Mercury and selenium in European catfish (Silurus glanis) from Northern Italian Rivers: Can molar ratio be a predictive factor for mercury toxicity in a top predator?

However, in 37% of analyzed samples, Hg exceeded the maximum level set by 1881/2006/EC and 629/2008/EC in fish muscle. The molar ratio of Se/Hg was <1 only in the presence of significantly high Hg levels (>0.5 mg/kg), and therefore the mean molar ratio cannot be considered as a safety criterion in top predator fish.