LONDON, Sep 24, 2001 (Reuters) - British doctors called Monday for routine blood screening of children with behavioral and learning problems, saying high levels of lead could be the cause.

Lead is a neurotoxin that has been blamed for a variety of learning problems in children, who can ingest up to three times as much of the mineral as adults by chewing on lead-bearing paint chips, objects and toys.

When doctors at the South & West Devon Health Authority in England measured lead levels in the blood of 69 children with behavior problems and compared them with 136 other youngsters, they found the problem youngsters had higher, and sometimes toxic, levels.

"Our results suggest that children with developmental and/or behavioral problems are more likely to have higher blood concentrations than the general childhood population," said Gill Lewendon.

She argues that screening children with behavior problems could help to pinpoint the cause and prevent further damage to the child's developing nervous system.

Simple and inexpensive blood tests are available, and there are effective methods for reducing children's blood lead concentrations.

"We argue that this group of children should be routinely screened for lead," Lewendon said in a report in the journal Archives of Disease in Childhood.

Experts estimate that as many as 1.7 million children in the United States alone are affected by lead poisoning.