Risk of central nervous system tumour incidence in a cohort of workers chronically exposed to ionising radiation.

The aim of the present study was to assess the risk of primary central nervous system (CNS) tumour incidence in a cohort of 22,377 Mayak Production Association workers chronically exposed to ionising radiation. There were 96 primary CNS tumours, including 42 cases of glioma and 44 cases of meningioma, registered during the whole follow-up period (1948-2018). The study demonstrated that the risk of primary CNS tumour incidence was associated with sex, attained age, calendar period, tall body height, age at the beginning of exposure, and facility type. There was no association found between risk of CNS tumour incidence and body mass index, smoking (males) and alcohol consumption status. The study did not find an effect of the total external gamma radiation dose absorbed in the brain on risk of CNS tumour incidence irrespective of whether an adjustment for the total external neutron dose absorbed in the brain was included or not. Excess relative risk per 1 Gy of external gamma brain dose was 0.05 (95% confidence interval (CI) -0.30; 0.70) for all CNS tumours, -0.18 (95% CI -; 0.44) for gliomas, and 0.38 (95% CI -0.32; 2.08) for meningiomas without adjustment for total neutron brain dose. There was no effect modification by sex, attained age, age at hire or facility.

Preliminary estimation of lung cancer risk of radon exposure in a uranium mine using different corrections / 中国职业医学

Objective: To explore the correction factors of lung cancer caused by radon exposure in a uranium mine, and estimate the excess relative risk (ERR) coefficient of lung cancer caused by radon in the uranium miners. Methods: Male miners who worked in a uranium mine more than one year in Hunan Province from 1958 to 2018 were selected. This study preliminarily estimated the ERR coefficient of lung cancer caused by radon in the miners with different corrections using the Possion regression model. Results: This study cohort included 4 851 uranium miners, with 187 miners died with lung cancer from 1958 to 2018, and cumulative follow-up of 207 251 person-year. The ERR coefficient of lung cancer caused by radon without correction factors was estimated to be 0.21%/WLM (95%CI: 0.04%/WLM-0.27%/WLM). In the final model, the exponential correction factors of radon-induced lung cancer were time since exposure and exposure rate. In this model, if time since exposure was 45 years and the average exposure rate was 0.14 WL, the estimated ERR coefficient was 1.73%/WLM (95%CI: 0.36%/WLM-3.11%/WLM). The ERR decreases by about 60.00% for every 10 years since exposure, and increases by about 30.00% for every one WL increase exposure rate. Conclusion: The correction factors of lung cancer caused by radon in uranium miners in this mine were the time since exposure and exposure rate. It was preliminarily estimated that the ERR coefficient of lung cancer caused by radon in the occupational radon exposed population in this uranium mine was 1.73%/WLM (95%CI: 0.36%/WLM-3.11%/WLM).

Mortality from various diseases of the circulatory system in the Russian Mayak nuclear worker cohort: 1948-2018.

This paper reports on the findings from the study of mortality from diseases of the circulatory system (DCS) in Russian nuclear workers of the Mayak Production Association (22 377 individuals, 25.4% female) who were hired at the facility between 1948 and 1982 and followed up until the end of 2018. Using the AMFIT module of the EPICURE software, relative risks (RRs) and excess RRs per unit absorbed dose (ERR/Gy) for the entire Mayak cohort, the subcohort of workers who were residents of the dormitory town of Ozyorsk and the subcohort of migrants from Ozyorsk were calculated based on maximum likelihood. The mean cumulative liver absorbed gamma-ray dose from external exposure was 0.45 (0.65) Gy (mean (standard deviation)) for men and 0.37 (0.56) Gy for women. The mean cumulative liver absorbed alpha dose from internal exposure to incorporated plutonium was 0.18 (0.65) Gy for men and 0.40 (1.92) Gy for women. By the end of the follow-up, 6019 deaths with DCS as the main cause of death were registered among Mayak Production Association workers (including 3828 deaths in the subcohort of residents and 2191 deaths in the subcohort of migrants) over 890 132 (622 199/267 933) person-years of follow-up. The linear model that took into account non-radiation factors (sex, attained age, calendar period, smoking status and alcohol drinking status) and alpha radiation dose (via adjusting) did not demonstrate significant associations of mortality from DCS, ischaemic heart disease (IHD) and cerebrovascular disease with gamma-ray exposure dose in the entire cohort, the resident subcohort or the migrant subcohort (either in men or women). For the subcohort of residents, a significant association with gamma dose was observed for mortality from ischaemic stroke in men with ERR/Gy = 0.43 (95% CI 0.08; 0.99); there were no significant associations with liver absorbed gamma dose for any other considered outcomes. As for internal exposure, for men no significant associations of mortality from any DCS with liver absorbed alpha dose were observed, but for women positive associations were found for mortality from DCS (the entire cohort and the resident subcohort) and IHD (the entire cohort). No significant associations of mortality from various types of DCS with neutron dose were observed either in men or women, although neutron absorbed doses were recorded in only 18% of the workers.

Analysis of causal mediation effect with odds ratio and excess relative risk as evaluation indexes / 四川精神卫生

The purpose of this paper was to introduce how to set the options of variable levels and multimodal covariates， and to demonstrate the causal mediation effect analysis method with odds ratio （OR） and excess relative risk （ERR） as evaluation indicators through examples. For treatment variables， mediator variables and covariates， the variable-level options of them could be set through the evaluate statement. For categorical variables and their interaction terms， they could be treated as multimodal covariates， and the variable levels could also be set for them by using the evaluate statement. Through an example， this paper used SAS to realize the causal mediation effect analysis and the decomposition of effect components with OR and ERR as the evaluation indicators.

Meta-analysis of published excess relative risk estimates.

A meta-analytic summary effect estimate often is calculated as an inverse-variance-weighted average of study-specific estimates of association. The variances of published estimates of association often are derived from their associated confidence intervals under assumptions typical of Wald-type statistics, such as normality of the parameter. However, in some research areas, such as radiation epidemiology, epidemiological results typically are obtained by fitting linear relative risk models, and associated likelihood-based confidence intervals are often asymmetric; consequently, reasonable estimates of variances associated with study-specific estimates of association may be difficult to infer from the standard approach based on the assumption of a Wald-type interval. Here, a novel method is described for meta-analysis of published results from linear relative risk models that uses a parametric transformation of published results to improve on the normal approximation used to assess confidence intervals. Using simulations, it is illustrated that the meta-analytic summary obtained using the proposed approach yields less biased summary estimates, with better confidence interval coverage, than the summary obtained using the more classical approach to meta-analysis. The proposed approach is illustrated using a previously published example of meta-analysis of epidemiological findings regarding circulatory disease following exposure to low-level ionizing radiation.

Joint nonparametric correction estimator for excess relative risk regression in survival analysis with exposure measurement error.

Observational epidemiological studies often confront the problem of estimating exposure-disease relationships when the exposure is not measured exactly. In the paper, we investigate exposure measurement error in excess relative risk regression, which is a widely used model in radiation exposure effect research. In the study cohort, a surrogate variable is available for the true unobserved exposure variable. The surrogate variable satisfies a generalized version of the classical additive measurement error model, but it may or may not have repeated measurements. In addition, an instrumental variable is available for individuals in a subset of the whole cohort. We develop a nonparametric correction (NPC) estimator using data from the subcohort, and further propose a joint nonparametric correction (JNPC) estimator using all observed data to adjust for exposure measurement error. An optimal linear combination estimator of JNPC and NPC is further developed. The proposed estimators are nonparametric, which are consistent without imposing a covariate or error distribution, and are robust to heteroscedastic errors. Finite sample performance is examined via a simulation study. We apply the developed methods to data from the Radiation Effects Research Foundation, in which chromosome aberration is used to adjust for the effects of radiation dose measurement error on the estimation of radiation dose responses.

Transfer of radiation related leukemia risk from Japanese population to Chinese population / 中华放射医学与防护杂志

Objective To estimate the averaged excess relative risk(ERR) in Chinese population based on the radiogenic cancer risk of leukemia in Japanese atomic bomb survivor cohort,and to discuss proper method suitable for risk transfer between populations.Methods Based on BEIR Ⅶ radiogenic cancer model and population transfer model,and the 2009 Chinese leukemia baseline rates given in 2012 Chinese Cancer Registry Annual Report,comparison was made of population incidences in seveal countries to adjust the weighting factors.Results The ERR of three subtypes of leukemia as a whole was obtained,and the weighting factors for risk transfer model was assumed.The additive factor for male was 0.2,and the multiplicative factor was 0.8,while the additive factor for female was 0.15,and the multiplicative factor was 0.85.Conclusions For the risk transfer between populations,weighting factor was adjusted as a whole to obtain the ERR value for estimating the risk to Chinese population.The risk transfer method suitable for Chinese population was obtained by using the incidence rate available for Chinese population to directly transfer radiation-induced leukemia risk to Chinese from Japanese.

Synergy between particles and nitrogen dioxide on emergency hospital admissions for cardiac diseases in Hong Kong.

BACKGROUND: Ambient air pollution is a complex mixture of particles and gaseous pollutants. Epidemiological studies are moving toward a multipollutant approach, requiring an understanding of possible interactions among the pollutants. We aim to estimate the joint effects of particles with an aerodynamic diameter less than 10 µm (PM10) and nitrogen dioxide (NO2) on emergency hospital admissions for cardiac diseases, and to explore the possible interactions between PM10 and NO2. METHODS: We collected daily time series data from 1998 to 2007 on emergency hospital admissions for cardiac diseases in Hong Kong, as well as PM10 and NO2 concentrations. Generalized additive Poisson model was used to examine the relationship between air pollution and hospital admissions. We then used three parallel time series approaches (bivariate response surface model, joint effect model and parametric stratified model) to explore the possible interactions between PM10 and NO2. RESULTS: Results showed the greatest joint effect of PM10 and NO2 on emergency cardiac hospitalizations when PM10 and NO2 concentrations were both at high levels. The effect of PM10 was significantly greatest on the days with high NO2 level, and vice versa. A 10 µg/m(3) increase of lag0 PM10 and NO2 was associated with an increase of emergency cardiac hospitalizations by 0.55% (95% CI: 0.29-0.80%) and 1.20% (95% CI: 0.87-1.53%) respectively, when the other pollutant was at high level. CONCLUSIONS: We found consistent synergistic interaction between PM10 and NO2 on emergency cardiac hospitalizations in Hong Kong. These findings contribute to the development of a new paradigm for multipollutant air quality management.

Cool and dry weather enhances the effects of air pollution on emergency IHD hospital admissions.

BACKGROUND: Associations between ambient pollution and cardiovascular morbidity including ischemic heart disease (IHD) have been confirmed. Weather factors such as temperature, season and relative humidity (RH) may modify the effects of pollution. We conducted this study to examine the effects of air pollution on emergency IHD hospital admissions varied across seasons and RH levels, and to explore the possible joint modification of weather factors on pollution effects. METHODS: Daily time series of air pollution concentrations, mean temperature and RH were collected from IHD hospital admissions from 1998 to 2007 in Hong Kong. We used generalized additive Poisson models with interaction term to estimate the pollution effects varied across seasons and RH levels, after adjusting for time trends, weather conditions, and influenza outbreaks. RESULTS: An increase in the detrimental effects of air pollution in cool season and on low humidity days was observed. In the cool and dry season, a 10 µg/m(3) increment of lag03 exposure was associated with an increase of emergency IHD admissions by 1.82% (95% CI: 1.24-2.40%), 3.89% (95% CI: 3.08-4.70%), and 2.19% (95% CI: 1.33-3.06%) for particles with an aerodynamic diameter less than 10 µm (PM10), nitrogen dioxide (NO2), and ozone (O3), respectively. The effects of pollutants decreased greatly and lost statistical significance in the warm and humid season. CONCLUSIONS: We found season and RH jointly modified the associations between ambient pollution and IHD admissions, resulting in increased IHD admissions in the cool and dry season and reduced admissions in the warm and humid season.

Transfer of ERR for radiation-related leukemia from Japanese population to Chinese population / 中华放射医学与防护杂志

Objective To establish a transfer model for excess relative risk (ERR) for radiation-related leukemia from Japanese population to Chinese population.Methods Combined ERR of several subtypes of leukemia published in 1994, with the corresponding leukemia baseline incidence rates obtained from Cancer Incidence in Five Continents Vol.Ⅸ (CI5-Ⅸ) for Japanese population and Chinese population, a weighted risk transfer model was employed between an additive model and a multiplicative model, to execute ERR transfer.Results A range of weighing factors was proposed for risk transfer models:weighing factor was 0.4 for male and 0.3 for female, acute lymphoblastic leukemia, acute myeloid leukemia and chronic myeloid leukemia.The uncertainty for ERR transfer was characterized by lognormal distribution.Conclusions Based on the difference of baseline incidence rate for subtypes of leukemia between Japanese population and Chinese population, the transfer model and these weighing factors discussed in the present study could be applicable to transfer ERR for radiation-related leukemia from Japanese population to Chinese population.