Risk of Needlestick Injury in the Use of Plastic Bottles as Containers for Needle Disposal

Dear Editor,

Injection therapies are accompanied by the production of medical waste, the needles used for injection. Some medical personnel in Japan instruct patients to store used needles in plastic bottles made of polyethylene terephthalate (PET), and then bring the bottles containing the needles to medical institutions for disposal. Therefore, medical personnel who handle this waste must to be careful to avoid needlestick injury. ¹ The risk of needlestick injury has recently increased with the increasing use of ultra-thin light plastic bottles. Referred to as ECO-bottles, these bottles pose increased risk of protrusion and thus needlestick injury when used as medical waste containers because of their ultra-thin nature. Despite this risk, no clear guidelines have been established regarding the handling of containers, including plastic bottles, for disposal of used needles, and no reports have evaluated the risk of needlestick injury by protrusion of needles from plastic bottles.

This study assessed the extent of penetration by 5 commonly used types of needles (NovoFine 30G × 8 mm [Novo Nordisk, Bagsværd, Denmark], Ultra-Fine 31G × 5 mm [BD, NJ, USA], NovoFine 32G × 6 mm [Novo Nordisk], Ultra-Fine 32G × 4 mm [BD], and Nanopass 34G × 4 mm [Terumo, Tokyo, Japan]) into 3 types of plastic bottles (ECO-bottle A [produced in the United States], ECO-bottle B [produced in Japan], and non-ECO plastic bottle [as control bottle]). The size of plastic bottles was 500 ml. ECO-bottle was defined as an ultra-thin plastic bottle weighing less than 15 g in an empty state and a non-ECO plastic bottle as weighing more than 25 g in an empty state. To assess risk of needlestick injury from each type of bottle, 13 medical personnel pricked 3 areas (top, middle, and bottom) of each type of plastic bottle with each type of needle once in a perpendicular direction to judge penetration.

Figure 1 shows the results of investigation of extent of needle penetration into plastic bottles. The extent of penetration into an ECO-bottle A and an ECO-bottle B was found to be the same, regardless of the type of needle, and greater than that into a non-ECO plastic bottle. Therefore, the risk of needlestick injury by protrusion of needles from the ECO-bottles is higher than that from a non-ECO plastic bottle. Moreover, needles of any type (ie, diameter) are able to penetrate any type of plastic bottle, indicating that all types of plastic bottles are inappropriate for use as containers in which to collect used needles.

Figure 1.

Extent of needle penetration into 3 types of plastic bottles as evaluated by 13 independent researchers (a total of 39 pricks for each plastic bottle). *P < .01 vs non-ECO plastic bottle by Fisher’s exact probability test.

Almost all patients currently treated with injection therapies and who have visited our hospitals reported that they usually recap needles (n = 171/177, 96.6 %), as they are instructed to do so; however, the presence of uncapped needles in plastic bottles collected from some of the patients (data not shown) strongly indicates that patients do not always cap used needles. Furthermore, there is always the possibility that the caps may come off during transportation.

Health care practitioners must advise patients to use containers that are not vulnerable to needle penetration.

Additional Remark

Our results should not be interpreted as a suggestion that the further development of environmentally friendly plastic bottles should be terminated.

Human and Animal Rights

This study was approved by the ethics committee of Yashio Central General Hospital (No. 11). All procedures were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008.