西藏居室内氡浓度调查及所致居民剂量估算

目的 在国内城市室内氡呈上升趋势的背景下,为了获取现阶段西藏地区室内氡浓度水平,开展本次西藏地区室内氡浓度调查工作。方法 采用KF606B型固体核径迹氡累积探测器,对西藏自治区居室氡浓度进行测量,测量周期6～12个月。结果 西藏地区138间居室内氡浓度范围为14～119 Bq·m^-3,均值为（47.8 ±23.0） Bq·m^-3。氡浓度大于100 Bq·m^-3房间有5个,占总调查房间数的4%。居室内氡所致西藏地区居民有效剂量范围为0.46～3.89 mSv·a^-1,均值为1.56 mSv·a^-1。文章还对不同调查地区、城镇/农村、不同建筑类型和不同建筑年代居室内氡浓度进行了比较分析。结论 本次居室内氡浓度调查结果比上世纪八九十年代西藏地区测量结果有显著增高。     

Population dose due to natural radiation in Hong Kong

In densely populated cities such as Hong Kong where people live and work in high-rise buildings that are all built with concrete, the indoor gamma dose rate and indoor radon concentration are not wide ranging. Indoor gamma dose rates (including cosmic rays) follow a normal distribution with an arithmetic mean of 0.22 +/- 0.04 microGy h(-1), whereas indoor radon concentrations follow a log-normal distribution with geometric means of 48 +/- 2 Bq m(-3) and 90 +/- 2 Bq m(-3) for the two main categories of buildings: residential and non-residential. Since different occupations result in different occupancy in different categories of buildings, the annual total dose [indoor and outdoor radon effective dose + indoor and outdoor gamma absorbed dose (including cosmic ray)] to the population in Hong Kong was estimated based on the number of people for each occupation; the occupancy of each occupation; indoor radon concentration distribution and indoor gamma dose rate distribution for each category of buildings; outdoor radon concentration and gamma dose rate; and indoor and outdoor cosmic ray dose rates. The result shows that the annual doses for every occupation follow a log-normal distribution. This is expected since the total dose is dominated by radon effective dose, which has a log-normal distribution. The annual dose to the population of Hong Kong is characterized by a log-normal distribution with a geometric mean of 2.4 mSv and a geometric standard deviation of 1.3 mSv.     

Exposure to benzene and urinary concentrations of 8-hydroxydeoxyguanosine, a biological marker of oxidative damage to DNA.

OBJECTIVES--Benzene is an established animal and human carcinogen. The mechanism of benzene toxicity, particularly its leukaemogenic effect, is not fully understood. The modified base 8-hydroxy-deoxyguanosine (8-OHdG) is a sensitive marker of the DNA damage due to hydroxyl radical attack at the C8 of guanine. This damage, if left unrepaired, has been proposed to contribute to mutagenicity and cancer promotion. We conducted this biomonitoring study with the aim of evaluating the association between excretion of 8-OHdG and level of exposure to benzene and other aromatic compounds among occupationally exposed people. METHODS--A random sample of 65 filling station attendants from Rome, Italy was studied for personal exposure to benzene, toluene, and xylenes, and excretion of 8-OHdG. Information about age, length of employment, smoking habits, and diagnostic exposure to x rays was collected by questionnaire. An average yearly level of exposure to benzene and methylbenzenes was calculated for each filling station attendant on the basis of about seven repeated personal samples collected during one year. A spot sample of 20 ml of urine was collected from each worker. Concentrations of 8-OHdG were determined by high performance liquid chromatography (HPLC) with coupled columns. RESULTS--A mean (SD) concentration of 1.36 (0.49) mumol of 8-OHdG/mol of creatinine was measured. A significant correlation was found between urinary 8-OHdG and exposure to benzene (r = 0.34). In a multiple regression analysis relating the concentration of urinary 8-OHdG with the age, length of employment, smoking, diagnostic exposure to x rays and personal exposure to benzene, an increase of 0.15 mumol/mol creatinine in urinary 8-OHdG/unit increase in the natural logarithm of the average yearly benzene concentration was estimated. CONCLUSION--This study shows a dose-response effect between personal exposure to benzene and urinary 8-OHdG concentration; further studies are needed to clarify the biological significance of 8-OHdG as a marker of cancer risk.     

Anomalously high radon concentrations in dwellings located on permeable glacial sediments.

Indoor radon concentrations were measured in different seasons in 104 dwellings located on a highly permeable ice-marginal moraine in Kinsarvik, Western Norway. The measurements revealed the highest indoor radon levels ever detected in Norway and extreme variations in seasonal and short-term indoor radon levels. Annual average indoor radon concentrations up to 56 000 Bq m(-3) and a mean value of 4340 Bq m(-3) for the whole residential area are reported. By using the ICRP conversion factors to effective dose, these indoor radon values correspond to a total annual effective dose of 930 mSv and 72 mSv, respectively. By using the conversion as recommended by UNSCEAR, the effective doses would be about 50% higher. The indoor radon concentrations are found to be strongly influenced by thermally induced flows of radon-bearing soil air directed towards the upper part of the ice-marginal deposit in winter and towards the area of lowest elevation in summer. The pattern of seasonal variations observed suggests that in areas where thermal convection may occur, annual average indoor radon levels should be derived from measurements performed both in summer and in winter.     

Study of radon concentrations in oil refinery premises and city dwellings.

Radon and its progeny concentrations were measured in several dwellings at an oil refinery premises and these concentrations were compared with those found in dwellings in Mathura and Agra cities. Radon progeny concentrations were measured using LR-115 type II nuclear track etch detectors. The radon concentrations were estimated by using a value of 0.42 for the equilibrium factor. The geometric means (GM) of radon concentrations in the refinery dwellings, Mathura city and Agra city dwellings were 97, 91 and 75 Bq m(-3) with geometric standard deviations of 1.7, 1.8 and 1.8 respectively. The average lifetime risk of lung cancer for an adjusted annual average chronic radon exposure of 69 Bq m(-3) (7.8 mWL; WL = working level) with an occupancy factor of 0.7 comes out to be 5.4 x 10(-3).     

A survey of 222Rn concentrations in dwellings of the town of Metsovo in north-western Greece

A radon survey has been carried out of indoor radon concentrations in dwellings located in the town of Metsovo, in north-western Greece. To measure indoor radon concentrations, CR-39 detectors were installed in randomly selected houses and were exposed for about 3 mo, during summer and winter. Gamma spectroscopy measurements of the soil's radium content also were performed. The indoor radon concentration levels varied from 17.6 to 750.4 Bq m(-3), while the radium concentration of soil varied from 4.9 to 97.1 Bq m(-3). Seasonal variation of the radon levels and the influence of house features and soil are discussed.     

Indoor radon determination in dwellings located at Dikili geothermal area in Western Turkey

This paper presents the indoor radon concentrations in dwellings located in the Dikili geothermal area in western Turkey. Indoor radon monitoring was performed for 3 mo using 121 detectors installed in the living rooms and bedrooms of 62 houses selected from the region. A passive time-integrating radon measuring technique was applied by using CR-39 solid-state nuclear track detectors. Average indoor radon levels for the houses varied from 31 to 280 Bq m(-3). Corresponding annual effective doses were calculated, and risks for lung cancer due to inhalation of indoor radon were estimated.     

The stability of the oxidative stress marker, urinary 8-hydroxy-2'- deoxyguanosine (8-OHdG), when stored at room temperature

We examined the stabilities of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) stored at room temperature (25 degrees C) for 24 h or at -80 degrees C for 800 days. Subjects were 19 males and 17 females aged 23-58 yr for the 24-h study, and 9 males and 4 females aged 24-54 yr for the 800-day study. We obtained information on the subjects by questionnaires and interviews. The level of urinary 8-OHdG was measured by HPLC using two-step separations. There were no significant changes of amount of urinary 8-OHdG under either storage conditions. We conclude that urine samples can be stored at 25 degrees C and below for 24 h, when the research purpose includes the determination of urinary 8-OHdG. Urinary 8-OHdG was also stable for over two years when stored at -80 degrees C.     

8-Hydroxydeoxyguanosine levels in human leukocyte and urine according to exposure to organophosphorus pesticides and paraoxonase 1 genotype

Objective In order to investigate a role of paraoxonase 1 (PON1) polymorphism in organophosphorus (OP)-induced 8-hydroxydeoxyguanosine (8-OHdG) levels, urinary metabolites of OP, PON1 genotypes, and 8-OHdG levels in leukocyte and urine were measured in OP indoor insecticide sprayers and controls in summer and winter. Methods The study population contained 18 male sprayers and age-matched 18 male controls. Sprayers were primarily exposed to OP insecticides (mainly fenitrothion, dichlorvos, chlorpyrifos, and diazinon), and partially to pyrethroids (mainly permethrin) and carbamates (mainly propoxur). Urinary metabolites of OP were measured by gas chromatography-mass spectrometry. 8-OHdG levels in leukocyte and urine were measured by ELISA kit. PON1 genotype was identified using allele-specific fluorogenic TaqMan probes. Results The mean concentrations of urinary dimethyl phosphate (DMP) and total dialkyl phosphates (DAP) in summer and those of 8-OHdG in summer and winter were significantly higher in OP sprayers than controls. This resulted in a significant positive correlation between 8-OHdG levels and urinary DMP or DAP, suggesting a correlation between OP metabolites and production of oxidative stress. Of PON1 genotypes, incidences of Q/Q, Q/R, and R/R types were 17, 39, and 44% in OP sprayers and controls, respectively. Although PON1 polymorphism did not contribute to the leukocyte and urinary 8-OHdG levels, the urinary OP metabolite concentrations in summer showed a significant decrease as the number Q allele decreased. Conclusion These results indicate that an increase in OP metabolites is associated with a high level of oxidative stress in OP sprayers, although the contribution of the PON1 polymorphism to the metabolism of OP is still unclear.     

Adult myeloid leukaemia, geology, and domestic exposure to radon and gamma radiation: a case control study in central Italy

OBJECTIVES: To investigate whether indoor randon or gamma radiation might play a part in myeloid leukaemia as suggested by studies based on crude geographical or geological data for exposure assessment. METHODS: For six months randon and gamma radiation was measured with solid state nuclear track detectors and thermoluminescent dosimeters in dwellings of 44 adult male cases of acute myeloid leukaemia and 211 controls (all subjects deceased). Conditional logistic regression ORs (ORs) and 95% confidence intervals (95% CIs) were estimated for quartiles of radon and gamma radiation and for municipality and dwelling characteristics. RESULTS: The risk of leukaemia was associated with an increasing urbanisation index (p value for trend = 0.008). An increased OR was found among those living in more modern houses (OR 3.0, 95% CI 1.4 to 6.6). Confirming the findings of a previous study in the same area, geological features bore a positive association with myeloid leukemia, even by adjusting for level of urbanisation. Contrary to expectations from the previous study, however, no association appeared between myeloid leukaemia and radon and gamma radiation; for the highest quartiles of exposure, ORs were 0.56 (95% CI 0.2 to 1.4) and 0.52 (95% CI 0.2 to 1.4), respectively. Considering only subjects who had lived > or = 20 years in the monitored home and adjusting for urbanisation, there was still no effect of exposure to radiation. CONCLUSIONS: In view of the limited numbers, the results do not in general refute a possible risk of myeloid leukaemia from exposure to indoor radon or gamma radiation, but decrease the credibility of such a relation in the area studied and also of other studies suggesting an effect without monitoring indoor radiation. Some other fairly strong determinants have appeared--that is, level of urbanisation and living in modern houses-- that might need further consideration.

 

     

焦炉工人血清谷胱甘肽硫转移酶活力和尿8-羟基脱氧鸟苷水平

目的 探讨血清谷胱甘肽硫转移酶（GST）和尿8-羟基脱氧鸟苷（8-OHdG）作为焦炉工人多环芳烃（PAHs）暴露生物监测标志的可行性.方法 用高效液相色谱-电化学方法和试剂盒分别检测47名男性焦炉工和31名男性对照者尿8-OHdG水平和血清GST活力;尿1-羟基芘（1-OHP）作为PAHs接触的内暴露标志,采用碱水解-高效液相色谱方法分析.结果 焦炉工人尿1-OHP浓度的中位数（P25～P75）为[5.7（1.4～12.0）μmol/mol Cr],血清GST活力为[22.1（14.9～31.2）U/ml],尿8-O-HdG水平为[1.9（1.4～15.4）μmol/mol Cr],均高于对照组工人[3.0（0.5～6.4）μmol/mol Cr、13.1（9.5～16.7）U/ml、1.3（1.0～4.0）μmol/mol Cr],差异均有统计学意义（P＜0.05或P＜0.01）.以吸烟分层,两组工人尿1-OHP浓度和血清GST活力仅在吸烟者中、尿8-OHdG水平仅在非吸烟者中差异有统计学意义（均P＜0.01）.焦炉工人血清GST活力和尿1-OHP浓度呈正相关（rs=0.31,P＜0.01,n=78）.多元Logistic回归分析显示,与对照工人相比,焦炉工人血清GST活力＞16.7 U/ml和尿8-OHdG水平＞1.8 μmol/mol Cr的OR值分别为13.2和4.4;高体重指数是影响尿8-OHdG水平下降的独立因素.结论 焦炉工人血清GST活力增强和氧化性DNA损伤增加,吸烟和职业暴露有交互作用;血清GST有可能作为PAHs暴露评价的生物标志;尿8-OHdG检测有助于焦炉工肺癌危险度评价.     

Association between nitric oxide and 8-hydroxydeoxyguanosine levels in semen of diabetic men

The incidence of diabetes mellitus is rapidly increasing in the world. One of the complications of diabetes includes disturbance of the reproductive tract, such as infertility, erectile dysfunction, and endocrine disruption. Nitric oxide (NO) is a free radical produced by most cells including the human male and female reproductive tracts. NO has a dual role where low concentrations are essential for homeostatic cellular biology and physiology, but high levels have detrimental effects relating to cellular damage from this reactive oxygen species (ROS). 8-hydroxydeoxyguanosine (8-OHdG) is an oxidized nucleoside of DNA that is currently used as a biomarker of cellular oxidative stress, where urinary levels can correlate with diabetic nephropathy and retinopathy. Our aim was to investigate the relationship between nitrate/nitrite levels and 8-OHdG levels in the semen of diabetic and non-diabetic men. Concentrations of nitrate/nitrite and 8-OHdG were examined in seminal plasma of 32 diabetic and 35 non-diabetic men. The level of nitrate/nitrite was assayed by colorimetric reaction and 8-OHdG was measured by ELISA. Our results showed that the seminal plasma nitrate/nitrite levels were significantly higher in the diabetic group (p?相似文献   

Oxidative DNA damage estimated by urinary 8-hydroxydeoxyguanosine and indoor air pollution among non-smoking office employees

This study investigated whether urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative stress, was associated with indoor air quality for non-smokers in high-rise building offices. With informed consents, urine samples from 344 non-smoking employees in 86 offices were collected to determine 8-OHdG concentrations. The concentrations of carbon dioxide (CO(2)) and total volatile organic compounds (TVOCs) in each office and outside of the building were simultaneously measured for eight office hours. The average workday difference between indoor and outdoor CO(2) concentrations (dCO(2)) was used as a surrogate measure of the ventilation efficiency for each office unit. The CO(2) levels in the offices ranged 467-2810ppm with a mean of 1170ppm, or 2.7 times higher than that in the outside air. The average urinary 8-OHdG levels among employees increased from 3.10 micro g/g creatinine, for those at the lowest tertile levels of both dCO(2) and TVOCs, to 6.27 micro g/g creatinine, for those at the highest tertile levels. Multivariate logistic regression analysis showed that the risk of having the urinary 8-OHdG level of greater than the median, 4.53 micro g/g creatinine, for participants was increased significantly at the highest tertile dCO(2) level of >680ppm (odds ratio (OR)=3.37, 95% confidence interval (CI)=1.20-9.46). The effect was significant at the middle tertile TVOCs level of 114-360ppb (OR=2.62, 95% CI=1.43-4.79), but not at the highest tertile. Inadequate ventilation in office increases the risk of building-related oxidative stress in non-smoking employees.     

Indoor radon in Kuwait

Indoor radon measurements were carried out in 300 dwellings in Kuwait using duplicate sets of charcoal detectors. Measurements were made at three different locations in the dwellings: living rooms, bedrooms, and basements. The results show that the radon concentration in the dwellings of Kuwait was found to vary in the range of 4.0-241.8 Bq m(-3) with a mean value of 32.8 Bq m(-3), and most values are confined within the range of 10-50 Bq m(-3) for all locations with few cases above the value of 100 Bq m(-3). Overall results show that the indoor radon concentration levels in Kuwait are relatively low, which is attributed to the use of air conditioning in summer and possible natural ventilation in winter. The radon concentration in basements was found to be relatively higher when compared to other rooms of the dwellings.     

Association of urinary 8-OHdG with lifestyle and body composition in elderly natural disaster victims living in emergency temporary housing

Objectives

Residents who lost land and houses due to disasterous heavy rainfall-related events on July 13, 2004 and the Chuetsu Earthquake on October 23, 2004 were moved to emergency temporary housing. The change in life style due to living under such conditions is assumed to increase oxidative stress level. In this study, we investigated the oxidative stress level in elderly residents of emergency temporary housing, and analyzed its association with lifestyle and body composition following these disasters.

Methods

A noninvasive oxidative stress marker, urinary 8-hydroxydeoxyguanosine (8-OHdG), and body composition were measured in 73 elderly residents of emergency temporary housing.

Results

In the elderly female residents, the urinary 8-OHdG level tended to decrease with time after the disasters. 8-OHdG levels were slightly higher in females than males and significantly higher among those who exercised regularly compared to those who did not, particularly in females. A weak correlation was noted between the urinary 8-OHdG level and muscle ratio in females.

Conclusions

The in vivo oxidative stress level in our study cohort of elderly residents of emergency temporary housing changed following the change in life style, but remained within the normal range. The increase in oxidative stress levels of elderly females was related to menopause. A decrease in estrogen levels due to menopause inhibits its antioxidant effects, which increases 8-OHdG levels. Although it is difficult to determine, a decrease in daily stressors over time following the disaster could be a cause of the decrease in oxidative stress levels. We suggest that the close evaluation of the stress level of disaster victims is desirable, in combination with evidence of antioxidative substances and the psychosocial influence of suffering as a consequence of the disaster.     

烹调油烟多环芳烃暴露与职业接触人群DNA氧化性损伤

目的 通过调查不同组别厨师和非暴露组尿中8-羟基脱氧鸟苷(8-OHdG)的排泄量,研究8-OHdG和1-羟基芘(1-OHP)之间的关系.方法 采集不同组别厨师组(n=86)和非暴露对照组(n=36)的尿液样本,观察对象均为年龄22～28岁男性,并有相似的吸烟习惯.在采样之前24 h内,以问卷调查的形式对研究对象的身体健康状况、职业史、吸烟习惯和酒精消费量进行评估.冷藏尿液样本,随后通过高效液相色谱法分析8-OHdG和1-OHP水平.结果 对照组尿液中8-OHdG的排泄量(平均1.2μmo1/mol肌酐,n=36)与厨房里有排烟设备运转的厨师组相似(平均1.5 μmol/mol肌酐,n=45).与对照组相比,接触油烟而排烟设备没有运转的厨师组,其尿8-OHdG的排泄量明显增加(平均2.3 μmol/mol 肌酐,n=18).经多元回归分析,尿ln 1-OHP和ln 8-OHdG的水平仍然呈明显的正相关.结论 接触油烟中的多环芳烃(PAH)或其他化合物可能导致DNA氧化损伤.     

Association between nitric oxide and 8-hydroxydeoxyguanosine levels in semen of diabetic men

The incidence of diabetes mellitus is rapidly increasing in the world. One of the complications of diabetes includes disturbance of the reproductive tract, such as infertility, erectile dysfunction, and endocrine disruption. Nitric oxide (NO) is a free radical produced by most cells including the human male and female reproductive tracts. NO has a dual role where low concentrations are essential for homeostatic cellular biology and physiology, but high levels have detrimental effects relating to cellular damage from this reactive oxygen species (ROS). 8-hydroxydeoxyguanosine (8-OHdG) is an oxidized nucleoside of DNA that is currently used as a biomarker of cellular oxidative stress, where urinary levels can correlate with diabetic nephropathy and retinopathy. Our aim was to investigate the relationship between nitrate/nitrite levels and 8-OHdG levels in the semen of diabetic and non-diabetic men. Concentrations of nitrate/nitrite and 8-OHdG were examined in seminal plasma of 32 diabetic and 35 non-diabetic men. The level of nitrate/nitrite was assayed by colorimetric reaction and 8-OHdG was measured by ELISA. Our results showed that the seminal plasma nitrate/nitrite levels were significantly higher in the diabetic group (p?<?0. 01). There were also significantly higher 8-OHdG levels in diabetic men compared to non-diabetic men (p?<?0.05). Regression analysis indicated that in diabetic men, nitrate/nitrite levels correlated well with 8-OHdG levels (r?=?0.64, p?<?0.001). A significant trend between nitrate/nitrite and sperm parameters was not observed. Our data suggests that high levels of nitrate/nitrite in the semen of diabetic men is suggestive of reactive oxygen species induced DNA damage that is correlated with 8-OHdG levels but not sperm parameters. These results support the further investigation of NO and 8-OHdG as biomarkers for assessing male infertility.     

Moderate alcohol consumption reduces urinary 8-hydroxydeoxyguanosine by inducing of uric acid.

Recent studies suggest that moderate alcohol consumption is associated with a low risk of cancer, coronary heart disease, and other diseases. Most of these diseases are considered to be related to the action of reactive oxygen species (ROS) at certain stages of disease progression. However, considerable evidence exists indicating that ethanol generates ROS in vivo. Thus, the reduced risk of disease as a result of alcohol consumption seems to contradict evidence suggesting the induction of ROS by ethanol. In the present study, we investigated whether oxidative stress was induced in moderate alcohol drinkers. We measured the total urinary biopyrrins and 8-hydroxydeoxyguanosine (8-OHdG) levels as a systemic oxidative stress marker and an oxidative DNA damage marker, respectively. Serum uric acid was also measured as an alcohol-induced antioxidant. We compared total urinary biopyrrins and 8-OHdG levels among groups with different alcohol habits. The results showed that total biopyrrins levels increased with the amount of alcohol consumed, but that the level of 8-OHdG significantly decreased with the amount of alcohol consumed. The decrease in 8-OHdG levels seemed to be associated with increasing levels of uric acid. Judging from the increasing level of total biopyrrins, alcohol may induce ROS. ROS may then cause cell damage in liver, as suggested by the positive correlation between the total biopyrrins levels and the serum GOT, GPT, and gammaGTP levels. However, since ROS may be more effectively counteracted by uric acid in organs other than the liver, DNA damage may be suppressed rather than induced. Accordingly, moderate alcohol consumption seems to have the overall effect of reducing DNA damage, as shown by the decrease in urinary 8-OHdG levels observed in our study.     

Childhood leukemia incidence and exposure to indoor radon, terrestrial and cosmic gamma radiation

This study was undertaken to evaluate the ecological association between terrestrial and cosmic gamma radiation, indoor radon, and acute leukemia incidence among children under 15 y of age. From 1990 to 2001, 5,330 cases of acute leukemia were registered by the French National Registry of Childhood Leukemia and Lymphoma. Exposure to terrestrial gamma radiation was based on measurements, using thermoluminescent dosimeters, at about 1,000 sites covering all the "Départements." In addition, 8,737 indoor terrestrial gamma dose rate measurements covering 62% of the "Départements" and 13,240 indoor radon concentration measurements covering all the "Départements" were made during a national campaign. Cosmic ray doses were estimated in each of the 36,363 "Communes" of France. There was no evidence of an ecological association between terrestrial gamma dose (range: 0.22-0.90 mSv y) or total gamma dose (range: 0.49-1.28 mSv y) and childhood acute leukemia incidence, for acute myeloid leukemia (AML) or for acute lymphoblastic leukemia (ALL), in univariate or multivariate regression analyses including indoor radon. A significant positive association between indoor radon (range: 22-262 Bq m) and AML incidence among children was observed and remained significant in multivariate regression analyses including either terrestrial gamma dose [SIR per 100 Bq m = 1.29 (1.09-1.53)] or total gamma dose [SIR per 100 Bq m = 1.29 (1.09-1.53)]. The study showed no ecological association between terrestrial gamma radiation and childhood leukemia for the range of variation in gamma dose rates observed in France. The moderate ecological association between childhood AML incidence and indoor radon does not appear to be confounded by terrestrial gamma dose.     

Seasonal variation in indoor radon concentrations in dwellings in six districts of the Punjab province, Pakistan

An indoor radon measurement survey has been carried out in six districts of the Punjab province. These included Gujranwala, Gujrat, Hafizabad, Sialkot, Narowal and Mandibahauddin districts. In each district, 40 representative houses were chosen and indoor radon levels were measured in these dwellings in autumn, winter, spring and summer seasons using CR-39 based NRPB radon dosimeters. After exposure to radon, the CR-39 detectors were etched in 25% NaOH at 80 degrees C and track densities were related to radon concentration levels. From the observed data, average radon concentration levels and a seasonal correction factor were calculated. The average 222Rn concentration level was found to vary from 40 +/- 15 to 160 +/- 32 Bq m(-3) and 38 +/- 17 to 141 +/- 26 Bq m(-3) in the bedrooms and living rooms of the houses surveyed, respectively. The annual mean effective dose received by the occupants has been calculated using ICRP (1993 Ann. ICRP 23) and UNSCEAR (2000 Sources and Effects of Ionizing Radiation (New York: United Nations)); it varied from 1.2 to 1.7 mSv and from 1.8 to 2.4 mSv, respectively.