Dioxin and PCBs

The primary chemical of concern in Budd Inlet is dioxin. a legacy of preserving pilings in the past with creosote. Concentrations at the head of East Bay exceed 200 ppt in surface layers and 1000 ppt in subsurface layers. The standard for open water disposal is 3.5 ppt. For MTCA cleanup sites 11 ppt.


Dioxin is probably the most biologically damaging non-radioactive chemical known. Its effects can be quantified in parts per trillion. These include cancer, birth defects and endocrine disorders.

 
The term dioxin actually refers to a group of chemicals. By definition we’d begin with the simple chemical compound C₄H₄O₂, furans being C₄H₄O. In the toxic forms, polychlorinated dibenzodioxin and polychlorinated dibenzofuran, one or more hydrogen is replaced with chlorine. The EPA calculates toxic equivalency (TEQ) values for each member of this category where the more toxic TCDD is expressed as 1.0 and less toxic as fractions.


Budd Inlet is also contaminated with PCBs, polychlorinated biphenyls, which also have a chemical structure made up of carbon, hydrogen and chlorine. Chlorine is a halogen, the second from the right column on a periodic table. Other halogens include bromine and fluorine, chemicals we find in fire retardants and fire fighting foam and food packaging.


All of these chemicals are similar in structure and can pose similar risks. They can damage the double helix. They break down very slowly and accumulate in our bodies. They have combined and cumulative effects.


Dioxin is lipophilic, attracted to fats. Human skin is fatty. It’s why we leave fingerprints. Dioxin will tend to adhere to skin and let go of soil. The primary method of testing dioxin toxicity is applying it to the back of a rat. It’s easily absorbed through skin. The public has been reassured that most people are exposed through their food. The reason more people aren’t exposed by wading in contaminated mud is because people rarely do that. The risks however to anyone who does are significant.


Consultants have convinced local governments that surface layers are assessed separately because they are what’s biologically availability. The bioactive zone in Puget Sound is actually between a foot and a meter deep, depending on whether geoducks are present. Sedimentation occurs in layers, the surface layers being the most recently laid down. Surface sediment contamination tells us that dioxin continues to enter Budd Inlet from uncontrolled sources, almost certainly on land.


Dioxin in the marine environment moves up from species to species and concentrates in apex predators. The latest orca death was a male in the prime of life. One suspected cause of death was cancer, one of the potential effects of these chemicals. An international team led by Jean-Pierre Desforges, a postdoctoral researcher at Aarhus University, determined that several orca populations worldwide are at risk of collapse in coming decades because of the accumulation of PCBs in their body burden.

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