Officials: Fish may be tainted

Copyright © 2009
Gallup Independent
By Kathy Helms
Diné Bureau

WINDOW ROCK — The New Mexico Environment Department, the state Department of Game and Fish and the state Department of Health have issued new advisories detailing the safe consumption of fish from the state’s rivers, streams and lakes.

There are advisories listed for 37 water bodies based on fish tissue samples collected across New Mexico, among them: San Juan River (Cañon Largo to Navajo Dam), Bluewater Lake, Navajo Lake, Lake Farmington (Beeline Lake), and Rio Grande (Chama River to Embudo Creek).

The Rio Grande/Chama River is posted for PCBs while all others listed above are posted for mercury. The fish advisory includes rainbow trout in the San Juan; carp, channel catfish and white sucker in the Rio Grande/Chama; bluegill, crappie, largemouth bass, northern pike, rainbow trout, smallmouth bass and white sucker at Navajo Lake; channel catfish and largemouth bass at Lake Farmington; and tiger muskie at Bluewater Lake.

Fish or bodies of water not listed in the advisory indicate data were not available for evaluation at the time the fish consumption advisories were issued.

Game and Fish stocked 3,500 9-inch rainbow trout into the San Juan River on March 12 and an additional 80,000 4-inch rainbow trout the following week. The San Juan is New Mexico’s premier trout fishing destination.

Gov. Bill Richardson has directed Game and Fish to fully investigate and address concerns raised recently over the quality of the river and has requested $400,000 for San Juan River habitat improvement in his 2010 budget. Economic impact studies of the San Juan fishery have determined its value at close to $40 million annually.

While fish are nutritious and can be an important part of a healthy diet, some fish may contain contaminants at levels that could lead to health problems if consumed over a long period of time.

The advisory lists mercury, DDT and PCBs found in different species of fish of varying size classes and offers recommendations on the maximum number of eight ounce meals eaten in a month. NMED’s data indicate other contaminants are at low enough levels that consumption of the fish is safe.

Fish tissue data show that larger fish contain more contaminants because they are older, have been in the water longer, and have absorbed more contaminants. Those advisories, however, do not change the state’s regulations on the size or numbers of fish anglers are allowed to keep.

The state periodically collects fish from bodies of water across New Mexico and analyzes them for contaminants. Based on the results of those analyses, the Environment Department developed recommendations for fish consumption. Those recommendations are based on guidance from the U.S. Environmental Protection Agency.

The new advisories replace all others previously issued.
Mercury contamination in fish is linked to air pollution from power plants and natural sources of mercury in the environment; PCBs can be traced primarily to the improper disposal and handling of electrical transformers; and DDT is linked to past pesticide application practices. Both PCBs and DDT have been banned from most uses in the United States since the 1970s.

Mercury in fish is in the form of methylmercury, a metal that is toxic at very low exposure levels. Each person’s exposure to methylmercury depends on the quantity in the fish they eat and how often they eat it. If consumed in large quantities over a long period of time, methylmercury damages the brain, nerves, kidneys, and may lead to other health problems such as those of the cardiovascular system. The brains of fetuses, babies, and young children are most at risk as they are still developing.

Eating large quantities of fish with PCBs may cause a variety of health problems, including those related to nerve development, reproduction, hormones, and cancer. The negative effects of PCBs on the development of infants and children whose mothers were exposed before becoming pregnant and during pregnancy are of particular concern. The effects in newborns and children may include a decrease in learning ability that may continue later in life. PCBs may cause cancer in humans, particularly liver and kidney cancer, because they are known to cause cancer in laboratory animals.

Excessive exposure to DDT through eating contaminated fish may cause a variety of health problems, including effects on reproduction, the nervous system, the immune system, and may increase the risk of cancer. DDT and its break-down products can mimic the action of natural hormones, potentially affecting pregnancy by increasing the chance of premature babies and reducing a mother’s ability to produce milk.

Information: ftp://ftp.nmenv.state.nm.us/www/swqb/MAS/
Advisories/FishConsumtionAdvisories-2009.pdf or www.wildlife.state.nm.us.