Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: Variation within species and relevance to risk communication

Abstract

There is an emerging consensus that people consuming large amounts of fish with selenium:mercury ratios below 1 may be at higher risk from mercury toxicity. As the relative amount of selenium increases compared to mercury, risk may be lowered, but it is unclear how much excess selenium is required. It would be useful if the selenium:mercury ratio was relatively consistent within a species, but this has not been the case in our studies of wild-caught fish. Since most people in developed countries and urban areas obtain their fish and other seafood commercially, we examined selenium:mercury molar ratios in commercial fish purchased in stores and fish markets in central New Jersey and Chicago. There was substantial interspecific and intraspecific variation in molar ratios. Across species the selenium:mercury molar ratio decreased with increasing mean mercury levels, but selenium variation also contributed to the ratio. Few samples had selenium:mercury molar ratios below 1, but there was a wide range in ratios, complicating the interpretation for use in risk management and communication. Before ratios can be used in risk management, more information is needed on mercury:selenium interactions and mutual bioavailability, and on the relationship between molar ratios and health outcomes. Further, people who are selenium deficient may be more at risk from mercury toxicity than others.

Mercury and selenium levels, and their molar ratios in several species of commercial shrimp in Japan regarding the health risk of methylmercury exposure

“…However, the bioavailability of Se can be sufficiently reduced by Hg to perturb the normal Se-dependent functions (Sørmo et al, 2011). Others have reported that Se/Hg molar ratios below one may lead to a higher risk from Hg toxicity (Ralston and Raymond, 2010;Burger and Gochfeld, 2013). Therefore, the Se/Hg molar ratio is an important piece of information when assessing the health risks from MeHg exposure due to fish consumption.…”

Selenium/mercury molar ratios in freshwater, marine, and commercial fish from the USA: variation, risk, and health management

“…Saltwater fish (including marine and estuarine species) were collected from New Jersey (2003-2011) (57,99,100) and from the Aleutians in Alaska (2003-2005) (101). Freshwater fish were collected from South Carolina (1997-1998) (102) and Tennessee (103).…”

“…Freshwater fish were collected from South Carolina (1997-1998) (102) and Tennessee (103). Commercial fish were purchased in New Jersey (2003)(2004) (104) and Illinois (2004) (57,105), and canned tuna and tuna sushi were purchased in New York and New Jersey (1998-2004) (106). Freshwater and saltwater samples were collected from fishermen or by state personnel under our direction.…”

“…Thus, exposure to MeHg has important public health consequences (54,55). Recreational fishermen often consume fish with Hg levels above the allowable daily intake and are interested in obtaining information on Hg in the fish they consume (56,57).…”

Children's Health Risk and Benefits of Fish Consumption: Risk Indices Based on a Diet Diary Follow-Up of Two Weeks

“…An increasing number of studies have also presented evidence of the nutritional benefits of selenium (Se), also commonly found in fish (Cabanero et al, 2005;Burger et al, 2011;Burger and Gochfeld, 2013). In addition to the benefits of Se as an antioxidant and for disease prevention, this element has been examined with respect to counteracting the adverse effects of Hg (Burger et al, 2011: Carvalho et al, 2012Cuvin-Aralar and Furness, 1991;Ralston and Raymond, 2010;Watanabe, 2002).…”