They are a popular accessory for parents hoping to keep their children entertained on long car journeys.
But back-seat DVD players could kill a child in a crash at only 28km/h, safety tests have shown.
The screens, commonly strapped to the back of front seats and costing a few hundred dollars, can easily fly off in a collision, hitting rear passengers in the head. The problem relates to systems bought as accessories rather thanĀ those built into headrests.
In a simulated collision, the DVD screen was sent hurtling from the front seat headrest into the head of a crash-test 'baby' sitting in a child safety seat in the back.
The test showed mobile phones and satellite navigation systems in holders attached to the dashboard or windscreen could also fly loose, hitting passengers' legs and feet.
The phone holders, which are fixed to the interior using suction pads, stayed in place, but the phones inside were thrown out.
A satnav system in a similar holder remained in place, but one attached to an air vent flew through the car.
The tests were carried out in Klettwitz in Germany by the safety body DEKRA.
A popular DVD player was fixed to the back of the front seats with a velcro strap. The device was fitted according to the manufacturer's instructions and the strap was in pristine condition.
But when the car was hit from behind at just 28km/h, the velcro fastening came apart causing the DVD player to fly off. The problem was highlighted in the motoring magazine Auto Express.
A spokesman for the magazine said āMust-have gadgets, including mobile phones, satnavs and in-car DVD players, can be lethal."
āIn the crash test, the velcro fastening was torn from the bag and the player hit the dummy's head.ā