71例男性乳腺癌患者临床与预后分析

目的探讨男性乳腺癌(MBC)患者临床病理特征及其预后。方法回顾性分析天津医科大学附属肿瘤医院2002年3月至2012年3月71例MBC患者的临床病理及生存资料。结果MBC患者年龄43~84(M=62)岁，中位年龄大于同期女性乳腺癌(FBC)患者(t=6．355，P=0．000)，与同期FBC例数之比为o．42%(71：16 796)；MBC病理类型以浸润性导管癌(x²=29．875，P=0．000)、临床分期以>ⅢA(x²=13．377，P=0．037)多见。MBC患者雌激素受体阳性率明显高于FBC患者，而人类表皮生长因子受体-2(HER-2)阳性率明显低于FBC患者x²=3．741，P=0．048；x²=12．845，P-0．002)。单因素和多因素分析发现MBC患者预后比FBC患者差(P-0.004，P=0.046)。MBC患者的HER-2表达水平是影响其预后的重要因素(x²=4．219，P=0．040)。结论MBC与FBC的临床特征及预后均存在显著差异。HER一2阳性可能对MBC的预后及治疗有重要意义。     

新疆维吾尔自治区2011－2018年手足口病发病与气象因素的相关性分析

目的 分析新疆维吾尔自治区（新疆）手足口病发病与气象因素的相关性,为新疆手足口病的预警预测和防控提供科学依据。方法 2011-2018年新疆手足口病疫情个案数据和同期人口数据来源于中国疾病预防控制信息系统,气象数据来源于天气后报网（http://www.tianqihoubao.com）。采用Excel 2007、SPSS 17.0软件对新疆手足口病发病数和气象因素进行相关性分析,采用ArcGIS 10.2软件绘制手足口病空间分布图。结果 新疆手足口病发病主要集中在4-7月,5、6月是发病人数最多的月份;气温与新疆手足口病的发病呈正相关（r=0.370,P<0.01）,降水量与手足口病的发病呈显著正相关（r=0.747,P<0.01）;适宜新疆手足口病发病的气温阈值为5℃~35℃。新疆手足口病发病高峰和降水量高峰错峰1个月;降水量与手足口病发病数呈幂函数关系y=0.009 4x^{2.332 9},R²=0.898 9。结论 2011-2018年新疆手足口病发病与气温、降水量相关,可以考虑作为手足口病预警参数。     

广西不同煤质煤矿尘肺流行病学比较分析

目的探讨不同煤质煤尘对尘肺患病的影响。方法用回顾性流行病学方法对广西3种不同煤质的12个煤矿进行尘肺患病率、历年粉尘浓度、粉尘游离二氧化硅含量情况进行调查分析。结果褐煤、烟煤、无烟煤作业场所历年平均粉尘浓度（mg／m^3）分别为68．75、24．01、17．18,游离二氧化硅含量（％）分别为11,07、59．77和13,78。褐煤、烟煤、无烟煤煤矿工人尘肺患病率（％）分别为0．15、6．70、1．58。褐煤矿接尘工人尘肺患病率明显低于烟煤、无烟煤矿工人（P〈0．001）。结论广西煤工尘肺患病率以烟煤矿最高,无烟煤矿次之,褐煤矿最低。不同煤质煤矿尘肺患病率差异除了与粉尘浓度和游离二氧化硅含量有关外,还可能有其它影响因素。研究结果提示,在今后修订煤尘卫生标准时,可能需要根据不同的煤质制订相应的卫生标准。     

山西省1 337名煤矿工人血脂异常患病情况及相关因素分析

目的 了解山西省煤矿工人血脂异常患病情况并分析其相关因素。方法 收集2016年4月在山西省太原市某煤矿1 337名工人体格检查与血液生化指标检测资料;按照2007年《中国成人血脂异常防治指南》诊断标准作为血脂异常的判定标准;采用χ²检验和非条件logistic回归模型对该煤矿工人血脂异常相关因素进行分析。结果 1 337例煤矿工人血脂异常总患病率为59.1%（790/1 337）,其中男性患病率为60.4%（708/1 173）,女性患病率为50.0%（82/164）,男性患病率高于女性（χ²=6.386,P<0.05）;20~34、35~49和≥50岁工人患病率分别为68.8%、58.7%和49.5%,20~34岁年龄组患病率最高。χ²检验结果显示,煤矿工人性别、年龄和BMI是血脂异常的相关因素（χ²=7.117,P<0.01;χ²=37.135,P<0.01;χ²=7.009,P<0.05）;非条件logistic回归分析结果显示,该煤矿工人性别、年龄、BMI水平、收缩压≥140 mmHg（1 mmHg=0.133 kPa）与血脂异常存在关联（P<0.05）;与女性矿工相比,男性矿工患血脂异常的风险是女性矿工的1.501倍（OR=1.501,95%CI：1.895~2.516）;从年龄分组看,35~49岁组、20~34岁组血脂异常患病风险分别为≥50岁组的1.672倍（OR=1.672,95%CI：1.501~2.392）和2.369倍（OR=2.369,95%CI：1.275~3.469）;较正常BMI组,高BMI组血脂异常患病风险为其1.443倍（OR=1.443,95%CI：1.139~1.828）;收缩压异常组血脂异常患病风险为正常组的1.829倍（OR=1.829,95%CI：1.152~2.906）;而舒张压、血糖、血尿酸、心电图检测结果与血脂异常的差异均无统计学意义。结论 该煤矿工人血脂异常患者主要为20~34岁男性,有高血压（收缩压异常）病史、高BMI（≥24.0 kg/m²）的该煤矿工人患血脂异常可能性较大,需要引起重视。     

海南省0~6岁儿童孤独症谱系障碍的现况调查及影响因素分析

目的 了解海南省0~6岁儿童孤独症谱系障碍的患病情况及其影响因素。方法 抽查海南省18个市（县）0~6岁儿童37 862人,采用儿童发育问题预警征象调查表筛查,再由专科医师现场诊断,采用一般描述统计、χ²检验、非条件logistic回归分析孤独症现况及影响因素。结果 共诊断235例孤独症儿童,总患病率为0.62%,其中男童为0.99%,女童为0.17%,男童高于女童（χ²=101.91,P=0.000）。随年龄增长孤独症患病率上升（χ²=288.62,P=0.000）。城市孤独症患病率高于其他地区,差异有统计学意义（χ²=114.77,P=0.000）。是否足月、新生儿窒息、父亲性格、父亲有嚼槟榔或吸烟习惯、母孕期总体情绪状态以及母亲人流史为孤独症的影响因素。结论 海南省0~6岁儿童孤独症谱系障碍的患病率居国内较高水平并受遗传因素、孕产过程、父母在孕前及孕期不良行为、习惯等综合因素的影响。     

浙江省非超重成年人血脂异常患病率及影响因素分析

目的 探讨浙江省非超重成年人血脂异常流行特征及影响因素。方法 选择参加2010年浙江省代谢综合征流行病学调查的10 868名年龄≥18周岁非超重/肥胖居民(BMI<24.0 kg/m²)为研究对象,进行问卷调查、体检和血脂检测,采用多因素logistic回归模型分析影响因素。结果 该人群血脂异常患病率为41.38%,男性(43.19%)显著高于女性(39.84%)(χ²=12.53,P<0.001);随年龄增长,男性血脂异常患病率降低(趋势χ²=47.61,P<0.001),女性患病率升高(趋势χ²=3.88,P<0.05),<50岁男性患病率明显高于女性;农村人群患病率(41.49%)略高于城市(41.21%),但差异无统计学意义(χ²=0.08,P=0.774);多因素logistic回归分析显示,性别、慢性病家族史、现在吸烟、现在饮酒、高肉蛋类饮食、烹调使用动物油、体力活动、中心性肥胖和BMI是非超重成年人血脂异常的影响因素。结论 浙江省非超重成年人血脂异常患病率较高,家族史、吸烟、高脂饮食、体力活动不足、中心性肥胖等是主要影响因素。     

内蒙古部分地区流动人口糖尿病现况调查

目的 了解内蒙古地区流动人口中糖尿病及糖尿病前期的患病现状。方法 采用按行业分层整群抽样方法进行等额抽样,调查内容包括问卷调查、身体测量和实验室检测。结果 内蒙古部分地区流动人口糖尿病及糖调节受损粗患病率分别为12.5%和12.8%,年龄标化患病率均为9.9%;男性糖尿病患病率高于女性,女性糖调节受损粗患病率高于男性;不同性别糖尿病患病率均随年龄的增长而增加（趋势χ²=11.162,P=0.001）;建筑业人群糖尿病患病率最高（19.2%）,糖调节受损患病率的差异无统计学意义;外省流入人群流动前糖尿病患病率高,糖调节受损患病率的差异无统计学意义,省内流动人群糖调节受损患病率随流动时间的增加而增长（趋势χ²=9.989,P=0.002）。结论 内蒙古部分地区流动人口糖尿病患病率较高,已接近大城市居民患病水平,其中中老年和建筑业人群患病率最高,省内流动人口糖尿病患病率对内蒙古地区流动人口患病率贡献较大。     

内蒙古自治区全人群脑血管病流行病学调查

目的 探讨内蒙古自治区全人群脑血管病流行病学特点。方法 2013年9月至2014年1月采用与人口规模成比例的PPS抽样方法,对内蒙古自治区全年龄组常住居民19 315人进行现场问卷调查及影像(CT/MRI)等辅助确诊和体格检查。结果 内蒙古自治区全人群脑血管病患病率为1 812.06/10万(男性2 008.86/10万,女性1 613.24/10万)。随年龄增加患病率升高,且男性高于女性,乡村人群高于城区,文化程度低者患病率较高。脑血管病发病率为392.54/10万,男女性别间发病率的差异无统计学意义(χ²=0.380,P=0.846);农村人群高于城市,差异有统计学意义(χ²=13.029,P=0.000),且随年龄增加发病率有逐渐升高的趋势(χ²=410.130,P=0.000)。脑血管病死亡率为149.67/10万,病死率为15.14%。中年组脑出血及脑梗死患病率均高于青年组(< 45岁)人群。结论 内蒙古自治区全人群脑血管病患病率、发病率、死亡率、复发率均较高,并以缺血型为主。     

宁夏回族自治区回、汉族居民烟草、酒精使用调查

目的 了解宁夏回族自治区(宁夏)回、汉族居民烟草、酒精使用情况及其分布特征,为民族地区改善戒烟、限酒措施提供参考。方法 采用多阶段系统抽样法,抽取宁夏地区≥18岁居民6 476人进行入户调查。烟草和酒精使用障碍根据国际疾病分类-10(ICD-10)标准采用复合型国际诊断交谈表3.0(CIDI 3.0)中文版评估。结果 共有5 811名受访者完成全部调查,目前吸烟率为19.15%,其中男性吸烟率高于女性(44.73% vs. 1.51%),差异有统计学意义(χ²=1 693.25,P< 0.001);男性中回族吸烟率低于汉族(33.19% vs. 51.95%),差异有统计学意义(χ²=79.99,P< 0.001)。男性烟草依赖患病率为1.75%,回、汉族男性烟草依赖患病率差异无统计学意义(χ²=0.02,P=0.958)。目前饮酒率为5.78%,其中男性饮酒率高于女性(12.48% vs. 1.16%),差异有统计学意义(χ²=329.94,P< 0.001);男性中回族饮酒率低于汉族(4.71% vs. 17.34%),差异有统计学意义(χ²=82.03,P< 0.001);男性酒精使用障碍患病率为6.03%,男性回族酒精使用障碍患病率低于汉族(3.50% vs. 7.61%),差异有统计学意义(χ²=16.68,P< 0.001)。结论 宁夏地区回族成年人烟草和酒精使用率低于同地区汉族,当地的回族文化对减少人群烟草、酒精使用可能具有积极的影响。     

北京市18~65岁居民高胆固醇血症流行现状与影响因素分析

目的 了解北京市18~65岁居民高胆固醇血症流行病学现状及影响因素,为其相关疾病的防控提供科学依据。方法 数据来自2014年北京市成人慢性病与危险因素监测。该监测以多阶段分层整群抽样方法在全市范围抽取调查对象进行问卷调查、身体测量和实验室检查。结果 17 662例有效样本中,血清胆固醇均值为（4.69±0.95）mmol/L,高胆固醇血症患病率为6.26%,边缘值升高率为21.34%。男性高胆固醇血症患病率为6.33%,女性为6.20%,差异无统计学意义（Z=1.64,P=0.10）;城区居民患病率为6.73%,高于郊区居民的5.59%（Z=-7.27,P<0.01）。高胆固醇血症患病率随年龄增加呈上升趋势（趋势检验 χ²=308.85, P<0.01）,其中男性（χ²=81.65,P<0.01）、女性（χ²=318.04, P<0.01）、城区居民（χ²=201.77, P<0.01）、郊区居民（χ²=114.65, P<0.01）均呈相同趋势。多因素logistic回归分析显示,高年龄组、女性（OR=1.23,95%CI：1.04~1.45）、超重（OR=1.56,95%CI：1.34~1.81）、肥胖（OR=1.82,95%CI：1.54~2.16）、每天吸烟（OR=1.24,95%CI：1.03~1.50）、每天饮酒（OR=1.40,95%CI：1.12~1.75）、牛羊肉摄入每周>1次（OR=1.19,95%CI：1.02~1.39）是高胆固醇血症的危险因素。结论 北京市18~65岁居民高胆固醇血症患病率低于全国平均水平,年龄、性别、地区、BMI、吸烟、饮酒、牛羊肉摄入频率为患病的主要影响因素。     

Radiographic outcomes among South African coal miners

Objectives: This study, the first to document the prevalence of pneumoconiosis among a living South African coal mining cohort, describes dose–response relationships between coal workers pneumoconiosis and respirable dust exposure, and relationships between pneumoconiosis and both lung function deterioration and respiratory symptoms. Methods: A total of 684 current miners and 188 ex-miners from three bituminous-coal mines in Mpumalanga, South Africa, was studied. Chest radiographs were read according to the International Labour Organization (ILO) classification by two experienced readers, one an accredited National Institute for Occupational Safety and Health (NIOSH) B reader. Interviews were conducted to assess symptoms, work histories (also obtained from company records), smoking, and other risk factors. Spirometry was performed by trained technicians. Cumulative respirable dust exposure (CDE) estimates were constructed from historical company-collected sampling and researcher-collected personal dust measurements. -Statistics compared the radiographic outcomes predicted by the two readers. An average profusion score was used in the analysis for the outcomes of interest. Because of possible confounding by employment status, most analyses were stratified on current and ex-miner status. Results: The overall prevalence of pneumoconiosis was low (2%–4%). The degree of agreement between the two readers for profusion was moderate to high (=0.58). A significant association (P<0.001) and trend (P<0.001) was seen for pneumoconiosis with increasing categories of CDE among current miners only. A significant (P<0.0001) additional 58 mg-years/m³ CDE was seen among those with pneumoconiosis compared to those without. CDE contributed to a statistically significant 0.19% and 0.11% greater decline in the percent predicted 1-second forced expiration volume (FEV₁) and forced vital capacity (FVC), respectively, among current miners with pneumoconiosis than among those without. Logistic regression models showed no significant relationships between pneumoconiosis and symptoms. Conclusions: The overall prevalence of pneumoconiosis, although significantly associated with CDE, was low. The presence of pneumoconiosis is associated with meaningful health effects, including deterioration in lung function. Intervention measures that control exposure are indicated, to reduce these functional effects.     

An investigation into the relationship between coal workers' pneumoconiosis and dust exposure in U.S. coal miners.

The National Study of Coal Workers' Pneumoconiosis (NSCWP) is a large, continuing epidemiologic study of the respiratory health of U.S. coal miners. By using information from the study, prevalence of coal workers' pneumoconiosis (CWP) was related to indexes of dust exposure obtained from research and compliance sampling data. Clear relationships between prevalences of both simple CWP and progressive massive fibrosis (PMF) and estimated dust exposure were seen. Additional effects independently associated with coal rank (% carbon) and age were also seen. Logistic model fitting indicated that between 2% and 12% of miners exposed to a 2-mg/m3 dust environment in bituminous coal mines would be expected to have Category 2 or greater CWP after a 40-yr working life; PMF would be expected for between 1.3% and 6.7%. The risks for anthracite miners appeared to be greater. There was a suggestion of a background level of abnormality, not associated with dust exposure, but increasing with age. Although there are certain weaknesses in the data used to derive these exposure estimates, the results are in general agreement with, but somewhat greater than, some recent findings for British coal miners.     

Airflow limitation among workers in a labour-intensive coal mine in Tanzania

Objectives To describe the relationship between cumulative respirable dust and quartz exposure and lung functioning among workers in a labour-intensive coal mine. Methods The study population comprised 299 men working at a coal mine in Tanzania. Lung function was assessed using a Vitalograph alpha III spirometer in accordance with American Thoracic Society recommendations. Multiple linear regression models were developed to study the relationship between forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC and the cumulative dust or quartz exposure while adjusting for age, height and ever smoking. To evaluate trends for dose response, cumulative exposure concentrations for respirable dust and quartz were ranked and categorized in quartiles and the highest decile, with the first quartile as the reference group. Logistic regression models were used to determine odds ratios for FEV₁/FVC < 0.7 and FEV₁% < 80 for categories of cumulative dust or quartz exposure. Results The prevalence of FEV₁/FVC < 0.7 among the workers was 17.3%. Workers in the development team (20.5%) had the highest prevalence of FEV₁% < 80%. The estimates of the effects of cumulative exposure on FEV₁/FVC were −0.015% per mg years m^–3 for respirable dust and –0.3% per mg years m^–3 for respirable quartz. In logistic regression models, the odds ratios for airway limitation (FEV₁/FVC < 0.7) for the workers in the highest decile of cumulative dust and quartz exposure versus the referents were 4.36 (95% confidence interval: 1.06, 17.96) and 3.49 (0.92, 13.21), respectively. The upper 10% of workers by cumulative dust and quartz exposure also had higher odds ratios for predicted FEV₁% < 80% than the reference group odds ratio: 10.38 (1.38, 78.13) and 14.18 (1.72, 116.59), respectively. The results must be interpreted with caution due to a possible healthy worker effect and selection bias. Conclusion Exposure to respirable coal mine dust was associated with airway limitation as measured by FEV₁/FVC and predicted FEV₁%.     

Pneumoconiosis and advanced occupational lung disease among surface coal miners--16 states, 2010-2011

Coal workers' pneumoconiosis (CWP) is a chronic occupational lung disease caused by long-term inhalation of dust, which triggers inflammation of the alveoli, eventually resulting in irreversible lung damage. CWP ranges in severity from simple to advanced; the most severe form is progressive massive fibrosis (PMF). Advanced CWP is debilitating and often fatal. To prevent CWP, the Coal Mine Health and Safety Act of 1969 established the current federal exposure limit for respirable dust in underground and surface coal mines. The Act also established a surveillance system for assessing prevalence of pneumoconiosis among underground coal miners, but this surveillance does not extend to surface coal miners. With enforcement of the exposure limit, the prevalence of CWP among underground coal miners declined from 11.2% during 1970-1974 to 2.0% during 1995-1999, before increasing unexpectedly in the last decade, particularly in Central Appalachia. Exposure to respirable dust is thought to be less in surface than underground coal miners. Although they comprise 48% of the coal mining workforce, surface coal miners have not been studied since 2002. To assess the prevalence, severity, and geographic distribution of pneumoconiosis among current surface coal miners, CDC obtained chest radiographs of 2,328 miners during 2010-2011 through the Coal Workers' Health Surveillance Program of the National Institute for Occupational Safety and Health (NIOSH). Forty-six (2.0%) of 2,257 miners with >1 year of surface mining experience had CWP, including 37 who had never worked underground. Twelve (0.5%) had PMF, including nine who had never worked underground. A high proportion of the radiographs suggested silicosis, a disease caused by inhalation of crystalline silica. Surface coal mine operators should monitor worker exposures closely to ensure that both respirable dust and silica are below recommended levels to prevent CWP. Clinicians should be aware of the risk for advanced pneumoconiosis among surface coal miners, in addition to underground coal miners, to facilitate prompt disease identification and intervention.     

Exposure-response analysis of mortality among coal miners in the United States

The quantitative relationship between exposure to respirable coal mine dust and mortality from nonmalignant respiratory diseases was investigated in a study of 8,878 working male coal miners who were medically examined from 1969 to 1971 and followed to 1979. Exposure-related mortality was evaluated using Cox proportional hazards modeling for underlying or contributing causes of death and modified lifetable methods for underlying causes. For pneumoconiosis mortality, the lifetable analyses showed increasing standardized mortality ratios (SMRs) with increasing cumulative exposure category. Significant exposure-response relationships for mortality from pneumoconiosis (P < 0.001) and from chronic bronchitis or emphysema (P < 0.05) were observed in the proportional hazards models after controlling for age and smoking. No exposure-related increases in lung cancer or stomach cancer were observed. Pneumo coniosis mortality was found to vary significantly by the rank of coal dust to which miners were exposed. Miners exposed at or below the current U.S. coal dust standard of 2 mg/m³ over a working lifetime, based on these analyses, have an elevated risk of dying from pneumoconiosis or from chronic bronchitis or emphysema.     

Detection of reactive free radicals in fresh coal mine dust and their implication for pulmonary injury

Freshly ground and aged anthracite and bituminous coal samples were investigated by electron spin resonance (ESR) spectroscopy to detect the presence, concentration and reactivity of free radicals. Freshly ground anthracite coal produced greater concentration of free radicals than the bituminous coal, and the radical reactivity was also greater for the anthracite. The reactivity of the newly produced free radicals in the anthracite dust correlated with the dust's toxicity. Furthermore, similar coal-based free radicals were detected in the lung tissue of autopsied coal miners, suggestive of persistent reactivity by the embedded coal dust leading to the progressive disease process. Results of the studies on the severity of coal workers' pneumoconiosis (CWP) and free radical concentration in lung tissue support this hypothesis.     

The relationship between coal rank and the prevalence of pneumoconiosis.

As part of the Periodic X-ray Scheme of the National Coal Board (NCB), a comparison is made between the previous and new films of all miners who were face-workers on the former occasion, five years earlier. This assessment is made by distributing the films randomly to all the NCB readers. This paper compares the rank of coal mined in each colliery with each colliery's percentage prevalence of pneumoconiosis of at least ILO category 1 in the films of previous face-workers obtained during the third survey round (1969-73). Of the NCB's 291 collieries in Britain, information enabling a rank classification to be made was available for 250, employing 62 362 face-workers. In these 250 mines a progressive and five-fold increase in prevalence was observed from collieries mining low-rank (bituminous) coal to those mining coal of high ranks (anthracite and high-grade steam and coking coal). A possible reason for this is that, in the past, high-rank collieries may have had the highest mass-concentrations of respirable dust.     

The relationship between coal rank and the prevalence of pneumoconiosis.

As part of the Periodic X-ray Scheme of the National Coal Board (NCB), a comparison is made between the previous and new films of all miners who were face-workers on the former occasion, five years earlier. This assessment is made by distributing the films randomly to all the NCB readers. This paper compares the rank of coal mined in each colliery with each colliery's percentage prevalence of pneumoconiosis of at least ILO category 1 in the films of previous face-workers obtained during the third survey round (1969-73). Of the NCB's 291 collieries in Britain, information enabling a rank classification to be made was available for 250, employing 62 362 face-workers. In these 250 mines a progressive and five-fold increase in prevalence was observed from collieries mining low-rank (bituminous) coal to those mining coal of high ranks (anthracite and high-grade steam and coking coal). A possible reason for this is that, in the past, high-rank collieries may have had the highest mass-concentrations of respirable dust.     

The derivation of estimated dust exposures for U.S. coal miners working before 1970.

A number of reports on the prevalence of coal workers' pneumoconiosis in U.S. coal miners have been published, yet very little is known about the relationship between dust exposure and pneumoconiosis levels in the U.S. This report describes the derivation of cumulative dust exposure estimates by back-extrapolation of data processed by the Mine Safety and Health Administration after 1970 by using a ratio of dust concentrations based on information collected during environmental surveys at certain U.S. mines by the Bureau of Mines between 1968 and 1969. Cumulative personal dust exposure estimates were calculated by using occupational histories obtained from the miners and job-specific estimates of dust concentration. In other reports, the resulting estimated exposures have been shown to correlate well with various measures of respiratory morbidity.     

Exposure to silica and silicosis among tin miners in China: exposure-response analyses and risk assessment

OBJECTIVES—To investigate the risk of silicosis among tin miners and to investigate the relation between silicosis and cumulative exposure to dust (Chinese total dust and respirable crystalline silica dust).
METHODS—A cohort study of 3010 miners exposed to silica dust and employed for at least 1 year during 1960-5 in any of four Chinese tin mines was conducted. Historical total dust data from China were used to create a job exposure matrix for facility, job title, and calendar year. The total dust exposure data from China were converted to estimates of exposure to respirable crystalline silica for comparison with findings from other epidemiological studies of silicosis. Each worker''s work history was abstracted from the complete employment records in mine files. Diagnoses of silicosis were based on 1986 Chinese pneumoconiosis Roentgen diagnostic criteria, which classified silicosis as stages I-III—similar to an International Labour Organisation (ILO) classification of 1/1 or greater.
RESULTS—There were 1015 (33.7%) miners identified with silicosis, who had a mean age of 48.3 years, with a mean of 21.3 years after first exposure (equivalent to 11.0 net years in a dusty job). Among those who had silicosis, 684 miners (67.4%) developed silicosis after exposure ended (a mean of 3.7 years after). The risk of silicosis was strongly related to cumulative exposure to silica dust and was well fitted by the Weibull distribution, with the risk of silicosis less than 0.1% when the Chinese measure of cumulative exposure to total dust (CTD) was under 10 mg/m³-years (or 0.36 mg/m³-years of respirable crystalline silica), increasing to 68.7% when CTD exposure was 150 mg/m³-years (or 5.4 mg/m³-years of respirable crystalline silica). Latency period was not correlated to the risk of silicosis or cumulative dose of exposure. This study predicts about a 36% cumulative risk of silicosis for a 45 year lifetime exposure to these tin mine dusts at the CTD exposure standard of 2 mg/m³, and a 55% risk at 45 years exposure to the current United States Occupational Safety and Health Administration and Mine Safety and Health Administration standards of 0.1 mg/m³ 100% respirable crystalline silica dust.
CONCLUSIONS—A clear exposure-response relation was detected for silicosis in Chinese tin miners. The study results were similar to most, but not all, findings from other large scale exposure-response studies.