COVID-19: incidence and mortality in Sweden comparing all foreign-born to all Swedish-born individuals in different occupations in an unvaccinated cohort of year 2020

OBJECTIVES

The aim was to analyse the incidence and mortality of COVID-19 in immigrants compared with Swedish born in inpatients and outpatient registers, respectively.

METHODS

The study population included all persons 20-88 years of age living in Sweden, 31 December 2019, including 1 676 516 foreign-born persons and 6 037 151 Swedish-born persons. The outcome was clinical cases of COVID-19 with a positive PCR test (ICD-10 U07.01) or without a positive PCR test (U07.2) from 1 January to 31 December 2020. Persons 20-64 years of age were classified with occupational titles according to the Swedish Standard Classification of Occupations. Residing municipality of each individual was coded according to the Swedish Association of Local Authorities. Relative risks (RR) were calculated by sex in 5 years age bands using Swedish born as reference. Age-adjusted RRs (adj RR) with 95% CIs were calculated in a Poisson regression model. Rural municipalities were used as the reference category.

RESULTS

Foreign born had consistently higher RRs in COVID-19, regardless of sex, with a peak in 50-69 years of age. Foreign born had a higher RR of death in COVID-19 above 50 years and 40 years of age in women and men, respectively. Among occupations, male drivers had the highest adj RR 4.37 (95% CI 3.45 to 5.54) and 5.09 (4.26 to 6.07) in outpatients and inpatients, respectively (U07.1). Persons living in commuting municipalities did not show any consistent increased risk for COVID-19.

CONCLUSION

Foreign born have a higher risk of COVID-19 compared with Swedish-born individuals at any age and occupation before vaccination began in 2021.

Hexavalent chromium still a concern in Sweden - Evidence from a cross-sectional study within the SafeChrom project

OBJECTIVES

Hexavalent chromium (Cr(VI)) is classified as a human carcinogen. Occupational Cr(VI) exposure can occur during different work processes, but the current exposure to Cr(VI) at Swedish workplaces is unknown.

METHODS

This cross-sectional study (SafeChrom) recruited non-smoking men and women from 14 companies with potential Cr(VI) exposure (n = 113) and controls from 6 companies without Cr(VI) exposure (n = 72). Inhalable Cr(VI) was measured by personal air sampling (outside of respiratory protection) in exposed workers. Total Cr was measured in urine (pre- and post-shift, density-adjusted) and red blood cells (RBC) (reflecting Cr(VI)) in exposed workers and controls. The Bayesian tool Expostats was used to assess risk and evaluate occupational exposure limit (OEL) compliance.

RESULTS

The exposed workers performed processing of metal products, steel production, welding, plating, and various chemical processes. The geometric mean concentration of inhalable Cr(VI) in exposed workers was 0.15 μg/m3 (95% confidence interval: 0.11-0.21). Eight of the 113 exposed workers (7%) exceeded the Swedish OEL of 5 μg/m3, and the Bayesian analysis estimated the share of OEL exceedances up to 19.6% for stainless steel welders. Median post-shift urinary (0.60 μg/L, 5th-95th percentile 0.10-3.20) and RBC concentrations (0.73 μg/L, 0.51-2.33) of Cr were significantly higher in the exposed group compared with the controls (urinary 0.10 μg/L, 0.06-0.56 and RBC 0.53 μg/L, 0.42-0.72). Inhalable Cr(VI) correlated with urinary Cr (rS = 0.64) and RBC-Cr (rS = 0.53). Workers within steel production showed the highest concentrations of inhalable, urinary and RBC Cr. Workers with inferred non-acceptable local exhaustion ventilation showed significantly higher inhalable Cr(VI), urinary and RBC Cr concentrations compared with those with inferred acceptable ventilation. Furthermore, workers with inferred correct use of respiratory protection were exposed to significantly higher concentrations of Cr(VI) in air and had higher levels of Cr in urine and RBC than those assessed with incorrect or no use. Based on the Swedish job-exposure-matrix, approximately 17 900 workers were estimated to be occupationally exposed to Cr(VI) today.

CONCLUSIONS

Our study demonstrates that some workers in Sweden are exposed to high levels of the non-threshold carcinogen Cr(VI). Employers and workers seem aware of Cr(VI) exposure, but more efficient exposure control strategies are required. National strategies aligned with the European strategies are needed in order to eliminate this cause of occupational cancer.

Average uranium bedrock concentration in Swedish municipalities predicts male lung cancer incidence rate when adjusted for smoking prevalence: Indication of a cumulative radon induced detriment

Bedrock U has been used as a proxy for local indoor radon exposure. A preliminary assessment of cancer incidence rate in a cohort of 809,939 adult males living in 9 different Swedish counties in 1986 has been used to correlate the cumulative lung cancer and total cancer (excluding lung) incidence rates between 1986 and 2020, respectively with the municipality average value of bedrock U concentration obtained from Swedish geological Survey (SGU). To control for regional difference in tobacco smoking, data on county average smoking prevalence, obtained from a survey conducted by the Public Health Agency of Sweden from 2001 to 2004, was used. Regression analysis shows that there is a significant positive correlation between smoking prevalence adjusted lung cancer incidence rate in males and the municipality bedrock U concentration (R² = 0.273 with a slope 5.0 ± 0.87·10^-3 ppm^-1). The correlation is even more significant (R² = 0.759 with a slope = 4.8 ± 0.25·10^-3 ppm^-1) when assessed on population weighted cancer incidence data binned in nine intervals of municipality average bedrock U concentration (ranging from 0.97 to 4.9 ppm). When assessing the corresponding correlations for total cancer incidence rate (excluding cancer of the lung) with adjustment for smoking prevalence, there appears to be no or little correlation with bedrock U concentration (R² = 0.031). We conclude that an expanded future study needs age-standardized cancer incidence data to obtain a more consistent exposure-response model. Such model could be used to predict future lung cancer cases based on geological survey maps of bedrock U as an alternative to laborious indoor radon measurements, and to discern what future lung cancer rates can be expected for a population nearing zero smoking prevalence, with and without radon prevention.

Sustainable Earnings among Immigrants, and the Role of Health Status for Self-Sufficiency: A 10-Year Follow-Up Study of Labour Immigrants and Refugees to Sweden 2000-2006

This study aimed to investigate economic self-sufficiency for immigrants, and how health status affected self-sufficiency. The proportion of self-sufficiency during years 1-10 after receiving a residence permit is presented for all non-European labour immigrants (n = 1259) and refugees (n = 23,859), aged 18-54, who immigrated to Sweden 2000-2006, and compared to a control group of Swedish-born (n = 144,745). The risk of not being self-sufficient in year 10 was analysed with Cox regression models, and the results are presented as hazard ratios (HRs) with 95% confidence intervals (CIs). Moreover, the impact on the self-sufficiency of having a diagnosis from specialised health care during the first five years in Sweden was analysed. The results showed that half of the refugees and three-quarters of the labour immigrants were self-sufficient 10 years after residency. The adjusted risk of not being self-sufficient at year 10 was 80% higher among labour immigrants (HR = 1.8; CI = 1.6-2.0) and more than two-fold among refugees (HR = 2.7; CI = 2.6-2.8) compared to the Swedish-born. Having a diagnosis from specialised health care during the first five years in Sweden had an impact on self-sufficiency in all groups; however, the impact of having a diagnosis did not differ between refugees and Swedish-born. Measures must be taken to increase immigrants' work participation.

Overqualification at work and risk of hospitalization for psychiatric and somatic diseases among immigrants in Sweden - a prospective register-based study

OBJECTIVES

This study aimed to (i) describe the prevalence of overqualification at work among immigrants in Sweden and (ii) analyze any association between overqualification and the risk of hospitalization for somatic and psychiatric disease among refugees and labor immigrants.

METHODS

We performed a prospective register study in a cohort of 120 339 adults who immigrated to Sweden in 1991-2005 and were employed in 2006. Education-occupation status was defined as the combination of an individual's highest level of education and their occupation skill level. Individuals were followed from 2007 to 2016 with regard to hospitalization for a psychiatric, cardiovascular, respiratory or musculoskeletal disease or diabetes. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated in a multivariate Cox regression analysis adjusted for age, gender, reason for residence and duration of residence.

RESULTS

The overall prevalence of overqualification among immigrants with an academic education was 39%. Overqualified individuals had an increased risk of hospitalization for any disease (HR 1.33, 95% CI 1.21-1.46) compared to "job-matched with an academic education". However, the risk estimates were lower than that of "job-matched with no academic education" (HR 1.56, 1.46-1.68). The increased risk of hospitalization for a psychiatric disease of overqualified individuals did not differ from that of job-matched with no academic education.

CONCLUSION

Our study showed that being overqualified was associated with poorer health outcomes than job-matched individuals with an academic education. Considering the high prevalence of overqualification in immigrants, this constitutes a concern, for both society and individuals.

Cancer incidence in a male adult population in relation to estimated protracted colon dose - A nested case control study in Northern Sweden after the Chernobyl Nuclear Power Plant accident

INTRODUCTION

Uncertainty in the dose-response of low dose radiation raised concern of an increased cancer incidence in Sweden after the Chernobyl Nuclear Power Plant (NPP) accident.

MATERIAL AND METHODS

A closed cohort was created of all males ≥18 years of age living in the Northern Sweden in 1986. In total 826,400 individuals were enrolled including 40,874 hunters. A nested case-control design was used with five controls randomly selected for each cancer case matched on year of diagnosis and year of birth. Individual absorbed colon dose was calculated 1986 to 2015. Allowing for a 5-year latency period Hazard Ratios (HR) per mGy with 95% Confidence Intervals (95% CI) were calculated in a conditional logistic regression adjusted by rural/non-rural living, length of education and pre-Chernobyl cancer incidence 1980 to 1985. A total of 127,109 cancer cases occurred from 1 January 1991 to 31 December 2015. Cancer was classified in: 1) Organ-specific (stomach, colon, liver, lung, prostate, urinary bladder, thyroid and leukaemia), 2) Other and 3) Not previously associated to ionizing radiation.

RESULTS

The average colon dose in cases was 1.77 mGy compared to controls 1.73 mGy. Hunters average colon dose was 2.32 mGy. Organ-specific cancers showed the highest HR per mGy both in the full cohort, adj HR 1.019 (1.014-1.024) and the hunter subcohort, adj HR 1.014 (1.001-1.027) during follow-up 1991 to 2015. Other cancer and Not previously associated with ionizing radiation showed lower HR per mGy. Therefore, the adj HR per mGy for Total cancer, 1.013 (1.009-1.017) was explained by Organ-specific cancer. Increased adj HR per mGy was seen in stomach, colon and prostate cancer, respectively in the full cohort and lung cancer in hunters.

CONCLUSIONS

Some cancer sites previously associated with ionizing radiation showed a positive adjusted HR per mGy both in the full cohort and in the hunter subcohort.

Absorbed dose rate coefficients for134Cs and137Cs with steady-state distribution in the human body:S-coefficients revisited

In the event of an accidental release of radioactive elements from a nuclear power plant, it has been shown that the radionuclides contributing the most to long-term exposure are¹³⁴Cs and¹³⁷Cs. In the case of nuclear power plant fallout, with subsequent intake of radionuclides through the food chain, the internal absorbed dose to target tissues from protracted intake of radionuclides needs to be estimated. Internal contamination from food consumption is not caused by a single intake event; hence, the committed equivalent dose, calculated by a dose coefficient or dose per content function, cannot be easily used to calculate the cumulative absorbed dose to relevant target tissues in the body. In this study, we calculated updated absorbed dose rate coefficients for¹³⁴Cs and¹³⁷Cs based on data from the International Commission on Radiological Protection (ICRP) on specific absorbed fractions. The absorbed dose rate coefficients are provided for male and female adult reference phantoms, respectively, assuming a steady-state distribution of Cs that we calculated from the ICRP biokinetic model for Cs. With these coefficients, the absorbed dose to the listed target tissues, separately and to the total body, are related to the number of nuclear transitions (time-integrated activity) in each listed source region. Our new absorbed dose rate coefficients are given for the complete set of target tissues and have not been presented before. They are also provided for aggregated categories of organs to facilitate epidemiological studies.

Increased cancer risk in male hunters compared to the general male population in Northern Sweden after the Chernobyl Nuclear Power Plant accident?

Male hunters in Swedish counties with high fallout of ¹³⁷Cs after the Chernobyl Nuclear Power Plant (NPP) accident have higher radiation exposure due to higher consumption of game compared with the general population.

Methods

Cancer incidence in Sweden was studied in 9 counties with different ¹³⁷Cs fallout after the Chernobyl NPP accident in 1986. In total, 9,267 cancer cases occurred in hunters and 138,909 cancer cases in non-hunters to 31 December 2015. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated using unexposed hunters, or non-hunters, as reference to study internal radiation exposure or hunter life style, respectively.

Results

Directly age standardized total cancer incidence showed an increasing trend in non-hunters. For hunters, the total cancer incidence was significantly lower up to 2001 when the total cancer incidence crossed over the weaker non-hunter trend and remained higher for the following 15 years. IRRs for total cancer in hunters versus non-hunters for each county did not show any clear exposure response pattern. IRRs for hunters versus non-hunters were higher regardless of rural/non-rural status with slightly higher risk estimates for the rural settings. The IRR for hunters was 1.06 (95% CI 1.04-1.08) 1986-2015, representing an excess of 531 cancer cases in hunters.

Conclusion

An increased total incidence of cancer was identified for male hunters compared with male non-hunters. No obvious association between cancer and ¹³⁷Cs from the Chernobyl NPP accident could be identified, although the exposure classification was too crude to exclude such an association.

Introduction of a method to calculate cumulative age- and gender-specific lifetime attributable risk (LAR) of cancer in populations after a large-scale nuclear power plant accident

The effect of age and gender in risk estimates related to long-term residence in areas contaminated by nuclear power plant fallout was evaluated by applying the lifetime attributable risk (LAR) concept to an existing exposure model that was previously used for cumulative effective dose estimates. In this study, we investigated the influence of age distribution on the number of cancer cases by applying five different age distributions from nuclear power-producing countries (India, Japan, South Korea, and the United States), and Egypt because of intentions to develop nuclear power. The model was also used to estimate the effective dose and gender-specific LAR as a function of time after fallout for the offspring of the population living in 137Cs fallout areas. The principal findings of this study are that the LAR of cancer incidence (excluding non-fatal skin cancers) over 70 y is about 4.5 times higher for newborn females (5.4% per MBq m-2 of initial 137Cs ground deposition) than the corresponding values for 30 y old women (1.2% per MBq m-2 137Cs deposition). The cumulative LAR for newborn males is more than 3 times higher (3.2% versus 1.0% per MBq m-2 137Cs deposition). The model predicts a generally higher LAR for women until 50 y of age, after which the gender difference converges. Furthermore, the detriment for newborns in the fallout areas initially decreases rapidly (about threefold during the first decade) and then decreases gradually with an approximate half-time of 10-12 y after the first decade. The age distribution of the exposed cohort has a decisive impact on the average risk estimates, and in our model, these are up to about 65% higher in countries with high birth rates compared to low birth rates. This trend implies larger average lifetime attributable risks in countries with a highly proportional younger population. In conclusion, the large dispersion (up to a factor of 4 between newborns and 30 y olds) in the lifetime detriment per unit ground deposition of 137Cs over gender and age in connection with accidental nuclear releases justifies the effort in developing risk models that account for the higher radiation sensitivity in younger populations.

Intergenerational Ethical Issues and Communication Related to High-Level Nuclear Waste Repositories

Purpose of Review

The nuclear power industry started in the 1950s and has now reached a phase of disposing high-level nuclear waste. Since the 1980s, the United Nations has developed a concept of sustainable development and governments have accordingly made ethical commitments to take responsibility towards future generations. The purpose of this review is to examine ethical dilemmas related to high-level nuclear waste disposal in a long-term perspective including potential access to the waste in the future. The time span considered here is 100,000 years based on current experts’ assessment of the radiological toxicity of the waste.

Recent Findings

In this review, we take into account findings on ethical issues related to the disposal of high-level nuclear waste put forward by the Radioactive Waste Management Committee (RWMC), the International Commission on Radiological Protection (ICRP), nuclear waste management companies (SKB in Sweden and Posiva Oy in Finland), and several researchers. Some historical examples are presented for potential guidance on methods of communication into the future.

Summary

According to the sustainable development ethical principle, adopted by the United Nations, we conclude that governments with nuclear energy have committed themselves to protect future generations from harm related to high-level nuclear waste. This commitment involves the necessity to convey information together with the nuclear waste. Our paper examines disposal options chosen by Sweden and Finland, as well as some contemporary and historical efforts to design messages towards the future. We conclude that the international community still needs to find methods to communicate in an intelligible way over long periods of time.

Corrigendum to: 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 (2019 J. Rad. Prot. 39(2) 522: doi: 10.1088/1361-6498/ab0577)

Four of the equations in the article "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 " were incomplete or erroneously expressed. A corrigendum is attached with the amended equations.

Modelling the effective dose to a population from fallout after a nuclear power plant accident-A scenario-based study with mitigating actions

The radiological consequences of a nuclear power plant (NPP) accident, resulting in the release of radionuclides to the environment, will depend largely on the mitigating actions instigated shortly after the accident. It is therefore important to make predictions of the radiation dose to the affected population, from external as well as internal exposure, soon after an accident, despite the fact that data are scarce. The aim of this study was to develop a model for the prediction of the cumulative effective dose up to 84 years of age based on the ground deposition of 137Cs that is determined soon after fallout. The model accounts for different assumptions regarding external and internal dose contributions, and the model parameters in this study were chosen to reflect various mitigating actions. Furthermore, the relative importance of these parameters was determined by sensitivity analysis. To the best of our knowledge, this model is unique as it allows quantification of both the external and the internal effective dose using only a fallout map of 137Cs after a nuclear power plant accident. The cumulative effective dose over a period of 50 years following the accident per unit 137Cs deposited was found to range from 0.14 mSv/kBq m-2 to 1.5 mSv/kBq m-2, depending on the mitigating actions undertaken. According to the sensitivity analysis, the most important parameters governing the cumulative effective dose to various adult populations during 50 years after the fallout appear to be: the correlation factor between the local areal deposition of 137Cs and the maximum initial ambient dose rate; the maximum transfer from regional average fallout on the ground to body burden; the local areal deposition of 137Cs; and the regional average 137Cs deposition. Therefore, it is important that mapping of local 137Cs deposition is carried out immediately after fallout from a nuclear power plant accident, followed by calculations of radiation doses for different scenarios using well-known parameters, in order to identify the most efficient mitigation strategies. Given this 137Cs mapping, we believe our model is a valuable tool for long-term radiological assessment in the early phase after NPP accidents.

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.

Modelling the external radiation exposure from the Chernobyl fallout using data from the Swedish municipality measurement system

In connection with the Chernobyl fallout and the subsequent deposition of radionuclides in Sweden, Swedish municipalities launched a measurement program to monitor the external radiation exposure. This program encompasses measurements of the ambient dose equivalent rate 1 m above ground at selected locations, and repeats those measurements at the same locations at 7-month intervals. Measurement data compiled from the seven locations with the highest deposition were combined with data from aerial surveys since May 1986 of ground deposition of ¹³⁷Cs, high-resolution gamma spectrometry performed at four locations in May 1986, and measurements from fixed continuous air gamma rate monitoring stations from 28 April to 15 May 1986. Based on these datasets, a model of the time pattern of the external dose rate in terms of ambient dose equivalent rate from the Chernobyl fallout was developed. The decrease in the ambient dose equivalent rate could, on average, be described by a four-component exponential decay function with effective half-times of 6.8 ± 0.3 d, 104 ± 26 d, 1.0 ± 0.02 y and 5.5 ± 0.09 y, respectively. The predominant contributions to the external dose rate in the first month were from short-lived fission products superseded by ¹³⁴Cs and then ¹³⁷Cs. Integrated over 70 y and using extrapolation of the curve fits, our model predicts that ¹³⁷Cs contributes about 60% and ¹³⁴Cs contributes about 30% of the external effective dose at these seven locations. The projected time-integrated 70 y external effective dose to an unshielded person from all nuclides per unit total activity deposition of ¹³⁷Cs is estimated to be 0.29 ± 0.0.08 mSv/(kBq m^-2). These results are in agreement with those found in Chernobyl contaminated Russian forest areas, and emphasize the usefulness of maintaining a long-term and regular measurement program in contaminated areas.

Estimated lifetime effective dose to hunters and their families in the three most contaminated counties in Sweden after the Chernobyl nuclear power plant accident in 1986 - A pilot study

Hunters and their families were one of the most exposed subpopulations in Sweden after the Chernobyl nuclear power plant accident in 1986. In this pilot study we used existing registries and whole-body measurements to develop algorithms to calculate lifetime effective doses and collective doses to some hunters in Sweden. Ten hunters and their family members were randomly selected from each of the three most contaminated counties in Sweden (Västernorrland, Uppsala, Gävleborg) using the register for hunting weapons from the Police Authority in 1985. Hence, this design can be regarded as a closed cohort only including hunters and their family members living in these three counties at the time of the accident. Statistics Sweden matched these individuals (n = 85) with their dwelling coordinates onto the digital map produced by the Swedish Radiation Safety Authority after aerial measurements of ¹³⁷Cs (kBq m^-2). Internal effective doses were estimated using aggregated transfer factors from ground deposition to in-vivo body concentration for ¹³⁴Cs and ¹³⁷Cs in hunters (Bq kg^-1). External effective doses were also calculated on the dwelling coordinate for ¹³⁴Cs, ¹³⁷Cs and short-lived nuclides in these three counties. Annual effective doses for external and internal doses were then cumulated up to a life expectancy of 80 years for men and 84 years for women, respectively. The total lifetime effective doses to the members of the hunter families in this cohort were on average 8.3 mSv in Västernorrland, 4.7 mSv in Uppsala and 4.1 mSv in Gävleborg. The effective dose to men were about 40% higher than in women. In all counties the internal dose was about 75% of the total lifetime effective dose. The collective dose for all hunters with family members, in total about 44,000 individuals, in these three counties could be approximated at about 256 manSv. This study shows it is possible to use register data to develop algorithms for calculating lifetime effective dose commitments for hunters with relatively accuracy.

Total cancer incidence in relation to 137Cs fallout in the most contaminated counties in Sweden after the Chernobyl nuclear power plant accident: a register-based study

OBJECTIVES

To determine the total cancer incidence in relation to a 5-year exposure to caesium-137 (¹³⁷Cs) from the 1986 Chernobyl nuclear power plant accident.

METHODS

A closed cohort was defined as all individuals living in the three most contaminated counties in mid-Sweden in 1986. Fallout of ¹³⁷Cs was retrieved as a digital map from the Geological Survey of Sweden, demographic data from Statistics Sweden, and cancer diagnosis from the National Board of Health and Welfare. Individuals were assigned an annual ¹³⁷Cs exposure based on their place of residence (1986-1990), from which 5-year cumulative ¹³⁷Cs exposures were calculated, accounting for the physical decay of ¹³⁷Cs and changing residencies. HRs were adjusted for age, sex, rural/non-rural residence and pre-Chernobyl total cancer incidence.

RESULTS

The 734 537 people identified were categorised by exposure: the first quartile was low exposure (0.0-45.4 kBq/m²), the second and third quartiles were intermediate exposure (45.41-118.8 kBq/m²), and the fourth quartile was the highest exposure (118.81-564.71 kBq/m²). Between 1991 and 2010, 82 495 cancer cases were registered in the 3 counties. Adjusted HRs (95% CI) were 1.03 (1.01 to 1.05) for intermediate exposure and 1.05 (1.03 to 1.07) for the highest exposure compared to the reference exposure.

CONCLUSIONS

We found a small overall exposure-response pattern of the total cancer incidence related to ¹³⁷Cs after adjustment for age, sex, rural residence and pre-Chernobyl cancer incidence.

[Immediate and delayed outcomes after electrical injury. A guide for clinicians]

Immediate and delayed outcomes after electrical injury. A guide for clinicians In Sweden about 300 electrical injuries are recorded each year at the Swedish National Electrical Safety Board. Most of our knowledge of the health consequences of these arise from clinical case series. Severe electrical injuries have direct thermal effects and may result in ventricular fibrillation, skin burns, as well as muscular and nerve affection. Long-term consequences include pain, vascular symptoms, cognitive and neurological symptoms and signs. These sequelae may occur even though the initial symptoms were relatively modest. Mechanisms are better understood for the immediate symptoms, compared to long-term and delayed non-thermal medical consequences. Attention to and treatment of patients with electrical injury needs to be improved to minimize long-term consequences. Good medical care in the acute phase and early multidisciplinary follow-up of severe cases will likely reduce associated morbidity. Each electrical injury should result in an inquiry to identify the cause of the accident in order to suggest actions to prevent new incidents.

Cancer incidence in northern Sweden before and after the Chernobyl nuclear power plant accident

Sweden received about 5 % of the total release of (137)Cs from the Chernobyl nuclear power plant accident in 1986. The distribution of the fallout mainly affected northern Sweden, where some parts of the population could have received an estimated annual effective dose of 1-2 mSv per year. It is disputed whether an increased incidence of cancer can be detected in epidemiological studies after the Chernobyl nuclear power plant accident outside the former Union of Soviet Socialist Republics. In the present paper, a possible exposure-response pattern between deposition of (137)Cs and cancer incidence after the Chernobyl nuclear power plant accident was investigated in the nine northernmost counties of Sweden (2.2 million inhabitants in 1986). The activity of (137)Cs from the fallout maps at 1986 was used as a proxy for the received dose of ionizing radiation. Diagnoses of cancer (ICD-7 code 140-209) from 1980 to 2009 were received from the Swedish Cancer Registry (273,222 cases). Age-adjusted incidence rate ratios, stratified by gender, were calculated with Poisson regression in two closed cohorts of the population in the nine counties 1980 and 1986, respectively. The follow-up periods were 1980-1985 and 1986-2009, respectively. The average surface-weighted deposition of (137)Cs at three geographical levels; county (n = 9), municipality (n = 95) and parish level (n = 612) was applied for the two cohorts to study the pre- and the post-Chernobyl periods separately. To analyze time trends, the age-standardized total cancer incidence was calculated for the general Swedish population and the population in the nine counties. Joinpoint regression was used to compare the average annual percent change in the general population and the study population within each gender. No obvious exposure-response pattern was seen in the age-adjusted total cancer incidence rate ratios. A spurious association between fallout and cancer incidence was present, where areas with the lowest incidence of cancer before the accident coincidentally had the lowest fallout of (137)Cs. Increasing the geographical resolution of exposure from nine county averages to 612 parish averages resulted in a two to three times higher value of variance in the regression model. There was a secular trend with an increase in age-standardized incidence of cancer in both genders from 1980 to 2009, but significant only in females. This trend was stronger and statistically significant for both genders in the general Swedish population compared to the nine counties. In conclusion, using both high quality cancer registry data and high resolution exposure maps of (137)Cs deposition, it was not possible to distinguish an effect of (137)Cs on cancer incidence after the Chernobyl nuclear power plant accident in Sweden.

Urinary 2,5-hexanedione excretion in cryptogenic polyneuropathy compared to the general Swedish population

Background

2,5-hexanedione (2,5-HD) is the main neurotoxic metabolite of methyl-n-butyl ketone (MBK) and n-hexane, and known to cause polyneuropathy. The aim of our study was to compare the urinary levels of 2,5-HD between cases with cryptogenic polyneuropathy and the general Swedish population, and to elucidate the role of certain external factors.

Methods

Morning urine samples were collected from 114 cases with cryptogenic polyneuropathy (77 men and 37 women) and 227 referents (110 men and 117 women) randomly selected from the population registry. None had any current occupational exposure to n-hexane or MBK. The urine samples were analysed by a gas chromatographic method based on acidic hydrolysis.

Results

Cases had statistically higher urinary levels of 2,5-HD (0.48 mg/L) than the general population (0.41 mg/L) and men higher excretion than women (0.48 mg/L and 0.38 mg/L, respectively). There was no difference in 2,5-HD levels between current smokers and non-smokers. Occupational exposure to xylene, alcohol consumption and ever exposed to general anaesthesia were associated with lower excretion in men while for occupational exposure to nitrous oxide in women higher excretion was seen. Higher excretion of 2,5 HD was inversely related to increasing age.

Conclusions

Significantly higher levels of urinary 2,5-HD were seen in men and cryptogenic polyneuropathy cases seemingly unexposed to n-hexane. Hypothetically, this might be due to either differences in metabolic patterns or some concealed exposure. The difference in means between cases and the general population is small and can therefore not allow any firm conclusions of the causality, however.

IgA antibodies against tissue transglutaminase, endomysium and gliadin in idiopathic polyneuropathy

OBJECTIVES

To study the prevalence of antibodies of IgA class against tissue transglutaminase (tTG), endomysium (EMA) and gliadin (AGA) in patients with chronic idiopathic axonal polyneuropathy (CIAP) and to characterize the patients clinically and neurophysiologically.

METHODS

Of 182 patients, 126 patients agreed to blood sampling. Sera were analysed by ELISAs detecting anti-tTG and AGA, whereas EMA was analysed by indirect immunofluorescence (IF) microscopy. Gastrointestinal symptoms were assessed by data from medical records and patient interviews.

RESULTS

Nine of 126 patients (7%) were seropositive in at least one test (five with positive anti-tTG and/or EMA and four with positive AGA only). One patient with elevated levels of all specificities had laboratory signs of malabsorption and gastrointestinal complaints with abdominal pain and diarrhoea.

CONCLUSIONS

Elevated levels of IgA-AGA were slightly more frequent in patients with CIAP (4%) compared to 2.5% in 1866 healthy blood donors. Highly specific serological markers indicative of coeliac disease (CD) (anti-tTG and EMA) were somewhat more common in our patients with CIAP (4%) than expected from normal reference values and from studies of the prevalence of CD in the general population. Even though these findings may indicate a relationship, the aetiological importance is unclear.

Polymorphisms of GSTT1, GSTM1, and EPHX genotypes in patients with cryptogenic polyneuropathy: a case-control study

The aim of this study was to analyze whether polymorphisms for the null alleles of Glutathione S-Transferase Mu-1 (GSTM1), Glutathione S-Transferase Theta-1 (GSTT1), and a low-activity genetic variation of epoxide hydrolase exon three (EPHX*3) affect the risk of developing polyneuropathy. The enzymes of these genes are important in the metabolism of toxic compounds. Seventy-nine patients with cryptogenic polyneuropathy (equivalent to chronic idiopathic axonal neuropathy) and 398 controls were tested for the genetic polymorphism. Medical records were reviewed to collect data regarding clinical findings at diagnosis, and exposure data was collected via questionnaires. The odds ratios (ORs) for the null forms of GSTM1 and GSTT1 and the normal activity YY form of EPHX*3 were close to one except GSTT1, which reached 1.86. The highest risk of polyneuropathy was found in smokers with GSTT1 null, who had a 3.7 times increased risk. Interactions between genes were analyzed and confirmed the increased OR for GSTT1, which was strongest if the patients had the low-activity HH form of EPHX*3 (OR 2.37). Our hypothesis is that the GSTT1 null polymorphism may be related to an impaired metabolism of toxic substances that could lead to nerve damage in the peripheral nervous system.

Risk of malignancies in relation to terrestrial gamma radiation in a Swedish population cohort

Results of epidemiological studies on terrestrial gamma radiation (TGR) and related malignancies have not been consistent. This study is a thorough examination of this relationship. Records on all individuals living in two Swedish counties in 1973, along with their annual dwelling coordinates during the 28-year follow-up period, were retrieved from the National Archives and Statistics Sweden. We used Geographical Information System (GIS) to match the individuals' dwelling coordinates annually to the TGR given in 200×200 m grids produced by the Geological Survey of Sweden. Cases of malignancies and deaths were retrieved from the Swedish Cancer Register. During the follow-up period 61,503 incident cases were included in the analyses and in total 11 million person-years were recorded. Cox regression was used both in a linear continuous model and analyses of six exposure categories. Adjustments were made for sex, age, and population density. The hazard ratio (HR) per 100 nanoGray/hour (nGy/h) was significantly increased for total malignancies and for several sites; however, contrary to expectations, an obvious and anticipated linear exposure-response relationship could not be identified. With the lowest exposure category (0-60 nGy/h) as reference, a statistically significantly increased HR for total malignancies was seen in all exposure categories, except in the highest category 96-366 nGy/h. For breast cancer, thyroid cancer and leukaemia an obvious exposure-response could not be seen.

Health-related quality of life in patients with cryptogenic polyneuropathy compared with the general population

PURPOSE

To evaluate the quality of life (QOL) in patients with cryptogenic polyneuropathy.

METHOD

Two validated instruments (SF-36 and EQ-5D) were sent to 86 patients with a 72% response rate (44 men, 18 women). As reference, 2721 individuals (1292 men, 1429 women; 59% response rate) from the general population responded to the same QOL instruments.

RESULTS

Compared to the general population, QOL was significantly more affected in patients with polyneuropathy concerning motor functions, with 42% of the patients reporting problems with walking, 7% having difficulties with washing and dressing, and 31% having problems with usual activities (work, study, household work, and family or leisure activities). The EQ-5D results showed that 85% of the patients were suffering from pain compared to 56% of the general population. Mental health was preserved among patients with polyneuropathy. Mobility was declining with increasing age in patients, but was not affected by disease duration.

CONCLUSIONS

Our study showed that patients with cryptogenic polyneuropathy have a lower QOL compared to the general population, although mental health scores did not differ between the groups. This information may be helpful when explaining the disease and its impact on newly diagnosed patients.

Parish classification or dwelling coordinate for exposure assessment in environmental epidemiology - a comparative study using Geographical Information System

BACKGROUND

Two previous epidemiological studies on the incidence of total malignancies in Sweden after the Chernobyl accident have shown consistently increased risks. The first study used an analogue map on (137)Cs from 1986 to classify individuals in terms of the parish they lived in. In the second study, dwelling coordinates were matched to a digital map from the year 2000 to assess the individual exposure. To establish the accuracy of the exposure assessment using the larger unit of parish, instead of coordinates, we decided to compare the methods.

METHODS

On the analogue map eleven isolines on the deposition of (137)Cs (kBq/m(2)) were used to classify all individuals in each of the 450 parishes. Using the digital map, by contrast, each dwelling with its inhabitants could be matched to (137)Cs deposition at a coordinate level. A population-weighted average of (137)Cs deposition was calculated for each parish. In total, 1,126,960 individuals and 450 parishes were included and analysed into six different exposure categories.

RESULTS

Using the new parish exposure index, 111 out of the 450 parishes were reclassified as a result of the increased resolution of the digital map (86 parishes) or unequal distribution of the population compared with the deposition (25 parishes). Seventy-five per cent of the parishes remained in the same exposure category as on the analogue map.

CONCLUSION

Using dwelling coordinates for exposure assessment may not always be superior to parish classification. Nor is it always a cost-effective way of estimating the exposure, especially if the exposure in a parish is relatively homogenous or if parishes can be merged into broader categories with little intra-parish difference.

Occupational Determinants of Cryptogenic Polyneuropathy

OBJECTIVES

The aim was to investigate different occupational and leisure time exposures as determinants for cryptogenic polyneuropathy.

METHODS

A case-referent study was conducted in Sweden including 232 cases of cryptogenic polyneuropathy 40-79 years of age at diagnosis who were enrolled from the out-patient neurology departments of 3 hospitals. From the population register 853 referents were randomly selected. Information on occupational and leisure time exposure was obtained from a postal questionnaire. The response rate was 71% for cases and for referents. Crude odds ratios (CORs) and logistic regression odds ratios (LORs) were calculated for exposures with 5 or more exposed cases and referents taken together. The reference category was defined as individuals unexposed to any of the occupational or leisure time risk factors in the questionnaire.

RESULTS

As expected, male sex and increasing age were significant determinants for cryptogenic polyneuropathy. Occupational exposures in men to Stoddard solvent, petrol exhausts, herbicides or hand and foot vibrations generated significantly increased CORs. LORs >3.50 were found in men for occupational exposure to sulphur dioxide, xylene, methyl ethyl ketone, herbicides and in women for occupational exposure to lead, nitrous oxide and insecticides. Only solvent exposure in leisure time remained significant in the regression analysis indicating that not only occupational exposures were of importance. Interactions between occupational and leisure time exposure were seen for several agents.

CONCLUSIONS

Several known determinants for polyneuropathy, from animal studies and case reports, were confirmed. New determinants were also indicated, i.e. sulphur dioxide, xylene and methyl ethyl ketone.

The risk for multiple sclerosis in female nurse anaesthetists: a register based study

BACKGROUND

Previous studies have suggested that exposure to organic solvents, including volatile anaesthetic agents, may be a risk factor for multiple sclerosis (MS), possibly in combination with genetic and other environmental factors.

AIMS

To further investigate the role of volatile anaesthetic agents having similar acute toxic effects to other organic solvents.

METHODS

Female nurse anaesthetists, other female nurses, and female teachers from middle and upper compulsory school levels were identified and retrieved from the 1985 census, Statistics Sweden. By means of the unique personal identity number in Sweden, these individuals were linked with the disability pension registers at The National Social Insurance Board and also with data on hospital care 1985-2000 at The National Board of Health and Welfare.

RESULTS

The cumulative incidence rate ratio of MS was found to be increased in female nurse anaesthetists in relation to other nurses (statistically not significant) and teachers (statistically significant), respectively.

CONCLUSIONS

These findings give some support to previous findings of an increased risk for MS in nurse anaesthetists. This is interesting in the context of previous observations of organic solvents in general as a potential risk factor in MS.

Increased incidence of malignancies in Sweden after the Chernobyl accident--a promoting effect?

BACKGROUND

After the Chernobyl accident in 1986, as much as 5% of the released caesium-137 was deposited in Sweden due to a heavy rainfall 2 days after the event. A study of increased incidence of malignancies was initiated after the accident.

METHODS

The cohort included 1,137,106 inhabitants who were 0-60 years old in 1986 and lived in 8 counties of Sweden with the highest fallout of caesium-137. With the dwelling coordinate, GIS-technique and a digital map on caesium-137, each individual was matched for the exposure. Adjustments were made for several potential confounding factors. During the follow-up 33,851 malignancies was recorded 1988-1999.

RESULTS

Exposure categories were: 0-8 (reference), 9-23, 24-43, 44-66, 67-84, and > or =85 nGy/hr. The corresponding adjusted Mantel-Haenszel incidence rate ratios for total malignancies during follow-up amounted to 1.000, 0.997, 1.072, 1.114, 1.068, 1.125, respectively. The excess relative risk per 100 nGy/hr with the same adjustments and time period was 0.042 95% confidence limit 0.001;0.084. An excess for thyroid cancer or leukemia could not be ruled out.

CONCLUSION

Increased incidence of total malignancies possibly related to the fallout from the Chernobyl accident is seen.

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.

Increase of regional total cancer incidence in north Sweden due to the Chernobyl accident?

STUDY OBJECTIVE

Is there any epidemiologically visible influence on the cancer incidence after the Chernobyl fallout in Sweden?

DESIGN

A cohort study was focused on the fallout of caesium-137 in relation to cancer incidence 1988-1996.

SETTING

In northern Sweden, affected by the Chernobyl accident in 1986, 450 parishes were categorised by caesium-137 deposition: < 3 (reference), 3-29, 30-39, 40-59, 60-79, and 80-120 kiloBecquerel/m(2).

PARTICIPANTS

All people 0-60 years living in these parishes in 1986 to 1987 were identified and enrolled in a cohort of 1 143 182 persons. In the follow up 22 409 incident cancer cases were retrieved in 1988-1996. A further analysis focused on the secular trend.

MAIN RESULTS

Taking age and population density as confounding factors, and lung cancer incidence in 1988-1996 and total cancer incidence in 1986-1987 by municipality as proxy confounders for smoking and time trends, respectively, the adjusted relative risks for the deposition categories were 1.00 (reference < 3 kiloBecquerel/m(2)), 1.05, 1.03, 1.08, 1.10, and 1.21. The excess relative risk was 0.11 per 100 kiloBecquerel/m(2) (95% CI 0.03 to 0.20). Considering the secular trend, directly age standardised cancer incidence rate differences per 100 000 person years between 1988 to 1996 and the reference period 1986-1987, were 30.3 (indicating a time trend in the reference category), 36.8, 42.0, 45.8, 50.1, and 56.4. No clear excess occurred for leukaemia or thyroid cancer.

CONCLUSIONS

Unless attributable to chance or remaining uncontrolled confounding, a slight exposure related increase in total cancer incidence has occurred in northern Sweden after the Chernobyl accident.

Cryptogenic polyneuropathy: clinical and neurophysiological findings

The purpose of this study was to describe the clinical and neurophysiological features of cryptogenic polyneuropathy in 168 patients in the neurological departments at three Swedish hospitals. The medical records of all patients aged 40-79 years with the diagnosis of cryptogenic polyneuropathy from 1993 to 2000 were analysed. One hundred and fourteen patients (68%) were men. The mean age at first symptom was 61 years and at diagnosis it was 64 years. Distal numbness (n = 115, 68%) was the most common symptom, but some patients complained of pain, pedal paresthesiae, and impairment of balance. The most common clinical findings were decreased or lost proprioception or sense of vibration (n = 135, 80%) and loss of ankle jerks (n = 131, 78%). Neurography in 139 patients showed mixed sensorimotor polyneuropathy of axonal or mixed axonal and demyelinating type in 97 (70%). Cryptogenic polyneuropathy is a slowly progressive sensorimotor nerve lesion of mainly axonal type. Men are more often affected than women. Most patients have a minor or moderate severe polyneuropathy.

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.

[Hairdressers live dangerously. Daily exposure to chemicals can cause respiratory tract problems]

Hairdressers are regularly exposed to toxic chemicals contained in bleach, hair spray, permanent wave solutions and hair dyes. Adequate ventilation and appropriate working procedures can reduce exposure, but never completely eliminate the risk for respiratory disease.

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.

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.

Hypertension and arsenic exposure in Bangladesh

-A prevalence comparison of hypertension among subjects with and those without arsenic exposure through drinking water was conducted in Bangladesh to confirm or refute an earlier observation of a relation in this respect. Wells with and without present arsenic contamination were identified, and we interviewed and examined 1595 subjects who were depending on drinking water from these wells for living, all >/=30 years of age. The interview was based on a questionnaire, and arsenic exposure was estimated from the history of well-water consumption and current arsenic levels. Of the 1595 subjects studied, 1481 had a history of arsenic-contaminated drinking water, whereas 114 had not. Time-weighted mean arsenic levels (in milligrams per liter) and milligram-years per liter of arsenic exposure were estimated for each subject. Exposure categories were assessed as <0.5 mg/L, 0.5 to 1.0 mg/L, and >1.0 mg/L and alternatively as <1.0 mg-y/L, 1.0 to 5.0 mg-y/L, >5.0 but </=10.0 mg-y/L, and >10.0 mg-y/L, respectively. Hypertension was defined as a systolic blood pressure of >/=140 mm Hg in combination with a diastolic blood pressure of >/=90 mm Hg. Corresponding to the exposure categories, and using "unexposed" as the reference, the prevalence ratios for hypertension adjusted for age, sex, and body mass index were 1.2, 2.2, 2.5 and 0.8, 1.5, 2.2, 3.0, in relation to arsenic exposure in milligrams per liter and milligram-years per liter, respectively. The indicated dose-response relationships were significant (P<<0.001) for both series of risk estimates. These results suggest that arsenic exposure may induce hypertension in humans.

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.