Selenium and mercury molar ratios in saltwater fish from New Jersey: Individual and species variability complicate use in human health fish consumption advisories

Abstract

Balancing risk versus benefits to humans and other organisms from consuming fish is a national concern in the USA, as well as in many other parts of the world. Protecting public health is both a federal and state responsibility, and states respond by issuing fish consumption advisories, particularly for mercury. Recently it has been emphasized that the protective role of selenium against mercury toxicity depends on their molar ratios, which should be evaluated as an indication of selenium’s protective capacity, and incorporated in risk assessments for fish consumption. However, there is no single “protective” ratio agreed upon. In this paper we examine the selenium:mercury (Se:Hg) molar ratios in a wide range of saltwater fish caught and eaten by recreational fishers along the New Jersey coast. We were particularly interested in interspecific and intraspecific variability, and whether the molar ratios were consistent within a species, allowing for its use in managing risk. The selenium–mercury molar ratio showed significant variation among and within fish species. The molar ratio decreased with the size of the fish species, decreased with the mercury levels, and within a fish species, the selenium:mercury ratio decreased with fish size. As an essential element, selenium undergoes some homeostatic regulation, but it is also highly toxic. Within species, mercury level tends to increase with size, accounting for the negative relationship between size and ratio. This variability may make it difficult to use the selenium:mercury molar ratio in risk assessment, risk management, and risk communication at this time, and more information is needed on how mercury and selenium actually interact and on the relationship between the molar ratios and health outcomes.

Total mercury and selenium concentrations in Sarpa salpa and Balistes capriscus and in their respective Digenean endoparasites Robphildollfusium fractum and Neoapocreadium chabaudi from Tunisia

“…Several authors have argued that higher Se:Hg molar ratios indicate a more protective effect of selenium against mercury toxicity (Ralston 2008;Peterson et al 2009a, b), even though contradictory results indicate that the effect of selenium on mercury bioaccumulation is an extremely complex process (Dang and Wang 2011). There has been a growing concern about the evaluation of Se:Hg molar ratios in fish muscle with focus on the methylmercury toxicity for humans as consumers of fish (Kaneko and Ralston 2007;Ralston 2008Ralston , 2009Ralston et al 2008;Burger and Gochfeld 2012). In the present study, the muscular Se:Hg molar ratio in S. salpa from Mahdia was significantly higher than in S. salpa from Sfax.…”

“…On the other hand, selenium is though to have a protective effect against mercury toxicity (Kaneko and Ralston 2007;Ralston 2008Ralston , 2009Ralston et al 2008;Burger and Gochfeld 2012) mainly because of the high affinity of selenium to mercury. In fact, selenium is thought to sequester methylmercury and reduce its bioavailability in organisms (Sørmo et al 2011).…”

Mercury in fishes from Augusta Bay (southern Italy): Risk assessment and health implication

“…Ralston et al (2008) showed that Se:Hg molar ratios above 1 protect against Hg toxicity. However this ratio definitively depends o species-specific toxic-kinetics processes (Watanabe, 2002;Burger and Gochfeld, 2012). This feature leads to a wide variability of Se:Hg molar ratios and makes difficult their use in risk assessment.…”

Nutritive values, flavor amino acids, healthcare fatty acids and flesh quality improved by manganese referring to up-regulating the antioxidant capacity and signaling molecules TOR and Nrf2 in the muscle of fish

“…Fish provide an important source of protein and omega-3 (n − 3) polyunsaturated fatty acids (PUFAs) for human (Albert et al, 2002;Burger & Gochfeld, 2012). However, deterioration of fish flesh quality leads to poor consumer acceptance, increases the risk of cardiovascular disease in humans and causes huge economic losses for producers (Hosseini et al, 2010).…”