: California, Massachusetts, New Jersey, Delaware, and Pennsylvania. Almost all fifty states have enacted drug paraphernalia laws similar to model legislation written by the Drug Enforcement Agency in 1979 under President Jimmy Carter. Drug paraphernalia laws are encouraged by United Nations anti-drug conventions, which call on governments to take aggressive law enforcement measures against illicit drug use.”
Human Rights Watch, “Injecting Reason: Human Rights and HIV Prevention for Injection Drug Users,” (September 2003)
http://www.hrw.org/reports/2003/usa0903/usa0903print.pdf

17. (Recommendation of British Advisory Council on Misuse of Drugs) “Recommendation 1. Local service planners need to review local needle and syringe services (and be supported in this work) in order to take steps to increase access and availability to sterile injecting equipment and to increase the proportion of injectors who receive 100 per cent coverage of sterile injecting equipment in relation to their injecting frequency.”
Advisory Council on the Misuse of Drugs, “The Primary Prevention of Hepatitis C Among Injecting Drug Users,” (London, United Kingdom: February 2009), p. 28.
https://www.gov.uk/government/uploads/system/uploads/attachment_data/fil…

18. (Syringe Access Through Pharmacies) “The purchase of syringes through pharmacies may be a major source of contact with the health service for some injectors, and the potential to exploit this contact point as a conduit to other services clearly exists. Work to motivate and support pharmacists to develop the services they offer to drug users could form an important part of extending the role of pharmacies, but to date only France, Portugal and the United Kingdom appear to be making significant investments in this direction.”
“Annual Report 2006: The State of the Drugs Problem in Europe,” European Monitoring Centre for Drugs and Drug Addiction (Luxembourg: Office for Official Publications of the European Communities, 2006), p. 79.
http://www.emcdda.europa.eu/attachements.cfm/att_37244_EN_ar2006-en.pdf

19. (Legality of Syringe Possession) According to a study in 1996, “Drug paraphernalia laws in 47 U.S. states make it illegal for injection drug users (IDUs) to possess syringes.” The study concludes, “decriminalizing syringes and needles would likely result in reductions in the behaviors that expose IDUs to blood borne viruses.”
Bluthenthal, Ricky N., Kral, Alex H., Erringer, Elizabeth A., and Edlin, Brian R., “Drug paraphernalia laws and injection-related infectious disease risk among drug injectors”, Journal of Drug Issues, 1999;29(1):1-16. Abstract available on the web at http://www.nasen.org/NASEN_II/research1.htm.
Pharmacy Access to Sterile Syringes

20. (Syringe Access Through Pharmacies) “Although most US states have legal restrictions on the sale and possession of syringes, pharmaceutical practice guidelines often allow pharmacists discretion in syringe sales decisions; this may lead to wide variation in syringe sales by individual pharmacists and to discrimination based on gender, age, race, ethnicity, or socioeconomic status. Individual-level factors associated with pharmacists’ relative willingness to sell syringes include familiarity with customers; concerns about deception, disease transmission, improperly discarded syringes, and staff and customer safety; business concerns, including fear of theft and harassment of other customers by IDU patrons; and fear of increased drug use because of easier syringe access.”
Diebert, Ryan J., MPH, Goldbaum, Gary, MD, MPH, Parker, Theodore R., MPH, Hagan, Holly, PhD, Marks, Robert, MEd, Hanrahan, Michael, BA, and Thiede, Hanne, DVM, MPH, “Increased Access to Unrestricted Pharmacy Sales of Syringe in Seattle-King County, Washington: Structural and Individual-Level Changes, 1996 Versus 2003,” American Journal of Public Health, Vol. 96, No. 8, Aug. 2006, p. 1347.
http://ajph.aphapublications.org/cgi/reprint/96/8/1347.pdf

21. (Over The Counter Syringe Availability) “The data in this report offer no support for the idea that anti-OTC laws prevent illicit drug injection. However, the data do show associations between anti-OTC laws and HIV prevalence and incidence. In an ongoing epidemic of a fatal infectious disease, prudent public health policy suggests removing prescription requirements rather than awaiting definitive proof of causation. Such action has been taken by Connecticut, by Maine, and, recently, by New York. After Connecticut legalized OTC sales of syringes and the personal possession of syringes, syringe sharing by drug injectors decreased. Moreover, no evidence showed increased in drug use, drug-related arrests, or needlestick injuries to police officers.”
Friedman, Samuel R. PhD, Theresa Perlis, PhD, and Don C. Des Jarlais, PhD, “Laws Prohibiting Over-the-Counter Syringe Sales to Injection Drug Users: Relations to Population Density, HIV Prevalence, and HIV Incidence,” American Journal of Public Health (Washington, DC: American Public Health Association, May 2001), Vol. 91, No. 5, p. 793.
http://ajph.aphapublications.org/cgi/reprint/91/5/791.pdf

Effectiveness, Effects, and Other Research

22. (SEPs and HIV Prevention) “Access to sterile needles and syringes is an important, even vital, component of a comprehensive HIV prevention program for IDUs. The data on needle exchange in the United States are consistent with the conclusion that these programs do not encourage drug use and that needle exchanges can be effective in reducing HIV incidence. Other data show that NEPs help people stop drug use through referral to drug treatment programs. The studies outside of the United States are important for reminding us that unintended consequences can occur. While changes in needle prescription and possession laws and regulations have shown promise, the identification of organizational components that improve or hinder effectiveness of needle exchange and pharmacy-based access are needed.”
Vlahov, David, PhD, and Benjamin Junge, MHSc, “The Role of Needle Exchange Programs in HIV Prevention,” Public Health Reports, Volume 113, Supplement 1, June 1998, p. 79.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1307729/pdf/pubhealthrep0003…

23. (SEPs and HIV) A literature review in 2004 by the European Union’s drug monitoring agency, the European Monitoring Centre on Drugs and Drug Addiction, found that “Major reviews (summarised in Vlahov and Junge, 1998; Bastos and Strathdee, 2000; Ferrini, 2000) suggest that NSPs (Needle and Syringe Programs) may reduce rates of seroconversion to HIV and hepatitis by one third or more, without negative side effects on the number of IDUs (Vlahov and Junge, 1998). A landmark study from Hurley et al. combined HIV seroprevalence data from 81 cities with (n=52) or without (n=29) NSPs (Hurley et al., 1997). They showed that the average annual seroprevalence was 11% lower in cities with an NSP than in cities without an NSP, providing important evidence on the effectiveness of NSPs in reducing the spread of HIV.”
de Wit, Ardine and Jasper Bos, “Cost-Effectiveness of Needle and Syringe Programmes: A Review of the Literature,” in Hepatitis C and Injecting Drug Use: Impact, Costs and Policy Options, Johannes Jager, Wien Limburg, Mirjam Kretzschmar, Maarten Postma, Lucas Wiessing (eds.), European Monitoring Centre on Drugs and Drug Addiction, 2004.

24. (SEPs and HIV) “We found that in cities with NEPs HIV seroprevalence among injecting drug users decreased on average, whereas in cities without NEPs HIV seroprevalence increased. A plausible explanation for this difference is that the NEPs led to a reduction in HIV incidence among injecting drug users.
“NEPs have the potential to decrease directly HIV transmission by lowering the rate of needle sharing and the prevalence of HIV in needles available for reuse, as well as indirectly through activities such as bleach distribution, referrals to drug treatment centres, provision of condoms, and education about risk behaviour. Although these mechanisms have strong theoretical support, the published evidence for NEP effectiveness is limited. Previous studies of the effect of NEPs on HIV incidence used observational designs or statistical models.
“Observational designs included case studies; crosssectional, serial cross-sectional, and cohort studies (often without comparison groups); and case-control studies.4,5 Only one study assessed the impact of NEPs on HIV incidence. Des Jarlais and colleagues7 estimated that the hazard for incident HIV infection was 3•3 for injecting drug users in four high-seroprevalence cities without NEPs, compared with continuous users of NEPs in New York City. One case study investigated HIV prevention activities for five cities with low seroprevalence, but did not formally compare these with other cities that had high seroprevalence.13 The most frequently cited statistical model for assessment of NEP effectiveness was developed by the New Haven NEP evaluators, and is based on the theory that NEPs decrease HIV transmission rates by lowering the time that needles are in circulation.14
“The conclusion of a 1993 review by a University of California team’ was that NEPs are associated with decreased HIV drug risk behaviour and are not associated with negative outcomes, but that there is no clear evidence that they decrease HIV infection rates.5 Few new data were available for the most recent US review by the Panel on Needle Exchange and Bleach Distribution Programs,4 which concluded that NEPs are effective, but acknowledged that the evidence was weak.
“Our study is distinguished from previous work by its worldwide scope and its design, which compares changes in HIV seroprevalence in cities with and without NEPs, rather than changes within a single city.”
Hurley, Susan F., Damien J. Jolley, John M. Kaldor, “Effectiveness of Needle-Exchange Programmes for Prevention of HIV Infection,” The Lancet, 1997; 349: 1797-1800, June 21, 1997.
http://www.druglibrary.net/schaffer/MISC/effectiveness_of_neps_for_preve…

25. (Syringe Access, Limits, and Infection Risk) “In multivariate analyses, we found that police contact was associated independently with residing in the area with no legal possession of syringes; among SEP users, those with access to SEPs without limits had lower syringe re-use but not lower syringe sharing; and that among non-SEP users, no significant differences in injection risk were observed among IDUs with and without pharmacy access to syringes.
“Conclusion: We found that greater legal access to syringes, if accompanied by limits on the number of syringes that can be exchanged, purchased and possessed, may not have the intended impacts on injection-related infectious disease risk among IDUs.”
Source:
Bluthenthal, Ricky N., Mohammed Rehan Malik, Lauretta E. Grau, Merrill Singer, Patricia Marshall & Robert Heimer for the Diffusion of Benefit through Syringe Exchange Study Team, “Sterile Syringe Access Conditions and Variations in HIV Risk Among Drug Injectors in Three Cities,” Addiction Journal, Vol. 99, Issue 9, p. 1136, Sept. 2004, abstract online at http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2004.00694.x/abst… last accessed June 8, 2013.

26. (Vulnerable Populations) “We found that a large proportion of SEP [syringe exchange program] participants in NYC do not obtain adequate numbers of syringes from the SEPs to meet their monthly injecting needs. In addition, characteristics of social marginalization and vulnerability – homelessness and public injecting – were associated with inadequate syringe acquisition. For SEP participants with inadequate coverage, most reported ‘not needing’ more syringes, but many also identified program limits and fear of police contact as main reasons for not obtaining adequate syringes at their most recent visit to the SEP.”
Daliah I Heller, Denise Paone, Anne Siegler and Adam Karpati, “The syringe gap: an assessment of sterile syringe need and acquisition among syringe exchange program participants in New York City,” Harm Reduction Journal (London, United Kingdom: January 2009), p. 4.
http://www.harmreductionjournal.com/content/pdf/1477-7517-6-1.pdf