The Comparative Effect of Oral Ingestion of Methyl Mercury on Chicks and Rats

Abstract

1968a. Limiting essential amino acids in soybean meal for growing chickens and the effect of heat upon the availability of the essential amino acids. Poultry Sci. ABSTRACTTwo experiments with day-old chicks and one experiment with weanling rats were conducted to determine: (1) whether low levels of mercury found in some feedstuffs would result in hazardous accumulations of mercury in their tissues, and (2) the effects of feeding various dietary levels of methyl mercury to chicks and rats. Data show that feeding animal protein (fish meal) containing higher than normal levels of mercury did not result in the concentration of mercury in poultry tissues that exceeded FDA guideline levels. In fact, breast muscle concentration of mercury averaged only 0.1 p.p.m. even when the fish meal made up 17% of the diet. Significant amounts of mercury were deposited in the feathers of the test birds. At 16.9 p.p.m. dietary mercury as methyl mercuric chloride, all chicks succumbed to mercury toxicity by 17 days of age. Total mercury dose was 28.3 mg./kg. body weight. At this level of dietary mercury, brain, liver, and breast tissue of chicks at death contained 19, 47, and 15 p.p.m., respectively. Within limits, tissue concentrations of mercury were proportional to dietary levels. After 7 weeks of mercury exposure chicks retained an average of 63% of the mercury consumed. During a 21-day depletion period, chicks excreted an average of 0.66% of the total body burden of mercury per day. Thus biological half-lives can be calculated to average about 97 days for all dietary levels. Rats fed diets containing 16 p.p.m. mercury did not show outward signs of toxicity until the 6th week of treatment. After 12 weeks of mercury exposure, the total mercury dose was 84 mg./kg. body weight. None of the rats receiving lower levels of mercury showed symptoms of toxicity. Liver and brain mercury levels in rats fed 16 p.p.m. mercury averaged 26 and 12 p.p.m., respectively. Male rats generally had higher tissue levels of mercury than females. In general, rats tolerated the highest level of dietary methyl mercury for a longer period of time than chicks which consumed three times as much mercury and deposited less mercury in their tissues.

Monitoring of heavy metal burden in mute swan (Cygnus olor)

“…The detected amount of it was 1.86±0.51 mg/kg in great tits (Parus major) in Belgium (Janssens et al, 2002), 0.66± 0.68 mg/kg in rural area and 1.09±0.40 in forest habitat in passerines in Portugal (Costa et al 2011) and 383 μg/kg in cattle egret (Bubulcus ibis) in Bali (Burger and Gochfeld 1997). Also, it has been found that young chickens can tolerate 1.35 mg/kg diet (March et al 1983), but 5 mg/kg increases mortality (Soares 1973). Bhatnagar et al (1982) examined that 0.5 mg Hg/kg diet as methylmercury has no effect on behavioural endpoints in ducks, although 3.8 mg/kg had adverse effects.…”

Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

“…Negative effects on the neurological (Chang, 1977;Burbacher et al, 1990;Nagashima, 1997) and immune systems (Ilback, 1991;Ilback et al, 1996) and other tissues (SnelgroveHobson et al, 1988) are well documented in humans and captive mammals. Effects of methylmercury exposure have been reported in captive birds (Borg et al, 1970;Fimreite and Karstad, 1971;Soares et al, 1973;Pass et al, 1975;Hughes et al, 1976;Heinz and Hoffman, 1998;Hoffman and Heinz, 1998), including trans-generational effects (Heinz, 1975(Heinz, , 1976(Heinz, , 1979. These studies have focused on non-piscivorous species, whereas the top predators in aquatic systems are often piscivorous mammals and birds.…”

Organometallic Compounds in the Environment

“…Laboratory mammals tended to show the greatest concentration of CH 3 HgCl in liver and kidney, with brain and muscle tissue also accumu lating appreciable quantities (136)(137)(138)(139)(140). Oysters (Crassostrea virginica) concentrated this compound predominantly in the gills (141).…”