More than 40 years after the U.S. stopped making the chemicals known as PCBs, the human-made lubricants are still causing problems in New Hampshire including new restrictions on eating fish caught in Squam Lake.
The state Department of Environmental Services has announced tighter restrictions on all types of fish caught in the popular lake, not just the smallmouth bass and perch that are already suspect because of decades of mercury buildup in the environment.
“The consumption guideline for smallmouth bass also extend to lake trout, salmon, hornpout and other fish species other than perch caught in Squam Lake,” the statement noted, although it added: “ there is no known risk to catching and handling of fish in Squam Lake, so catch and release fishing is not impacted.”
The state collected 55 fish for analysis by an EPA contract lab. The samples were analyzed for PCBs, PFAS and mercury, although only PCB data is available at this time.
PCBs are chemicals used as coolants and lubricants in electrical equipment because they don’t burn easily and are good insulators. The manufacture of PCBs was stopped in the U.S. in 1977 because they build up in the environment and don’t break down, which is why they are still showing up in the food chain four decades later.
The obvious question is: Where is the PCB in Squam Lake coming from, and does it exist in fish elsewhere? Here’s what David Neils, Chief Aquatic Biologist and director of the Jody Connor Limnology Center for DES, wrote in an email to me:
“We do not have a single suspected source of PCBs to Squam Lake. There are a few working hypotheses such as legacy oil used on dirt roads for dust suppression and mutiple high water events that may have flushed remnant soil into the lake. However, these are unproven and are likely to be difficult to prove definitively. The only thing we can say for sure is that we now have evidence of PCBs in loons, fish, crayfish, and sediment from Squam Lake.
Your last question regarding the potential of PCBs to be in fish tissue from other lakes is an interesting one and one we have been discussing. To our knowledge, there has never been a statewide survey of contaminants in fish tissue besides mercury (see link) Therefore, we really don’t know but we would like to find out.
The department said for smallmouth bass and other fish other than yellow perch, adults and children over age 7 are limited to three, 8-ounce servings a year, or one meal every four months, with smaller servings and fewer meals for women of childbearing age and children younger than 7.
For yellow perch, one 8-ounce meal every month was recommended for adults and children over age 7, with smaller servings and fewer meals for the other groups.
Restrictions on eating fish from even the most remote New Hampshire lakes have been in place for many years because mercury was deposited in them by decades of exhaust from coal-fired power plants.
Return to the Concord Monitor