D. Kello

Influence of age and milk diet on cadmium absorption from the gut

Abstract Cadmium absorption was studied in different age groups of rats (1, 3, 6, and 52 weeks) fed milk or standard rat diet by determining the whole body retention of orally applied 115m CdCl 2 . The whole body retention curves determined over 2 weeks after the 115m Cd administration showed highest values in newborn rats. All animals on the milk diet had higher retention values than controls. Within each diet group the retention curves declined with age and the lowest values were obtained in the oldest group of animals. These results indicate that age and diet independently influence cadmium absorption and that the highest values in the newborn most probably result from a combined effect of age and milk diet.

Influence of Sex and Dietary Calcium on Intestinal Cadmium Absorption in Rats

The influence of sex and dietary calcium on whole-body retention of orally administered 115mCdCl2 has a half-life of 43 days, distinguishing it from 115Cd of half-life 2.3 days was studied in one-year-old control and gonadectomized male and female rats. Gonadectomy was performed at the age of four months. Each of the four experimental groups was divided into three subgroups that were fed rat food with a different calcium content (2.4, 0.7, and 0.3% Ca) throughout the experiment. Regardless of sex and gonadectomy the mean percent values of 115mCd retention in the whole body decreased with increasing dietary calcium level. Male rats retained less cadmium than all other experimental groups of animals. These data clearly point out that sex and diet might influence the level of ingested cadmium in the body.

Influence of age on whole-body retention and distribution of 115mCd in the rat

Abstract The influence of age on whole-body retention and organ distribution of intraperitoneally applied 115mCdCl2 was studied in 1-, 3-, 6-, and 52-week-old rats. The mean percent values of 115mCd retention in the whole body decreased with increasing age. The distribution of 115mCd in the body on the 14th day after application shows that in all age groups most of the cadmium is accumulated in the liver (45–56%) and kidneys (4–6%). In younger rats the percentage of cadmium in the kidney and blood was always higher than in older animals in contrast to the liver where it was lower. The percentage of the dose in the liver, kidneys, and blood represents however, a considerably lower fraction of the total whole-body retention in younger animals than in older rats. It is therefore concluded that age bears a significant influence on cadmium metabolism. This might be important for estimating cadmium body burden and critical organ exposure in the youngest age group.

Bioavailability of lead in rats fed “human” diets

SummaryThe bioavailability of lead was studied in rats fed various baby foods (Babymix-turkey, Babymix-vegetables, Frutolino-fruit, Frutamix-bananas, Babyron-S-26, Truefood), cows milk, bread, liver and standard rat diet. Lead absorption was determined by measuring the whole body retention of Pb 6 days after a single oral application. Highest absorption values ranging from 17 to 20% were obtained in animals fed cows milk and fruit foods. Rats on other “human” diets absorbed between 3 and 8% of the radioactive lead dose. Only in animals on rat diet lead absorption was below 1%. It is concluded that rats fed “human” diets show absorption values similar to those in humans. This might indicate that the bioavailability of lead is primarily dependent on dietary habits. This experimental model, if confirmed by further work, might be useful for obtaining preliminary data on the bioavailability of metals from various foods.

Comparative metabolism of lead and calcium in young and adult rats

SummaryThe influence of age on the comparative metabolism of lead and calcium was studied by application of radioactive markers (47Ca and203Pb) orally or intraperitoneally to female rats aged 4 weeks and 4 months. The body retention of both radioisotopes was determined over a period of 8 days. All retention values were higher in the younger group of animals. They were 3–4 times higher after oral and 1.3–1.7 times higher after intraperitoneal application of both markers. This indicates that the age related differences in metabolism are very similar for lead and calcium and that they are mostly due to changes in intestinal absorption.

Lead and cadmium in hair as an indicator of body burden in rats of different age

SummaryThe purpose of this work was to evaluate whether hair values of lead and cadmium can be used as an indicator of the body burden of these metals in different age groups.The experiments were performed on rats aged 2 and 18 weeks, which received203pb and115mcd by intraperitoneal injection. The whole body retention and the retention of these radioisotopes in the hair (including the skin) was determined 7 days later. Younger animals showed a higher retention in the whole body and hair of radioactive lead and cadmium. The hair values when expressed as the percentage of the whole body retention were for203pb the same in young and adult rats but for115mcd they were 2 to 3 times higher in young animals than in adults. It is concluded that lead hair values are a good indicator of the total body burden in both age groups. However, the cadmium body burden of young animals would be greatly overestimated if based on hair values only. This findings might be relevant for interpreting results of hair concentrations of lead and cadmium in children.

Effect of a Metal Mixture in Diet On the Toxicokinetics and Toxicity of Cadmium, Mercury and Manganese in Rats

The purpose of this work was to determine whether a metal mix ture added to diet influences the toxicokinetics and toxicity of some elements. The metal mixture (MM) used in these experiments was ash (slag) from a coal gasification plant. The effect of this mixture (5 percent in diet) on the toxicokinetic and on the acute or subchronic toxicity of Cd, Hg, Mn was determined in rats of different ages. Rats were exposed for five weeks in toxicokinetic and six weeks in acute tox icity experiments. Sucklings were exposed through their mothers, which received the MM in diet over the pregnancy and lactation period. In toxicokinetic studies, half of the animals additionally received Cd, Hg or Mn (100, 50 or 2000 ppm, respectively) in drinking water. In subchronic experiments, six-week-old albino rats of both sexes were given MM in the diet and Cd, Hg or Mn in drinking water for 16 weeks. In toxicokinetic studies, 115mCd, 203 Hg or 54Mn were administered orally or intraperitoneally to mothers and pups. Exposure to MM had no effect on the absorption, retention and organ distribution of these elements determined six days after radioisotope administra tion. In acute toxicity studies, exposure to MM in diet had no effect on LD 50 values obtained eight days after oral administration of Cd, Hg or Mn to rats of different ages. In subchronic experi ments, the effect of individual metals (Cd, Hg or Mn) was similar in animals with and without simultaneous exposure to the metal mixture (only a slight potentiation of a few health-effect parameters of cadmium was noticed in some animals). It is concluded that oral exposure to MM in the diet had almost no effect on the toxicokinetics and toxicity of Cd, Hg and Mn. This could be explained by the low level or low bioavailability of ele ments from MM, by the metal-metal interaction within the mixture or by the choice of health effect indicators determined. These results are presented as one of the potential approaches for study ing the health effect of a metal mixture as occurring in the environment.

Chronic and reproduction studies in rats exposed to gasifier ash leachates

Ash from the coal gasification process contains a broad spectrum of elements which through leaching (gasifier ash leachates) may enter into the environment. The health effect of such leachates i.e. complex mixtures of inorganic elements is insufficiently known. We investigated the effect of gasifier ash leachates in a chronic-(9-month) and in a three-generation reproduction study. The leachates were prepared weekly by water extraction of ash from a Lurgi coal gasification plant in Yugoslavia, and given to experimental animals instead of drinking water. In the chronic experiment exposed animals showed no changes in mortality rate, haematological findings, concentration of Fe, Zn, Mn in kidneys, liver, testicles and femur, as well as in femur composition and morphometry, gross pathology and organ histology. In the reproduction study the number of pregnancies, weight and number of newborns, and concentration of Fe, Zn, Mn in carcasses of sucklings were the same in control and experimental animals.

Sex factors and plasma levels of oxytetracycline (OTC) in rats

Sex related differences in plasma OTC concentrations were found in rats 4–24 h after a single i.p. application of 100 and 50 mg/kg OTC.