Gejiu City Research Articles

Quantitative Analysis of Soil Cd Content Based on the Fusion of Vis-NIR and XRF Spectral Data in the Impacted Area of a Metallurgical Slag Site in Gejiu, Yunnan

Vis-NIR and XRF spectroscopy are widely used in monitoring heavy metals in soil due to their advantages of being fast, non-destructive, cost-effective, and non-polluting. However, when used individually, XRF and vis-NIR may not meet the accuracy requirements for Cd determination. In this study, we focused on the impact area of a non-ferrous metal smelting slag site in Gejiu City, Yunnan Province, fused the pre-selected vis-NIR and XRF spectra using the Pearson correlation coefficient (PCC), and identified the characteristic spectra using the competitive adaptive reweighted sampling (CARS) method. Based on this, a quantitative model for soil Cd concentration was established using partial least squares regression (PLSR). The results showed that among the four fusion spectral quantitative models constructed, the model combining vis-NIR spectral second-order derivative transformation and XRF spectral first-order derivative transformation (D2(vis-NIR) + D1(XRF)) had the highest coefficient of determination (R2 = 0.9505) and the smallest root mean square error (RMSE = 0.1174). Compared to the estimation models built using vis-NIR and XRF spectra alone, the average computational time of the fusion models was reduced by 68.19% and 63.92%, respectively. This study provides important technical means for real-time and large-scale on-site rapid estimation of Cd content using multi-source spectral fusion.

Application of Opposing Coils Transient Electromagnetics in Mine Roadway Prospecting in Gejiu City

Application of Opposing Coils Transient Electromagnetics in Mine Roadway Prospecting in Gejiu City

Phytoremediation potential of indigenous plants growing in soils affected by mine activities in Gejiu City, Yunnan Province

Indigenous plants growing in mining spoils for phytoremediation have attracted great interest. To search the suitable plants, six plant species popular in the mine slag heaps of Gejiu City were collected and metal concentrations in plants and rhizosphere soils were analyzed. Results showed that the soils were greatly influenced by mine activities and heavy metal contents in plants were dependent upon those in the rhizosphere soils. However, the adaptation strategies varied among them. Bothriochloa ischcemum (Linn.) Keng and Equisetum ramosissimum Desf. had the Cr bioaccumulation factor (BAF) of 1.48 and 1.34, respectively, even though the rhizosphere soils were not contaminated by Cr. However, B. ischaemum and Agave americana Linn. showed the BAF for Pb, Zn Cu and Sn < 1.0, and Cyperus rotundus Linn. showed the similarly low BAF for Zn and Cu. Therefore, the three species had a great tolerance to phytostabilize these metals. Gymnema sylvestre (Retz.) Schult showed the translocation factor (TF) > 1.0 for Pb, Cu and Sn, so translocating these metals to the aboveground parts would be a feasible option. Similarly, Euphorbia cyathophora Murr. demonstrated the high phytotranslocate capacity for Cd and Sn, so it could be employed to remedy Cd and Sn-contaminated soils.

The field survey and deformation characteristics of exit slope of Qingshuigou tunnel in the southwest of China

The stability of the slope under excavation in various engineering is a hot issue, and both engineering disturbances and other internal factors have contributed to the instability of the slope. The study focused on the deformation characteristics mechanism of exit slope of Qingshuigou tunnel in Jiasha Town, Gejiu City, Honghe Prefecture, Yunnan, China. Field survey and monitoring are performed to reveal deformation mechanism of the exit slope, which is associated with hydrogeologic conditions, natural weathering, and excavation activities. The exit slope at the interface of the overburdened layer and bedrock has the possibility of landslide through the joint force of rainfall and artificial construction. According to the deformation characteristics of the exit slope and monitoring analysis, the results indicate that the surface displacement at the back scarp of the exit slope is larger than that at the head scarp of the exit slope. The deep displacement at the back scarp is 2–4 times of that at the head scarp of the slope. Based on the geophysical analysis, the overburdened layer mostly has low resistivity. The deformation mechanism of the exit slope is revealed ultimately based on the combined influences of hydrogeologic conditions, natural weathering, and excavation activities. Based on the deformation characteristics and mechanism of the exit slope, comprehensive stabilization treatment measures are proposed to prevent the exit slope from further deformation.

Propioniciclava soli sp. nov., isolated from forest soil, Yunnan, China, and reclassification of the genus Brevilactibacter into the genus Propioniciclava, and Brevilactibacter sinopodophylli, Brevilactibacter flavus, and Brevilactibacter coleopterorum as Propioniciclava sinopodophylli comb. nov., Propioniciclava flava comb. nov., and Propioniciclava coleopterorum comb. nov., respectively.

A Gram-stain-positive, coccus-shaped, facultatively anaerobic, non-motile bacterial strain, designated YIM S02567T, was isolated from a forest soil sample collected from Gejiu City, Yunnan Province, southwest PR China. Growth was observed at 10-45°C, at pH 6.0-9.5, in the presence of up to 4.0% (w/v) NaCl on R2A medium. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM S02567T was most closely related to the type strain of Brevilactibacter sinopodophylli (95.4%) and Propioniciclava tarda (94.7%), and phylogenetic analysis based on genome data showed that strain YIM S02567T should be assigned to the genus Propioniciclava. The cell-wall diamino acid was meso-diaminopimelic acid. The major cellular fatty acids were identified as anteiso-C15:0 and C16:0, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and two unidentified glycolipids. The predominant menaquinone was MK-9(H4). The genomic DNA G + C content was 71.2mol%. Based on the polyphasic taxonomic evidence, strain YIM S02567T is assigned to a novel member of the genus Propioniciclava, for which the name Propioniciclava soli sp. nov., (type strain YIM S02567T = CCTCC AB 2020128T = CGMCC 1.18504T = KCTC 49478T) is proposed. Furthermore, we propose the reclassification of Brevilactibacter as Propioniciclava gen. nov.

The spatiotemporal distribution of Japanese Encephalitis cases in Yunnan Province, China, from 2007 to 2017.

Japanese encephalitis (JE) is a vector-borne disease with a high prevalence in Yunnan Province, China. However, there has been a lack of a JE epidemic systematic analysis, which is urgently needed to guide control and prevention efforts. This study explored and described the spatiotemporal distribution of JE cases observed among two different age groups in Yunnan Province from 2007 to 2017. The epidemiological features and spatial features were analyzed according to basic statistics, ArcGIS software (version 9.3; ESRI, Redlands, CA) and SPSS software (version 20; IBM Corp., Armonk, New York). Overall, the whole province had a high incidence of JE. The annual incidence rates in 2007 and 2017 were 1.668/100,000 and 0.158/100,000, respectively. The annual mortality was under 0.095/100,000 for these years. Although the whole province was in danger of JE, the Diqing autonomous prefecture and the Lijiang autonomous prefecture had no JE cases recorded for over 10 years. The JE cases were reported by hospitals located in 60 counties of 14 municipalities. The top ten areas with the most JE cases were Kunming City, Zhaotong City, Jinghong City, Wenshan City, Mangshi City, Pu'er City, Baoshan City, Dali City, Chuxiong City, and Gejiu City. The incidence declined smoothly, with a peak occurring from June to September, which accounted for 96.1% of the total cases. Children whose age was equal or less than 10 years old (LEQ10) still maintained a high frequency of JEV infection, and a large number of cases were reported in August, despite the Expanded Program on Immunization (EPI), which was established in April 2008. There was no difference in the quantity of cases between the two groups (t = -0.411, P>0.05); additionally, the number of JE cases among patients LEQ10 were significantly greater than those among patients older than 10 years (GTR10). Further analysis using local indicators of spatial association (LISA) revealed that the distribution of JE exhibited a high-high cluster characteristic (Z = 2.06, P<0.05), which showed that Jinghong City, Guangnan County, Yanshan County, Funing County, and Mengzi City were hot spots for the JE epidemic. Although the EPI was established in 2008 and the incidence of JE declined smoothly in Yunnan Province, there was no difference in the number of cases between the two age groups, which reveals that the EPI has been conducted with a low level success. In the context of limited vaccine supply capacity, we should strengthen the implementation of the children's immunization program before strengthening other immunization programs.

Numerical estimation of fracture network permeability based on GEOFRAC model for groundwater modeling in a tin mine

Abstract Numerous geological research studies and mining operations have proved that fracture is one of the important factors controlling groundwater flow, mineralization, and ore distribution in metallic deposits. Most current approaches to groundwater flow simulation of naturally fractured media rely on the calculation of equivalent permeability tensors from a discrete fracture network (DFN). This study is aimed at developing a rational two-dimensional DFN by GEOFRAC, a geostatistical method of fracture direction and locations of sample data from a tin mine in the Gaosong area, Gejiu city, southwest China, and utilizing 3,724 outcrop fractures sampled on the ground of mountain Gaosong. Principal inputs of the DFN are density, direction, and continuity of disks that constitute a fracture plane. Fractures simulated by GEOFRAC were validated in that their directions corresponded well with those of the sample fractures. The permeability tensor of each modeling grid was then calculated based on the fracture network constructed. The results showed that GEOFRAC is valuable for two-dimensional DFN modeling in mines and other fracture-controlled geological phenomena, such as groundwater flow and slope failure.

人类活动的景观生态响应——以个旧市为例

人类活动的景观生态响应——以个旧市为例

A new species of the genus Kurixalus from Yunnan, China (Anura, Rhacophoridae).

A new species of the genus Kurixalus (Anura: Rhacophoridae) is described from Yunnan, China based on morphological and molecular evidence. The new species, Kurixalus lenquanensis sp. n., is distinguished from other congeneric species by a combination of (1) smaller body size (SVL in males ranges from 25.0 to 28.9 mm), (2) obtusely pointed snout with no prominence on tip, (3) rough and brown dorsum with darker mark, (4) absence of large dark spots on ventral surface, (5) brownish clouded chin, (6) granular throat, chest, and belly, (7) presence of vomerine teeth, (8) serrated dermal fringes along outer edge of limbs, (9) slight nuptial pad, (10) golden brown iris, and (11) single internal vocal sac. The new species is known only from montane scrub vegetation at the type locality (Lenquan Village, Mengzi City, Yunnan Province) and Yangjiatian Village, Gejiu City, Yunnan Province. Genetically, the new species is nested within a clade of Taiwanese Kurixalus and recovered as the sister taxon to Kurixalus idiootocus with strong support values, indicating that the ancestor of this new species might have come from Taiwan Island or the ancestor of this new species may have been widespread in southern China and the descendent species in between Taiwan and Yunnan has become extinct.

Study of particles from the Kafang copper deposit in Gejiu city, Yunnan

Samples were collected from the mining area, limestone area, and prospective area proximal to the Kafang copper deposit. The particles were analysed by the transmission electron microscopy (TEM) and the soil samples in the mining area were analysed by the X-ray diffraction (XRD). In the mining area and prospective area, metallic elements in the particles are Cu, Pb, Zn, As, Hg, and Co. Particles collected in the limestone area contain few metallic elements that exist in the ore minerals. Based on analysis of these particles, the following conclusions are made: (1) sizes of the collected particles are 20 – 300 nm; (2) the composition of the soil samples and the particulate samples are significantly different because particles in the particulate samples reflect an origin from geogas; (3) geogas particles have different elemental contents because of different physicochemical properties of the elements and physicochemical environment that the geogas particles experienced; and (4) the Kafang stratiform copper deposit is a granite-related hydrothermal deposit. Metallic elements in geogas particles occur in the ore minerals and have similar compositions to those of geogas particles in the sampling sites. The geogas particles most likely originate from concealed deposits. Supplementary material: EDS spectra of particles and coordinates of sampling points in the mining area, limestone area, and prospecting area are available at: https://doi.org/10.6084/m9.figshare.c.3820687

Age and petrogenesis of Anisian magnesian alkali basalts and their genetic association with the Kafang stratiform Cu deposit in the Gejiu supergiant tin-polymetallic district, SW China

Gejiu is geographically located near Gejiu city, SW China. It is one of the largest tin-polymetallic districts in the world and contains approximately 3milliontons (Mt) of Sn and smaller quantities of Cu, Pb, and Zn. The deposit primarily yields three different types of ore: skarn-hosted ore, basalt-hosted stratiform ore, and carbonate-hosted stratiform ore. Kafang is one of the primary ore deposits in the Gejiu district and is an unusual occurrence hosted in basaltic rocks. Genetic models of the Kafang deposit suggest that it is related either to Anisian (Lower stage of Middle Triassic) Gejiu basalts or to Cretaceous Gejiu granite. In this study, we performed zircon SIMS U–Pb dating, major and trace element analyses, and Sr–Nd–Pb isotopic analyses for the Gejiu basalts and S isotopic analyses for stratiform Cu ore. Our results and previous studies are used to interpret the petrogenesis of the Gejiu basalts and the origin of the basalt-hosted stratiform Cu deposit. The SIMS zircon U–Pb analyses of the Gejiu basalts yield an age of 244.4Ma. The trace element ratios of the Gejiu basalts are similar to those of ocean island basalt and have positive εNd(t) values (ranging from 0.6 to 2.5) and uniform (87Sr/86Sr)i values (ranging from 0.70424 to 0.70488). These ratios are close to those of the Permian Emeishan flood basalt. Thus, the Gejiu basalts may represent coeval volcanisms within the plate involving remelting of the Emeishan plume head through a stress relaxation process after the main plume event. The Pb and S isotopic compositions of the Gejiu basalts and the stratiform Cu ores indicate that the source of Cu and S is primarily derived from the Gejiu basalts. However, the age of sulfide mineralization (84.2–79.6Ma) and the age of hydrothermal alteration (85.5–81.9Ma) are temporally consistent with the age of the Cretaceous granite emplacement (85.5–83.3Ma). From a petrological and geochemical study, we determine that the Gejiu basalts may have been subjected to pervasive granite-related hydrothermal alteration during the emplacement of granite. These processes increase the K and Mg contents of basalt and probably caused the formation of the Cu ores. Thus, the Kafang stratiform Cu deposit can be considered as a granite-related hydrothermal deposit.

Study on Heavy Metal Accumulation of Plantsin Gejiu Tin Mining Area

Based on determination of heavy metal contents in soils and plants, understanding pollution of heavy metal in soils and plants, as well as the heavy metal accumulation in plants, in order to provide scientific basis for phytoremediation of heavy metals in mining areas. The determination and analysis on the concent of Zn, Cu, Pb, Cd, Mn was made in Niuba and southern mining area in Gejiu City. The result showed that the soil pollution from Cd is the most serious while the pollution from Zn was relative to minimum in Niuba abandoned mining area. In southern mining area, Pb in soil pollution was the most serious while Cu was relative to minimum Analysis on correlation between the heavy metal content in plants and soils was made based on the 5 plant samples (Pyracantha fortuneana, Zea mays, Acroptilon repens, Equisetum ramosissimum and Cucurbita moschata) collected from Niuba reclamation area and 5 plant samples (Corylus yunnanensis, Alnus nepalensis, Pyracantha fortuneana,Cupressus torulosa,Acacia dealbata) from recovery area of southern mining area. The results show that Pyracantha fortuneana has a better correlation with soil than other plants, Cucurbita moschata and soil have poor correlation, Corylus yunnanensis has better correlation with soil compared to other plants, Acacia dealbata has poor correlation with soil.

MicroRNA-21 (miR-21) regulates cellular proliferation, invasion, migration, and apoptosis by targeting PTEN, RECK and Bcl-2 in lung squamous carcinoma, Gejiu City, China.

BackgroundIn South China (Gejiu City, Yunnan Province), lung cancer incidence and associated mortality rate is the most prevalent and observed forms of cancer. Lung cancer in this area is called Gejiu squamous cell lung carcinoma (GSQCLC). Research has demonstrated that overexpression of miR-21 occurs in many cancers. However, the unique relationship between miR-21 and its target genes in GSQCLC has never been investigated. The molecular mechanism involved in GSQCLC must be compared to other non-small cell lung cancers in order to establish a relation and identify potential therapeutic targets.Methodology/Principal FindingsIn the current study, we initially found overexpression of miR-21 occurring in non-small cell lung cancer (NSCLC) cell lines when compared to the immortalized lung epithelial cell line BEAS-2B. We also demonstrated that high expression of miR-21 could increase tumor cell proliferation, invasion, viability, and migration in GSQCLC cell line (YTMLC-90) and NSCLC cell line (NCI-H157). Additionally, our results revealed that miR-21 could suppress YTMLC-90 and NCI-H157 cell apoptosis through arresting cell-cycle at G2/M phase. Furthermore, we demonstrated that PTEN, RECK and Bcl-2 are common target genes of miR-21 in NSCLC. Finally, our studies showed that down-regulation of miR-21 could lead to a significant increase in PTEN and RECK and decrease in Bcl-2 at the mRNA and protein level in YTMLC-90 and NCI-H157 cell lines. However, we have not observed any remarkable difference in the levels of miR-21 and its targets in YTMLC-90 cells when compared with NCI-H157 cells.Conclusions/SignificancemiR-21 simultaneously regulates multiple programs that enhance cell proliferation, apoptosis and tumor invasiveness by targeting PTEN, RECK and Bcl-2 in GSQCLC. Our results demonstrated that miR-21 may play a vital role in tumorigenesis and progression of lung squamous cell carcinoma and suppression of miR-21 may be a novel approach for the treatment of lung squamous cell carcinoma.

Heavy metal and sulfur concentrations and mycorrhizal colonizing status of plants from abandoned lead/zinc mine land in Gejiu, Southwest China

A field survey of heavy metals and sulfur concentrations and mycorrhizal status of plants grown in abandoned lead/zinc mine land was conducted in Gejiu City, Yunnan Province, Southwest China. Low or no root arbuscular mycorrhizal fungi (AMF) infection was detected in most of the plants for 21 species of 13 families collected from the abandoned Pb/Zn mine land. The maximum concentrations of Pb, Zn, Cd and As was up to 11255.3 ± 1887.2, 5884.2 ± 531.9, 70.5 ± 0.8 and 498.9±38.1 mg/kg in soils, respectively. The maximum concentration of Pb, Zn, Cd and As in plants shoot was 2323.4 ± 125.0, 1273.7 ± 140.0, 238.5 ± 19.5 and 326.7 ± 53.2 mg/kg, and which in plants root was 3480.0 ± 642.9, 1421.6 ± 251.3, 291.8 ± 11.2 and 390.6 ± 30.1 mg/kg, respectively. The average S concentrations were 0.29 and 0.19% DW in plants shoots and roots, respectively. Significant correlation between S and Pb, Zn, As concentrations in plants shoots, and between S and Pb, Zn, Cd, As concentrations in plants roots was observed. Key words: Lead/zinc mine, heavy metal, sulfur, arbuscular mycorrhizal fungi, relation, Gejiu.

HIV-1 and STIs Prevalence and Risk Factors of Miners in Mining Districts of Yunnan, China

To assess HIV/sexually transmitted infection (STI) prevalence and associated risk factors among miners in Yunnan, China. A cross-sectional study was conducted among 1798 miners in 2 townships of Gejiu City, Yunnan, from March to May 2006. Standardized interviewer-administered questionnaires were completed and specimens collected for HIV/STI testing. The prevalence of HIV, Chlamydia trachomatis, Neisseria gonorrhoeae, syphilis, herpes simplex virus-2, and any STIs among all miners was 0.7%, 4.8%, 0.8%, 1.8%, 9.6%, and 14.9%, respectively. One fifth of miners reported patronizing female sex workers (FSWs) at least once, and of these, 72% never used a condom with a FSW. Miners who visited FSWs had a higher prevalence of HIV (1.8% vs. 0.5%) and any STI (23.2% vs. 4.3%), including C. trachomatis (6.9% vs. 4.3%), N. gonorrhoeae (2.1% vs. 0.5%), and herpes simplex virus-2 (14.9% vs. 8.4%), and higher rates of illegal drug use compared with miners who visited no FSWs. High prevalence of HIV/STIs among miners in Gejiu warrants special attention to this population, and vigorous interventions should address both sexual and drug use-related risk.

HIV and STIs in Clients and Female Sex Workers in Mining Regions of Gejiu City, China

To investigate HIV/sexually transmitted infections (STIs) among female sex workers (FSWs) and clients in a mining region of China. To estimate HIV/STI prevalence and to identify HIV risk factors among FSWs and miner clients. A cross-sectional study of 96 FSWs and 339 miner clients. In FSWs, prevalence of HIV was 8.3%, herpes simplex virus-2 70.8%, syphilis 12.5%, Neisseria gonorrhoeae 36.8%, Chlamydia trachomatis 46.3%, Trichomonas vaginalis 22.1%, and 90.6% were infected with any STI. Illegal drug use was associated with HIV [adjusted odds ratio (OR) = 45.1, 95% confidence interval, 6.4-317.9] in FSWs, and 45.8% reported no condom use with the last client. In miner clients, HIV prevalence was 1.8%, herpes simplex virus-2 14.9%, syphilis 2.4%, N. gonorrhoeae 2.1%, C. trachomatis 6.5%, and 23.2% were infected with any STI. Never using condoms with FSWs and regular partners were reported in 61.2% and 84.1%, respectively. Independent risk factors for HIV in miner clients were illegal drug use (OR 190.2), symptoms of urethral discharge or frequent urination (OR 32.9), early sexual debut (OR 7.1), and visiting 4 or more FSWs in the last 12 months (OR 11.5). HIV/STI prevalence is high among FSWs and moderate among clients in mining regions of Gejiu City. Drug use is the most important factor placing FSWs and miner clients at risk for HIV in Gejiu City; risky sexual characteristics such as early sexual debut, frequent visits to FSWs, and STI symptoms are also important factors for miner clients. FSWs and miner clients may constitute bridging groups for HIV to low-risk populations.

HIV/AIDS Related Discrimination in Health Care Service: a Cross-sectional Study in Gejiu City, Yunnan Province

To investigate discrimination against people living with HIV (PLWH) and its impacts. Forty people who were either HIV positive (7/40) or had high risk behavior (33/40) were interviewed. Focus group discussion was held in the interview with people who were suspected to be infected with HIV, and in-depth interview was conducted in the survey of HIV positive persons whose privacy was strictly protected to ensure the confidentiality of the collected information. It was identified that six forms of discrimination against people living with HIV occurred in health care service in Gejiu, including speaking to patients in an insulting manner, refusing to provide health care service, delaying treatment, treating differently, uncovering patients' privacy, and over-protecting themselves against patients. Discrimination against people living with HIV greatly affected their health conditions. Discrimination against people living with HIV in health service has negative impact on their physical and mental health.

Epidemiologic study on STD/HIV infections among tin mining workers in Gejiu, Yunnan province

To estimate human immunodeficiency virus (HIV)/sexually transmitted diseases (STDs) related knowledge, the prevalence and risk factors for HIV/STDs among tin miners in Gejiu, Yunnan Province. A cross-sectional study was conducted in tin miners working at 5 mining regions from March to June 2006 in Gejiu City, Yunnan Province. A total of 1796 miners were enrolled in the study, and a standardized questionnaire was administered probing socio-demographic factors, knowledge of HIV/STDs and sexual behavior. 7 ml-volume venous blood and 15 ml urine specimens were collected for HIV/STDs testing. Twelve participants [0.7%] (12/1760) were identified HIV positive. While, the positive proportions for syphilis, herpes simplex virus type-2 (HSV-2), Neisseria gonorrhea and Chlamydia trachoma were 1.8% (31/1760), 9.6% (169/1760), 0.8% (14/1773), 4.8% (85/1773), respectively. The total prevalence of STDs was 14.9% (264/1776). Factors associated with HIV infection were illegal drug use (adjusted OR = 17.8; 95% CI: 4.0 - 78.8), frequencies of visiting female sex workers in the past twelve months (adjusted OR = 8.7; 95% CI: 1.9 - 39.0), tattoos (adjusted OR = 6.6; 95% CI: 1.8 - 24.0), surgical operation experiences (adjusted OR = 6.0; 95% CI: 1.6 - 22.5) and toothbrush sharing (adjusted OR = 5.6; 95% CI: 1.0 - 31.3). Factors associated with STDs infection were race (adjusted OR = 2.0; 95% CI: 1.5 - 2.7), age (adjusted OR = 1.7; 95% CI: 1.0 - 2.9), illegal drug use (adjusted OR = 2.3; 95% CI: 1.0 - 5.2), living with spouses (adjusted OR = 1.4; 95% CI: 1.1 - 1.9) and visiting female sex workers (adjusted OR = 1.9; 95% CI: 1.4 - 2.6). Only 4.1% (49/1201) of respondents aware the correct transmission routes of HIV. 21.6% (339/1569) of the miners who had previous sexual experience self-reported visiting female sex workers. HIV and other STDs are highly prevalent amongst miners in this region. In addition, the awareness of HIV/STDs is low and multiple routes of HIV transmission, such as heterosexual intercourse and IDU, were also observed in these study subject. HIV/STDs interventions should therefore be reinforced among the miners in this region.

Quantitative evaluation of the radon and lung cancer association in a case control study of Chinese tin miners : Lubin JH, Qiao Y-L, Taylor PR et al. Epidemiology Methods Section, Biostatistics Branch, Division of Cancer Etiology, National Cancer Institute, Rockville, MD 20892. Cancer Res 1990;50:174-80

Studies of underground miners have consistently shown an increased risk of lung cancer with cumulative exposure to radon-222 and its decay products. Although the deleterious effects of high radon exposure are clear, questions regarding the shape of the exposure-response relationship, and the effects of time factors such as attained age, time since exposure and early age at first exposure, the effect of exposure rate, and the joint association of radon exposure and tobacco use have not yet been fully clarified. This report considers these questions by fitting various models for the relative odds of disease to 74 male lung cancer cases who were diagnosed between 1981 and 1984 and were alive in 1985 and an equal number of controls. All subjects are current or past employees of the Yunnan Tin Corporation, Gejiu City, China, who reside in the local area. Workers were interviewed to obtain information on work history, from which radon exposure in cumulative working level months and arsenic exposure were estimated, and on tobacco use. Results indicate that excess relative risk increases by 1.7% per cumulative working level month [95% confidence interval (0.5, 5.4)]. The linear exposure response relationship significantly declines with year since last radon exposure (P = 0.02). The risk trend also declines with increasing exposure rate (P = 0.001), indicating that long duration of exposure at a low rate may be more deleterious than short duration of exposure at a high rate. A unique aspect of this study population is the very early ages at first radon exposure for many of the workers, about 37% of the radon-exposed workers were first exposed under the age of 13 years. The analysis shows no modification of the radon lung cancer relationship with age at first exposure. These patterns of risk with radon exposure are generally consistent with those reported in the recent National Academy of Sciences' Biological Effects of Ionizing Radiations IV report. The primary method of tobacco consumption in this area of China is by waterpipe. Lung cancer risk increases with pipe-years of use. The joint analysis of tobacco use and radon exposure supports the Biological Effects of Ionizing Radiations IV conclusion that the most likely model is between additive and multiplicative. The variations of the radon lung cancer relationship by years since last exposure and exposure rate are not affected by adjustment for arsenic exposure.