Incidence rates of chronic lymphocytic leukemia in US states are associated with residential radon levels

Short Communication: Radon testing via a state tobacco quitline

Objective

Exposure to radon gas at home is the second largest cause of lung cancer after smoking and dramatically increases smokers' risk of lung cancer. State tobacco quitlines are uniquely positioned to inform smokers about radon, yet, to our knowledge, none does so. We explored the feasibility of introducing free radon tests via the tobacco quitline in North Dakota, a state with one of the highest radon levels in the U.S.

Methods

Five hundred consecutive callers to the ND Quits Tobacco quitline from February 2021 to February 2023 were invited to complete a brief radon questionnaire and receive a free radon test kit. Radon tests were bar-coded so that the return rate of the tests and the radon levels could be determined.

Results

Two hundred fifty-one (51 %) callers completed the questionnaire and seventy-five radon tests were successfully returned to the laboratory. More than one third of the test results were ≥ 4.0 pCi/L, the action level recommended by the EPA. Only 1 in 5 participants reported knowing that radon caused lung cancer.

Conclusion

Radon knowledge among ND smokers is poor. Radon test distribution via quitlines is feasible and may be a valuable addition to quitline services, particularly in states with high radon levels.

Links among Obesity, Type 2 Diabetes Mellitus, and Osteoporosis: Bone as a Target

Obesity, type 2 diabetes mellitus (T2DM) and osteoporosis are serious diseases with an ever-increasing incidence that quite often coexist, especially in the elderly. Individuals with obesity and T2DM have impaired bone quality and an elevated risk of fragility fractures, despite higher and/or unchanged bone mineral density (BMD). The effect of obesity on fracture risk is site-specific, with reduced risk for several fractures (e.g., hip, pelvis, and wrist) and increased risk for others (e.g., humerus, ankle, upper leg, elbow, vertebrae, and rib). Patients with T2DM have a greater risk of hip, upper leg, foot, humerus, and total fractures. A chronic pro-inflammatory state, increased risk of falls, secondary complications, and pharmacotherapy can contribute to the pathophysiology of aforementioned fractures. Bisphosphonates and denosumab significantly reduced the risk of vertebral fractures in patients with both obesity and T2DM. Teriparatide significantly lowered non-vertebral fracture risk in T2DM subjects. It is important to recognize elevated fracture risk and osteoporosis in obese and T2DM patients, as they are currently considered low risk and tend to be underdiagnosed and undertreated. The implementation of better diagnostic tools, including trabecular bone score, lumbar spine BMD/body mass index (BMI) ratio, and microRNAs to predict bone fragility, could improve fracture prevention in this patient group.

Radon Exposure, Clonal Hematopoiesis, and Stroke Susceptibility in the Women's Health Initiative

BACKGROUND AND OBJECTIVES

Studies suggest that clonal hematopoiesis of indeterminate potential (CHIP) may increase risk of hematologic malignancy and cardiovascular disease, including stroke. However, few studies have investigated plausible environmental risk factors for CHIP such as radon, despite the climate-related increases in and documented infrequency of testing for this common indoor air pollutant.The purpose of this study was to estimate the risk of CHIP related to radon, an established environmental mutagen.

METHODS

We linked geocoded addresses of 10,799 Women's Health Initiative Trans-Omics for Precision Medicine (WHI TOPMed) participants to US Environmental Protection Agency-predicted, county-level, indoor average screening radon concentrations, categorized as follows: Zone 1 (>4 pCi/L), Zone 2 (2-4 pCi/L), and Zone 3 (<2 pCi/L). We defined CHIP as the presence of one or more leukemogenic driver mutations with variant allele frequency >0.02. We identified prevalent and incident ischemic and hemorrhagic strokes; subtyped ischemic stroke using Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria; and then estimated radon-related risk of CHIP as an odds ratio (OR) and 95% CI using multivariable-adjusted, design-weighted logistic regression stratified by age, race/ethnicity, smoking status, and stroke type/subtype.

RESULTS

The percentages of participants with CHIP in Zones 1, 2, and 3 were 9.0%, 8.4%, and 7.7%, respectively (ptrend = 0.06). Among participants with ischemic stroke, Zones 2 and 1 were associated with higher estimated risks of CHIP relative to Zone 3: 1.39 (1.15-1.68) and 1.46 (1.15-1.87), but not among participants with hemorrhagic stroke: 0.98 (0.68-1.40) and 1.03 (0.70-1.52), or without stroke: 1.04 (0.74-1.46) and 0.95 (0.63-1.42), respectively (pinteraction = 0.03). Corresponding estimates were particularly high among TOAST-subtyped cardioembolism: 1.78 (1.30-2.47) and 1.88 (1.31-2.72), or other ischemic etiologies: 1.37 (1.06-1.78) and 1.50 (1.11-2.04), but not small vessel occlusion: 1.05 (0.74-1.49) and 1.00 (0.68-1.47), respectively (pinteraction = 0.10). Observed patterns of association among strata were insensitive to attrition weighting, ancestry adjustment, prevalent stroke exclusion, separate analysis of DNMT3A driver mutations, and substitution with 3 alternative estimates of radon exposure.

DISCUSSION

The robust elevation of radon-related risk of CHIP among postmenopausal women who develop incident cardioembolic stroke is consistent with a potential role of somatic genomic mutation in this societally burdensome form of cerebrovascular disease, although the mechanism has yet to be confirmed.

Comparing Communication Methods to Increase Radon Knowledge and Home Testing: A Randomized Controlled Trial in a High-Radon City

INTRODUCTION

Exposure to residential radon is a preventable cause of cancer. Prevention requires testing, but the percentage of homes that have been tested is small. One reason for the low testing rates may be that printed brochures fail to motivate people to obtain and return a radon test.

METHODS

We developed a radon app for smartphones that contained the same information as printed brochures. We conducted a randomized, controlled trial that compared the app to brochures in a population comprised largely of homeowners. Cognitive endpoints included radon knowledge, attitudes toward testing, perceived severity and susceptibility to radon, and response and self-efficacy. Behavioral endpoints were participants' requests for a free radon test and the return of the test to the lab. Participants (N = 116) were residents of Grand Forks, North Dakota, a city with one of the nation's highest radon levels. Data were analyzed by general linear models and logistic regression.

RESULTS

Participants in both conditions showed significant increases in radon knowledge (p < 0.001), perceived susceptibility (p < 0.001), and self-efficacy (p = 0.004). There was a significant interaction, with app users showing greater increases. After controlling for income, app users were three times more likely to request a free radon test. However, contrary to expectation, app users were 70% less likely to return it to the lab (p < 0.01).

CONCLUSIONS

Our findings confirm the superiority of smartphones in stimulating radon test requests. We speculate that the advantage of brochures in promoting test returns may be due to their ability to serve as physical reminders.

Interventions to promote home radon testing: A randomized clinical trial of a smartphone app vs. printed brochures

Radon is a preventable cause of lung cancer, but the percentage of homes tested for radon is low. We previously developed a smartphone app that informs users about radon and allows them to request a free radon test. Here we conducted a randomized, controlled trial comparing the radon app versus printed brochures on radon knowledge, attitudes, and behaviors, including the proportion of participants requesting radon tests. Participants (N = 138) were undergraduates at a midwestern university. Data were analyzed by t-tests, general linear models, and logistic regression. App users showed significantly greater increases in radon knowledge (p = 0.010) and self-efficacy (p < 0.001) and requested tests three times more often than brochure recipients (41.4% vs. 13.2%, p < 0.001). However, the rate of test usage in each condition was low, ~3%. In conclusion, the radon app markedly outperformed brochures in increasing knowledge and requests for radon tests. Future work should focus on methods to increase test usage.

Residential radon exposure and leukemia: A meta-analysis and dose-response meta-analyses for ecological, case-control, and cohort studies

INTRODUCTION

In this study, the authors conducted a comprehensive systematic review and meta-analysis (including a dose-response meta-analysis) for a possible causal association between residential radon exposure and leukemia. All 3 types of study design, including ecological, case-control, and cohort studies, were included in this study. In particular, different measurement units of radon exposure among studies were dealt with and analyzed thoroughly.

METHODS

A medical librarian searched MEDLINE (PubMed), EMBASE, and the Cochrane Library (from January 01, 1970 to November 05, 2020). For ecological studies, a conventional meta-analysis and subgroup analyses with meta-ANOVA analyses were conducted. For case-control and cohort studies, a two-stage dose-response meta-analysis was conducted.

RESULTS

A total of 8 ecological, 9 case-control, and 15 ecological-cohort studies were analyzed. For ecological studies, the pooled correlation coefficient was 0.48 (95% CI 0.41-0.54). In the meta-analysis of variance (ANOVA) analyses, the age group (childhood vs. adult) showed a statistically significant result (Q = 7.93 and p = 0.019) with the pooled correlation coefficient for childhood, adult, and all age group of 0.67 (95% CI 0.53-0.77), 0.46 (95% CI 0.05-0.74), and 0.44 (95% CI 0.36-0.51), respectively. For case-control studies, the dose-response meta-analysis showed the pooled OR increase of 1.0308 (95% CI 1.0050-1.0573) for each 100 Bq/m³ increase of radon dose. The pooled OR increase was 1.0361 (95% CI 1.0014-1.0720) for each 100 Bq/m³ increase of radon dose for lymphoid leukemia subgroup and 1.0309 (95% CI 1.0050-1.0575) for each 100 Bq/m³ increase of radon dose for childhood leukemia subgroup. Because of the inclusion of ecological studies with larger exposure assessment units, the pooled RR from ecological-cohort studies should be interpreted conservatively (a tendency towards a higher risk estimate). The overall pooled RR increase for each 100 Bq/m³ increase of radon dose was 1.1221 (95% CI 1.0184-1.2363). The pooled RR increase was 1.2257 (95% CI 1.0034-1.4972) for each 100 Bq/m³ increase of radon dose for the myeloid leukemia subgroup and 1.2503 (95% CI 1.0233-1.5276) for each 100 Bq/m³ increase of radon dose for adult leukemia subgroup.

DISCUSSION

A number of epidemiologic concepts, including the issue of sample size justification, the possibility of differential participation selection bias for case-control studies, the possibility of random and systematic errors in radon measurement, ecological fallacy for ecological studies, were discussed. The effect of age group, socioeconomic status, and gamma radiation exposure was also discussed. Future more accurate and conclusive large-scale case-control and cohort studies are needed.

Brain cancer incidence rates and the presence of nuclear reactors in US states: a hypothesis-generating study

BACKGROUND

The etiology of brain cancer is poorly understood. The only confirmed environmental risk factor is exposure to ionizing radiation. Because nuclear reactors emit ionizing radiation, we examined brain cancer incidence rates in the USA in relation to the presence of nuclear reactors per state.

METHODS

Data on brain cancer incidence rates per state for Whites by sex for three age groups (all ages, 50 and older, and under 50) were obtained from cancer registries. The location, number, and type of nuclear reactor, i.e., power or research reactor, was obtained from public sources. We examined the association between these variables using multivariate linear regression and ANOVA.

RESULTS

Brain cancer incidence rates were not associated with the number of nuclear power reactors. Conversely, incidence rates per state increased with the number of nuclear research reactors. This was significant for both sexes combined and for males in the 'all ages' category (β = 0.08, p = 0.0319 and β = 0.12, p = 0.0277, respectively), and for both sexes combined in the'50 and older' category (β = 0.18, p = 0.0163). Brain cancer incidence rates for counties with research reactors were significantly higher than the corresponding rates for their states overall (p = 0.0140). These findings were not explicable by known confounders.

CONCLUSIONS

Brain cancer incidence rates are positively associated with the number of nuclear research reactors per state. These findings merit further exploration and suggest new opportunities for research in brain cancer epidemiology.

Chronic Lymphocytic Leukemia

Patients with chronic lymphocytic leukemia can be divided into three categories: those who are minimally affected by the problem, often never requiring therapy; those that initially follow an indolent course but subsequently progress and require therapy; and those that from the point of diagnosis exhibit an aggressive disease necessitating treatment. Likewise, such patients pass through three phases: development of the disease, diagnosis, and need for therapy. Finally, the leukemic clones of all patients appear to require continuous input from the exterior, most often through membrane receptors, to allow them to survive and grow. This review is presented according to the temporal course that the disease follows, focusing on those external influences from the tissue microenvironment (TME) that support the time lines as well as those internal influences that are inherited or develop as genetic and epigenetic changes occurring over the time line. Regarding the former, special emphasis is placed on the input provided via the B-cell receptor for antigen and the C-X-C-motif chemokine receptor-4 and the therapeutic agents that block these inputs. Regarding the latter, prominence is laid upon inherited susceptibility genes and the genetic and epigenetic abnormalities that lead to the developmental and progression of the disease.

Communicating radon risk via a smartphone app: a pilot intervention study

Background

Residential radon is a major preventable cause of lung cancer. However, prevention requires radon testing and it has proven very challenging to motivate individuals to test their homes for hazards like radon that are invisible and whose health effects occur after a long latency following exposure. Novel approaches to radon communication are urgently needed.

Methods

We created a novel radon-education app for smartphones and examined its effectiveness in increasing radon knowledge and radon testing. We studied radon knowledge and attitudes and behavior relevant to radon testing before and after app use.

Results

Ninety-seven undergraduates installed the app on their smartphones and used it for a month. App use resulted in higher scores in the domains of radon knowledge (p < .001); self-efficacy (p < .001), and response efficacy (p < .001). Twenty-three participants (24%) used the app to obtain a free radon test kit. Self-efficacy (p < .05) and response efficacy (p < .01) were positive predictors of ordering a test kit. The test process completion rate (the fraction of participants who ordered test kits, used them to test their houses and sent the kits to the lab) was 9%.

Conclusions

A smartphone app is a promising venue for communicating radon risk and for stimulating radon testing. Future interventions designed to increase actual test kit use are required to maximize the benefit of the app.

Geographic distribution and environmental risk factors of lymphoma in dogs under primary-care in the UK

OBJECTIVES

To integrate external data sources with VetCompass postcode data to explore the spatial distribution and examine potential associations with environmental risk factors in dogs diagnosed with lymphoma at primary care veterinary practices.

MATERIALS AND METHODS

Cases of lymphoma were identified from electronic patient records of 455,553 dogs under primary veterinary care during 2013 in the UK. Cases were defined as either laboratory-confirmed or non-laboratory-confirmed. Disease maps at the postcode-district level were used to define the geographic distribution of lymphoma incidence and spatial clustering was explored. Environmental risk factors from external data sources were transferred to a compatible format and logistic regression modelling was used to examine associations between environmental herbicide, fungicide and radon concentrations with lymphoma.

RESULTS

From the denominator population of 455,553 dogs, 279 lymphoma cases (187 with laboratory confirmation and 93 without) were identified. Heterogeneous geographic variation was observed with weak evidence of clustering around London and the south-west of England. Herbicide and fungicide exposures were weakly associated with a diagnosis of lymphoma in the univariable analysis. After accounting for the age at diagnosis and breed in the multivariable analysis, herbicide exposure was associated with a diagnosis of lymphoma.

CLINICAL SIGNIFICANCE

The heterogeneous distribution of lymphoma in UK dogs provides further evidence for geographic variation of lymphoma, perhaps in part associated with underlying environmental risk factors. The results suggest an association between environmental herbicide and canine lymphoma.

DOMESTIC RADON EXPOSURE AND CHILDHOOD LEUKAEMIA AND LYMPHOMA: A POPULATION-BASED STUDY IN CANADA

In this paper, we revisit the possibility, first raised using a data set collected in the 1970s, that there is a link between average radon concentrations and the incidence of childhood leukaemia and lymphoma in Canada. Following the launch of the National Radon Program in 2007, Health Canada completed a long-term radon survey in 33 census metropolitan areas (CMAs), which covers about 70% of the Canadian population. We used this data, together with leukaemia and lymphoma incidence rates among children (0-14 years of age) in the past decade (2006-15), and tried to link the city-level average radon concentrations to the leukaemia and lymphoma incidence rates in 33 major Canadian cities. Analyses were conducted for six subtypes (ALL, AML, CMD, HL, NHL and BL) of leukaemia and lymphoma. Estimated doses to red bone marrow from domestic radon exposure were low and we did not find any association between radon exposure at home and the increased risk for developing leukaemia among children under 15 years of age living in the CMAs. The results indicate a slight positive association for AML among 1-4 year males in CMAs of Peer Group C and NHL among 5-9 year females in CMAs of Peer Group A; however, these should be interpreted with caution owing to the crude exposure assessment and possibilities of other confounding factors.

Fungal-contaminated grass and well water and sporadic amyotrophic lateral sclerosis

Fungi are important infectious disease-causing agents, but are often overlooked as environmental factors in disease. We review several lines of evidence that point to a potential fungal origin of sporadic amyotrophic lateral sclerosis (ALS), the most common form of motor neurone disease. Approximately 90% cases of ALS are sporadic, and the aetiology of sporadic ALS is still unknown. We have previously postulated that grass or soil-associated fungal infections may be a leading cause of sporadic ALS. Herein we extend this proposal to water-associated fungi. A wide variety of fungi have been reported in drinking water including Acremonium, Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium and Trichoderma. Some of these are known to produce neurotoxic mycotoxins. Despite this, drinking water is not routinely monitored for fungal contamination. Fungal contamination could explain the close correlation between distribution of well water and cases of sporadic ALS in the United States. We propose several mechanisms by which an opportunistic fungal infection from environmental exposure (to water, soil or plants) can lead to long term neuronal degradation resulting in the hallmarks of ALS. If confirmed, the association between fungal infection and sporadic ALS could lead to novel treatment strategies for this progressive and fatal disease.

Human lung epithelial cells cultured in the presence of radon-emitting rock experience gene expression changes similar to those associated with tobacco smoke exposure

Radon is the second leading cause of lung cancer, after tobacco smoke. While tobacco smoke-induced carcinogenesis has been studied extensively, far less is known about radon-induced carcinogenesis, particularly in relation to the influence of radon on gene expression. The objectives of the work described herein were to (a) determine if and how exposure to low dose radon-emitting rock influences cells, at the gene expression level, and (b) compare any gene expression changes resulting from the exposure to radon-emitting rock with those induced by exposure to tobacco smoke. Any potential radiation-induced gene expression changes were also compared to those induced by exposure to cannabis smoke, a non-carcinogen at low doses, used here as a smoke exposure comparator. Human lung epithelial cells were exposed to radon-emitting rock, tobacco smoke or cannabis smoke, over months, and RNA-sequencing was carried out. We found that the rock-exposed cells experienced significant gene expression changes, particularly of the gene AKR1C3, and that these changes, over time, increasingly reflected those associated with exposure to tobacco, but not cannabis, smoke. We postulate that the early gene expression changes common to both the radiation and tobacco smoke exposures constitute a related - potentially pre-carcinogenic - response. Our findings suggest that the length of time a dividing population of cells is exposed to a constant low concentration of radon (with a potential cumulative absorbed dose) could be an important risk parameter for neoplastic transformation/carcinogenesis.

Radon and lung cancer: What does the public really know?

Radon causes approximately 21,000 deaths annually from lung cancer, making it the second most important cause of lung cancer after smoking. However, the extent of public knowledge about radon is unclear. We systematically reviewed the epidemiologic literature in order to assay the public's understanding about radon and specifically, whether radon is known to cause lung cancer. Radon knowledge has most often been gauged via telephone and in-person responses to the question, "Have you heard about radon?" Our review of 20 such studies reveals that although many individuals have "heard about" radon, many segments of the population, particularly individuals younger than thirty and those with less education, do not know what radon is. Of those who have heard about radon, the majority of respondents in many studies did not know that radon causes lung cancer. Conversely, misinformation about radon is common; approximately 50% of respondents in many studies reported the erroneous belief that radon causes headaches. This suggests that the public has confused the effects of radon with those of carbon monoxide. Rates of radon testing and mitigation are correpondingly low and appear to reflect cognitive defense mechanisms by which individuals believe that their risks from radon are lower than the risks faced by others. Our review suggests that public information materials about radon require revision. Specifically, these should emphasize that radon causes lung cancer and that household carbon monoxide detectors do not detect it. Radon education provided by realtors at the time of residential home sales may be a promising venue to increase radon testing and remediation.

Assessing cancer risk factors faced by an Ancestral Puebloan population in the North American Southwest

Ancestral Puebloan people in the North American Southwest suffered high rates of disease, poor health, and early age-at-death. Four individuals with skeletal expressions of cancer were found in a pre-Columbian population in the Taos Valley - Reports of malignant neoplasms in the archaeological record are uncommon and their presence in four of 82 individuals is a high occurrence. This study continues Whitley and Boyer's (2012) research testing whether concentrations of ionizing radiation were sufficiently high to induce cancer and related health issues. Access to a preserved and partly reconstructed subterranean pit structure inhabited between AD 1120 and 1170, allows us to test radon concentrations in a residential dwelling. This study found radon occurring in high levels, 19.4-20.3 pCi/L (717.8-751.1 Bq/m3) within the structure. Epidemiological reports are inconsistent when linking specific cancers and radon exposure. However, this study can control for many of the confounding factors plaguing other studies, provide unique data that have the potential to initiate dialogue on the etiology of neoplastic disease in the American Southwest, and add new dimensions to the study of the living conditions and health of the Ancestral Puebloans and their descendants.

Radon Levels in Indoor Environments of the University Hospital in Bari-Apulia Region Southern Italy

Since 1988, the International Agency for Research on Cancer (IARC) has classified radon among the compounds for which there is scientific evidence of carcinogenicity for humans (group 1). The World Health Organization (WHO) recommends a reference radon level between 100 and 300 Bq/m³ for homes. The objective of this study is to measure the radon concentrations in 401 workplaces, different from the patient rooms, in 28 different buildings of the university hospital in Bari (Apulia region, Southern Italy) to evaluate the exposure of health care workers. Radon environmental sampling is performed over two consecutive six-month periods via the use of passive dosimeters of the CR-39 type. We find an average annual radon concentration expressed as median value of 48.0 Bq/m³ (range 6.5–388.0 Bq/m³) with a significant difference between the two six-month periods (median value: February/July 41.0 Bq/m³ vs. August/January 55.0 Bq/m³). An average concentration of radon lower than the WHO reference level (100 Bq/m³) is detected in 76.1% of monitored environments, while higher than 300 Bq/m³ only in the 0.9%. Most workplaces report radon concentrations within the WHO reference level, therefore, the risk to workers’ health deriving from occupational exposure to radon can be considered to be low. Nevertheless, the goal is to achieve near-zero exposures to protect workers’ health.

Variance in State Protection from Exposure to NORM and TENORM Wastes Generated During Unconventional Oil and Gas Operations: Where We Are and Where We Need to Go

Radioactive materials for the medical, technological, and industrial sectors have been effectively regulated in the United States since as early as 1962. The steady increase in the exploration and production of shale gas in recent years has led to concerns about exposures to Naturally Occurring Radioactive Materials (NORM) and Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) in oil and gas waste streams. This study applied policy surveillance methods to conduct a cross-sectional fifty-state survey of law and regulations of NORM and TENORM waste from oil and gas operations. Results indicated that seventeen states drafted express regulations to reduce exposure to oil and gas NORM and TENORM waste. States with active oil and gas drilling that lack regulations controlling exposure to NORM and TENORM may leave the public and workers susceptible to adverse health effects from radiation. The study concludes with recommendations in regard to regulating oil and gas NORM and TENORM waste.

Coexistence of t(2;14;11)(p16.1;q32;q23) and t(14;19)(q32;q13.3) chromosome translocations in a patient with chronic lymphocytic leukemia: A case report

RATIONALE

With combination of multiple techniques, we have successfully characterized unique, complex chromosomal changes in a patient with chronic lymphocytic leukemia (CLL), a lymphoproliferative disorder.

DIAGNOSES

The diagnosis was based on white blood cell, flow cytometry, and immunophenotypes and confirmed by karyotype, fluorescence in situ hybridization, and array comparative genomic hybridization from the patient's blood culture.

INTERVENTIONS

The patient was given fludarabine, cyclophosphamide and rituximab (FCR) for 6 cycles.

OUTCOMES

After completion of 6 cycles of FCR, the computed tomography scans of the neck/chest/abdomen/pelvic showed that the patient in CR. During the 10-month follow-up, the patient's clinical course remained uneventful.

LESSONS

The translocation t(14;19) identified in this patient is a recurrent translocation found in patients with chronic B-cell lymphoproliferative disorders and the 3-way translocation involving chromosomes 2, 14, and 11 may play a role as an enhancer.

County level incidence rates of chronic lymphocytic leukemia are associated with residential radon levels

Aim:

We previously reported that incidence rates for chronic lymphocytic leukemia (CLL) among US states are significantly correlated with levels of residential radon (RR). Because these correlations could be influenced by confounding and/or misclassification among large geographic units, we reinvestigated them using smaller geographic units that better reflect exposure and disease at the individual level.

Methods:

We examined the relationships between CLL and RR per county in 478 counties with publicly-available data.

Results:

After adjustment for ultraviolet radiation, a possible risk factor for CLL, county rates for CLL and RR were significantly correlated among males and females both together and separately (p < 0.0001).

Conclusion:

CLL is significantly associated with RR at the county level.

Geographical Correlations between Indoor Radon Concentration and Risks of Lung Cancer, Non-Hodgkin's Lymphoma, and Leukemia during 1999-2008 in Korea

Indoor radon is the second most important risk factor for lung cancer and may also be a risk factor for hematopoietic cancers, particularly in children and adolescents. The present study measured indoor radon concentration nationwide at 5553 points during 1989–2009 and spatially interpolated using lognormal kriging. The incidences of lung cancer, non-Hodgkin’s lymphoma (NHL), and leukemia, stratified by sex and five-year age groups in each of the 234 administrative regions in the country during 1999–2008, were obtained from the National Cancer Registry and used to calculate the standardized incidence ratios. After considering regional deprivation index values and smoking rates by sex in each region as confounding variables, the cancer risks were estimated based on Bayesian hierarchical modeling. We found that a 10 Bq/m³ increase in indoor radon concentration was associated with a 1% increase in the incidence of lung cancer in male and a 7% increase in NHL in female children and adolescents in Korea aged less than 20 years. Leukemia was not associated with indoor radon concentration. The increase in NHL risk among young women requires confirmation in future studies, and the radon control program should consider children and adolescents.

Motor neuron disease mortality rates in U.S. states are associated with well water use

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with an unknown cause and invariably fatal outcome. We sought to evaluate a correlation between motor neuron disease (MND) mortality rates and residential radon levels that was previously reported for counties in the United Kingdom. We examined the relationships between age-adjusted MND mortality rates in U.S. states with residential radon levels, well water use, and other variables using structural equation modeling. We observed a significant correlation between MND mortality rates and radon levels. However, in structural equation models, radon did not have a significant, direct effect on MND mortality rates. Conversely, MND mortality rates were significantly and directly predicted by race and by the percentage of the population of each state using well water (p < 0.001 and p = 0.022). We observed similar, significant effects for well water use and MND mortality for males and females separately (p < 0.05). In conclusion, we hypothesize that the association of MND mortality rates with well water use reflects contamination of wells with Legionella, a bacterium common in well water that is known to cause neurologic disease. A Legionella hypothesis is a biologically plausible cause of ALS and suggests new avenues for etiologic research.

Residential radon exposure and risk of incident hematologic malignancies in the Cancer Prevention Study-II Nutrition Cohort

Dosimetric models show that radon, an established cause of lung cancer, delivers a non-negligible dose of alpha radiation to the bone marrow, as well as to lymphocytes in the tracheobronchial epithelium, and therefore could be related to risk of hematologic cancers. Studies of radon and hematologic cancer risk, however, have produced inconsistent results. To date there is no published prospective, population-based study of residential radon exposure and hematologic malignancy incidence. We used data from the American Cancer Society Cancer Prevention Study-II Nutrition Cohort established in 1992, to examine the association between county-level residential radon exposure and risk of hematologic cancer. The analytic cohort included 140,652 participants (66,572 men, 74,080 women) among which 3019 incident hematologic cancer cases (1711 men, 1308 women) were identified during 19 years of follow-up. Cox proportional hazard regression was used to calculate multivariable-adjusted hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for radon exposure and hematologic cancer risk. Women living in counties with the highest mean radon concentrations (>148Bq/m(3)) had a statistically significant higher risk of hematologic cancer compared to those living in counties with the lowest (<74Bq/m(3)) radon levels (HR=1.63, 95% CI:1.23-2.18), and there was evidence of a dose-response relationship (HRcontinuous=1.38, 95% CI:1.15-1.65 per 100Bq/m(3); p-trend=0.001). There was no association between county-level radon and hematologic cancer risk among men. The findings of this large, prospective study suggest residential radon may be a risk factor for lymphoid malignancies among women. Further study is needed to confirm these findings.