Mercury levels in Koreans’ blood are three times higher than those of Americans and five times higher than those of Germans, a new study found.

This, however, does not necessarily mean that Koreans experience more adverse health effects from the toxic heavy metal, as the concentrations were under levels associated with health problems, it said.

The study, conducted by the state-run National Institute of Environmental Institute, found that the average concentration of mercury in the blood to be 3.08 micrograms per liter, much less than the advisory level of 5 micrograms.

Yet, it was far higher than the corresponding figures for Americans and Germans, which were 0.94 and 0.58, respectively. The U.S. and Germany are two of a few countries with comparable test results.

Researchers attributed the higher mercury levels among Koreans mainly to dietary intake of methyl mercury through fish.

In the human body, mercury accumulates in the liver, kidney, brain, and blood. It can affect the nervous system and harm the brain, heart, kidneys, lungs and immune system.

The Korea Center of Disease Control and Prevention advises pregnant and breastfeeding women and children against eating too much tuna, swordfish and other fish that contain high levels of mercury.

The study also found that Koreans have higher levels of lead in the blood: 1.77 micrograms per deciliter, compared to Americans’ 1.38. The figure for Germans was 3.07. Sources of lead exposure include lead-based paints, food grown in lead-contaminated soil and fish. Exposure to high lead levels is known to have adverse effects on the brain, kidneys and the nervous system.

As for cadmium, which at excessive levels may cause kidney damage, bone mineral density loss and hypertension, Koreans also showed higher concentration of the metal in their urine.

The urinary cadmium among Koreans averaged at 0.58 micrograms per liter, compared to 0.23 of Americans and Germans. Drinking water, diet, and cigarette smoking are considered major sources of exposure.

The NIEI researchers tested some 6,300 Korean adults for concentrations of 16 different kinds of heavy metals and toxic chemicals in their blood and urine. It was the first large-scale testing of its kind ever conducted in Korea.

“Almost 70 percent of those who took part in the test had all 16 kinds of heavy metals and toxic chemicals in their blood or urine,” they said in the study, which was released Tuesday. “The findings buttress the need for a lifestyle change to reduce exposures to toxic heavy metals and chemicals.”

By Lee Sun-young (milaya@heraldcorp.com)