Certain paper wrappers that are used for junk foods such as popcorn are leaving dangerous chemicals within foods, a recent study suggests.

Traces of chemicals were located within the blood of individuals who had eaten foods that were wrapped in paper packaging, according to new research by the University of Toronto.

Substances entitled perfluorinated carboxylic acids (PFCAs) were found in chemicals that are made when particular food products are being wrapped, including microwavable popcorn products.

Scott Mabury, the lead researcher and a professor in the department of chemistry at the University of Toronto, said: "Those chemicals called PAPs move into food, make it into humans upon ingestion and metabolically are transformed into the PFCAs."

Meanwhile, a Heart UK representative has said that dark chocolate can decrease cholesterol levels in people if it is the replacement for other sources of saturated fats.

The food contains flavonoids in its cocoa solids that can work as antioxidants, which are believed to help in preventing cholesterol being implanted in blood vessel walls.