TUESAY September 2, 2008 (foodconsumer.org) -- Fish used to be one of the best foods you can eat in the world.   Environmental pollutants may have changed its status.   A new study warns that PCBs in fish can be a concern for childbearing women.

A study published online on August 21, 2008 American Journal of Epidemiology showed that contaminants PCbs in fish may affect fatal growth resulting in low birth weight.

The Danish study was meant to examine the association between fatty fish intake and plasma concentrations of polychlorinated biphenyls (PCBs) in childbearing women and also the association between maternal PCB concentrations and fetal growth.

For the study, T. I. Halldorsson at Statens Serum Institut in Denmark and colleagues selected 100 nulliparous women age 25 to 35 from 70,000 women who participated in the Danish National Birth Cohort between 1996 and 2002 based on their intake of fatty fish.

The researchers found women with high intake of fatty fish (more than 4 meals per month) had 50 percent higher plasma PCB concentrations than those with low intake (0 meals per month).

They also found maternal plasma PCB concentrations were inversely linked with birth weight and placental weight.   The difference between 75th and 25th PCB percentiles was -155 gram for birth weight and -81 gram for placental weight.

Previous studies showed similar results while it's often recommended that fatty fish should be consumed weekly.

The researchers said the results suggest that the potential exposure of PCBs should be carefully weighed when considering to recommend such intakes for women of childbearing age.

PCBs was a common group of chemicals used as flame retardants. It was banned in 1970s, but it persists in the environment.