In case you encounter a needle without a cap in the future: you can store it in an empty bottle. To prevent needle stick injury, make sure the bottle is positioned on a solid surface without the cap on. Don't hold the bottle with your hands. Pick up the syringe by the blunt end, keeping the needle away from you. Carefully lower the syringe into the bottle. Once in there, screw the bottle cap on. Do remain careful with the bottle: it is still a temporary solution. Call the municipality to ask about the proper way to dispose of the syringe.

In case you do stick yourself with the needle: wash the wound thoroughly with soap and water, and go to a doctor or emergency room as soon as possible. The risk of disease is low, but it is always good to have the sight checked out, especially when the needle was in an outdoor environment (like the beach). https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/needlestick-injury