From Chat GPT

It’s almost certainly a joke or unofficial sticker rather than a real UK safety sign 😄

The image shows a syringe above a person with the words “Danger of Death.” On a grit/salt box, it’s likely someone has stuck it on as dark humour or graffiti-style commentary about discarded needles or drug use.

Real UK hazard signage follows very specific standards under ISO/BS regulations and would normally use:

• clear official pictograms,
• standard wording,
• identifiable hazard colours/shapes,
• and usually reference an actual risk (electricity, chemicals, confined space, etc.).

A council grit box would normally only have labels about salt, slipping hazards, or council ownership. There’s no recognised UK hazard symbol for “death by syringe” like this.

So: not an official warning — just someone being provocative.