signatures of the PBDEs themselves were not evaluated. The carbon-14 may instead be in methoxy groups enzymatically added to man-made PBDEs. A 2010 study found that children with higher concentrations of PBDE congeners 47, 99 and 100 in their umbilical cord blood at birth scored lower on tests of mental and physical development between the ages of one and six. Developmental effects were particularly evident at four years of age, when verbal and full IQ scores were reduced 5.5 to 8.0 points for those with the highest prenatal exposures after correcting for sex, ethnicity, tobacco smoke exposure, and mother's IQ. Sediment contamination Increasing environmental concentrations and changing distributions of PBDEs in sediments of the Clyde River Estuary in Scotland, UK have been assessed. Analysis of six sediment cores each of 1 m depth from Glasgow city to Greenock revealed that total concentrations increased toward the river bed surface (0–10 cm). Amounts of PBDE ranged from 1 to 2,645 µg/kg (dry wt. sediment) with a mean of 287 µg/kg (dry wt. sediment). Down-core PBDE congener profiles showed that higher concentrations were due to elevated levels of BDE-209. The majority of the sediment records clearly showed a change from mainly lower molecular weight BDEs 47,99, 183, 153 at lower depths to BDE-209 near the surface, a change in congener and homologue group patterns that corresponds to the restrictions of penta- and octaBDE commercial mixtures under EU law in 2004–2006. While biodegradation is not considered the main pathway for PBDEs, photolysis and pyrolysis can be of interest in studies of transformation of PBDEs. Regulations of PBDEs In August, 2003, the State of California outlawed the sale of penta- and octaBDE and products containing them, effective January 1, 2008. PBDEs are ubiquitous in the environment, and, according to the EPA, exposure may pose health risks. According to U.S. EPA's Integrated Risk Information System, evidence indicates that PBDEs may possess liver toxicity, thyroid toxicity, and neurodevelopmental toxicity. In June 2008, the U.S. EPA set a safe daily exposure level ranging from 0.1 to 7 ug per kg body weight per day for the four most common PBDE congeners. In April 2007, the legislature of the state of Washington passed a bill banning the use of PBDEs. The State of Maine Department of Environmental Protection found that all PBDEs should be banned. In May 2007, the legislature of the state of Maine passed a bill phasing