Gro R. Wesenberg

Zinc in primary teeth from children in Norway.

Human primary teeth have been used as indicators of exposure to several heavy metals both in Norway and elsewhere. Local dentists in all 19 counties of Norway collected 2747 primary teeth during 1990-1994. Samples of tooth powder from whole, ground teeth were analyzed for zinc concentration by flame atomic absorption spectrophotometry. The overall geometrical mean was 144.5 micrograms of Zn/g of tooth substance (S.D. = 1.6). The result represents a small increase (5.2%) compared with a similar investigation in the 1970s. However, the mean zinc concentrations in the geographically matching parts of the two materials did not differ significantly. The variation in tooth zinc concentrations between the different counties declined from the 1970s to the 1990s. We found no correlation between the tooth zinc concentration and available environmental data on zinc in drinking-water, discharge of zinc from industrial point sources or population density in the same geographical areas. The zinc concentrations varied significantly with caries status, tooth type and root length. Few samples had a zinc concentration below 90 micrograms/g, indicating that most children consume sufficient zinc. Some very high values could not immediately be explained, but may be caused by contamination from zinc-containing dental restorations.

Lead, cadmium, zinc and copper in deciduous teeth of norwegian children in the pre‐industrial age

By restoration of the 12th century Uvdal stave church in Buskerud county during the summer of 1978, numerous graves were uncovered underneath the floor. The burials had occurred within a time span of more than 600 years, terminating in the year 1804. Seventy‐nine deciduous teeth were collected and analysed for trace elements. It was concluded that there has been an increase of lead in the environment in Norway, concomitant with urbanization and industrialization, while no such increase of cadmium has occurred. It was further concluded that zinc supply was uniform and optimal in preindustrial Uvdal parish, and that this may not be so in many modern rural districts of Norway.

Lead and cadmium in teeth, bone and kidneys of rats with a standard Pb‐Cd supply

Male Wistar rats received a combination of 25 ppm PbCl2 and 5 ppm CdCl2 in drinking water at different developmental stages. Pb and Cd levels of incisors, molars, epiphyses, diaphyses and kidney cortex were recorded by atomic absorption spectrophotometry. The results confirmed that Pb has an affinity for hard tissue and especially to teeth, but it also accumulated in soft tissues under the above conditions. In addition, the results indicated none or only a moderate placental or mammary barrier for Pb, and suggested a high absorption of lead from the intestine of sucklings. The results also confirmed that kidney cortex is a primary target for Cd, and indicated that Cd has crossed the placental and mammary barriers to some degree. The positive significant correlation between Cd levels in molars and kidney cortex suggested that rodent molars indicate a degree of Cd absorption, whereas incisors do not. It is supposed that rodent molars are comparable to human deciduous teeth. It is thus confirmed that human d...

Cadmium content of indicator and target organs in rats after graded doses of cadmium

Eleven groups of inbred Wistar rats, five males and five females in each group, received graded doses of CdCl2, from 0–25 ppm, in the drinking water from conception until sacrifice at ten weeks of age. Litter‐size, weight and water consumption were recorded at different ages of the animals. The Cd levels of indicators as blood, hair, incisors and molars, and target organs as femur, kidney cortex, liver, spleen, heart, gastrocnemius muscle and adrenal glands were recorded by atomic absorption spectrophotometry. Cd in the drinking water had no influence on number of animals in each litter, water consumption and growth of the animals. The results further confirmed that the primary target organs of Cd were the soft tissues, but that Cd can to some degree accumulate in teeth and bone, especially molars. The Cd content of all tissues, both indicators and targets, was positively and significantly correlated with dose. The positive significant correlation between the Cd levels of hair or molars, and every target ...

Lead in primary teeth from Norway: changes in lead levels from the 1970s to the 1990s

Lead is one of the most important and widely distributed pollutants in the environment. In the human population children are particularly at risk. Local dentists in all 19 counties in Norway collected 2746 primary teeth from 1990 to 1994. Tooth substance from whole, ground teeth were analyzed for lead concentration by electrothermal atomic absorption spectrophotometry. The geometrical mean for the entire material was 1.27 micrograms lead/g tooth substance (S.D. 1.87). The mean lead levels in each of the counties were significantly lower than those obtained in a corresponding study in the 1970s. Two counties, Oslo and Vest-Agder, had significantly higher lead levels than the majority of the other counties. Tooth lead concentration and atmospheric deposition of lead in the same areas were significantly and positively correlated, as shown by analysis of naturally growing moss. We conclude that lead concentrations in primary teeth from children in Norway have been reduced by approx. 50% from the 1970s to the 1990s. The reduction probably reflects a decrease in the environmental lead burden in Norway.

A simple system for generating low-dosage mercury vapor for animal experiments

A system using unlabeled, metallic mercury for generating low-dosage vapor for animal experiments is described. The system consists of four acrylic plastic chambers: one chamber containing the mercury source, one for mixing the mercury vapor with air, one exposure chamber, and one containing activated coal filters and mechanisms for regulating the airflow. The chambers are connected to each other by means of 80-mm-diameter polyvinyl chloride tubes reinforced with wire. Additional control and supporting equipment is also used. The system is easy to set up and requires minimal attendance during use. A standard deviation of 3-4% in the mercury vapor level during 6 h of exposure is typical. The conditions for the animals during exposure and the safety for the personnel during use are optimal.

Trace elements in primary teeth from six areas in Hungary

One hundred and eighty five primary teeth were in 1989–90 collected by local dentists from six different areas in Hungary. The teeth were analyzed for lead, cadmium, mercury and zinc. Both rural, industrialized and urban areas were represented. It was found that the city of Veszprem had significantly higher tooth lead levels than the other areas investigated, including the capital. Two areas had significantly higher tooth‐mercury levels than the other areas, but were just represented by four and six primary teeth, respectively. No area had significantly different cadmium or zinc levels than the other areas investigated. Further study of lead levels in primary teeth from Hungary is suggested.

Effect of cadmium on the immune response in rats

Adult male inbred Wistar rats were given a subtoxic dose of cadmium (25 ppm) orally for 4 weeks prior to and during immunization with sheep erythrocytes (E). The control group received tap water during the experimental period. No difference in the antibody response to E was found between the two groups. Mononuclear peripheral blood cells from experimental and control rats were stimulated with concanavalin A (Con A). The experimental rats had received 25 ppm Cd in the drinking water from weaning until sacrifice at 15 weeks of age. There was no difference in [3H]thymidine incorporation between the cells of the experimental group and those of the control group. Addition of Cd at very low concentrations to the cultures significantly depressed the [3H]thymidine incorporation of the cells from both groups of rats. Thus, a subtoxic dose of Cd apparently had no effect on the in vivo immune response in rats.

The distribution of lead in human hemopoietic tissue and spongy bone after lead poisoning and Ca-EDTA chelation therapy

Two iliac crest needle biopsies were taken from a 43-year-old lead-poisoned woman during and after completion of a Ca-EDTA treatment. By atomic absorption spectroscopy the first and second biopsy were found to contain 56, respectively 41.6 μg lead/g wet tissue. In both biopsies 36% of the lead was extractable in 0.1 N HCl. Electron microbeam X-ray analysis proved to have too low sensitivity for quantitation of the lead in these biopsies. Laser microbeam mass analysis (LAMMA), performed only on the second biopsy, revealed a high and fairly constant residual lead concentration in all bone marrow cell nuclei (approximately 55 μg/g) and a low lead concentration in the cytoplasm of the same cells (4–12 (μg/g). The extracellular bone matrix lead was greatly concentrated in the superficial 3–6 μm osteoid zone of the bony trabeculae and totally absent from deeper parts of the mineralized matrix. The LAMMA results are in good agreement with those of subcellular fractionation experiments and atomic absorption spectroscopy, provided that the relative volume fraction of nucleus and cytoplasm is accounted for. The high residual osteoid lead after completed chelation therapy indicates that lead has a stronger affinity for the organic than the mineral components of bone matrix.

The effect of graded doses of cadmium on lead, zinc and copper content of target and indicator organs in rats

Eleven groups of inbred Wistar rats, five males and five females in each group, received graded doses of CdCl2, from 0–25 ppm, in the drinking water from conception until sacrifice at the age of ten weeks. The Pb, Zn and Cu levels of various indicators and target organs were recorded by atomic absorption spectrophotometry. Cd concentrations above 5 ppm caused a significant increase in Zn content of kidneys, liver, spleen, heart and adrenal glands in most of the experimental groups, and in addition a significant positive correlation between Cd and Zn in the same tissues. With concentrations above 10 ppm, Zn contents of epiphyses and diaphyses decreased significantly, and through all groups there was a significant negative correlation between Zn and Cd in diaphysis. This local Zn deficit may cause a retarded growth of long bones. Cd supply resulted in a significant decrease in Zn content of incisors and molars, but did not significantly affect the Cu content. Neither were Zn nor Cu concentrations in hair af...