People are being warned to be extra vigilant after a man had to be treated in hospital because he cut himself on a hypodermic syringe in Pearson Park.
A 49-year-old man was using a hand rail in the popular facility when he suffered a small cut on October 24.
He looked at the rail to discover a syringe blue-tacked to the underside of the bar.
While police believe this is an isolated incident, they are urging members of the public to be careful.
A spokesman for Humberside Police said: "The victim received treatment at Hull Royal Infirmary for the cut.
"We have had no reports of similar incidents and believe it is isolated.
"However, those using the park should stay vigilant and report anything suspicious to the police."
Anyone with information can call Humberside Police on 101, quoting 2076384 or call Crimestoppers anonymously on 0800 555 111.
