Parents are warned to keep children and animals away from a white waxy substance after it washed up on Polzeath beach.
The latest pollution comes after reports of white and yellow waxy substances being washed up on a number of South Cornwall beaches in October.
Cornwall Council said it was informed of the incident following the death of a dog on December 11 and "immediately" erected warning signs on the beach.
Adding that this is the fourteenth report of substances being washed up on beaches in Cornwall over the past two months.
Staff from the Council are working closely with the Maritime and Coastguard Agency, Environment Agency and Natural England to monitor the situation and are on stand by to take further action if required.
A spokesman said: "Members of the public are asked to report any sightings of substances being washed up on any beach in Cornwall to the council as quickly as possible and to ensure that children and dogs are kept away from the material."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here