IT MAY be one of the most loved activities of hyperactive children and the parents who love them: bouncing in a jumping castle.

But, according to Attorney-General Jerry Brown of California, it may also be toxic.

A lawsuit filed on Wednesday by Mr Brown's office claims that some of the inflatable bounce houses that help entertain - and exhaust - the young guests at children's parties have unsafe levels of lead, sometimes dozens of times the federal limit.

''I was surprised,'' said Mr Brown, who is running for governor in a state with 2.7 million children under five. ''But as we test more and more of these products, we find dangers.''

The suit was prompted by an investigation by the Centre for Environmental Health in Oakland, an advocacy group that tested dozens of jumping castles, concentrating on the vinyl that gives them their bounce.