A Bay Area environmental group purchased swordfish and tuna from Bay Area markets. Ten out of 24 contained high levels of mercury.
Buffy Martin Tarbox gets ready to take the fish samples to the lab. The group Got Mercury of Marin County purchased 24 tuna and swordfish to survey the extent of mercury poisoning.
Concern is especially high for children and women of childbearing age.
"Children's brains are still developing and because mercury is a neurotoxin, it can really create some harm on their developing brains and their developing systems," Martin Tarbox said.
Dr. Jane Hightower wrote the book "Diagnosis Mercury: Money, Politics and Poison" and has been researching this issue for more than a decade. She has seen elevated levels of mercury in many of her patients.
"They had trouble thinking, memory loss, tremor, muscle and body aches, joint pain, insomnia, hair loss, stomach upset, those kind of symptoms," she said.
Got Mercury had its fish tested at a state certified lab in Emeryville, Micro Analytical Systems. The lab put pieces of fish the size of a rice grain into its mercury analyzer.
The Food and Drug Administration sets the allowable maximum level of mercury in fish at one part per million and 10 out of the 24 fish failed to meet that standard.
"That's pretty shocking to me so people are out there purchasing fish, not even realizing how high the mercury levels are that they're potentially ingesting," Martin Tarbox said.
The California Grocers Association told 7 On Your Side via e-mail: "Most commercial fish can be eaten safely in moderate amounts." That is something Got Mercury agrees with.
However, the types of fish selected for this test are often found to have higher levels of mercury than other fish. That's because tuna and swordfish are predators and eat smaller fish also contaminated with mercury.
All nine swordfish tested failed at an average rate 50 percent above FDA guidelines. Only one of 15 tuna fish failed to meet the FDA standard.
Hightower says that's because the standards are too relaxed.
"The regulation of mercury in fish used bad data and I want that changed. I want modern data to take another look at how much mercury should be allowed in our fish," she said.
And it isn't just relaxed standards, but relaxed testing and enforcement that concern the testers at micro analytical systems.
"The FDA standard is almost meaningless because it is a standard, but it's a standard that's not enforced," said Micro Analytical Systems President Malcolm Wittenberg.
The FDA responded by e-mail, saying: "The one part per million standard is based on chronic exposure, and that consuming the occasional fish that contains mercury concentration above 1 ppm does not adversely impact health as long as the mean exposure is below 1 ppm."
It also says the standard is essentially "advisory only and not enforceable."
In the meantime, Got Mercury is calling for the state legislature to mandate warning signs at grocery stores and restaurants about high mercury content.
That's something the fishing industry opposes.
"I wouldn't support warning signs because that creates a stigma in people's mind, in the consumer minds that something is really wrong," Wayne Heikkila from the Western Fish Boat Owners Association said.
The Western Fish Boat Owners Association argues the fish is safe to eat.
Got Mercury features a calculator on its website that helps you determine how much fish you can eat safely based on your body weight. The calculator uses much stricter standards established by the Environmental Protection Agency for fish caught recreationally.