The arrests came after a 30-year woman felt a sharp pain in her thigh, which was later confirmed as a puncture wound thought to have been inflicted by a hypodermic needle.
The report recommended the city install more trash cans and public toilets, provide soap, water and hand basins, step up waste collection, implement a vermin-control programme and monitor for hypodermic needle litter.
The youngster's parents believe he was stabbed by a fellow pupil with a discarded hypodermic needle, but school bosses say the instrument has never been found.
As part of the research, which was funded by The British Skin Foundation, volunteers received an injection by one of two types of micro-needle (of two different micro-needle lengths), or a 25-gauge hypodermic needle and syringe - the standard, or commonly used size - into one of their buttocks.
All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.