There are, as we know, a sizeable number of youngsters currently experimenting with all sorts of drugs in a very dangerous way

Les Vasey

The product - said to "empower people to get involved in drug rehabilitation in the privacy of their homes" - costs �10.

Mr Vassey said: "It's as easy as cleaning your teeth.

"We see it as a way of parents getting involved to make informed decisions.

"It's a way of determining what sort of risks someone is taking.

"It's also a way of demonstrating that people are clean.

"One of the complaints parents have is that they can't get involved effectively."

Family rows

But some believe the device could cause too much conflict between parents and their offspring.

One Bradford man said: "Kids try to hide that they're taking drugs at the weekend.

"If you force them to take the test they might leave home and get themselves into worse trouble."

But Mr Vasey said that parents could use the the kit while keeping the trust of their children.

"We're saying it has to be a partnership in every sense of the word.

"There are, as we know, a sizeable number of youngsters currently experimental with all sorts of drugs in a very dangerous way.

"Recently, and most disturbingly, this has been with Class A heroin.

"There are scenarios where parents want to get involved."