Toxics in Harbor Seals
This indicator describes the presence and effect of persistent bioaccumulative toxics (PBTs) in harbor seals and in the fish they eat. PBTs are chemicals that dissolve easily in animal fat and do not break down readily, causing them to build up or bioaccumulate in the food web.

Why is this happening?

High concentrations of PBDEs and other PBTs in harbor seals are due to a combination of several factors:

• Elevated production and consumption of PBDEs in North America, with the highest levels occurring in the U.S.
• Migration of PBDEs and other PBTs out of the products in which they are used and subsequent entry into the aquatic environment and its food webs
  
• PBDEs are found in sediments, sewage sludge, fish, birds, seals and humans
  
• Puget Sound appears to be relatively vulnerable to contamination by PBTs, representing a confined estuary with limited sedimentation (hence limited burial of PBTs) and limited water exchange with the Pacific Ocean
  

PBDEs of Concern: Production and Migration

PBDEs are part of the class of brominated flame retardants that are used in plastic appliances and household electronics (e.g.; TV and computer casings, hair dryers, printers, coffee makers), textiles, polyurethane foam (furniture padding), paints and lacquers, rubber, wire and cable insulation, and electrical and electronic connections).

They can constitute up to 30 percent by weight of the final consumer product. Brominated flame retardants are the most widely used because of their low cost and high efficiency.²⁴

There are 209 types, or congeners, of PBDEs. The types of most immediate concern include:

• Penta-BDE is used primarily in foam products such as seat cushions and other household upholstered furniture as well as in rigid insulation and includes the congener BDE-47 (contains 2,2',4,4'-tetraBDE). BDE-47 is found widely in both wildlife as well as household dust.²⁵ Penta was withdrawn from the U.S. market and production ceased in December 2004 and has been banned by some U.S. States.
• Octa-BDE is used in high-impact plastic products, such as housings for fax machines and computers, automobile trim, telephone handsets and kitchen appliance casings. Octa was withdrawn from the U.S. market and production ceased in December 2004 and has been banned by some U.S. States.
• Deca-BDE is used in plastics, such as wire and cable insulation, adhesives, coatings and textile coatings. Typical end products include housing for television sets, computers, stereos and other electronics and audiotape cassettes. Deca-BDE also is used as a fabric treatment and coating on carpets and draperies. Deca-BDE is not used in clothing.²⁶ Deca continues to be used throughout the world, including the United States and Canada.

Approximately 67,390 metric tonnes (1 metric tonne=1,000 kg= 2, 205 lbs) of PBDEs are sold globally each year. The highest producer and consumer of PBDEs in the world is the United States.²⁷

Sources of and Exposure to PBDEs

Exposure to PBDEs occurs through multiple pathways.

• Manufacturing: There are two PBDE manufacturing sites in North America, both located in Arkansas: Great Lakes Chemical Corporation (now Chemtura Corporation) and Albermarle Corporation.

• In-house dust: Some PBDEs are additives mixed into polymers and are not chemically bound to the plastic or textiles. As a result, they may separate or leach from the surface of their product applications into the environment. Indoor dust is responsible for PBDE exposure to infants and toddlers (Washington State Department of Ecology and Washington State Department of Health).²⁸

  It is likely that as household products treated with flame retardants degrade from light and use, PBDEs become airborne in both outdoor and indoor air.²⁹ PBDEs may be more prone to environmental degradation than PCBs because the carbon-bromine bonds are weaker than carbon-chlorine bonds in PCBs.³⁰ PBDEs are found in household dust samples, similar to phthalates, which also do not bind to the polymer molecules to which they are added. As a result, the PBT migrates into the air surrounding the products that contain them.³¹

• During disposal: During electronic recycling, landfilling and incineration, PBDEs spread in the environment, but it is unclear in what quantities or through which pathways. Halogenated compounds such as PBDEs, when incinerated, form polybromodibenzofurans, another PBT.³²

• In the diet: Harbor seals, herring and people are exposed to PBDEs through their diets. PBDEs are also found in sewage sludge that is spray applied to certain lands in which food is grown. Most adults are exposed to PBDEs through food.³³

 

   

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