School pupils have been warned that a bizarre new trend of snorting Smarties could result in nasal maggots, lung infections and internal bleeding.

Parents at Portsmouth Middle School in Rhode Island received an email outlining the health risks of their children snorting or smoking sweets.

The reports of these trends began circulating in 2007, but the effects have largely remained unknown. As seen in YouTube videos, students crush the sweets and use rolled-up paper to snort the powder. To smoke sweets, children crust the sweets in the wrapper, before inhaling and exhaling the particles.

According to the school, the consequences could be dire. Some parents have criticised the letter for being "hysterical" and scaremongering.

John McDaid, a father and blogger, made the email public to warn other parents of the effects.

It read: "We have recently become aware of an unsafe, new trend among some of our middle school students - smoking or snorting the candy, Smarties.

"Our research has taught us this is a widespread phenomenon and is the subject of many YouTube videos."

The email continues on to list the dangers of the trend, such as fragments of the sweets which "act like razor blades cutting the tissue with which they come in contact".

Infection is also a risk, as the "sugar residue may remain in the nasal cavity, sinuses and/or lungs". The residue could lead to infections, coughing, wheezing, and possible respiratory arrest.

As well as scarring of the nasal cavity and irritation of the lungs, the letter suggests snorting sweets could lead to nasal maggots.

It reads: "Dr Oren Friedman, a Mayo Clinic nose specialist, has cautioned that frequent snorting could even rarely lead to maggots feeding on the sugary dust wedged inside the nose."

The action may also be a "precursor to future cigarette smoking and drug use". Although there is no solid evidence, there are fears the behaviour may tempt young people into smoking later in life.