Indoor 222Rn Research Articles

Estimation of indoor 222 Rn and 220 Rn concentration and annual inhalation dose in the indoor environment around Kolar district of Karnataka state, India

The indoor 222Rn and 220Rn were measured by using deposition progeny sensors and single-entry pinhole dosimeter around Kolar Gold Fields of Karnataka state, India. The thirty different places were identified and fixed the dosimetry cups for the determination. The 222Rn and 220Rn concentrations of indoor environment range from 26.2 ± 1.3 to 138.4 ± 1.6 and 21.2 ± 0.8 to 133.3 ± 1.5 Bq/m3 with a mean value of 68.8 ± 1.6 and 61.8 ± 1.5 Bq/m3, respectively. The equivalent concentrations of 222Rn and 220Rn values vary from 0.9 ± 0.4 to 7.6 ± 1.1 and 6.8 ± 0.8 to 19.8 ± 1.8 Bq/m3 with a standard value of 4.3 ± 0.8 and 14.2 ± 1.3 Bq/m3, respectively. The values between the equilibrium factor between 222Rn, 220Rn, and their daughter were also calculated and found to be 0.23 and 0.07, respectively. The average annual intake of 222Rn, 220Rn, and their daughters' products is 2.28 mSv/y1, slightly below the global average of 2.4 mSv/y1from all components. The data obtained compare average values in the world.

Investigation of the indoor 222Rn and 220Rn levels in the residential environment and estimation of the annual effective radiation dose for ordinary residents.

To evaluate the health risk of radon and its progeny, a large amount of accurate monitoring data is needed according to the theory and practice of health risk assessment. However, the indoor radon levels in different regions in China and worldwide reveal temporal and spatial variations. In addition, the residents living in different areas follow distinct living modes. Therefore, it is recommended and accepted by many researchers to detect the radon level in local areas and subsequently conduct health risk assessments based on local detection data. In this study, 21 bedrooms of households in Weifang city were selected, and the indoor 222Rn and 220Rn levels were detected with RAD7 radon detector in winter, while the annual effective radiation dose was calculated for ordinary residents in Weifang city. Our investigation showed that the 24- and 12-hour average levels of 222Rn were 35.7±15.2 Bq/m3 and 36.2±15.8 Bq/m3, respectively. The 24- and 12-hour average levels of 220Rn were 30.4±12.3 Bq/m3 and 22.4±11.6 Bq/m3, respectively. There were significant differences in the average levels of 222Rn and 220Rn between floors. The estimated annual effective radiation dose received by ordinary residents in Weifang city was 1.7193 mSv, of which 0.9479 mSv originated from 222Rn and its progeny and 0.7714 mSv originated from 220Rn and its progeny, accounting for 55.1% and 44.9%, respectively, of the total dose. Our findings suggest that 220Rn should not be ignored by local residents in Weifang city, and more attention should be paid to 220Rn in future research.

Measurement of radon exhalation rate from building materials: The case of Highland Region of Ecuador

Exposure to 222-Radon (Rn) usually occurs in closed environments as effect of the Rn exhaled from building materials, soil or water. While building materials provide a protection barrier to outdoor natural radiation (terrestrial and cosmic), their radionuclide composition could increase the indoor Rn exposure. In fact, the Rn exhalation of building materials is of great importance from the viewpoint of mitigation and public health in very specific conditions. This work presents the Rn exhalation rates of 40 building materials (concrete blocks, clay brick, granite and concrete samples) produced and used in Ecuador, as well as the effective dose for a reference dwelling. Rn concentration measurements were performed using the closed chamber method and a RAD7 equipment. The resulting Rn exhalation rates were found to be in the range from 0 to 7.83 Bq·m-2·h-1. The highest surface exhalation rate was detected in granite samples, while clay bricks show Rn exhalation below the minimum detection level (0.05Bq·m-2·h-1). In the reference dwelling, the effective dose rates caused by Rn exhalation from building material range from 0.019 up to 0.112 mSv/y. However, the effective dose rate depends on the exposure time and quantity of granite used. Our results could be of immediate help to choose suitable building materials to ensure a safe indoor environment for the dwellers.

Comparison experiments for radon and thoron measuring instruments at low-level concentrations in one room of a Japanese concrete building

A comparison on commercially available radon (222Rn) measuring instruments (three types of continuous monitors and a passive 222Rn-thoron (220Rn) discriminative alpha track detector) was carried out at low-level concentrations in one room of a concrete building. The agreements between the continuous monitors were within 15%, while the agreements between each instrument were within 20%. It was also observed that the indoor 220Rn concentration measured by the continuous monitor was quite different from those by the passive detectors due to the mean concentration less than the limit of detection of both measuring instruments.

Mapping indoor radon hazard in Germany: The geogenic component.

Indoor radon is considered as an indoor air pollutant due to its carcinogenic effect. Since the main source of indoor radon is the ground beneath the house, we utilize the geogenic radon potential (GRP) and a geogenic radon hazard index (GRHI) for predicting the geogenic component of the indoor Rn hazard in Germany. For this purpose, we link indoor radon data (n=44,629) to maps of GRP and GRHI and fit logistic regression models to calculate the probabilities that indoor Rn exceeds thresholds of 100Bq/m3 and 300Bq/m3. The estimated probability was averaged for every municipality by considering only the estimates within the built-up area. Finally, the mean exceedance probability per municipality was coupled with the respective residential building stock for estimating the number of buildings with indoor Rn above 100Bq/m3 and 300Bq/m3 for each municipality. We found that (1) GRHI is a better predictor than GRP for indoor radon hazard in Germany, (2) the estimated number of buildings above 100Bq/m3 and 300Bq/m3 in Germany is ~2 million (11.6% of all residential buildings) and~350,000 (1.9%), respectively, (3) areas where 300Bq/m3 exceedance is greater than 10% comprise only 0.8% of the German building stock but 6.3% of buildings with indoor Rn exceeding 300Bq/m3, and (4) most urban areas and, hence, most buildings (77%) are located in low hazard regions. The implications for Rn protection are twofold: (1) the Rn priority area concept is cost-efficient in a sense that it allows to find the most buildings that exceed a threshold concentration with a given amount of resources, and (2) for an optimal reduction of lung cancer risk areas outside of Rn priority areas must be addressed since most hazardous indoor Rn concentrations occur in low to medium hazard areas.

Measurement of Indoor Thoron Gas Concentrations Using a Radon-Thoron Discriminative Passive Type Monitor: Nationwide Survey in Japan.

As part of a nationwide survey of thoron (220Rn) in Japan, the indoor 220Rn gas concentrations in 940 dwellings were measured throughout one year, from 1993 to 1996, using a passive type 222Rn-220Rn discriminative monitor. The monitor was placed in a bedroom or a living room in each house for four successive three-month periods. The mean annual indoor 220Rn concentration was estimated from the four measurements in each house. The arithmetic mean, the median and the geometric mean for indoor 220Rn concentrations in 899 dwellings were 20.1, 9.6 and 10.0 Bq m−3, respectively. The 220Rn concentrations exhibited a log-normal distribution. It was found that the 220Rn concentrations were dependent on the nature of the materials used for wall construction and also on the distance of measurement from the wall. Significant seasonal variations in the 220Rn concentration were not observed. It would seem that the nature of the wall material contributed to the increased indoor 220Rn concentrations.

Activity concentrations of 226Ra, 232Th, 40K, and 222Rn in the indoor air and surface soil in Ho Chi Minh City, Vietnam: Methods for estimating indoor 222Rn and health risks to the population

Activity concentrations of 226Ra, 232Th, 40K, and 222Rn in the indoor air and surface soil in Ho Chi Minh City, Vietnam: Methods for estimating indoor 222Rn and health risks to the population

Lung dose measurement from indoor 222Rn and 220Rn in dwellings of Fatehgarh district of Punjab, India

In order to study the health risk factors caused by indoor radon and thoron gases, environmental testing of these gasses has been carried out in various dwellings in the Fatehgarh district of Punjab. The average concentration of indoor 222Rn (CR) and indoor 220Rn (CT) is 59.8±15.9 Bq/m3 and 70.6±22.4 Bq/m3. The equivalent dose rate for lung (H) ranges from 33.54 to 82.60 nSv with mean dose of 47.85±12.73 nSv. The Effective dose rate to lungs (DLung) due to radon emitted alpha particles and progenies ranges from 1.68 to 4.13 nGy h-1 with mean of 2.39±0.63 nGy h-1. The effective dose rates trachea-bronchial (DT-B) and pulmonary + pulmonary lymph (DP+PI) ranges from 2.01 to 4.96 nSv with average value of 2.86±0.63 nSv. The rate of lung dose DRL owing to radon varies from 4.03 to 9.91 nSv with average value of 5.74±1.52 nSv. The average of the 222Rn and 220Rn inhalation dose in the study region is not as much of the 222Rn and 220Rn overall average inhalation dose worldwide.

Assessment of radon, thoron, and their progeny concentrations in the dwellings of Shivalik hills of Jammu and Kashmir, India.

The present work determines the contents of active and passive indoor 222Rn, 220Rn, and their daughter in the 32 houses of the Reasi district of J&K, India. The passive 222Rn and 220Rn concentration was measured by dosimeters, whereas the active content was measured by active radon monitor. Progeny sensors and integrated samplers were operated for the evaluation of passive and active daughter contents of 222Rn and 220Rn. The measured averaged values of indoor 220Rn and 222Rn were 73 ± 40 and 22 ± 8Bqm-3, respectively. The radon and thoron equilibrium factor has varied from 0.3 to 1.7 and from 0.006 to 0.6. The fine fraction of the above-mentioned gases was also calculated. The results of Mann-Whitney test statistically demonstrated significant differences between the content of indoor 222Rn, 220Rn, and their daughter for different seasons. The values of 222Rn, 220Rn, and their daughter content were appeared to be elevated in set of mud houses among all sets of houses. The values of all daughter concentration and indoor 222Rn were appeared to lie within the limit proposed by various agencies. The total doses were detected less than range commended by ICRP that suggested the district is safe as a health hazard point of view.

222Rn concentration level and inhalation exposure assessment for the population residing in Singhbhum copper belt of Jharkhand

The present investigation has been carried out in the copper mineralized region of Jharkhand, India. Apart from the natural deposit of copper minerals, which is found along with uranium in this region, different industrial sites of copper were accounted for, in the study. The integrated radon measurement technique has been used with dosimeter deployment interval of 90 days. The indoor 222Rn activity concentration varied at different locations from 58.4 to $$100.7\,{\text{Bq}}\,{\text{m}}^{ - 3}$$ with an average of $$79.8 \pm 14.5 \,{\text{Bq}}\,{\text{m}}^{ - 3}$$ . In the outdoor environment, annual average 222Rn activity concentration varies from 36.5 to $$75.8 \,{\text{Bq}}\,{\text{m}}^{ - 3}$$ with an average of $$57.9 \pm 14.0 \,{\text{Bq}}\,{\text{m}}^{ - 3}$$ . The corresponding annual inhalation dose due to indoor and outdoor 222Rn activity concentration to the inhabitants of the region has been worked out as $$1.95\,{\text{mSv}}\,{\text{year}}^{ - 1}$$ to $$3.28\,{\text{mSv}}\,{\text{year}}^{ - 1}$$ respectively with a mean of $$2.60 \pm 0.38\,{\text{mSv}}\,{\text{year}}^{ - 1}$$ .

Mapping the geogenic radon potential for Germany by machine learning

The radioactive gas radon (Rn) is considered as an indoor air pollutant due to its detrimental effects on human health. In fact, exposure to Rn belongs to the most important causes for lung cancer after tobacco smoking. The dominant source of indoor Rn is the ground beneath the house. The geogenic Rn potential (GRP) - a function of soil gas Rn concentration and soil gas permeability - quantifies what “earth delivers in terms of Rn” and represents a hazard indicator for elevated indoor Rn concentration. In this study, we aim at developing an improved spatial continuous GRP map based on 4448 field measurements of GRP distributed across Germany. We fitted three different machine learning algorithms, multivariate adaptive regression splines, random forest and support vector machines utilizing 36 candidate predictors. Predictor selection, hyperparameter tuning and performance assessment were conducted using a spatial cross-validation where the data was iteratively left out by spatial blocks of 40 km*40 km. This procedure counteracts the effect of spatial auto-correlation in predictor and response data and minimizes dependence of training and test data. The spatial cross-validated performance statistics revealed that random forest provided the most accurate predictions. The predictors selected as informative reflect geology, climate (temperature, precipitation and soil moisture), soil hydraulic, soil physical (field capacity, coarse fraction) and soil chemical properties (potassium and nitrogen concentration). Model interpretation techniques such as predictor importance as well as partial and spatial dependence plots confirmed the hypothesized dominant effect of geology on GRP, but also revealed significant contributions of the other predictors. Partial and spatial dependence plots gave further valuable insight into the quantitative predictor-response relationship and its spatial distribution. A comparison with a previous version of the German GRP map using 1359 independent test data indicates a significantly better performance of the random forest based map.

Abstract 2338: Comparison of genomic alterations in lung cancer specimens from high and low radon zones: Search for a genomic fingerprint

Abstract Introduction: Radon-222 (Rn) is a radioactive gas found in rocks and soil. It emits alpha particles that cause dsDNA breaks and increases potential for carcinogenesis. Rn is the 2nd leading cause of lung cancer in the US after smoking, with EPA estimates of >15000 deaths. A significant portion of land in US has high Rn soil levels; ‘action level' for indoor Rn mitigation is >4pci/L. Rhode Island (RI) contains several high Rn areas. We hypothesize that specific cellular and molecular mechanisms play a role in the neoplastic potential of Rn, detectable as signature genetic profiles. Our aim is to identify molecular patterns in patients (pts) from high Rn zones, by evaluating next generation sequencing (NGS) based assays in advanced lung cancer pts. Methods: Using a commercially available NGS assay, we retrospectively analyzed genomic DNA alterations in 324 genes from FFPE specimens of 159 stage IV lung cancer pts treated at Lifespan Cancer Institute at Brown University from 2014- 2019. Based on EPA Rn maps, we identified counties in RI with high indoor Rn levels (>4 pci/L), and compared the gene mutation patterns with those residing in low Rn areas (<4 pci/L). Results: Of the 159 pts (median age= 58), 35 (22%) belonged to high Rn and 124 (78%) to low Rn zones. Both groups had predominantly adenocarcinoma histology and high smoking prevalence (75-80%). Most prevalent genomic alterations in both cohorts were TP53, KRAS and CDKN2A mutations. In the high Rn group, we identified more frequent recurrent mutations in two DNA repair genes: ATM (11% in high Rn vs 1% in low Rn areas, p=0.00086) and CHEK2 (6% vs 0%, respectively, p=0.047). We then classified all detected genomic alterations into major pathways implicated in lung carcinogenesis; DNA repair, cell cycle, tyrosine kinase, and apoptosis. The only observed statistically significant difference in the frequency of mutations was for the DNA repair pathway (29% in high Rn vs 13% in low Rn, p=0.038). Conclusion: To our knowledge, this is the first report of a novel and mechanistically unique insight into the pathobiology of Rn induced lung cancer. Our observations suggest that Rn induced dsDNA breaks may constitute an oncogenic hit in cells which are unable to efficiently repair them because of DNA repair pathway mutations (particularly ATM and CHEK2). We are further testing this “second hit” hypothesis in a larger nationwide dataset comparing NGS profiles of lung cancers from low and high Rn areas in the US. Top 10 mutated genes in High and Low Radon groups (rank; frequency, %)High RnLow RnP value1. TP53 (63)1. TP53 (70)0.422. KRAS (26)2. KRAS (28)0.833. CDKN2A (23)3. CDKN2A (24)0.994. RB1 (17)4. RB1 (20)0.815. EGFR (14)7. EGFR (10)0.546. CDKN2B (14)6. CDKN2B (15)0.997. STK11 (11)5. STK11 (19)0.338. RBM10 (11)-. RBM10 (3)0.07-. SMARCA4 (3)8. SMARCA4 (8)0.469. NF1 (11)9. NF1 (7)0.4910. ATM (11)-. ATM (1)0.008-. MYC (6)10. MYC (5)0.99 Citation Format: Hina Khan, Harish Saiganesh, Adam J. Olszewski, Christopher G. Azzoli, Howard Safran. Comparison of genomic alterations in lung cancer specimens from high and low radon zones: Search for a genomic fingerprint [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2338.

Assessment of radiological dose from exposure to attached and unattached fractions of radon (222Rn) and thoron (220Rn) in indoor atmosphere

In this study pin hole dosimeter with deposition based progeny sensors were used to estimate 222Rn, 220Rn and their daughters in the indoor atmosphere. The estimated annual average indoor 222Rn and 220Rn activity concentration were found to be 76.4 Bq m−3 and 93.5 Bq m−3, respectively. The mean value of EEC for radon and thoron was 45.5 Bq m−3 and 1.3 Bq m−3 respectively. The annual effective dose due to indoor 222Rn and 220Rn were found to be 2.9 mSv y−1 and 0.4 mSv y−1 respectively. The estimated effective doses are well below the safe limit as suggested by ICRP for indoor exposure.

Numerical simulation of 222Rn profiling in an experimental chamber using CFD technique

Measurement of indoor 222Rn concentration and interpretation of distribution patterns are important for inhalation dosimetry in occupational and residential areas. Experimental determination of 222Rn concentration distribution and estimation of inhalation doses depend on the underlying aspects such as calibration of the detectors, accuracy of the techniques etc. Therefore, 222Rn concentration distribution needs to be very well understood in a closed domain for the controlled studies. In the recent times, Computational fluid dynamics (CFD) technique has gained a lot of attention for the prediction and visualization of indoor 222Rn concentration profiles and their mixing ability in the domain. The present study aims to simulate the effect of forced mixing on the 222Rn concentration profile in a 22 m3 experimental chamber. This chamber is designed for carrying out the controlled experiments, calibration and inter-comparison studies of various types of 222Rn detectors. Effect of different parameters such as time, flow rates, fan-off and fan-on conditions have been studied on the transient response, extent of the air mixing patterns and subsequently on 222Rn concentration profile in the chamber. Further, Non uniformity index (NUI) is introduced as a measure of the uniformity of the distribution in the closed domain. NUI is estimated for different cases in order to efficiently interpret the effect of above mentioned parameters on 222Rn profile in the chamber. This study will be useful to represent the turbulent conditions in real indoor domains and occupational facilities as U-mines during calibration and inter-comparison exercises of different 222Rn detectors.

Abstract C075: Indoor radon exposure and thyroid cancer incidence among Guam residents

Abstract The natural radioactive decay of radon (222Rn) gas gives rise to many products that release ionizing radiation, proven to be harmful to human health. Perhaps the best-known source of radiation that has been linked to thyroid cancer (TC) is the chronic inhalation of radon gas. Indoor 222Rn levels in Guam have been documented to be as high as 220 picocuries per liter (pCi/L), exponentially higher than the United States Environmental Protection Agency (USEPA) baseline standard of just 4 pCi/L. Thyroid cancer is the fifth common cancer in women on Guam and Filipinos had the highest thyroid cancer incidence rates compared to other ethnic groups in Guam. The objective of this study is to determine whether there is an association between thyroid cancer incidence, geographic location (village/zone), ethnicity, and amount of indoor radon exposure in Guam. The data sets used in this ecological study came from three major independent data collecting sources: Guam Environmental Protection Agency (GEPA) indoor 222Rn data (2002-2009), Guam Cancer Registry thyroid cancer incidence data (1998-2013), and Guam Census 2000 and 2010 demographic data. Simple linear regression analysis was performed to determine the relationship between mean indoor 222Rn levels and thyroid cancer incidence in Guam villages. Multiple regression analysis was conducted to account for the confounding effects of ethnicity (% Filipino), and zone. Results indicated that radon in Guam was found to be highest in Zone 1, the geographic villages situated atop a limestone plateau in the northern region where approximately 66% of Guam residents and over 90% of Filipinos live. In both univariate and ethnicity-adjusted regression analysis, a significant positive association was found between mean 222Rn level and thyroid cancer incidence (P = .024, and P = .048, respectively). When univariate and multiple regression analysis was conducted on the two GEPA 222Rn zone strata (Zone 1 and Zone 2/3), the relationship remained positive but not statistically significant. The positive correlation between mean 222Rn levels and thyroid cancer incidence suggested that more exposed individuals have increased susceptibility to cancer and possibly explained higher rate among Filipinos. Citation Format: Candice S. Arceo, Grazyna Badowski, Gary R.W. Denton, Renata Bordallo. Indoor radon exposure and thyroid cancer incidence among Guam residents [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C075.

Parameter sensitivity analysis of the theoretical model of a CR-39-based direct 222Rn/220Rn progeny monitor

Abstract The deposition-based direct indoor 222Rn and 220Rn progeny measurement techniques are mostly affected by the indoor environmental conditions, such as the ventilation, concentration of condensation nuclei, and reactions with the structure and its furnishings. In this study, a theoretical model of a direct 222Rn and 220Rn progeny monitor based on allyl diglycol carbonate (ADC or CR-39) was established to analyse the factors that influence the detection process by using the parameter sensitivity analysis. The aerosol parameters contributed the highest to the variance, followed by the aerodynamic parameters. With respect to the result of the Spearman’s correlation analysis, the aerosol-related and the room-related parameters are positive, whereas the aerodynamic parameters – which affect the turbulence of indoor deposition – are negative. It means that both the attachment process and the deposition process of 222Rn and 220Rn progenies are important to the performance of the progeny monitor.

Indoor and outdoor 222Rn and 220Rn and their progeny levels surrounding Bayan Obo mine, China

Abstract More than half of the total natural ionizing radiation dose received by the human population is caused by radon and thoron (Rn and Tn) and their progeny. To estimate the level of radiation due to radon and thoron and their progeny, an investigation was conducted in a residential area near the world’s largest open-pit mine of Bayan Obo in Inner Mongolia, China. The concentration of Rn, Tn, and their decay products in air and soil were studied by using AlphaGUARD, RAD7, and ERS-RDM-2S for a discrete period of time in three different locations. The average indoor concentration of radon and thoron was 62.6 ± 44.6 Bq/m3 and 108.3 ± 94.5 Bq/m3 respectively, and the outdoor concentration was 12.9 ± 6.3 Bq/m3 and 55.8 ± 18.5 Bq/m3, respectively. Relatively high concentrations were recorded in the area near to the mine, with a significant increasing trend observed in indoor thoron concentration. A prominent hotspot in thoron concentration was found in a single-story house with values 747 ± 150 Bq/m3. The equilibrium equivalent thoron concentration (EECTn) varies from 0.48 Bq/m3 to 2.36 Bq/m3 with an arithmetic mean of 1.37 ± 0.64 Bq/m3, and comparatively higher than EECRn. Concluding that the mining activity at Bayan Obo mine is significantly increasing the level of indoor thoron and its progeny in surroundings. It is suggested to further systematically investigate the indoor Rn and Tn progeny concentrations in the residential dwellings of the Bayan Obo mining area, and 232Th content of the building materials, to provide a basis for calculating the radiation dose.

Excessive radon-based radiation in indoor air caused by soil building materials in traditional homes on Đồng Văn karst plateau, northern Vietnam

Radon-based radiation from natural soil building materials is an important factor likely influencing residents’ health as a contributing source of natural radiation. This survey aims to quantify the nuclide-specific α-radiation of isotopes 222Rn and 220Rn in common types of houses in a region of northern Vietnam, Đồng Văn karst plateau, to preliminarily (i) evaluate the total annual effective dose rates and (ii) assess the relative risk of cancer induction from indoor α-radiation for inhabitants. The average 222Rn concentrations in all house types were lower than 100 Bq m−3, but 220Rn abundances were far higher than 222Rn, even up to >1000 Bq m−3 in air close to a wall of unfired-soil bricks. The estimated total annual effective dose rates from indoor 222Rn and 220Rn and their progenies to residents with daily exposure of 13 h in the various types of houses range from 3.1 to 4.3 mSv a−1 for houses constructed with modified materials, but up to higher than 6 mSv a−1 in houses with raw building materials. The average risk of developing lung cancer as a consequence of a lifetime exposure to indoor α-radiation in affected homes ranges from 3.9% to 14.6%. 220Rn and its metallic progenies contribute more than 80% of the total average lung cancer risk from total radon, being responsible for a range of 2.7–14.6% of the risk of developing lung cancer.

Is there a genomic fingerprint of Radon (Rn)-induced lung cancer (LC)? Comparison of genomic alterations in LC specimens from high and low Rn zones.

1572 Background: Rn-222 is a radioactive gas found in rocks and soil. It emits alpha particles that cause dsDNA breaks and increase potential for carcinogenesis. Rn is the 2nd leading cause of LC in the US after smoking. EPA estimates >15,000 deaths/yr (9% of LC deaths) from Rn. We hypothesize that the impact of Rn exposure may be reflected in LC gene mutation (mut) profiles. Methods: Using commercial NGS assays, we retrospectively analyzed genomic DNA alterations in FFPE specimens from 159 LC patients (pts) from the Lifespan Cancer Institute in Rhode Island (2014- 2019), followed by validation in a larger cohort of 5,532 pts using Caris platform. Based on EPA Rn maps, we identified counties with high indoor Rn levels (>4 pci/L; HR), and compared gene mut patterns with those from low Rn zones (<4 pci/L; LR). Based on pt’s zip code of residence, we categorized them to HR and LR. In the validation cohort, p values adjusted for multiple comparison (q) of < .05 were considered significant. Results: In the pilot cohort, 35 pts (22%) were in HR and 124 (78%) in LR zones. Adenocarcinoma histology was most frequent (73%) and smoking prevalence was high (75%) in both groups. Most prevalent alterations were TP53, KRAS and CDKN2A muts. In the HR, we noted more frequent recurrent muts in 2 DNA repair genes (DDR): ATM (11 vs 1%, p= .00086) and CHEK2 (6 vs 0%, p= .047) when compared to LR group. When classified into major pathways implicated in lung carcinogenesis, higher frequency of mutations were seen in DDR in HR zones vs. LR (29 vs 13%, p= .038). In the validation cohort, 1,433 (26%) pts were in HR and 4099 (74%) in LR zones. Among the DDR genes, ATM muts in HR group tended to be more frequent (4.7 vs 3.4% in LR, p= .03) as well as PALB2 (0.9 vs 0.4%, p= .02) while no difference seen in CHEK2. Other genes with significantly higher prevalence in HR were TP53, SMARCA4 and NFE2L2 (q< .05); while KMT2D, KEAP1, CDKN2A, MET, NF2, DNMT3A, CCND1 and FAS show a trend (p< .05). EGFR muts were significantly more frequent in LR zones (8.4 vs 14.6%, q= .001). Similar to the pilot cohort, DDR pathway alterations trend to be higher in HR zones (14 vs 12%, p= .05). Using a high TMB cut-off >10, tumors from HR zones had significantly higher TMB when compared to LR zones (56 vs 48%, q= .0005). Conclusions: To our knowledge, this is the first attempt to elucidate the pathobiology of Rn induced LC using gene mut analyses. Our observations suggest that LC associated with higher Rn exposure may have disabled DNA repair pathways and higher TMB. Assuming uniform tobacco smoke exposure, higher Rn was not associated with EGFR mut.

THE INDOOR RADON AND THORON CONCENTRATIONS IN SCHOOLS OF SKOPJE (REPUBLIC OF NORTH MACEDONIA) AND BANJA LUKA (REPUBLIC OF SRPSKA) CITIES MEASURED BY RADUET DETECTORS

Radon (222Rn) and thoron (220Rn) are natural radioactive gases, generated in the terrestrial materials. They are the main sources of public exposure to ionising radiation in any of indoor environment worldwide. Differences in half-lives of 222Rn (T1/2 = 3.8 d) and 220Rn (T1/2 = 55.6 s) lead to its different indoor behavior. Several studies of indoor 222Rn and 220Rn in Northern Macedonia have been performed, starting with measurements in dwellings in 2008 and continuing with measurements in schools during 2012. The surveys in the Republic of Srpska began later (in 2011) with the simultaneous 222Rn and 220Rn measurements in the dwellings and schools of Banja Luka cities. This paper, as a result of our cooperation, summarizes the results and general conclusions obtained from 222Rn and 220Rn measurements in schools of capitals. In both cities, the measurements were made using Raduet - nuclear track detectors; deployed at distances: >0.5m (Skopje) and 0.2m (Banja Luka); and exposed in a period: March 2012 - May 2012 (Skopje) and April 2011 - May 2012 (Banja Luka). Results for 222Rn and 220Rn concentrations in both cities have a log-normal distribution. The 222Rn geometric mean value of 71 Bq/m3 in Skopje is higher than in Banja Luka city (GM = 50 Bq/m3). Among different radon potential in the cities, this difference could be related to the different exposure time of detectors. Furthermore, the dispersion of the 222Rn results in each city expressed through geometric standard deviation is relatively low: GSD = 2.13 (Skopje) and GSD = 2.11 (Banja Luka) indicating relatively homogeneous data sets. The 220Rn concentrations in Banja Luka (GM = 51 Bq/m3) were higher than in Skopje (GM = 11 Bq/m3). It is obvious that in the case of 220Rn, the exposure period did not play a significant role. One of the reasons for this difference could be the position of the detectors as well as the different building materials in the schools. On the contrary, the dispersion of the 220Rn results in Skopje (GSD = 3.38) was greater than in Banja Luka (GSD = 2.07).