Jens C. Hansen

Organochlorines and heavy metals in pregnant women from the Disko Bay area in Greenland

Recent studies from Greenland and the Canadian Arctic have shown high concentrations of heavy metals, such as mercury, and organochlorines in the blood and fatty tissue of the Inuit. This is attributed in particular to their high consumption of the meat and blubber of marine mammals. In the present study, 180 pregnant women and 178 newborn babies were studied, amounting to 36% of the total number of births in the Disko Bay area during 1994-1996. The pesticides found in the highest concentrations in maternal blood were DDE (4.8 micrograms/l wet wt.), trans-nonachlor (1.6 micrograms/l) and hexachlorobenzene (1.2 micrograms/l) while the total concentration of PCB (Aroclor 1260) was 19.1 micrograms/l. Calculated on a lipid basis, concentrations were slightly higher in maternal than in cord blood. The mercury concentrations were 16.8 micrograms/l in maternal blood and 35.6 micrograms/l in cord blood. In a linear regression analysis, the concentrations of organochlorines, mercury and selenium increased with maternal age. Concentrations of mercury and cadmium increased with the consumption of marine mammals, and cadmium was associated with smoking. The contaminants are potentially toxic for several organ systems but the high concentrations of pollutants have so far not been shown to influence health in Greenland.

Vitamin D Insufficiency in Greenlanders on a Westernized Fare: Ethnic Differences in Calcitropic Hormones Between Greenlanders and Danes

We studied the influence of age, gender, latitude, season, diet and ethnicity on plasma 25-hydroxyvitamin D 25 OHD, PTH, 1,25-dihydroxyvitamin D, vitamin D-binding protein, bone-specific alkaline phosphatase, and osteocalcin levels in 46 Greenlanders living in Nuuk (64°N) on a traditional fare (group A), 45 Greenlanders living in Nuuk on a westernized fare (group B), 54 Greenlanders (group C), and 43 Danes (Group D) living in Denmark (55°N) on a westernized fare. Blood specimens were drawn both summer and winter. Vitamin D insufficiency (plasma 25 OHD <40 nmol/l) was common in all four study groups during summer (23–74%) and winter (42–81%). Compared to groups A and D, vitamin D insufficiency was significantly more frequent in groups B and C. In all groups, summer levels of 25 OHD were above winter levels. Multiple regression analysis revealed a significant effect of ethnicity. Compared to Danes, Greenlanders had higher 1,25-dihydroxyvitamin D levels, but lower 25 OHD and PTH levels despite relatively low plasma calcium concentrations. In addition to ethnicity, 25(OH)D levels were influenced by age, season (summer > winter), and diet (a traditional Inuit diet>westernized diet). Ethnical differences exist between Greenlanders and Danes. Our results suggest that Greenlanders may have an inherent lower “set-point” for calcium-regulated PTH release or an enhanced renal 1,25(OH)2D production. In addition to ethnicity, age, season, and diet were important determinants of vitamin D status. Changes from a traditional to a westernized fare are associated with a reduced vitamin D status in Greenlanders. Vitamin D supplementation should be considered.

Selenium Treatment in Rheumatoid Arthritis

A low selenium level has been reported in rheumatoid arthritis and juvenile chronic arthritis. Selenium is an essential part of the enzyme glutathione peroxidase, which catabolizes peroxides, compounds which are suggested to be of pathogenetic importance in rheumatic diseases. To assess a possible antirheumatic effect of selenium, 40 patients with active RA were included in a 6-month double-blind clinical study of selenium versus placebo. The patients in the selenium group were given daily supplements of 256 micrograms selenium in selenium-enriched yeast. Although concentrations of selenium in serum and erythrocytes increased considerably, no significant antirheumatic effect of selenium could be demonstrated.

Low Selenium Level in Severe Rheumatoid Arthritis

Serum selenium concentrations were measured in 87 patients with rheumatoid arthritis. The serum selenium levels of the whole group of patients was significantly reduced (70.2 +/- 13.3 micrograms/l, p less than 0.001) when compared with the reference material (79.8 +/- 10.6 micrograms/l). However, the reduction was not equally pronounced in three groups of patients representing different courses of the disease. One group with an active, disabling disease of long duration had a very reduced serum selenium level (63.7 +/- 14.1 micrograms/l, p less than 0.001). Another group, with a protracted but mild disease had a slightly reduced level (74.1 +/- 10.8 micrograms/l, p less than 0.01), and a group with mild disease of short duration had a slightly but not significantly reduced selenium level (75.9 +/- 10.8 micrograms/l, p less than 0.1). Significant correlation was found between serum selenium and the number of joints with limitation of motion, number of joints with active arthritis, haemoglobin concentration and IgG concentration. No correlation was found between serum selenium and disease duration, morning stiffness, ESR, C-reactive protein, rheumatoid factor titre, serum albumin, IgM and IgA. Selenium is part of the enzyme glutathione peroxidase that catabolizes peroxides which are suggested to be actively involved in inflammation. A low selenium level may thus be a further factor in the pathogenesis of rheumatoid arthritis.

Prenatal Exposure to Methyl Mercury among Greenlandic Polar Inuits

During the period 1982 to 1988, 37 paired samples of blood from Inuit women and their newborn children were collected in North Greenland. The samples were analyzed for whole blood content of total mercury (tot-Hg) and for content of methyl mercury (Me-Hg). In maternal blood, 80% of the tot-Hg was found to be methylated in contrast to 98% in cord blood. Concentrations of Me-Hg in maternal and cord blood were significantly correlated, and the mean ratio between fetal and maternal blood Me-Hg was 1.9. Concentrations of Me-Hg in cord blood were closely related to the marine food intake of the mothers. Eighty-four percent of the mothers had blood concentrations of Me-Hg above 0.11 mumol/l (23 micrograms/l), which corresponds to the provisional limit of tolerable intake set by the World Health Organization. This indicates that the majority of the pregnant woman have an unacceptable high intake of methyl mercury.

Environmental contaminants and human health in the Arctic

Monitoring of human exposure to persistent organic pollutants POPs and heavy metals have taken place since 1994 in a circumpolar study conducted under the Arctic monitoring and assessment programme (AMAP). The study has confirmed that Arctic populations relying on marine food (Inuit) have an exposure level of POPs and methyl mercury related to the amount of traditional food eaten and in some areas at a level where health effects cannot be excluded. Weighing the benefits of traditional food against the risks, AMAP have so far recommended that consumption of traditional food continues. There is a need for dietary advice to Arctic peoples so they can make informed choices concerning the food they eat.

Lead sources in human diet in Greenland

Although blood lead levels have declined in Greenland, they are still elevated despite the fact that lead levels in the Greenland environment are very low. Fragments of lead shot in game birds have been suggested as an important source of dietary exposure, and meals of sea birds, particularly eider, contain high concentrations of lead. In a cross-sectional population survey in Greenland in 1993–1994, blood lead adjusted for age and sex was found to be associated with the reported consumption of sea birds. Participants reporting less than weekly intake of sea birds had blood lead concentrations of approximately 75 μg/L, whereas those who reported eating sea birds several times a week had concentrations of approximately 110 μg/L, and those who reported daily intake had concentrations of 170 μg/L (p = 0.01). Blood lead was not associated with dietary exposure to other local or imported food items.

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.

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.

Distribution of dietary mercury in a dog. Quantitation and localization of total mercury in organs and central nervous system

An Alsatian dog which had been fed fish contaminated with methyl mercury for 7 years was examined after its death at the age of 12, 4 years after the exposure to methyl mercury had ceased. Two dogs of the same age and breed served as controls. In the exposed dog, mercury was found in all of the organs examined; the highest concentrations were found in the kidneys, and the lowest in the gastrointestinal tract and skeletal muscles. In the central nervous system (CNS) the mercury was fairly uniformly distributed, with 93% in the inorganic state, whereas the skeletal muscles contained approximately 30% inorganic mercury. This demonstrates time-dependent demethylation and suggests a variation in the rate from one type of tissue to another. At the time of death, the mercury level in the dog was still falling. In the control dogs, detectable amounts (0.01 mg kg-1) of mercury were only found in the kidney and liver. The distribution of mercury was determined by a histochemical method (autometallography) for locating mercury in tissue sections. Sections from autometallography of the central nervous system showed large deposits of mercury in all areas of the cerebral hemispheres, the brainstem and the spinal cord, including nerve cells, astrocytes, microglial cells and vessel walls. The granular layer of the cerebellar hemispheres was especially loaded, while only a few granules were present in the Purkinje cells. In the leptomeninges the vessels and the macrophages were heavily encrusted. High amounts of histochemically demonstrable mercury were observed in the liver, thyroid gland and kidney. In the control dogs, all the organs examined were practically devoid of deposits.