Baton Rouge – Above-normal levels of mercury have been found in the blood of some people who consume large amounts of fish from select waterways in north Louisiana. The findings are the result of a five-month study that included 77 participants (43 males and 34 females) from Morehouse, Ouachita and Union parishes.

The LDH Office of Public Health began conducting blood mercury screenings in 1998 to determine if Louisiana residents contracted health problems from eating mercury-contaminated fish. Following that initial screening, health officials discovered a small group of people from Ouachita and Morehouse parishes who had elevated blood mercury levels. LDH also investigated a case of an individual with mercury poisoning who ate fish caught from a waterway that had a mercury advisory. These circumstances resulted in this latest screening.

There are several benchmarks for blood mercury levels currently used by health officials. Amounts less than 10 parts per billion (ppb) are considered normal background levels. Levels between 10 ppb and 35 ppb are not known to pose health risks, but people are advised to limit their consumption of fish. Finally, when levels exceed 35 ppb, health officials suggest people seek medical advice. For women of childbearing age, LDH urges they seek medical advice when levels exceed 15 ppb.

The results of the most recent tests show 68 percent of those screened had blood mercury levels below 10 ppb. There were 25 percent who had levels between 10 and 34 ppb, and 7 percent had levels greater than 35 ppb. All participants have received letters with their individual test results. Those with blood levels greater than 35 ppb were advised to be evaluated by a physician.

The screenings were done on a volunteer basis. In January, LDH announced the screening and sought public participation. In addition, special outreach efforts were conducted to target at-risk groups including commercial fishermen and their families (especially those who fish in Bayou Bartholomew or the Ouachita River), people who regularly eat fish (particularly bass and bowfin), women of childbearing age, infants and young children.

Mercury is an element that occurs naturally. It is released into the environment by both natural processes and human activity. Methyl mercury accumulates in fish and then in humans who eat fish. Health officials everywhere are wary of high levels of mercury collecting in humans over long periods of time because of its potential for causing health problems. The primary source of environmental exposure to mercury in the general population is through consumption of contaminated fish. An increased mercury level in humans can cause damage to the nervous system and is dangerous to pregnant or nursing mothers.

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