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Contaminants in Coastal Waters Decline Yet Concerns Remain

(Beyond Pesticides, May 19, 2008) A 20-year study by the National Oceanic and Atmospheric Administration (NOAA) shows that environmental laws enacted in the 1970s are having a positive effect on reducing overall contaminant levels in coastal waters of the U.S. However, the report points to continuing concerns with elevated levels of metals and organic contaminants found near urban and industrial areas of the coasts. The report, “NOAA National Status and Trends Mussel Watch Program: An Assessment of Two Decades of Contaminant Monitoring in the Nation’s Coastal Zone from 1986-2005,” findings are the result of monitoring efforts that analyze 140 different chemicals in U.S. coastal and estuarine areas, including the Great Lakes.“It’s interesting to note that pesticides, such as DDT, and industrial chemicals, such as PCBs, show significant decreasing trends around the nation, but similar trends were not found for trace metals,” said Gunnar Lauenstein, manager of the NOAA Mussel Watch program. “What is of concern is that there are contaminants that continue to be problematic, including oil-related compounds from motor vehicles and shipping activities.”

Significant findings from this report include the following:

  • Decreasing trends nationally of the pesticide DDT are documented with a majority of the sites monitored along the Southern California coast.
  • Decreasing trends also were found for the industrial chemicals PCBs. The Hudson-Raritan Estuary, one area of the country where some of the highest concentrations of these chemicals were found, now shows 80 percent of monitored sites with significantly decreasing trends for this pollutant.
  • Tributyl-tin (TBT), a biocide used as a compound to reduce or restrict the growth of marine organisms on boat hulls, was found to have greater than anticipated consequences as it affected not only the targeted organisms, but also other marine and fresh water life as well. First regulated in the 1980s, this compound is now decreasing nationally.

The NOAA Mussel Watch Program also quantifies contaminants that are still entering the nation’s waters and two major groups raise concern:

  • Oil related compounds (PAHs) from motor vehicles and shipping activities continue to flow into coastal waters daily. Because NOAA has been monitoring these areas for extended periods, baseline data already exist to help define the extent of environmental degradation. For example, PAH levels following the 2007 Cosco Busan oil spill in San Francisco Bay showed concentrations at the monitoring site near the spill were the highest ever recorded.
  • Flame retardants known as PBDEs are a new class of contaminants currently being evaluated by NOAA to determine whether they are increasing in coastal waters and what effects they may have on both marine and human health. NOAA plans to issue a report on flame retardants in coastal waters later this year.

NOAA’s Mussel Watch Program, founded in 1986, is the nation’s longest continuous national contaminant-monitoring program in U.S. coastal waters. The program keeps collected tissue samples frozen so that overlooked or newly emerging contaminants can be retroactively analyzed, as is currently being done with flame retardants.

Although NOAA found DDT in coastal waters to be decreasing, Marine biologists from the Virginia Institute of Marine Science studying the fate and effect of organic contaminants in the Antarctic, has found that DDT concentrations in penguins has remained at the same levels as they were 30 years ago, when DDT was widely used. Arctic animals such as whales, seals and birds have had a significant decline in their DDT levels during the past decades, while the more stationary Antarctic penguins have not. The scientists identify the melting snow and ice as the continued source of total DDT in this southern ecosystem.

Last year NOAA and the Environmental Protection Agency (EPA) reported extremely high concentrations of the pesticide DDT in fish caught in California’s Los Angeles county waters. According to the survey, the fish caught in the area contain the world’s highest-known DDT concentrations.

DDT, or dichloro diphenyl trichloroethane, while highly persistent in the environment, was initially found to be effective against mosquitoes and the diseases they carry such as malaria. However, insect resistance to the chemical has been documented since 1946. DDT was banned in the U.S. in 1972 after it was linked to the decline of the bald eagle and other raptors, and it continues to be linked to health problems. The benefits of the use of DDT for mosquito control are still debated, especially in developing nations that are plagued with high infection rates of malaria. Some countries are continuing to use DDT to prevent malaria, while others insist that the health and environmental risks are too great citing alternatives and an international agreement to phase-out the remaining uses of the persistent chemical.

Last summer, the bald eagle was removed from the ESA’s “threatened” list. Bald eagle populations declined dramatically in the last century, attributed mostly to the accumulation of the pesticide DDT in fish, a staple of the eagle’s diet. The pesticide gradually poisoned females, causing them to produce thinly-shelled eggs that broke easily, preventing the embryos from growing.

TBT is a cheap, but highly toxic barnacle and algae killer once used on nearly all of the world’s 30,000 commercial ships. A treaty, overseen by the U.N. International Maritime Organization (IMO), prohibiting its use went into effect this past January. The ban on TBT, deemed by EPA as the most toxic chemical ever deliberately released into the world’s waters, is endorsed by U.S. and European cruise lines, freighter and container fleets, as well as shipyard and marina operators. Researchers have linked TBT to adverse environmental and health effects. Studies first linked it to disorders in mollusks in the Arcachon Basin in western France, where shellfish beds adjoined a marina. According to Jill Bloom, an EPA chemical-review manager who worked on the treaty, the most worrisome were “profound reproductive effects” coupled with diminished marine-species populations. IMO notes that TBT “persist(s) in the water, killing sea life, harming the environment and possibly entering the food chain… [TBT] has been proven to cause deformations in oysters and sex changes in whelks.”

For more information on pesticides and water, see Daily News, Pesticides and Degradates Widely Found in USGS Chesapeake Bay Study, and Beyond Pesticides water report.


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