Thyroid-disrupting chemicals found in Washington's Puget Sound

According to a recent study, most toxic pollution falling into Washington State's Puget Sound has decreased below earlier estimates. Despite the overall decline, the study found that industrial areas like Tacoma still have the highest air-deposited contamination levels in this area, including toxins that may cause thyroid and brain problems.

The study, which is conducted by researchers at the Department of Energy's Pacific Northwest National Laboratory (PNNL) and Texas A&M University at Galveston, found that the amount of trace metals like arsenic, lead and copper that fall onto the Tacoma region have decreased significantly since PNNL last measured air-deposited pollution there in 1991. However, other contaminants like polybrominated diphenyl ethers (PBDEs) showed no decline.

PBDEs have been used as flame retardants since the 1970s, but have only recently come under scrutiny for accumulating in humans and wildlife. Previous research showed that they may cause problems in the thyroid and alter brain development. This study showed that between 35 to 53 pounds of PBDEs enter the Puget Sound directly from the air each year.

"Regulations and increased public focus on pollution prevention appear to be paying off," said the study's lead researcher, PNNL marine chemist Jill Brandenberger. "But our awareness of some chemicals wasn't very high when those initial laws were passed decades ago. As a result, chemicals like flame retardants weren't included, allowing them to accumulate in the Puget Sound."