According to research conducted by Ovsicori-UNA and Wesleyan University in Connecticut, USA, approximately 60% of human hair samples collected in the Central Valley area exceeded the alert level for mercury.

The information, which was posted on the National University’s (UNA) Observatorio Vulcanológico y Sismológico (Ovsicori/UNA) Facebook page, stated that the population may show high mercury levels as a result of consuming fish such as tuna, shark, swordfish and marlin, as well as canned fish that is both locally produced or imported, and not through mercury emitted from volcanoes, as scientists had proposed in their research hypothesis. In order to reach this conclusion, researchers took hair samples from 53 people between June and July 2011 in different towns spread over an area between Alajuela, Heredia, San José and Cartago.

Their results showed the mercury (Hg) content in hair samples reached levels that ranged between 97 and 13.840 parts per billion (ppb), as opposed to the maximum hair mercury levels of 1,000 ppb accepted by the U.S. Environmental Protection Agency (EPA or USEPA).

María Martínez, researcher at OVSICORI-UNA, explained that nearly 60% of those in the sampled group showed mercury concentrations at or above the level accepted by EPA. In addition, maximum values found in three individuals with mercury levels of almost 14,000 ppb are also of great concern for Costa Rica.

Mercury-Filled Fish
During the hair sampling process, study participants were asked about their eating habits, finding that most individuals admitted to eating fish on a regular basis.

“When it comes to large migratory fish that are caught in Costa Rica for local consumption, such as sailfish and marlin, it is likely that they have gradually acquired their mercury load during migration from northern latitudes to Costa Rica, with mercury levels in body tissues of up to 2000 and 3000 ppb”, affirmed Martínez.

She added that the bigger the migrating fish, the greater its mercury content, as mercury (Hg) builds up in tissue as the fish grows. Furthermore, calculations based on fish consumption and the participants body weight showed that 76% of sampled individuals had a mercury intake (mainly through seafood consumption) above the reference dose allowed for mercury by EPA of only 0.1 micrograms per kilogram of body weight per day.
Martínez affirmed it is necessary to determine whether saltwater fish consumption is currently exposing the country’s population to any health-related risks; therefore, the study should be extended to the rest of the country, including coastal areas.

Harmful to Your Health

According to EPA, exposure to high mercury levels can affect the brain, heart, kidneys and lungs, as well as the immune system in people of all ages. In addition, it has been shown that high levels of methylmercury (an organic mercury compound) in the bloodstream of unborn babies and young children can be quite harmful to their developing nervous system, thereby hampering the infant’s reasoning and learning process.

It’s worth mentioning that on March 29th, authorities from the Costa Rican Fishing Institute (Instituto Costarricense de Pesca, Incopesca) and from the Ministry of Agriculture Toxicology Laboratory reported that no advisory notice or warnings had been issued as a result of mercury levels in fish.