Some man-made chemicals can “bioaccumulate” from very small amounts in water to up to a million times higher in the tissues of fish. One of the ways these chemicals can be monitored is to collect a fish sample, grind up the tissues in a laboratory, and chemically analyze them. The Indiana Department of Environmental Management (IDEM) estimates from samples collected and analyzed this way over the past decade that there are now 5,453 river miles in Indiana that are not supporting their designated use for fishing due to potentially unsafe levels of chemicals in fish. When high levels of these pollutants occur, they can cause detrimental health effects to humans and wildlife species that eat fish. Polychlorinated biphenyls (PCBs) and mercury are the primary chemicals of concern in Indiana, although several other formerly-used pesticides such as DDT and chlordane still show up at high levels in some fish. The Indiana State Department of Health (ISDH) regularly updates its fish consumption advisory based on the latest sampling results for Indiana fish and distributes advice from nutrition scientists at Purdue University for commercial fish.
Fish can be an important part of our diet. Fish can be high in omega-3 fatty acids, which are important for fetal brain and eye development and have been associated with a reduced risk for cardiovascular diseases. However it is important to eat fish with low levels of toxicants. Several streams in the state are contaminated by PCBs from previous industrial activity and the sediments there still provide an ongoing source of bioaccumulation. Fish from 12 streams (listed in Group 5 of the ISDH fish consumption advisory, below) should not be consumed by anyone. Additional restrictions are recommended for women capable of becoming pregnant, who are pregnant or breast-feeding, and for children under the age of 15. Additionally, children under 6 are most susceptible to the health risks of toxins in fish because their brains are in a critical development period.
Tracking sources of chemicals that bioaccumulate in fish is a challenge because the chemicals may occur in water in concentrations that are usually too low to detect with current analytical methods. One of the promising new source-tracking methods is the use of semipermeable membrane devices (SPMDs) that act as a “virtual fish.” These are a special kind of plastic bag containing purified oil. The bag allows contaminants to pass through small pores in its surface. The contaminants are trapped within the bag and then accumulate in the oil inside the bag in a process similar to what occurs in fish. As it accumulates, the contaminant concentrations become high enough to be chemically analyzed. Because they do not move and do not have to be fed, SPMDs can be excellent monitoring devices to help determine sources of bioaccumulating contaminants. Additional information regarding bioaccumulation sampling methods and fish consumption advisories are listed in the related resources below.
Water Resource Professionals in Indiana Focusing on Toxic Substances in Fish Tissue
- Megan Meade (Indiana State Dept. of Health)
- Greg Bright (Commonwealth Biomonitoring)
- Jim Stahl (Indiana Dept. of Environmental Management)
- Ali Meils (Indiana Dept. of Environmental Management)
Indiana Department of Environmental Management, 2014, Indiana Integrated Water Monitoring and Assessment Report, Office of Water Quality, Nonpoint Source Branch, accessed April 25, 2014 at:http://www.in.gov/idem/nps/2639.htm.
Indiana State Department of Health, 2015, Fish Consumption Advisory: About fish consumption and the Indiana Fish Consumption Advisory, accessed May 18, 2015 at: http://www.in.gov/isdh/23650.htm.
Great Lakes Information Network, 2014, Fish Consumption in the Great Lakes, Great Lakes Commission, accessed April 25, 2014 at: http://www.great-lakes.net/humanhealth/fish/index.html.
Ohio River Fish Consumption Advisory Workgroup, 2014, Ohio River Fish Consumption Advisories, Ohio River Valley Water Sanitation Commission (ORSANCO), accessed May 18, 2015 at: http://126.96.36.199/comm/fishconsumption/default.asp.
Real-Time Online Access of Fish Consumption Advice: Angling Indiana, 2014, Purdue University Dept. of Foods and Nutrition, accessed May 7, 2014 at: http://fn.cfs.purdue.edu/prodaai/main/php.
U.S. Geological Survey, 2015, The virtual fish: SPMD basics, Columbia Environmental Research Center, accessed June 1, 2015 at: http://wwwaux.cerc.cr.usgs.gov/spmd/.
This page written and maintained by Greg Bright of Commonwealth Biomonitoring.