With the continuous control of anthropogenic emissions,China’s air quality has improved significantly in recent years.Given this background,research on how the short-term exposure risks caused by air pollution in Chi...With the continuous control of anthropogenic emissions,China’s air quality has improved significantly in recent years.Given this background,research on how the short-term exposure risks caused by air pollution in China have changed is insufficient.This study utilized hourly concentration data from ground observation stations and the official air quality guidelines of the Ministry of Ecology and Environment of China and the World Health Organization as standards to systematically investigate the spatiotemporal characteristics and short-term exposure risks of air pollution in China from 2015 to 2022.The results indicate that various atmospheric pollutants except for ozone showed a decreasing trend yearly.Nationwide,both single pollutant air pollution days(SAPDs)and multiple pollutant air pollution days(MAPDs)showed varying degrees of reduction within 15 and 25 days,respectively.SAPD was dominated mainly by excessive PM_(2.5)and PM_(10)pollutants,while MAPD was dominated mainly by excessive pollutant combinations,including PM_(2.5)+PM_(10),CO+PM_(2.5)+PM_(10),and SO_(2)+PM_(2.5)+PM_(10).As the concentration of atmospheric pollutants decreased,the total excess risk(ER)decreased yearly from 2015 to 2022,but there were significant regional differences.Now,the ER is less than 0.25%in southern China,in the range of 0.25%-0.5%in the North China Plain and some cities in the northeast,and higher than 1%in the northwest.Particulate matter is currently the primary pollutant posing short-term exposure risk in China,especially due to the impact of sandstorm weather.This study indicates that China’s atmospheric cleaning action is significantly beneficial for reducing health risks.展开更多
The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highwa...The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highway in Delhi city, India. The sampling has been carried out for 12-hour using Ecotech Intruments, APM550. The PM2.5 has been collected on PTFE filter papers for the winter season. Later, the filter papers have been analysed for various heavy metal concentrations using ED-XRF. It has been observed that the metals concentrations are in this trend: Si > K > S > Ca = Fe > Zn = Pb > Br. it is observed that Si has high co-relation with Ca, Fe and K, which may be due to crustal origin of all three elements;while S, Br and Pb may be from vehicular exhaust emissions and/or abrasions due to brake and tyre wear. The potential health risks associated with different carcinogenic heavy metals have also been calculated. One of the health risk indicators, the excess cancer risk (ECR), is found to be in the order as As > Cd > Pb > Cr > Ni.展开更多
Thirty-one samples of cigarettes have been collected from local markets of different types of origins. The samples were selected according to a survey distributed to smokers by paper and digital survey to see the most...Thirty-one samples of cigarettes have been collected from local markets of different types of origins. The samples were selected according to a survey distributed to smokers by paper and digital survey to see the most heavily traded among smokers and in addition to a number of questions to see how the awareness and the culture of smokers in diseases caused by smoking and considered this study the first survey in Iraq. The aim of this research is to assess the number of cancer cases due to cigarette smoking. Through the use of High-Purity Germanium system (HPGe) (efficiency 40%) we determinated the radionuclides in cigarette tobacco. The average values were (14.86 ± 3.76, 10.84 ± 3.13, 1050.64 ± 47.57) Bq/kg for Ra-226, Th-232 and K-40, respectively, and the excess lifetime of cancer risk values ranged from 0.54 to 130 at average of 76 per million person per year. Raeq values varied from 18.50 to 87.21.4 Bq/kg with an average value of 39.51 Bq/kg for tobacco samples. The annual effective dose (HE) varies from 16.38 μSv/y to 44.69 μSv/y with an average value of 24.97 μsv/y. The Annual Gonadal Dose Equivalent (AGDE) varies from 0.3 to 0.64 (mSv/y) with an average value of 0.42 for all tobacco samples under investigation.展开更多
The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Ar...The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Area of Taraba State, Nigeria. The activity concentrations were determined with the aid of High Purity Germanium detector. The absorbed dose and excess lifetime cancer risk were evaluated and forecasted for 60 years using the ResRad off-site model. The average activity concentration of <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U in the soil samples were 633.13, 141.15, and 71.20 Bq·kg<sup>-1</sup> respectively, for the Jalingo study area, and while that of the Wukari study area was;199.21, 87.23, and 25.37 Bq·kg<sup>-1</sup> respectively. The average soil-to-plant transfer factors for <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U were 0.51, 0.10, and 0.27 respectively for the Jalingo study area while that of Wukari are 0.40, 0.57, and 0.74 respectively. The mean annual effective dose equivalent for the study area is higher than the world average of 0.07 mS·vy<sup>-1</sup>. The excess lifetime cancer risk for the study areas has values that are higher than the safety limit. The ResRed model showed that direct radiation from the crops is the major contributor to excess cancer risk among other pathways. The radiological hazard indices reveal health risks to farmers, especially in the Jalingo area.展开更多
For this study, bromide and bromate ions in various commercial brands of Indian bottled water samples were estimated using ion chromatography. The measured mean concentration of bromide and bromate ions in water sampl...For this study, bromide and bromate ions in various commercial brands of Indian bottled water samples were estimated using ion chromatography. The measured mean concentration of bromide and bromate ions in water samples was found to be 28.13 μg/L and 11.17 μg/L respectively. The average level of bromate in Indian bottled water was found to be slightly higher (~ 12%) than the acceptable limits (10 μg/L) recommended by USEPA (US Environmental Protection Agency). Though, kinetically, it is predicted that 62.5% (6.25 μg/L) of bromide in bottled water is needed to convert into bromate upon ozonation to exceed the minimum acceptable limits, but the average formation of bromate determined to be only 26.77% of the predicted concentration. Bromate concentration in bottled water showed a strong correlation with bromide suggesting that its formation in water is very much influenced and controlled by bromide content. The objective of the present study was to determine the BrO3–) content of commercially available different brands of bottled drinking water in India and to estimate the health risks to population due to ingestion. Results of estimated excess cancer risk and chemical toxicity risk to Indian population due to ingestion of bottled water were presented and discussed.展开更多
Background:It has been well-established that acute radiation exposures increase the risk of leukemia.However,it is still unknown whether these leukemia risk estimates could be extrapolated to occupational populations ...Background:It has been well-established that acute radiation exposures increase the risk of leukemia.However,it is still unknown whether these leukemia risk estimates could be extrapolated to occupational populations who receive repeated low-dose radiation exposure.The purpose of this study was to estimate quantified associations between low-dose radiation exposures and leukemia.Methods:The Chinese medical X-ray worker study(CMXW)included 27,011 medical X-ray workers employed at major hospitals in 24 provinces in China from 1950 to 1980,and a control population of 25,782 physicians matched by hospital,who were unexposed to X-ray equipment.Poisson regression models were used to esti-mate the excess relative risk(ERR)and excess absolute risk(EAR)for the incidence of leukemia associated with cumulative doses.A meta-analysis of the published literature on low-dose occupational radiation exposure and leukemia risk was also conducted.Results:The incidence rates of leukemia in X-ray workers and the control group were 6.70 and 3.39 per 100,000 person-years,respectively.Among X-ray workers,the average cumulative red bone marrow dose was 0.046 Gy.We found a positive relationship between 2-year lagged cumulative red bone marrow dose and risk of leukemia excluding chronic lymphocytic leukemia(CLL)(ERR=0.66 per 100 mGy,90%CI:0.09,1.53;EAR=0.29 per 104 PY-100 mGy,90%CI:0.07,0.56).The excess risk was largely driven by myeloid leukemia(ERR=1.06 per 100 mGy,90%CI:0.22,2.51).Based on the meta-analysis,the pooled ERR at 100 mGy was 0.19(95%CI:0.08,0.31).Conclusion:This study provides strong evidence of a positive and linear doseresponse relationship between cu-mulative red bone marrow dose and the incidence of non-CLL leukemia.展开更多
Background:This study investigated the relationship between meteorological factors and daily outpatient visits to rabies post-exposure prophylaxis clinics to inform animal injury prevention strategies.Methods:Daily ou...Background:This study investigated the relationship between meteorological factors and daily outpatient visits to rabies post-exposure prophylaxis clinics to inform animal injury prevention strategies.Methods:Daily outpatient visit data from rabies post-exposure prophylaxis clinics in Jinan and corresponding meteorological data were collected from January 1,2020,to December 31,2022.A generalized additive model was used to quantitatively assess the relationship between these factors.A total of 202,010 patients visited these clinics during this period.Results:Daily mean,maximum,and minimum temperatures,and relative humidity were positively associated with outpatient visits.A 1°C increase in mean,maximum,and minimum temperatures corresponded to increases in daily visits of 1.65%(95%Confidence Interval(CI):1.55–1.76),1.59%(95%CI:1.50–1.69),and 1.27%(95%CI:1.17–1.36)respectively.Each 1%increase in relative humidity was associated with a 0.18%(95%CI:0.15–0.20)increase in visits.Mean pressure was negatively associated with outpatient visits,the outpatient visits decreased by 0.91%(95%CI:−1.71 to−0.11)for every 1 kPa increased in mean pressure.Conclusion:The change of meteorological factors will lead to the increase of outpatient visits in rabies exposure treatment clinic.展开更多
Introduction: Studies on RA (rheumatoid arthritis) and cardiovascular risk in African countries are scarce. Objective: To investigate the relationship between RA and cardiovascular risk in Cameroonian patients. Method...Introduction: Studies on RA (rheumatoid arthritis) and cardiovascular risk in African countries are scarce. Objective: To investigate the relationship between RA and cardiovascular risk in Cameroonian patients. Methodology: In 50 Black RA patients and 51 matched healthy individuals from the general population, we studied cardiovascular risk factors validated by the WHO. Cardiovascular risks estimates were carried out using WHO risk charts for the African region. Epi-info, R and SPPS were used for the statistical analysis. Results: Overall and abdominal adiposity as expressed by increased body mass index and abdominal obesity, were all markedly increased in RA patients compared to non-RA subjects [70% vs. 47%, OR (95% CI) = 2.62 (1.16 - 5.94), p = 0.026;and 54% vs. 33%, OR (95% CI) = 2.34 (1.05 - 5.25), p = 0.045 respectively]. RA patients were more physically inactive than their non-RA counterparts (20% vs. 0, p = 0.001). Whereas RA was associated with a reduced odds of alcoholism [OR (95% CI) = 0.19 (0.06 - 0.62), p = 0.005]. Increased BMI seemed to occur independently of methotrexate (p = 0.76), hydroxychloroquine (p = 0.59), corticosteroids (p = 0.79) treatments, and independently of sex (p = 0.15), age (p = 0.67), and sedentary lifestyle (p = 0.16) in RA patients;but their BMI was weakly correlated with disease duration (r = 0.26;p = 0.074). Meanwhile, male gender was associated with a reduced odds of abdominal obesity [OR (95% CI) = 0.02 (0 - 0.4), p = 0.011]. Cardiovascular risk, comparable by proportions between RA and non-RA subjects, was low in 26 patients (78.8%) and 30 non-RA subjects (83.3%) respectively. Conclusion: Despite the high adiposity burden and a sedentary lifestyle experienced by RA patients compared to their healthy counterparts, RA was not associated with cardiovascular risk as estimated by WHO risk charts.展开更多
Objective To assess the excess life time cancer risk(ELCR)due to radon exposure in small scale Tanzanite mines in Northern Tanzania.Methods Radon concentrations were measured using the solid state nuclear track detect...Objective To assess the excess life time cancer risk(ELCR)due to radon exposure in small scale Tanzanite mines in Northern Tanzania.Methods Radon concentrations were measured using the solid state nuclear track detectors(SSNTD)type CR-39.Three to six CR-39 detectors were placed in the underground working environment of each mine for a period of four months then removed and sent to Niton laboratory in Italy for processing and determination of radon concentrations.The obtained radon concentrations were used to estimate exposure to radon progenies,excess relative risk(ERR)of developing lung cancer,total lung cancer risk(TCR)and excess lifetime cancer risk(ELCR)using standard equations.Results The radon levels in 58%of the assessed mines were below the action level of 300 Bq/m^(3) recommended by the International Commission on Radiological Protection(ICRP)while 42%were above this limit.The estimated mean exposure to radon and its progenies ranged from 0.08 to 1.18 WLM corresponding to annual effective doses of 0.8 and 11.8 mSv/year,for the minimum and maximum values respectively.These values are below the annual limit of 20mSv for occupational exposure recommended by the ICRP.The ELCR estimated using simplified linear model from BEIR IV report ranged from 0 to 0.03%which is below the U.S.EPA action level of 1.3%due to radon exposure of 148 Bq/m^(3).Conclusion The ELCR due to exposure to radon in the assessed mines is negligible.However,follow up studies are recommended as the depths of the mines increase especially in the mines were radon concentrations exceeded the action level.展开更多
基金supported by the National Natural Science Foundation of China(No.42205178)China Postdoctoral Science Foundation(No.2022M720459).
文摘With the continuous control of anthropogenic emissions,China’s air quality has improved significantly in recent years.Given this background,research on how the short-term exposure risks caused by air pollution in China have changed is insufficient.This study utilized hourly concentration data from ground observation stations and the official air quality guidelines of the Ministry of Ecology and Environment of China and the World Health Organization as standards to systematically investigate the spatiotemporal characteristics and short-term exposure risks of air pollution in China from 2015 to 2022.The results indicate that various atmospheric pollutants except for ozone showed a decreasing trend yearly.Nationwide,both single pollutant air pollution days(SAPDs)and multiple pollutant air pollution days(MAPDs)showed varying degrees of reduction within 15 and 25 days,respectively.SAPD was dominated mainly by excessive PM_(2.5)and PM_(10)pollutants,while MAPD was dominated mainly by excessive pollutant combinations,including PM_(2.5)+PM_(10),CO+PM_(2.5)+PM_(10),and SO_(2)+PM_(2.5)+PM_(10).As the concentration of atmospheric pollutants decreased,the total excess risk(ER)decreased yearly from 2015 to 2022,but there were significant regional differences.Now,the ER is less than 0.25%in southern China,in the range of 0.25%-0.5%in the North China Plain and some cities in the northeast,and higher than 1%in the northwest.Particulate matter is currently the primary pollutant posing short-term exposure risk in China,especially due to the impact of sandstorm weather.This study indicates that China’s atmospheric cleaning action is significantly beneficial for reducing health risks.
文摘The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highway in Delhi city, India. The sampling has been carried out for 12-hour using Ecotech Intruments, APM550. The PM2.5 has been collected on PTFE filter papers for the winter season. Later, the filter papers have been analysed for various heavy metal concentrations using ED-XRF. It has been observed that the metals concentrations are in this trend: Si > K > S > Ca = Fe > Zn = Pb > Br. it is observed that Si has high co-relation with Ca, Fe and K, which may be due to crustal origin of all three elements;while S, Br and Pb may be from vehicular exhaust emissions and/or abrasions due to brake and tyre wear. The potential health risks associated with different carcinogenic heavy metals have also been calculated. One of the health risk indicators, the excess cancer risk (ECR), is found to be in the order as As > Cd > Pb > Cr > Ni.
文摘Thirty-one samples of cigarettes have been collected from local markets of different types of origins. The samples were selected according to a survey distributed to smokers by paper and digital survey to see the most heavily traded among smokers and in addition to a number of questions to see how the awareness and the culture of smokers in diseases caused by smoking and considered this study the first survey in Iraq. The aim of this research is to assess the number of cancer cases due to cigarette smoking. Through the use of High-Purity Germanium system (HPGe) (efficiency 40%) we determinated the radionuclides in cigarette tobacco. The average values were (14.86 ± 3.76, 10.84 ± 3.13, 1050.64 ± 47.57) Bq/kg for Ra-226, Th-232 and K-40, respectively, and the excess lifetime of cancer risk values ranged from 0.54 to 130 at average of 76 per million person per year. Raeq values varied from 18.50 to 87.21.4 Bq/kg with an average value of 39.51 Bq/kg for tobacco samples. The annual effective dose (HE) varies from 16.38 μSv/y to 44.69 μSv/y with an average value of 24.97 μsv/y. The Annual Gonadal Dose Equivalent (AGDE) varies from 0.3 to 0.64 (mSv/y) with an average value of 0.42 for all tobacco samples under investigation.
文摘The activity concentrations of radionuclides, absorbed dose rate, excess lifetime cancer risk, and soil-to-plant transfer factor have been evaluated in soil and crop samples from Jalingo and Wukari Local Government Area of Taraba State, Nigeria. The activity concentrations were determined with the aid of High Purity Germanium detector. The absorbed dose and excess lifetime cancer risk were evaluated and forecasted for 60 years using the ResRad off-site model. The average activity concentration of <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U in the soil samples were 633.13, 141.15, and 71.20 Bq·kg<sup>-1</sup> respectively, for the Jalingo study area, and while that of the Wukari study area was;199.21, 87.23, and 25.37 Bq·kg<sup>-1</sup> respectively. The average soil-to-plant transfer factors for <sup>40</sup>K, <sup>232</sup>Th, and <sup>238</sup>U were 0.51, 0.10, and 0.27 respectively for the Jalingo study area while that of Wukari are 0.40, 0.57, and 0.74 respectively. The mean annual effective dose equivalent for the study area is higher than the world average of 0.07 mS·vy<sup>-1</sup>. The excess lifetime cancer risk for the study areas has values that are higher than the safety limit. The ResRed model showed that direct radiation from the crops is the major contributor to excess cancer risk among other pathways. The radiological hazard indices reveal health risks to farmers, especially in the Jalingo area.
文摘For this study, bromide and bromate ions in various commercial brands of Indian bottled water samples were estimated using ion chromatography. The measured mean concentration of bromide and bromate ions in water samples was found to be 28.13 μg/L and 11.17 μg/L respectively. The average level of bromate in Indian bottled water was found to be slightly higher (~ 12%) than the acceptable limits (10 μg/L) recommended by USEPA (US Environmental Protection Agency). Though, kinetically, it is predicted that 62.5% (6.25 μg/L) of bromide in bottled water is needed to convert into bromate upon ozonation to exceed the minimum acceptable limits, but the average formation of bromate determined to be only 26.77% of the predicted concentration. Bromate concentration in bottled water showed a strong correlation with bromide suggesting that its formation in water is very much influenced and controlled by bromide content. The objective of the present study was to determine the BrO3–) content of commercially available different brands of bottled drinking water in India and to estimate the health risks to population due to ingestion. Results of estimated excess cancer risk and chemical toxicity risk to Indian population due to ingestion of bottled water were presented and discussed.
基金supported by the CAMS Innovation Fund for Med-ical Science(2019-I2M-2-006 and 2021-I2M-1-042)the Fundamen-tal Research Funds for the Central Universities(3332021066 and 3332020104)+1 种基金the National Natural Science Foundation of China(81772243,81803172,81803167,31800703,31971168,81972976,31900891,32071241,32171239,and 82072331)the Natural Sci-ence Foundation of Tianjin(19JCYBJC26600 and 20JCQNJC00340).
文摘Background:It has been well-established that acute radiation exposures increase the risk of leukemia.However,it is still unknown whether these leukemia risk estimates could be extrapolated to occupational populations who receive repeated low-dose radiation exposure.The purpose of this study was to estimate quantified associations between low-dose radiation exposures and leukemia.Methods:The Chinese medical X-ray worker study(CMXW)included 27,011 medical X-ray workers employed at major hospitals in 24 provinces in China from 1950 to 1980,and a control population of 25,782 physicians matched by hospital,who were unexposed to X-ray equipment.Poisson regression models were used to esti-mate the excess relative risk(ERR)and excess absolute risk(EAR)for the incidence of leukemia associated with cumulative doses.A meta-analysis of the published literature on low-dose occupational radiation exposure and leukemia risk was also conducted.Results:The incidence rates of leukemia in X-ray workers and the control group were 6.70 and 3.39 per 100,000 person-years,respectively.Among X-ray workers,the average cumulative red bone marrow dose was 0.046 Gy.We found a positive relationship between 2-year lagged cumulative red bone marrow dose and risk of leukemia excluding chronic lymphocytic leukemia(CLL)(ERR=0.66 per 100 mGy,90%CI:0.09,1.53;EAR=0.29 per 104 PY-100 mGy,90%CI:0.07,0.56).The excess risk was largely driven by myeloid leukemia(ERR=1.06 per 100 mGy,90%CI:0.22,2.51).Based on the meta-analysis,the pooled ERR at 100 mGy was 0.19(95%CI:0.08,0.31).Conclusion:This study provides strong evidence of a positive and linear doseresponse relationship between cu-mulative red bone marrow dose and the incidence of non-CLL leukemia.
基金supported by Chinese Association of Preventive Medicine-Vaccine and Immunization Youth Talent Support Project(CPMAQT-YM0314)Shandong medical and health science and technology development plan project(202012050267)Shandong Center for Disease Control and Prevention-Youth Innovation Fund Project(QC-202301).
文摘Background:This study investigated the relationship between meteorological factors and daily outpatient visits to rabies post-exposure prophylaxis clinics to inform animal injury prevention strategies.Methods:Daily outpatient visit data from rabies post-exposure prophylaxis clinics in Jinan and corresponding meteorological data were collected from January 1,2020,to December 31,2022.A generalized additive model was used to quantitatively assess the relationship between these factors.A total of 202,010 patients visited these clinics during this period.Results:Daily mean,maximum,and minimum temperatures,and relative humidity were positively associated with outpatient visits.A 1°C increase in mean,maximum,and minimum temperatures corresponded to increases in daily visits of 1.65%(95%Confidence Interval(CI):1.55–1.76),1.59%(95%CI:1.50–1.69),and 1.27%(95%CI:1.17–1.36)respectively.Each 1%increase in relative humidity was associated with a 0.18%(95%CI:0.15–0.20)increase in visits.Mean pressure was negatively associated with outpatient visits,the outpatient visits decreased by 0.91%(95%CI:−1.71 to−0.11)for every 1 kPa increased in mean pressure.Conclusion:The change of meteorological factors will lead to the increase of outpatient visits in rabies exposure treatment clinic.
文摘Introduction: Studies on RA (rheumatoid arthritis) and cardiovascular risk in African countries are scarce. Objective: To investigate the relationship between RA and cardiovascular risk in Cameroonian patients. Methodology: In 50 Black RA patients and 51 matched healthy individuals from the general population, we studied cardiovascular risk factors validated by the WHO. Cardiovascular risks estimates were carried out using WHO risk charts for the African region. Epi-info, R and SPPS were used for the statistical analysis. Results: Overall and abdominal adiposity as expressed by increased body mass index and abdominal obesity, were all markedly increased in RA patients compared to non-RA subjects [70% vs. 47%, OR (95% CI) = 2.62 (1.16 - 5.94), p = 0.026;and 54% vs. 33%, OR (95% CI) = 2.34 (1.05 - 5.25), p = 0.045 respectively]. RA patients were more physically inactive than their non-RA counterparts (20% vs. 0, p = 0.001). Whereas RA was associated with a reduced odds of alcoholism [OR (95% CI) = 0.19 (0.06 - 0.62), p = 0.005]. Increased BMI seemed to occur independently of methotrexate (p = 0.76), hydroxychloroquine (p = 0.59), corticosteroids (p = 0.79) treatments, and independently of sex (p = 0.15), age (p = 0.67), and sedentary lifestyle (p = 0.16) in RA patients;but their BMI was weakly correlated with disease duration (r = 0.26;p = 0.074). Meanwhile, male gender was associated with a reduced odds of abdominal obesity [OR (95% CI) = 0.02 (0 - 0.4), p = 0.011]. Cardiovascular risk, comparable by proportions between RA and non-RA subjects, was low in 26 patients (78.8%) and 30 non-RA subjects (83.3%) respectively. Conclusion: Despite the high adiposity burden and a sedentary lifestyle experienced by RA patients compared to their healthy counterparts, RA was not associated with cardiovascular risk as estimated by WHO risk charts.
文摘Objective To assess the excess life time cancer risk(ELCR)due to radon exposure in small scale Tanzanite mines in Northern Tanzania.Methods Radon concentrations were measured using the solid state nuclear track detectors(SSNTD)type CR-39.Three to six CR-39 detectors were placed in the underground working environment of each mine for a period of four months then removed and sent to Niton laboratory in Italy for processing and determination of radon concentrations.The obtained radon concentrations were used to estimate exposure to radon progenies,excess relative risk(ERR)of developing lung cancer,total lung cancer risk(TCR)and excess lifetime cancer risk(ELCR)using standard equations.Results The radon levels in 58%of the assessed mines were below the action level of 300 Bq/m^(3) recommended by the International Commission on Radiological Protection(ICRP)while 42%were above this limit.The estimated mean exposure to radon and its progenies ranged from 0.08 to 1.18 WLM corresponding to annual effective doses of 0.8 and 11.8 mSv/year,for the minimum and maximum values respectively.These values are below the annual limit of 20mSv for occupational exposure recommended by the ICRP.The ELCR estimated using simplified linear model from BEIR IV report ranged from 0 to 0.03%which is below the U.S.EPA action level of 1.3%due to radon exposure of 148 Bq/m^(3).Conclusion The ELCR due to exposure to radon in the assessed mines is negligible.However,follow up studies are recommended as the depths of the mines increase especially in the mines were radon concentrations exceeded the action level.
