Health Consultation for TPWD Workers with Potential Occupational Exposure to PCDDs/PCDfs in Sediments from the San Jacinto River, Houston Ship Channel, and Upper Galveston Bay - Harris and Chambers Counties, Texas



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Texas Department of State Health Services


The Texas Department of State Health Services (DSHS) and the Agency for Toxic Substances and Disease Registry (ATSDR) were asked to evaluate the potential risks from exposure to dioxin-contaminated sediments for TPWD staff who routinely collect fish and other aquatic life samples from the San Jacinto River (SJR), the Houston Ship Channel (HSC), and Upper Galveston Bay (UGB) [1]. For this health consultation, DSHS and ATSDR reviewed the sampling results that were collected and submitted as part of the Texas Commission on Environmental Quality (TCEQ) Hazard Ranking System Documentation Record for the San Jacinto River Waste Pits NPL site [2] as well as samples collected by the University of Houston as part of the Dioxin Total Maximum Daily Loads (TMDL) Project [3]. The most frequently noted health effect in people exposed to very high levels of dioxins is chloracne, a severe acne-like skin rash affecting the face and upper body. Other effects include other skin rashes, skin discoloration, excessive body hair, hepatotoxicity (liver damage), and peripheral neuropathy (a form of peripheral nerve damage). Lower level exposures in animals have caused impaired resistance to infection, decreased thymus weight, and altered social behavior in the offspring of mothers exposed to dioxin during pregnancy. These effects represent the critical effects for acute, intermediate, and chronic duration exposures, respectively. Since TCDD is a carcinogen, longer term exposures present a theoretical cancer risk for exposed individuals. Individual oral and dermal exposure levels for TPWD staff could not be determined from the description of their activities; thus, we made a number of health-protective assumptions about possible oral and skin exposures and created three scenarios to describe a range of possible exposures. The first scenario is that of routine daily exposure for technicians who may collect samples from a particular location 5 days per week, 50 weeks per year, for 30 years. The second scenario is that of frequent periodic exposure for technicians who may collect samples from a particular location 1 day per week, 26 weeks per year, for 30 years. The third scenario is that of sporadic exposure for technicians who may collect samples from a particular location 5 times per year, for 15 years. All scenarios assume that, on visiting the site, technicians would get contaminated sediments on their hands and forearms, leading to exposures by mouth as well as through skin contact. The first two scenarios very likely over-estimate exposure frequencies and theoretical risks; the third scenario may be somewhat more realistic but still probably over-estimates real-life exposures for most TPWD employees. For this public health consultation (PHC), the ATSDR used a risk-based approach for evaluating the public health significance of exposures to the various SJR-HSC-UGB sediment samples under each of the three exposure scenarios described above. As explained in the paragraphs above, it is considered unlikely that any TPWD technicians have been exposed to sufficient dioxins levels in sediments to expect to see any observable adverse health effects.


118 pages; available for download at the link below.


Dioxin Total Maximum Daily Loads, Upper Galveston Bay, Houston Ship Channel, San Jacinto River, public health, dioxin exposure, hazardous substances