5 questions: Is it safe to eat the fish in Philly-area waterways?
Now that spring is finally here, anglers are breaking out their tackle and heading for the rivers and streams, hoping to land a big one.
But in this region, many of those waterways carry pollutants — often remnants of our industrial past — that wind up in the fish. To help protect angler health, agencies in Pennsylvania, New Jersey and Delaware have devised fish consumption advisories that are designed to advise certain groups of people, including children and women of childbearing age, about the maximum amounts of wild caught fish that they can safely eat.
Aquatic biologist Ann Faulds, associate director of Sea Grant Pennsylvania, an educational program led by Penn State, has years of experience educating people about the local fish they may want to eat. She recently spoke to us about it.
Bottom line: Are fish in the Delaware estuary safe to eat?
It depends. There are very few places in the Delaware Estuary where there is across-the-board advice of “do not eat.” Also, the amount of fish that is safe to eat depends on who you are. Women who are pregnant, who may become pregnant or are nursing need to be more careful about what they eat because the contaminants can cause developmental and neurological problems. Children under the age of 5 also are at risk. People with compromised immune systems also may have reason to be a little more cautious. So, it all depends.
What are fish consumption advisories and how are they compiled?
Fish consumption advisories are put together to protect human health. They advise people about the maximum amount that is safe to eat.
A team of people from different state agencies — such as health, environment and fish and wildlife agencies — often work together. Multiple fish of the same kind and the same size are collected from the same location. The meat is combined and pulverized, then tested by a sophisticated laboratory following standard procedures that are approved by the U.S. Environmental Protection Agency. Then, the risk is estimated based on studies of health impacts associated with known exposures.
The advisory itself is a list, water body by water body, that includes specific amounts of fish that are safe to eat, and the contaminant of concern for that location. Some types of fish have a diet higher in contaminants. For instance, predator fish in general have higher levels of contamination. Sometimes, the size of the fish is a factor, as well. Larger fish are older, and so have eaten more meals and accumulated more contaminants.
What are the main fish contaminants in the Delaware basin and where do they come from?
The main contaminants fall into two groups. One group is organochlorine compounds. The other group is methylmercury.
Organochlorines include PCBs, dioxins, the insecticide chlordane and some other insecticides that are like chlordane. These fat-soluble contaminants are generally associated with an elevated risk of cancer.
PCBs were mainly used as lubricants and coolants in transformers and other electrical equipment. Before it was understood that they were a problem for health, they were sometimes dumped on the land. So they continue to work their way into the watershed, little by little. But as time goes on, the PCB levels are dropping because we’ve dealt with the big sources. And PCBs were banned in 1979. Nevertheless, PCBs are the contaminants of most health concern in the estuary.
Dioxins are produced any time plastics are burned, such as in waste incinerators.
Chlordane has been banned for quite some time — since 1988. But it was a long-acting insecticide that was sometimes used to replace DDT when that was banned. Today chlordane tends to be a problem in specific places where there might have been a spill of some sort.
Methylmercury in freshwater fish from our region originates mainly from the burning of fossil fuels. In this area, it’s mainly from coal-fired power plants in the Ohio River Valley. There are trace amounts of mercury in the coal. When it burns, it goes into the air as mercury vapor, or pure mercury. The prevailing winds blow from the west and carry the emissions from the power plants. Then, the mercury gets incorporated with the rain and gets into the waterways. Once in an aquatic system, microbes change it to methylmercury, which is more toxic. Methylmercury is a neurotoxin and can cause neurodevelopmental problems in unborn children and young kids. In large doses, it can also cause liver damage.
If the fish in a certain location aren’t safe to eat, is it safe to stand in the water while you’re fishing?
There’s a big difference in the dose of contaminants between eating them and touching them. I don’t know of any Delaware basin waters that are unsafe to stand in because of contaminants. Still, in urban areas it’s always a good idea to bathe after being in contact with water, particularly after a rain. That has to do with bacteria and viruses that can wash off the land.
What else should people know?
There are ways to prepare your fish to reduce the fat-soluble contaminants like PCBs by as much as a half. So if you filet and skin the fish, and remove the fatty dark meat, that can reduce the PCBs. When you cook a piece of fish, any time you can allow the juices to drip away from the meat — by broiling or grilling — that will also reduce the fat, and thus the PCBs.
One of the things that is really important to mention is that there are many benefits to eating fish. Right now, leading fish consumption researchers are looking at the risks versus the benefits to gain a more balanced perspective. In one 2005 risk-benefit study, the authors predicted that if a group of 100,000 people were to consume six ounces of salmon once a week for a 70-year lifetime, there would be eight to 24 cancer deaths, but it would save more than 7,000 lives from coronary heart disease deaths. In other words, the heart benefits of eating fish, in certain cases, can outweigh the cancer risk by a factor of 300. One thing we want to be sure of is not to scare people away from eating fish altogether; there can be a risk to health from not eating fish.