Relative ultraviolet spectral intensity of direct solar radiation, sky radiation and surface reflections. Relative contribution of natural sources to the outdoor UV irradiation of man.

Relative measurements of UVA and UVB radiation from the sun and the sky, as well as the reflected intensity from various land and water surfaces, have been carried out in the Copenhagen area. The measurements were taken in January and in the period April through July and supplemented by measurements in Greenland during May. Likewise, the angular distribution of direct solar radiation and sky radiation close to the direction of the sun was measured with a 0.5 degree field of view. Absolute UV irradiances were measured with detector-filter combinations. Calculations of the relative contributions of direct solar radiation, sky radiation and reflected radiation to the irradiation of a standing person show, in particular, that if seawater with waves is the surrounding scene, its reflected radiation will account for more than 10% of the received UV dose.

Sister chromatid exchange (SCE) in Greenlandic Eskimos. Dose-response relationship between SCE and seal diet, smoking, and blood cadmium and mercury concentrations.

The mutagenicity of the chromosomes of the peripheral lymphocytes of 147 Greenlandic Eskimos living in the district of Angmagssalik, Greenland, and in Denmark, was evaluated by means of the sister chromatid exchange (SCE) test. Thirty cells from each person were examined. The purpose of the investigation was to determine if there was any relationship between mutagenic activity and diet, and hence the elements selenium, cadmium, mercury and lead. The probands were divided into three groups according to their intake of seal meat or industrially prepared food: group 1, those eating seal at least six times per week; group 2, two to five times per week; and group 3 once each week or not at all. The statistical analysis was performed by means of multiple linear regression analyses, with diet, living district, sex, age, tobacco smoking, and blood lead and mercury concentrations as variables. Forty-eight percent of the variation in SCE could be explained by differences in diet, living district, age, and tobacco consumption. Groups 1 and 2 had a 1.7 and 0.65 times higher SCE/cell, respectively, than group 3. For every additional 10 years of age of the probands, the SCE/cell increased by 0.4, and for every 10 g of tobacco smoked per day the SCE/cell was 0.7 higher compared to non-smokers. When priority was given to blood Hg concentration in the calculation, 16.3% of the total variation in SCE/cell could be explained. An increase in the blood Hg concentration of 10 micrograms l-1 corresponded to an increase of 0.3 SCE/cell. In 92 individuals blood Se and Cd concentrations were also analysed. The variables, tobacco smoking, diet, living district and Cd explained 53% of the total variation in SCE. Giving priority to the blood Hg and Cd concentrations, explained 21.4% of the total variation in SCE/cell. An increase of 10 micrograms l-1 in blood Cd and Hg corresponded to an increase in SCE/cell of 0.7 and 0.2, respectively. No influence on the SCE/cell could be attributed to the blood Pb and Se concentrations. Evaluated by the SCE test, seal diet, smoking, living district and blood Hg and Cd concentrations all contribute to mutagenicity in Greenlandic Eskimos, with seal diet as the most important of the factors examined.

Cadmium concentrations in blood samples from an East Greenlandic population.

An analysis for cadmium was made of 101 human blood samples from the district of Angmagssalik, East Greenland, and 29 from East Greenlanders living temporarily in Copenhagen. No relationship could be found between concentrations of blood cadmium and ethnic origin (Eskimos--Danes), sex, age or amount of seal eaten. Only smoking habits were reflected, as a median of 2.2 micrograms/l was found in smokers and 1.1 in non-smokers. Since analyses of organs from seals have suggested that the WHO provisional, tolerable weekly intake is exceeded by a factor as high as 10 as a result of seal eating, it is surprising that seal eating is without any effect on the blood concentration.

Selenium and its interrelation with mercury in wholeblood and hair in an East Greenlandic population.

138 Blood samples and 12 hair samples from the district of Angmagssalik, East Greenland, have been analysed for selenium and mercury. It was found that selenium like mercury, was absorbed in accordance with the amount of marine food eaten. The mean blood concentration in the group eating most marine food was 173 and 186 micrograms Hg/1 for men and women, respectively, while in the group eating the lowest quantity of marine food, the mean values were 86 and 118 micrograms Hg/1. In blood, the selenium and mercury did not correlate in individuals, but only in groups according to eating habits. On a molar basis, selenium is present in blood in excess as compared to mercury, while the opposite is the case for hair. It is concluded that only part of the selenium interacts with mercury, and that blood, but not hair, reflects present dietary intake. The righ supply of selenium in relation to mercury exposure through the traditional arctic food is probably able to alleviate the hazards from dietary mercury exposure.

Effect of luteinizing hormone on Leydig cell structure and testosterone secretion.

Hypophysectomy or sc implantation of testosterone-estradiol 17 beta (T-E) filled polydimethylsiloxane capsules for 5 days caused a dramatic reduction in testosterone secretion when testes subsequently were perfused in vitro. The diminution in testosterone-secreting capacity of testes from T-E treated rats was coupled closely with reductions in the membrane surface areas of Leydig cell cytoplasmic organelles, particularly those of the smooth endoplasmic reticulum. Simultaneous treatment of T-E implanted rats with LH (12 micrograms/day), but not with FSH, PRL, TSH, or GH, maintained both the Leydig-cell cytoplasmic membranes and the capacity of testes to secrete testosterone in vitro. Testosterone secretion by testes from hypophysectomized rats treated simultaneously with T-E plus LH was identical to that in control rats. Therefore, T-E did not inhibit directly the Leydig cell steroidogenic apparatus. Taken together these results suggest that one of the trophic effects of LH in the Leydig cell is to maintained the integrity of smooth endoplasmic reticulum and enzymes responsible for the conversion of pregnenolone to testosterone.

Human exposure to heavy metals in East Greenland. I. Mercury.

The concentration of mercury in 178 blood samples and 32 hair samples from the Angmagssalik district in East Greenland has been determined. For Greenlanders mercury concentrations are highly dependent on the amount of seal eaten. In the most heavily exposed group (eating more than six meals of seal per week), a significant positive correlation between blood mercury and age was demonstrated. No differences according to sex were demonstrated when the mean values were corrected for influence of age. In the most heavily exposed group, a mean value of 62.5 micrograms Hg/l was found, while in the group eating 1 meal of seal or less per week, the mean value was 22.2 micrograms Hg/l. In the control group consisting of Danes living temporarily in the district, the mean blood mercury concentration was 5.8 corresponding to the fact that they eat seal only occasionally. Hair mercury concentrations were found to correlate well with blood mercury concentrations (r=0.9222). The hair/blood ratio was estimated to 289. It is concluded that the present relatively high mercury exposure in Greenland does not exert any immediate risk of intoxication to the adult population, but supplementary investigation on fetal exposure is needed.

Human exposure to heavy metals in East Greenland. II. Lead.

The concentration of lead in 175 blood samples originating from the district of Angmagssalik, East Greenland and 130 from Aarhus, Denmark, has been determined. Both Greenland and Danish males had significantly higher (5%) blood lead than females (Eskimoan males 14.8 micrograms Pb/100 ml, females 12.8 micrograms Pb/100 ml; Danish males 10.5 micrograms Pb/100 ml, females 7.7 micrograms Pb/100 ml). For Danes living temporarily in Greenland the values were: males 10.5 and females 10.2 micrograms Pb/100 ml. Eskimos of both sexes were found to have higher blood lead values than Danes living in the same area. Danish males from Greenland and Denmark were not found to be different, whereas Danish women living in Greenland had a significantly higher (5%) mean value than women living in Denmark. In the Eskimo group, but not in the Danish, a weak, positive, but significant age correlation was found. 4 samples of Eskimo origin exceeded 35 micrograms Pb/100 ml accepted in the EEC as a maximum value for non-occupationally exposed persons. When re-examined 5 months later, all values were below this limit. The influence of eating habits (local or imported food) and smoking habits was tested, but not found to influence the blood lead concentration. The results have confirmed that blood lead levels in Greenland are comparable to those found in European industrialized areas. The reason for the unexpected high level in the arctic area with minimum car driving and industry remains to be clarified.

Skin cancer in Greenland 1955-1974.

During the period from 1955 to 1974, a total of 23 cases of skin cancer in indigenous Greenlanders was diagnosed, 15 in males and eight in females. There were ten basal cell carcinomas, four squamous-cell carcinomas, five malignant melanomas of the skin, and four sarcomas. Eight of the ten basal cell carcinomas were located on the head, half of these on the eyelids. Three of the four squamous-cell carcinomas were found on the lower lip. The number of malignant melanomas in females and the number of remaining, nonmelanotic skin cancers in both males and females were significantly lower than expected if the incidence in the Greenland population had been the same as in Denmark. Since recent investigations seem to indicate that the annual ultraviolet radiation is of almost the same magnitude as in northwest Europe, the low incidence may be due to less skin exposure and/or ethnic factors such as a higher degree of pigmentation. No accumulation of cases within definite geographical areas was found and no occupational clustering was apparent. As regards both squamous-cell carcinomas and malignant melanomas, the degree of metastases and survival indicated that Greenlandic patients sought medical assistance very late.

Fertility and mortality 1950-1974 in the Upernavik district, Greenland.

A descriptive study of fertility and mortality in a Greenlandic whaling and sealing community of approximately 1 800 individuals during the period 1950-74 was performed on the basis of data from parish records and medical reports. Fertility was on the increase until approximately 1960 after which it declined considerably. No significant reduction in the high stillbirth and infant mortality rates could be demonstrated. A considerable reduction in overall mortality was observed and could be attributed to the eradication of tuberculosis as a cause of death. The results are discussed in the light of data from Greenland as a whole, which in general has been characterized by intense industrialization and social development. Further comparative studies in Arctic communities characterized by varying degrees of socio-economic development are recommended.

PIP: A descriptive study of fertility and mortality in a Greenlandic whaling and sealing community of approximately 1800 individuals during the period 1950-74 was performed on the basis of data from parish records and medical reports. Fertility was on the increase until approximately 1960, after which it declined considerably. No significant reduction in the high stillbirth and infant mortality rates could be demonstrated. A considerable reduction in overall mortality was observed and could be attributed to the eradication of tuberculosis as a cause of death. The results are discussed in light of data from Greenland as a whole, which in general has been characterized by intense industrialization and social development. Further comparative studies in Arctic communities, characterized by varying degrees of socioeconomic development are recommended.

Chondrodermatitis nodularis chronica helicis treated with curettage and electrocauterization: follow-up of a 15-year material.

During the 15-year period from 1965 to 1979 a total of 142 cases of chondrodermatitis nodularis chronica helicis were diagnosed. 32% were women, a higher proportion than in earlier materials. The treatment was principally curettage followed by electrocauterization. 78 patients were re-examined after an average lag of 7.1 years. The relapse rate was 31%. This simple surgical technique seems equal to the more elaborate procedures in respect of recurrence rate and more satisfactory from a cosmetic point of view.

Differences in single dose phenytoin kinetics between Greenland Eskimos and Danes.

Phenytoin (PHT) disposition was studied in Greenland Eskimos and in Caucasians (Danes) in order to reveal possible ethnic differences in the pharmacokinetics. PHT was administered i.v. as a single, subsaturation does to healthy adult volunteers and determined in plasma by thin-layer chromatography. Based on the time/concentration curves obtained, the half-life, volume of distribution, the area under the curve, and the total body clearance were calculated. The protein binding was measured by ultrafiltration. Three groups were studied: Group 1 were Eskimos living in East Greenland, group 2 were Eskimos living in Denmark, and group 3 were comparable Caucasians, as a reference group. The total body clearance of PHT per kg body weight was almost twice as high in Eskimos, irrespective of place of living or sex, compared with the Danish group. The volume of distribution was larger in the Eskimo group, but the protein binding did not differ. The reason for the differences in clearance and volume of distribution between the two ethnic groups is not clear, but the results emphasize that ethnic differences in pharmacokinetics can be of significance. The total body clearance values for PHT in Caucasians found in the present study agreed with results from other European investigations that used the same dose, but different analytical assays.

Testosterone secretion by rat, rabbit, guinea pig, dog, and hamster testes perfused in vitro: correlation with Leydig cell ultrastructure.

Stereological methods were employed to determine volume and surface densities of cytoplasmic organelles in Leydig cells of hamster, rat, rabbit, dog, and guinea pig testes. Contralateral testes were perfused in vitro with maximally stimulating gonadotropin concentrations to determine the capacity of these testes to secrete testosterone. Significantly different amounts of testosterone were secreted by in vitro perfused testes of the five species when maximally stimulated with ovine LH. Significant differences also were seen in the volume and surface densities of smooth endoplasmic reticulum, mitochondria, rough endoplasmic reticulum, and lipids in Leydig cell cytoplasm of the five species. Most interestingly, linear positive correlations were seen between testosterone secretion and smooth endoplasmic reticulum volume (r = 0.99) and surface (r = 0.99) densities. Thus, virtually all of the differences in testosterone secretion by maximally stimulated testes of five species could be accounted for by between-species differences in the amount of Leydig cell smooth endoplasmic reticulum.