New research indicates even small amounts of so-called "gender bender" chemicals can cause preschool children to switch their traditional gender roles.

In a long-term study, Erasmus University Rotterdam researchers measured the levels of polychlorinated biphenyls (PCBs) in the blood and breast milk of 207 mothers during various phases of maternity, then asked the parents involved to report on their children's behavior seven years later.  The findings indicate that girls whose mothers had higher PCB levels were more likely to play with guns and pretend to be soldiers, while boys were more likely to play with dolls and wear female clothing (Geoffrey Lean, London Independent, Oct. 20).

The report follows a recent warning by the World Health Organization that the long-term effects of gender-benders could wreak havoc on human health and fertility.

The Dutch researchers also examined dioxin levels, which were found to increase traditionally feminine activity in both sexes (Tim Utton, London Daily Mail, Oct. 21).  The researchers discovered that both PCBs and dioxins in even routine amounts induced gender-role changes.

PCBs have previously been found to cause hermaphroditism in wildlife.  Although the chemicals have been banned in industrialized countries, nearly 1.5 million metric tons of PCBs contained in paint, plastics and other materials are said to have been spread around the world, persisting in the environment and in body fat.  In previous studies, scientists have blamed the chemicals for damage to children's immune systems, neurological development and intelligence (Lean, London Independent).