I'll try to answer your questions the best I can.
1) At this time it's unclear what the source of the contamination is. The Texas Commission on Environmental Quality is the state agency responsible for identifying the sources and have them cleaned up. There has been a recent discovery of an old waste storage facility that was originally located along the banks of the San Jacinto River, just north of I-10. Over time the river has changed its' route in this area and the waste disposal site is now located in part of the river. The company who owned the site has long since gone out of business but the site was recently added to the Superfund Site list which should lead to its' cleanup. You can find more information about this at
http://www.tceq.state.tx.us/implementation/water/tmdl/26-hscdioxin.html and
http://epa.gov/superfund/sites/npl/nar1773.htm.2) I'm no medical doctor so really can't answer your question however, I'd suggest checking one of these sites for more information about exposure levels. Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs -
http://www.stsdr.cdc.gov/toxfaq.html or ATSDR Public Health Statements -
http://www.atsdr.cdc.gov/phshome.html3) The Texas Department of State Health Services, Seafood and Aquatic Life Group conducted all of the sampling that led to this advisory. Due to the high costs associated with this type of sampling ($2,000 per fish) and no funding to the Dept. for this type of work (this sampling was conducted using research grant funds from other organizations) the sampling area was directed at Galveston Bay and the other associated bays within the system (East Bay, Trinity Bay, West Bay, Chocolate Bay). Christmas Bay and the beaches along the Gulf adjacent to these bays were not included in the advisory primarily because no samples were taken from these areas.
4) The Texas Department of State Health Services, Seafood and Aquatic Life Group is the agency responsible for assessing human health risks from eating fish and shellfish. There are some lakes and rivers that have consumption advisories associated with certain species of fish. A complete list of all of the consumption advisories throughout the state can be found at
http://dshs.state.tx.us/seafood/. Click on the link to "Fish Consumption Advisory" located on the left side of the page.
I hope this helps answer your questions. Please feel free to contact me if you have others.
Lance Robinson
TPWD - Coastal Fisheries
Dickinson Marine Laboratory
lance.robinson@tpwd.state.tx.us