Camilla Pedersen

Distance to High-Voltage Power Lines and Risk of Childhood Leukemia – an Analysis of Confounding by and Interaction with Other Potential Risk Factors

We investigated whether there is an interaction between distance from residence at birth to nearest power line and domestic radon and traffic-related air pollution, respectively, in relation to childhood leukemia risk. Further, we investigated whether adjusting for potential confounders alters the association between distance to nearest power line and childhood leukemia. We included 1024 cases aged <15, diagnosed with leukemia during 1968–1991, from the Danish Cancer Registry and 2048 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132–400 kV overhead power line. Concentrations of domestic radon and traffic-related air pollution (NOx at the front door) were estimated using validated models. We found a statistically significant interaction between distance to nearest power line and domestic radon regarding risk of childhood leukemia (p = 0.01) when using the median radon level as cut-off point but not when using the 75th percentile (p = 0.90). We found no evidence of an interaction between distance to nearest power line and traffic-related air pollution (p = 0.73). We found almost no change in the estimated association between distance to power line and risk of childhood leukemia when adjusting for socioeconomic status of the municipality, urbanization, maternal age, birth order, domestic radon and traffic-related air pollution. The statistically significant interaction between distance to nearest power line and domestic radon was based on few exposed cases and controls and sensitive to the choice of exposure categorization and might, therefore, be due to chance.

Residential Radon and Lung Cancer Incidence in a Danish Cohort

High-level occupational radon exposure is an established risk factor for lung cancer. We assessed the long-term association between residential radon and lung cancer risk using a prospective Danish cohort using 57,053 persons recruited during 1993-1997. We followed each cohort member for cancer occurrence until 27 June 2006, identifying 589 lung cancer cases. We traced residential addresses from 1 January 1971 until 27 June 2006 and calculated radon at each of these addresses using information from central databases regarding geology and house construction. Cox proportional hazards models were used to estimate incidence rate ratios (IRR) and 95% confidence intervals (CI) for lung cancer risk associated with residential radon exposure with and without adjustment for sex, smoking variables, education, socio-economic status, occupation, body mass index, air pollution and consumption of fruit and alcohol. Potential effect modification by sex, traffic-related air pollution and environmental tobacco smoke was assessed. Median estimated radon was 35.8 Bq/m(3). The adjusted IRR for lung cancer was 1.04 (95% CI: 0.69-1.56) in association with a 100 Bq/m(3) higher radon concentration and 1.67 (95% CI: 0.69-4.04) among non-smokers. We found no evidence of effect modification. We find a positive association between radon and lung cancer risk consistent with previous studies but the role of chance cannot be excluded as these associations were not statistically significant. Our results provide valuable information at the low-level radon dose range.

Residential radon and brain tumour incidence in a Danish cohort.

Background Increased brain tumour incidence over recent decades may reflect improved diagnostic methods and clinical practice, but remain unexplained. Although estimated doses are low a relationship between radon and brain tumours may exist. Objective To investigate the long-term effect of exposure to residential radon on the risk of primary brain tumour in a prospective Danish cohort. Methods During 1993–1997 we recruited 57,053 persons. We followed each cohort member for cancer occurrence from enrolment until 31 December 2009, identifying 121 primary brain tumour cases. We traced residential addresses from 1 January 1971 until 31 December 2009 and calculated radon concentrations at each address using information from central databases regarding geology and house construction. Cox proportional hazards models were used to estimate incidence rate-ratios (IRR) and 95% confidence intervals (CI) for the risk of primary brain tumours associated with residential radon exposure with adjustment for age, sex, occupation, fruit and vegetable consumption and traffic-related air pollution. Effect modification by air pollution was assessed. Results Median estimated radon was 40.5 Bq/m3. The adjusted IRR for primary brain tumour associated with each 100 Bq/m3 increment in average residential radon levels was 1.96 (95% CI: 1.07; 3.58) and this was exposure-dependently higher over the four radon exposure quartiles. This association was not modified by air pollution. Conclusions We found significant associations and exposure-response patterns between long-term residential radon exposure radon in a general population and risk of primary brain tumours, adding new knowledge to this field. This finding could be chance and needs to be challenged in future studies.

Residential Distance to High-voltage Power Lines and Risk of Neurodegenerative Diseases: a Danish Population-based Case-Control Study

The aim of this study was to investigate the possible association between residential distance to high-voltage power lines and neurodegenerative diseases, especially Alzheimers disease. A Swiss study previously found increased risk of Alzheimers disease for people living within 50 m of a power line. A register-based case-control study including all patients diagnosed with neurodegenerative diseases during the years 1994-2010 was conducted among the entire adult population of Denmark. Using conditional logistic regression models, hazard ratios for ever living close to a power line in the time period 5-20 years before diagnosis were computed. The risks for developing dementia, Parkinsons disease, multiple sclerosis, and motor neuron disease were not increased in persons living within close vicinity of a power line. The risk of Alzheimers disease was not increased for ever living within 50 m of a power line (hazard ratio = 1.04, 95% confidence interval: 0.69, 1.56). No dose-response according to number of years of living within 50 m of a power line was observed, but there were weak indications of an increased risk for persons diagnosed by the age of 75 years. Overall, there was little support for an association between neurodegenerative disease and living close to power lines.

Residential exposure to extremely low-frequency magnetic fields and risk of childhood leukaemia, CNS tumour and lymphoma in Denmark

Background:We previously reported that children exposed to elevated extremely low-frequency magnetic fields (ELF-MF) had a five to six times higher risk of leukaemia, central nervous system (CNS) tumour and malignant lymphoma. Here we extend the study from 1968 to 1986 through 2003.Methods:We included 3277 children with leukaemia, CNS tumour or malignant lymphoma during 1968–2003 recorded in the Danish Cancer Registry and 9129 controls randomly selected from the Danish childhood population. ELF-MF from 50 to 400 kV facilities were calculated at the residences.Results:For recently diagnosed cases (1987–2003), the relative risk (RR) was 0.88 (95% confidence interval (CI): 0.32–2.42), while for the total period (1968–2003) it was 1.63 (95% CI: 0.77–3.46) for leukaemia, CNS tumour and malignant lymphoma combined for exposures ⩾0.4 μT compared with <0.1 μT. These results were based on five cases (recent period) and 11 cases (total period) in the highest exposure group.Conclusions:We did not confirm the previous finding of a five- to six-fold higher risk for leukaemia, CNS tumour and malignant lymphoma when including data from the more recent time period. For the total time period, the results for childhood leukaemia were in line with large pooled analyses showing RRs between 1.5 and 2.

Residential Radon Exposure and Skin Cancer Incidence in a Prospective Danish Cohort

Background Although exposure to UV radiation is the major risk factor for skin cancer, theoretical models suggest that radon exposure can contribute to risk, and this is supported by ecological studies. We sought to confirm or refute an association between long-term exposure to residential radon and the risk for malignant melanoma (MM) and non-melanoma skin cancer (NMSC) using a prospective cohort design and long-term residential radon exposure. Methods During 1993–1997, we recruited 57,053 Danish persons and collected baseline information. We traced and geocoded all residential addresses of the cohort members and calculated radon concentrations at each address lived in from 1 January 1971 until censor date. Cox proportional hazards models were used to estimate incidence rate-ratios (IRR) and confidence intervals (CI) for the risk associated with radon exposure for NMSC and MM, and effect modification was assessed. Results Over a mean follow-up of 13.6 years of 51,445 subjects, there were 3,243 cases of basal cell carcinoma (BCC), 317 cases of squamous cell carcinoma (SCC) and 329 cases of MM. The adjusted IRRs per 100 Bq/m3 increase in residential radon levels for BCC, SCC and MM were 1.14 (95% CI: 1.03, 1.27), 0.90 (95% CI: 0.70, 1.37) and 1.08 (95% CI: 0.77, 1.50), respectively. The association between radon exposure and BCC was stronger among those with higher socio-economic status and those living in apartments at enrollment. Conclusion and Impact Long-term residential radon exposure may contribute to development of basal cell carcinoma of the skin. We cannot exclude confounding from sunlight and cannot conclude on causality, as the relationship was stronger amongst persons living in apartments and non-existent amongst those living in single detached homes.

Dopamine and dobutamine reduce myocardial d-propoxyphene content in experimentally intoxicated rats.

The effect of sympathomimetic intervention with dopamine or dobutamine on the myocardial uptake of d-propoxyphene was investigated experimentally in rats. The d-propoxyphene (19 mg kg-1 h-1) was continously infused, intravenously, over 45 min. After 20 min of infusion the rats were given either dopamine (12.5 ?g kg-1 min-1 or 25 ?g kg-1 min-1), dobutamine (25 ?g kg-1 min-1 or 45 ?g kg-1min-1) or normal saline (control). Each group consisted of eight rats. The myocardial d-propoxyphene content was significantly lower in the two groups given dopamine and in the group given dobutamine 45 ?g kg-1 min-1 than in the control group (P < 0.05). This finding indicates the benefit of early sympathomimetic intervention with either dopamine or dobutamine in d-propoxyphene intoxication.

Proximity to overhead power lines and childhood leukaemia: an international pooled analysis

BackgroundAlthough studies have consistently found an association between childhood leukaemia risk and magnetic fields, the associations between childhood leukaemia and distance to overhead power lines have been inconsistent. We pooled data from multiple studies to assess the association with distance and evaluate whether it is due to magnetic fields or other factors associated with distance from lines.MethodsWe present a pooled analysis combining individual-level data (29,049 cases and 68,231 controls) from 11 record-based studies.ResultsThere was no material association between childhood leukaemia and distance to nearest overhead power line of any voltage. Among children living < 50 m from 200 + kV power lines, the adjusted odds ratio for childhood leukaemia was 1.33 (95% CI: 0.92–1.93). The odds ratio was higher among children diagnosed before age 5 years. There was no association with calculated magnetic fields. Odds ratios remained unchanged with adjustment for potential confounders.ConclusionsIn this first comprehensive pooled analysis of childhood leukaemia and distance to power lines, we found a small and imprecise risk for residences < 50 m of 200 + kV lines that was not explained by high magnetic fields. Reasons for the increased risk, found in this and many other studies, remains to be elucidated.

Urinary Cadmium and Breast Cancer: A Prospective Danish Cohort Study

Background: Cadmium is a human lung carcinogen, and recent evidence suggests it may play a role in hormone‐related cancers because of its estrogenic activity. Case‐control studies consistently show higher cadmium concentrations in urine from women diagnosed with breast cancer compared with control women. Our aim was to investigate the association between urinary cadmium and breast cancer in a prospective design. Methods: We conducted a case‐cohort study using the population‐based Danish Diet Cancer and Health Cohort. Women age 50 to 64 years were recruited in 1993‐1997 and provided urine for analysis. We identified 900 incident case patients in the Danish Cancer Registry and compared with 898 individuals in a subcohort. Urine samples collected at enrollment into the cohort were analyzed for cadmium and creatinine. We estimated incidence rate ratios (IRRs) for breast cancer in Cox proportional hazards models with age as time axis and calculated 95% confidence intervals (CIs). Results: The linear analysis showed no association between urinary cadmium and risk for breast cancer (IRR = 1.00, 95% CI = 0.81 to 1.24 per ng Cd/mL urine). The categorical analyses showed a slightly higher risk for breast cancer for the second (IRR = 1.10, 95% CI = 0.86 to 1.42) and third (IRR = 1.14, 95% CI = 0.83 to 1.55) exposure tertiles compared with the lowest tertile. Results were similar in analyses of breast cancer subtypes defined by estrogen and progesterone receptor status and by histology, and analyses stratified by years from baseline to diagnosis. Conclusions: This large prospective study showed no association between urinary concentration of cadmium and subsequent risk for development of postmenopausal breast cancer.