Sharps disposal (revision 35)

Sharps disposal is the containment, transport and destructive treatment of used needles, cannulae, lancets, blades and other items capable of penetrating skin. In the regulatory frameworks of most jurisdictions such items constitute a distinct waste stream, separated from other clinical waste because the hazard they present is mechanical as well as infectious: a sharp can injure a handler through a bag that would safely contain a contaminated dressing.^[1]

The hazard is quantified through the epidemiology of occupational needlestick injury. Percutaneous exposure to blood carries a documented risk of transmission of hepatitis B, hepatitis C and HIV, with reported per-exposure probabilities differing between the three by roughly two orders of magnitude. Those figures underpin both the design requirements for sharps containers and the occupational rules that prohibit practices such as recapping.^[2][3]

Container standards specify puncture resistance, resistance to spillage when overturned, an aperture that admits a sharp but resists retrieval, a temporary closure and an irreversible final closure, and a legible fill line. The dominant international standard is ISO 23907-1; national schemes add colour coding that encodes the required treatment route, so that a container of sharps contaminated with cytotoxic medicinal product is routed differently from a container of clean lancets.^[4][1]

For an individual administering subcutaneous injections outside a clinical setting, the available routes are jurisdiction-dependent and frequently poorly signposted: pharmacy take-back, municipal household collection, mail-back services and clinical-waste contracts all exist in some places and not others. Household refuse is prohibited for sharps in many jurisdictions and permitted, subject to containment requirements, in others.^[5]

Definitions of sharp are functional rather than enumerative. Health Technical Memorandum 07-01, the waste-management guidance for the English health service, defines sharps as items capable of causing cuts or puncture wounds, and includes needles, cannulae, scalpel blades, broken glass ampoules, stitch cutters and lancets. The United States occupational standard defines contaminated sharps as any contaminated object that can penetrate the skin, listing needles, scalpels, broken capillary tubes and exposed dental wires.^[1][6]

Two boundary cases recur in the peptide-handling context.

Syringes without needles

A barrel from which the needle has been removed is not itself a sharp, but the act of removal is a recognised injury mechanism, and guidance therefore generally treats the assembled device as a single unit for disposal rather than encouraging separation.^[7]

Empty glass vials

A vial is not a sharp while intact. Broken glass is. Waste guidance in several jurisdictions accordingly treats pharmaceutical glass as sharps waste when it has contained a medicinal product, on the grounds that it will break in the waste stream.^[1]

The classification consequence of contamination with a medicinal product is significant and often overlooked. A needle used to inject a medicine is not merely infectious waste; it is infectious waste contaminated with a pharmaceutical, and in the European classification scheme that changes the applicable waste code and therefore the permitted treatment. Codes in chapter 18 of the European List of Waste distinguish waste whose collection and disposal is subject to special requirements in order to prevent infection — 18 01 03*, an absolute hazardous entry — from other clinical waste, and separate entries exist for cytotoxic and cytostatic medicines.^[1]

Sharps generated outside healthcare — by self-administration at home, by people who inject drugs, by veterinary use — fall outside occupational frameworks entirely and are addressed, where they are addressed at all, through municipal waste law and voluntary schemes. This is the principal reason authoritative guidance for a domestic user is harder to locate than the equivalent guidance for a hospital.^[5]

The evidence base for sharps regulation is the epidemiology of occupational percutaneous injury, which is unusually well characterised because it has been under structured surveillance in several countries for decades.

Figures are those given in the United States Public Health Service guidelines and are widely reproduced.^[2] Three features of the table shape practice. The ordering — hepatitis B far above hepatitis C, hepatitis C far above HIV — is the reverse of the ordering of public concern. The hepatitis B figures predate routine immunisation of healthcare workers and are not the current occupational risk where immunisation is universal. And all three are per-exposure figures conditional on the source being infected, so absolute risk in any population depends on prevalence.

Injury surveillance adds a second dimension: when injuries occur. Reports from the EPINet surveillance network and from national schemes consistently find that a substantial fraction of injuries occur after use and before disposal — during device disassembly, during transfer to a container, and from sharps left in unexpected places such as bedding, laundry or waste bags. Injuries during disposal itself, including from overfilled containers and from attempts to force a sharp into a full container, form a recognised subgroup.^[8][3]

This distribution is why the regulatory response is directed at the interval between use and containment rather than at the moment of injection. The prohibition on recapping needles by hand, the requirement that a container be available at the point of use, and the fill-line requirement all address that interval.^[6][9]

ISO 23907-1 specifies performance requirements and test methods for single-use sharps containers. Its requirements are functional and testable rather than descriptive, and the principal ones are:

• Puncture resistance of walls and base, tested by applying a defined force through a needle;
• Resistance to leakage and spillage, including when the closed container is dropped and when it is inverted;
• Aperture design that permits one-handed insertion of a sharp and resists its withdrawal or the insertion of a hand;
• Temporary closure that can be operated between uses and final closure that cannot be reopened without visible damage;
• Fill-line marking at a defined proportion of internal volume, conventionally three-quarters;
• Colour, labelling and the biohazard symbol, with a legible statement of contents;
• Stability so that the container does not overturn in normal use.

The standard replaced and harmonised a set of national specifications, of which the British Standard BS 7320 is the best known and is still referenced in older documents.^[4]

National colour coding encodes the treatment route rather than the hazard. The English scheme, set out in Health Technical Memorandum 07-01 and adopted widely in the United Kingdom, is representative:

A needle used to administer a peptide preparation falls in the yellow stream under this scheme, because it is contaminated with a medicinal product; a lancet used for capillary blood sampling falls in the orange stream.^[1]

Containers are regulated as medical devices in some jurisdictions. In the United States the Food and Drug Administration reviews sharps disposal containers intended for use with contaminated sharps, and consumer guidance directs users toward containers cleared for that purpose rather than improvised alternatives.^[5]

The three-quarters fill convention exists to preserve headroom, so that a sharp can be dropped in without contact with the contents and so that the container closes without compression. Injury reports associated with overfilled containers describe two mechanisms: contact with protruding sharps at the aperture, and puncture through the container wall when a full container is compressed during closure or transport.^[8][4]

The fill line is a marked feature under ISO 23907-1, which makes overfilling an observable rather than a judgement-based failure. Guidance therefore treats reaching the line as the trigger for closure regardless of elapsed time, and separately imposes a maximum period a container may remain open — commonly three months in United Kingdom practice — to limit the interval over which contents accumulate.^[1]

Once closed, a sharps container enters a regulated transport stream. Under the United Nations model regulations for the transport of dangerous goods, clinical waste of this kind is assigned to UN 3291, clinical waste, unspecified, n.o.s., in Class 6.2 (infectious substances), with packaging requirements that a compliant sharps container is designed to satisfy as an inner or single packaging within an outer container.^[10]

Treatment routes are incineration, steam sterilisation followed by mechanical destruction, or chemical disinfection with maceration. The choice is constrained by the contents: where a container may hold cytotoxic or cytostatic residues, high-temperature incineration is generally required, because autoclaving destroys pathogens but not pharmaceutical molecules. This is the practical reason the colour coding exists, and the reason mixing streams is treated as a compliance failure rather than a housekeeping one.^[1]

Routes available to an individual differ markedly by jurisdiction and, within jurisdictions, by locality:

Pharmacy or clinic return

Some jurisdictions require or encourage pharmacies to accept sharps generated by self-administering patients; others prohibit it, because accepting the waste makes the pharmacy a waste producer with attendant duties.

Municipal collection

Household hazardous-waste facilities and kerbside collection of sharps in supplied containers exist in some municipalities.

Mail-back services

Commercial schemes supply a container with prepaid return packaging that satisfies transport requirements. Availability depends on postal regulations for infectious substances.

Clinical waste contract

An individual may contract directly with a licensed carrier, which is the arrangement used by home-care services.

Household refuse

Prohibited for sharps in many jurisdictions. Where permitted, guidance generally requires a rigid, sealed, puncture-resistant container and explicitly excludes glass and plastic bottles.^[5]

The regulatory patchwork is itself a documented obstacle. Reviews of community sharps management have repeatedly found that a substantial proportion of self-injecting individuals report disposing of sharps in household refuse, and have attributed this primarily to the absence of a signposted alternative rather than to disregard of the risk.^[7]

Where compliant containers are unavailable, improvised rigid containers are widely used and widely described in guidance with varying degrees of approval. The failure modes are specific and are worth recording because they explain why particular substitutes are singled out.

• Plastic drink bottles fail on wall puncture resistance and on aperture geometry: the neck is narrow enough to require manipulation of the sharp near the opening, and the wall is thin enough for a needle to penetrate under modest force.
• Glass jars fail because breakage converts the container into additional sharps waste.
• Cardboard and thin-walled tubs fail on puncture resistance and on liquid retention.
• Metal tins resist puncture but generally lack an irreversible closure and may present a cutting edge when opened.
• Rigid opaque detergent containers with screw closures are the substitute most often tolerated in guidance where no alternative exists, on the grounds that they satisfy puncture resistance and closure even though they satisfy neither labelling nor aperture requirements.^[5][1]

• Subcutaneous injection
• Insulin syringe
• Syringe dead space
• Injection site rotation
• Peptide harm reduction
• Multi-dose vial

• World Health Organization. WHO Best Practices for Injections and Related Procedures Toolkit. Geneva (2010).
• Prüss-Üstün A, Rapiti E, Hutin Y. "Estimation of the global burden of disease attributable to contaminated sharps injuries among health-care workers." American Journal of Industrial Medicine 48(6):482–490 (2005).