Flame retardant creates hyperactive mice

Flame retardant creates hyperactive mice


A commonly used flame retardant routinely found in people and house dust alters behavior and brain development in mice, causing hyperactivity and adjustment difficulties that worsened with age.


A chemical that makes electronics and other household products safe from fire disrupts behavior in mice, suggesting that the chemical alters brain development. The behavioral effects were seen at fairly low doses, were worse at the higher doses tested and grew stronger as the mice aged.

The findings indicate that very early life exposure to the chemical — called deca-BDE — has lasting effects on the brain. The chemical may affect behavior by interfering with a neurotransmitter — a nervous system signaling molecule — called acetylcholine.

Polybrominated biphenyl ethers, or PBDEs, are common flame retardant chemicals used in consumer products. Foam padding in furniture, upholstery and electronics can contain the fire reducing agents.

Deca-BDE is a specific, widely-used type of PBDE. Two other commercial PBDE mixtures — octa and penta — are largely banned or discontinued in the US and around the world.

This is one of the first studies to examine how deca-BDE might affect the brain. Other studies find brain development effects from exposure to other forms of PBDEs.

In general, PBDEs are released from products and contaminate the indoor and outdoor environments. Most exposure for adults and children is likely through food and dust.

Levels in dust are higher in US homes than in Europe, and may be particularly high in California, the state with the strongest furniture flammability standards. A recent study found that PBDE levels in California homes were 4-10 times higher than in other US homes and up to 200 times higher than in European homes.

The same is true for people. Americans have between 10 and 100 times higher PBDE levels in their bodies than Europeans and Japanese. Californians have twice as much in their blood as other Americans.

Male mice in this study ate a single dose of 1.4, 2.3, 14 or 21 micromoles deca-BDE per kilogram of body weight on their third day of life. Their behavior and  nervous system were evaluated when the mice were adults, at 2 and 4 months old.

The treated mice showed significantly more hyperactive behavior (locomotion, rearing and total activity) and decreased ability to adjust to new surroundings at both 2 and 4 months old. The differences were more pronounced at the higher doses for both age groups and worsened in the older group as the animals aged.

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