Birds brain mercury concentrations

In birds, a brain mercury concentration of less than 2 ppm wet weight was associated with reduced egg laying, and impaired nest and territory fidelity in common loons (Barr 1986). Black duck embryos with brain mercury concentrations of 4 to 6 ppm failed to hatch (Finley and Stendall 1978). Brain mercury concentrations of 20 ppm caused 25% mortality in mercury-exposed zebra finches (Scheu-hammer 1988). 

FW in whole organism. Mercury concentrations considered acceptable to protect representative species of birds, in mg total mercury/kg FW, include less than <0.5-<1.0 in eggs, <5.0 in feather, <5.0 in liver, and <20.0 in kidneys. Diets of sensitive fisheating birds should contain less than 20.0 jig Hg as methylmercury/kg FW or < 100.0 jig total mercury/kg FW daily intake should not exceed 640.0 xg total mercury/kg body weight. For most species of nonhuman mammals, recommended mercury levels include daily intake of < 250.0 xg total mercury/kg FW body weight, diets that contain <1.1 mg total mercury/kg FW, and <0.002 (xg total mercury in drinking water supply of livestock however, diets of fish-eating mammals should contain < 100.0 (Jtg total mercury/kg FW. Tissue mercury concentrations in sensitive mammals, in mg total mercury/kg FW, should probably not exceed 10.0 in liver, 2.0 in hair, 1.5 in brain, and 0.5 in blood. All these proposed criteria provide, at best, miiumal protection. 

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