A model for estimating the total absorbed dose to the thyroid in Swedish inhabitants following the Chernobyl Nuclear Power Plant accident: implications for existing international estimates and future model applications.

The time-integrated absorbed dose to the thyroid gland in the years after a fallout event can indicate the potential excess number of thyroid cancers among young individuals after a radionuclide release. Typical mean values of the absorbed dose to the thyroid have been calculated previously using reported data on radioiodine obtained from air sampling and dairy milk surveys in Sweden after the Chernobyl fallout, not including the contribution from 134Cs and 137Cs. We have developed a model for Swedish conditions taking these additional dose contributions into account. Our estimate of the average time-integrated absorbed dose to the thyroid, D th,tot, during the first 5 years after fallout ranged from 0.5-4.1 mGy for infants and from 0.3-3.3 mGy for adults. The contribution to D th,tot from 131I through inhalation and milk consumption varied considerably among different regions of Sweden, ranging from 9%-79% in infants, and from 4%-58% in adults. The external irradiation and exposure from the ingestion of 134,137Cs in foodstuffs accounted for the remaining contributions to D th,tot (i.e. up to 96% for adults). These large variations can be explained by the highly diverse conditions in the regions studied, such as different degrees of fractionation between wet and dry deposition, different grazing restrictions on dairy cattle, and differences in 134,137Cs transfers through food resulting from differences in the local fallout. It is our conclusion that the main contribution to D th,tot from nuclear power plant fallout in areas subjected to predominantly wet deposition will be from external exposure from ground deposition, followed by internal exposure from contaminated food containing the long-lived fission product 137Cs and the neutron-activated fission product 134Cs. The contribution from 134,137Cs to the thyroid absorbed dose should thus be taken into account in future epidemiological studies.

Urinary 8-hydroxydeoxyguanosine in Belarussian children relates to urban living rather than radiation dose after the chernobyl accident: a pilot study.

As a result of the Chernobyl accident in 1986, exposure to radioactive cesium is still a concern in the contaminated regions of Belarus. We tested the hypothesis that long-term radiation exposure from the Chernobyl accident might increase the urinary excretion of the oxidative stress marker, 8-hydroxydeoxyguanosine (8-OHdG), in Belarussian children. Urinary 8-OHdG was determined in two groups of children (-n = 31 and n = 46) -living in contaminated and uncontaminated areas of Belarus, respectively (the majority of the unexposed children lived in the capital Minsk). The children from the contaminated areas had a significantly higher annual summary effective dose but significantly lower urinary 8-OHdG levels than the children from the uncontaminated areas. Unexpectedly, children living in uncontaminated urban areas had significantly higher urinary 8-OHdG levels than children living in uncontaminated rural areas. There was no statistically significant effect of sex or body mass index on urinary 8-OHdG, but there was a weak significant inverse correlation to age as well as to the annual summary effective dose. These findings suggest that radiation from the Chernobyl accident is now a less important contributor to oxidative stress in Belarussian children than urban living.

Glutathione S-transferases M1-1 and T1-1 as risk modifiers for renal cell cancer associated with occupational exposure to chemicals.

AIMS: To investigate the possible interaction between occupational risk factors and genotype for glutathione S-transferases M1 and T1 (GSTM1 and GSTT1) in renal cell cancer (RCC). METHODS: One hundred patients with RCC and 200 outpatient controls were enrolled at Parma University Hospital. The polymorphisms of glutathione S-transferase M1-1 (GSTM1) and T1-1 (GSTT1) were investigated by PCR; occupational history was collected by a structured questionnaire. RESULTS: Subjects with GSTM1 present genotype showed higher risks for RCC, compared to GSTM1 null subjects, if exposed to metals (OR 2.73; 95% CI 0.91 to 8.22 v 1.14; 95% CI 0.46 to 2.82) or pesticides (OR 3.46; 95% CI 1.12 to 10.74 v 1.59; 95% CI 0.48 to 5.34). The GSTT1 present genotype also enhanced the risk (about twofold) of RCC among subjects exposed to solvents and pesticides, compared with those GSTT1 null. CONCLUSIONS: Results support the hypothesis that GSTM1 and GSTT1 polymorphisms can interact with several occupational exposures to significantly modify the risk of RCC among exposed subjects.

Occupational risk factors for renal cell cancer. An Italian case-control study.

AIM: To examine possible associations between occupational and environmental risk factors and renal cell cancer (RCC), a tumour with unclear aetiology and increasing incidence. METHODS: A questionnaire-based case-control study of 100 histologically verified cases of RCC and 200 controls was conducted at Parma University Hospital. The control group was enrolled from patients attending different outpatient departments and represented the same residential area as the cases. For all exposure variables under study, two levels of duration were defined: "short" and "prolonged" for less than 10 years or more, respectively. RESULTS: The highest risk estimates for RCC were found for "prolonged" exposure to organic solvents with an odds ratio (OR) of 2.2 (95% confidence interval, CI: 1.0-4.8). "Prolonged" exposures to pesticides and copper sulphate were also associated with increased risk, OR 2.0 (95% CI: 0.8-4.7) and OR 2.7 (95% CI: 1.3-5.5), respectively. CONCLUSIONS: Our data suggests an association between RCC and exposure to organic solvents, pesticides and copper sulphate. A risk gradient as a function of exposure duration was found for organic solvents (p = 0.044) and copper sulphate (p = 0.036), but not for pesticides.

Relations between exposure to arsenic, skin lesions, and glucosuria.

OBJECTIVES: Exposure to arsenic causes keratosis, hyperpigmentation, and hypopigmentation and seemingly also diabetes mellitus, at least in subjects with skin lesions. Here we evaluate the relations of arsenical skin lesions and glucosuria as a proxy for diabetes mellitus. METHODS: Through existing measurements of arsenic in drinking water in Bangladesh, wells with and without arsenic contamination were identified. Based on a questionnaire, 1595 subjects > or = 30 years of age were interviewed; 1481 had a history of drinking water contaminated with arsenic whereas 114 had not. Time weighted mean arsenic concentrations and mg-years/l of exposure to arsenic were estimated based on the history of consumption of well water and current arsenic concentrations. Urine samples from the study subjects were tested by means of a glucometric strip. People with positive tests were considered to be cases of glucosuria. RESULTS: A total of 430 (29%) of the exposed people were found to have skin lesions. Corresponding to drinking water with < 0.5, 0.5-1.0, and > 1.0 mg/l of arsenic, and with the 114 unexposed subjects as the reference, the prevalence ratios for glucosuria, as adjusted for age and sex, were 0.8, 1.4, and 1.4 for those without skin lesions, and 1.1, 2.2, and 2.6 for those with skin lesions. Taking exposure as < 1.0, 1.0-5.0, > 5.0-10.0 and > 10.0 mg-years/l of exposure to arsenic the prevalence ratios, similarly adjusted, were 0.4, 0.9, 1.2, and 1.7 for those without and 0.8, 1.7, 2.1, and 2.9 for those with skin lesions. All series of risk estimates were significant for trend, (p < 0.01). CONCLUSIONS: The results suggest that skin lesions and diabetes mellitus, as here indicated by glucosuria, are largely independent effects of exposure to arsenic although glucosuria had some tendency to be associated with skin lesions. Importantly, however, glucosuria (diabetes mellitus) may occur independently of skin lesions.

The relationship of arsenic levels in drinking water and the prevalence rate of skin lesions in Bangladesh.

To determine the relationship of arsenic-associated skin lesions and degree of arsenic exposure, a cross-sectional study was conducted in Bangladesh, where a large part of the population is exposed through drinking water. Four villages in Bangladesh were identified as mainly dependent on wells contaminated with arsenic. We interviewed and examined 1,481 subjects [Greater/equal to] 30 years of age in these villages. A total of 430 subjects had skin lesions (keratosis, hyperpigmentation, or hypopigmentation). Individual exposure assessment could only be estimated by present levels and in terms of a dose index, i.e., arsenic levels divided by individual body weight. Arsenic water concentrations ranged from 10 to 2,040 microg/L, and the crude overall prevalence rate for skin lesions was 29/100. After age adjustment to the world population the prevalence rate was 30. 1/100 and 26.5/100 for males and females, respectively. There was a significant trend for the prevalence rate both in relation to exposure levels and to dose index (p < 0.05), regardless of sex. This study shows a higher prevalence rate of arsenic skin lesions in males than females, with clear dose-response relationship. The overall high prevalence rate in the studied villages is an alarming sign of arsenic exposure and requires an urgent remedy.

Diabetes mellitus associated with arsenic exposure in Bangladesh.

The objective of this study was to assess whether arsenic exposure is a risk factor for diabetes mellitus as indicated in a few earlier studies. Arsenic in drinking water is known to occur in western Bangladesh, and in 1996, two of the authors conducted a survey of the prevalence of diabetes mellitus among 163 subjects with keratosis taken as exposed to arsenic and 854 unexposed individuals. Diabetes mellitus was determined by history of symptoms, previously diagnosed diabetes, glucosuria, and blood sugar level after glucose intake. The crude prevalence ratio for diabetes mellitus among keratotic subjects exposed to arsenic was 4.4 (95% confidence interval 2.5-7.7) and increased to 5.2 (95% confidence interval 2.5-10.5) after adjustment for age, sex, and body mass index. On the basis of a few earlier measurements of arsenic concentrations in drinking water by the authorities in Bangladesh and another 20 new ad hoc analyses, approximate time-weighted exposure levels to arsenic in drinking water could be estimated for each subject. Three time-weighted average exposure categories were created, i.e., less than 0.5, 0.5-1.0, and more than 1.0 mg/liter. For the unexposed subjects, the corresponding prevalence ratios were 1.0, 2.6, 3.9, and 8.8, representing a significant trend in risk (p < 0.001). The result corroborates earlier studies and suggests that arsenic exposure is a risk factor for diabetes mellitus.

Incidence of neoplasms in ages 0-19 y in parts of Sweden with high 137Cs fallout after the Chernobyl accident.

The incidence of neoplasms in childhood and adolescence in northern and central Sweden before and after the radioactive fallout from the Chernobyl accident was investigated in an ecologic study, 1978 to 1992. The study included all parishes in the six most contaminated counties classified after aerial mapping of ground radiation from 137Cs and investigated 746 cases of neoplasms in ages 0-19 y, diagnosed in the six counties. Incidence and relative risks of neoplasms were compared in areas with high, intermediate, and low contamination after versus before the Chernobyl accident in 1986. A continuous increase of brain tumor incidence in the ages 0-19 y during the period 1978-92 without clear relationship to the Chernobyl fallout was discovered. No clear relationship between the incidence of brain tumor and the exposure to varying levels of radiation from 137Cs was apparent. A somewhat decreased relative risk of acute lymphatic leukemia appeared in areas with increased exposure. Other neoplasms showed no changes in incidence over time or with regard to exposure. Until now, there is no indication that the Chernobyl accident has affected the incidence of childhood and adolescence neoplasms in Sweden, but it is still too early for any final conclusion about the effect of this event.

Myelofibrosis and benzene exposure.

Petrol station attendants are exposed to benzene, a well-known carcinogen for blood malignancies. A case of myelofibrosis in a petrol station attendant is presented, along with other reports of myelofibrosis after benzene exposure obtained from the Swedish Cancer Environment Register. Findings of an increased risk for myelofibrosis in the transport sector also suggest a causal relationship with benzene.