Low-level exposure to arsenic in drinking water and incidence rate of stroke: A cohort study in Denmark.

INTRODUCTION: High arsenic concentration in drinking water is associated with a higher incidence rate of stroke, but only few studies have investigated an association with arsenic in drinking water at low concentration (<50 µg/L). OBJECTIVE: To examine if arsenic in drinking water at low concentration was associated with higher incidence rate of stroke in Denmark. METHODS: A total of 57,053 individuals from the Danish Diet, Cancer, and Health cohort was included in the study (enrolment in 1993-1997, age 50-64 years), of which 2195 individuals had incident stroke between enrolment and November 2009. Individuals were enrolled in two major cities (Copenhagen and Aarhus). Residential addresses in the period 1973-2009 were geocoded and arsenic concentration in drinking water at each address was estimated by linking addresses with water supply areas. Associations between arsenic concentration and incidence rate of stroke were analysed using a generalized linear model with a Poisson distribution. Incidence rate ratios (IRR) were adjusted for differences in age, sex, calendar-year, lifestyle factors, and educational level. RESULTS: Median arsenic concentration in drinking water was 0.7 µg/L at enrolment addresses (range: 0.03 to 25 µg/L), with highest concentrations in the Aarhus area. The adjusted IRRs were 1.17 (95% CI: 1.04-1.32) for the highest arsenic quartile (1.93-25.3 µg/L) when compared with the lowest quartile (0.049-0.57 µg/L), but the highest IRR was seen in the second quartile (0.57-0.76 µg/L) (IRR = 1.21; 95% CI: 1.07-1.36). The highest IRR in the upper quartile was seen in the Aarhus area (IRR = 1.79; 95% CI: 1.41-2.26). Having ever been exposed to10 µg/L or more arsenic in drinking water resulted in an IRR at 1.44 (95% CI: 1.00-2.08) for all strokes and 1.63 (95% CI: 1.11-2.39) for ischemic strokes. CONCLUSION: The results indicate that arsenic in drinking water even at low concentration is associated with higher incidence rate of stroke.

Low-level arsenic in drinking water and risk of incident myocardial infarction: A cohort study.

BACKGROUND: Epidemiological studies have shown that intake of drinking water with high levels of arsenic (>100µg/L) is associated with risk for cardiovascular diseases, but studies on lower levels of arsenic show inconsistent results. OBJECTIVE: The aim of this study was to investigate the relationship between exposure to low level arsenic in drinking water and risk of myocardial infarction in Denmark. METHODS: From the Danish Diet, Cancer and Health cohort of 57,053 people aged 50-64 years at enrolment in 1993-1997, we identified 2707 cases of incident myocardial infarction from enrolment to end of follow-up in February 2012. Cohort participants were enrolled in the Copenhagen and Aarhus areas. We geocoded residential addresses of the cohort members and used a geographic information system to link addresses with water supply areas. Arsenic in tap water at each cohort members address from 1973 to 2012 was estimated for all cohort members. Poisson regression was used to estimate incidence rate ratios (IRRs) for myocardial infarction after adjustment for lifestyle factors and educational level. RESULTS: Arsenic levels in drinking water at baseline addresses ranged from 0.03 to 25.34µg/L, with the highest concentrations in the Aarhus area. We found no overall association between 20-years average concentration of arsenic and risk of myocardial infarction. However, in the Aarhus area, fourth arsenic quartile (2.21-25.34µg/L) was associated with an IRR of 1.48 (95% confidence interval (CI): 1.19-1.83) when compared with first quartile (0.05-1.83µg/L). An IRR of 1.26 (95% CI: 0.89-1.79) was found for ever (versus never) having lived at an address with 10µg/L or more arsenic in the drinking water. CONCLUSIONS: This study provides some support for an association between low levels of arsenic in drinking water and the risk of myocardial infarction.

Long-term exposure to fine particulate matter and incidence of diabetes in the Danish Nurse Cohort.

AIMS/HYPOTHESIS: It has been suggested that air pollution may increase the risk of type 2 diabetes but data on particulate matter with diameter <2.5µm (PM2.5) are inconsistent. We examined the association between long-term exposure to PM2.5 and diabetes incidence. METHODS: We used the Danish Nurse Cohort with 28,731 female nurses who at recruitment in 1993 or 1999 reported information on diabetes prevalence and risk factors, and obtained data on incidence of diabetes from National Diabetes Register until 2013. We estimated annual mean concentrations of PM2.5, particulate matter with diameter <10µm (PM10), nitrogen oxides (NOx) and nitrogen dioxide (NO2) at their residence since 1990 using a dispersion model and examined the association between the 5-year running mean of pollutants and diabetes incidence using a time-varying Cox regression. RESULTS: Of 24,174 nurses 1137 (4.7%) developed diabetes. We detected a significant positive association between PM2.5 and diabetes incidence (hazard ratio; 95% confidence interval: 1.11; 1.02-1.22 per interquartile range of 3.1µg/m(3)), and weaker associations for PM10 (1.06; 0.98-1.14 per 2.8µg/m(3)), NO2 (1.05; 0.99-1.12 per 7.5µg/m(3)), and NOx (1.01; 0.98-1.05 per 10.2µg/m(3)) in fully adjusted models. Associations with PM2.5 persisted in two-pollutant models. Associations with PM2.5 were significantly enhanced in never smokers (1.24; 1.09-1.42), and augmented in obese (1.25; 1.06-1.47) and subjects with myocardial infarction (1.32; 0.86-2.02), but without significant interaction. CONCLUSIONS/INTERPRETATION: Fine particulate matter may the most relevant pollutant for diabetes development among women, and non-smokers, obese women, and heart disease patients may be most susceptible.

Social inequality and incidence of and survival from cancers of the oesophagus, stomach and pancreas in a population-based study in Denmark, 1994-2003.

We investigated the effect of socioeconomic, demographic and health-related indicators on the incidence of and survival from cancers of the oesophagus, stomach and pancreas diagnosed during 1994-2003 with follow-up through 2006 in Denmark using information from nationwide registers. The analyses were based on data on 2075 patients with cancer of the oesophagus, 2673 with stomach cancer and 3657 with pancreatic cancer in a cohort of 3.22 million persons born between 1925 and 1973 and aged >or=30 years. Overall, we found decreasing incidence rates of all three gastrointestinal cancers with increasing social advantage; this was most pronounced for oesophageal cancer and least for pancreatic cancer. The effect of socioeconomic position on survival after these cancers was less clear, perhaps due to the poor relative survival from these cancers and the fact that all three cancers are relatively rare in Denmark.

Arsenic in drinking-water and risk for cancer in Denmark.

BACKGROUND: Arsenic is a well-known carcinogen, which is often found in drinking-water. Epidemiologic studies have shown increased cancer risks among individuals exposed to high concentrations of arsenic in drinking-water, whereas studies of the carcinogenic effect of low doses have had inconsistent results. OBJECTIVE: Our aim was to determine if exposure to low levels of arsenic in drinking-water in Denmark is associated with an increased risk for cancer. METHODS: The study was based on a prospective Danish cohort of 57,053 persons in the Copenhagen and Aarhus areas. Cancer cases were identified in the Danish Cancer Registry, and the Danish civil registration system was used to trace and geocode residential addresses of the cohort members. We used a geographic information system to link addresses with water supply areas, then estimated individual exposure to arsenic using residential addresses back to 1970. Average exposure for the cohort ranged between 0.05 and 25.3 microg/L (mean = 1.2 microg/L). Cox's regression models were used to analyze possible relationships between arsenic and cancer. RESULTS: We found no significant association between exposure to arsenic and risk for cancers of the lung, bladder, liver, kidney, prostate, or colorectum, or melanoma skin cancer; however, the risk for non-melanoma skin cancer decreased with increasing exposure (incidence rate ratio = 0.88/microg/L average exposure; 95% confidence interval, 0.84-0.94). Results adjusted for enrollment area showed no association with non-melanoma skin cancer. CONCLUSIONS: The results indicate that exposure to low doses of arsenic might be associated with a reduced risk for skin cancer.