青春发动时相提前与心理行为问题关联性的性别差异

目的 探讨青少年青春发动时相提前与心理行为问题的关联及性别差异。方法 2014年11月采用整群抽样方法,对北京市和沈阳市各2所小学在校2～3年级女生、3～4年级男生和各2所中学在校7～8年级男女生进行问卷调查,问卷内容包括一般情况、体力活动、户外活动时间、视频时间、青春发育量表(PDS)和长处与困难问卷(SDQ),对青春发动时相提前及心理行为问题检出率进行描述统计分析,运用单因素和多项logistic回归分析比较青春发动时相提前对心理行为问题的影响。结果 共纳入3 253名学生,其中518人青春发动时相提前;情绪因子、品行因子、多动/注意缺陷、同伴交往因子、亲社会行为和客观困难异常检出人数(率)分别为269 (8.3%)、297(9.1%)、 211(6.5%)、534(16.4%)、299(9.2%)和448(13.8%)。多项logistic回归分析显示,青春发动时相提前是女生品行异常(OR=2.260,95%CI:1.322～3.863)和多动/注意缺陷(OR=1.980,95%CI:1.111～3.527)的危险因素,青春发动时相提前是男生客观困难异常的危险因素(OR=1.449,95%CI:1.018～2.063)。结论 青春发动时相提前会增加女生品行异常和多动/注意缺陷的风险,青春发动时相提前的男生客观困难异常风险增加,青少年心理行为干预应考虑性别特点。     

童年期虐待的不同形式与中学生自杀行为关联性研究

目的 探讨不同形式的童年期虐待与中学生自杀行为的关系。方法 采用分层整群抽样的方法,以广州、新乡、沈阳和重庆4个地区14221名中学生为研究对象,使用问卷调查了解一般人口统计学指标、心理问题症状、童年期虐待经历及自杀行为等信息,建立多因素logistic回归模型,分析不同形式的童年期虐待对自杀行为发生的影响。结果 中学生童年期总体虐待、躯体虐待、情感虐待、性虐待、自杀意念、自杀计划和自杀未遂的检出人数(率)分别为7246(51.0%)、5824(41.0%)、5409(38.0%)、1039(7.3%)、2042(14.4%)、1174(8.3%)和548(3.9%)。男生躯体虐待的检出率高于女生,女生情感虐待和自杀意念的检出率高于男生,组间差异有统计学意义(P<0.01);童年期性虐待、自杀计划和自杀未遂的检出率在不同性别间的差异无统计学意义(P>0.01)。控制相关混杂因素的作用后,童年期虐待经历会增加男生自杀意念(OR=2.03,95%CI:1.72~2.40)和自杀计划(OR=1.93,95%CI:1.57~2.37)的发生风险,增加女生自杀意念(OR=2.45,95%CI:2.12~2.82)、自杀计划(OR=2.46,95%CI:2.02~3.00)和自杀未遂(OR=2.12,95%CI:1.61~2.78)的发生风险。除童年期躯体虐待与男生自杀未遂外,不同类型的童年期虐待均是男女中学生自杀行为发生的危险因素(P<0.01)。随着童年期虐待种类数的增加,男女生自杀行为的发生风险亦呈增高趋势(P<0.01)。持续受虐以及施虐人为父母/其他的中学生,自杀行为的发生风险显著增加。结论 童年期虐待经历是中学生自杀行为发生的重要危险因素。     

儿童期不良经历与成年后慢性病的相关性研究

目的 了解18～59岁成年人儿童期不良经历的流行特征,探讨与成年后慢性病发病的相关性,为慢性病早期预防提供依据。方法 采用横断面研究,在湖北省麻城市龙池、南湖和鼓楼3个街道随机整群抽取18～59岁成年人,回顾性调查儿童期不良经历与成年后的慢性病患病情况,采用单因素和多因素logistic回归分析相关性。结果 共调查1 767名18～59岁成年人,其中1 501份问卷有效。男女性平均年龄分别为(36.32±10.20)岁和(35.72±9.08)岁。儿童期不良经历的发生率为66.22%,包括情感忽视(26.65%)、身体虐待(21.52%)、父母分居/离异(21.45%)、受到欺负(3.33%)、家庭物质滥用(1.53%)等。儿童期不良经历可增加成年后的慢性病发病风险,随着儿童期不良经历评分的增加,慢性病发病风险有增加趋势(Z=-5.902 1,P< 0.000 1)。多因素分析显示,家庭物质滥用(OR=2.82,95%CI:1.16～6.80)、受到欺负(OR=2.59,95%CI:1.39～4.80)、躯体虐待(OR=1.93,95%CI:1.41～2.64)和父母分居/离异(OR=1.51,95%CI:1.09～2.09)增加成年后慢性病发病风险。结论 儿童期不良经历发生率较高,可增加成年后慢性病发病风险,慢性病的早期预防应从儿童期开始。     

宁夏农村地区7～12岁儿童虐待现状及其影响因素分析

目的 了解宁夏农村地区7～12岁儿童虐待的现状,并探讨其影响因素。方法 采用多阶段抽样法抽取宁夏西吉县和隆德县农村地区7～12岁的儿童及其监护人,采用百分比描述儿童虐待现状,采用logistic回归模型筛选儿童虐待的相关影响因素。结果 共调查西吉县和隆德县15个村的704名7～12岁儿童。最近一年内经历过任何类型的虐待（包括躯体虐待、忽视、情感虐待、性虐待）的儿童有359人（50.2%）,其中以躯体虐待为主（44.6%）。仅有10名（1.4%）儿童能正确全面理解儿童虐待问题,经历虐待时,55.5%的儿童会通过上报的形式寻求帮助。男童（OR=1.37,95%CI：1.01～1.85）、汉族人群（OR=1.49,95%CI：1.06～2.08）、低年龄 （OR=1.16,95%CI：1.05～1.28）、父母一方在家（OR=2.05,95%CI：1.16～3.64）、家庭经济相对富裕（OR=1.55,95%CI：1.03～2.33）的儿童更易经历虐待。 结论 宁夏农村地区7～12岁儿童虐待严重,儿童自身对虐待问题的认知水平较低。应关注男童、汉族人群、低年龄、父母一方在家的儿童,促进儿童身心健康发展。     

青春发育与女性甲状腺形态及功能状况的关联研究

目的 探讨不同青春发育分期对女性甲状腺形态及功能状况的影响。方法 2017年10-11月,采用分阶段整群抽样的方法,分别在上海市闵行区、江苏省海门市、浙江省玉环市、浙江省德清县各选定1所初中,将4所初中所有初一年级女生共491名纳入研究。对研究对象进行甲状腺B超检查、体格检查以及尿碘、甲状腺激素水平检测;采用《青春发育事件自我评定量表》（PDS）评价青春发育分期;采用多重线性回归模型及多因素logistic回归模型分析不同青春发育分期对甲状腺容积及激素水平的影响。结果 不同青春发育阶段女性的甲状腺状况存在差异。甲状腺容积大小、结节检出率及FT4水平均表现为青春期前期 < 青春发动期 < 青春期后期（P<0.05）;TT3及FT3水平表现为青春期前期 > 青春发动期 > 青春期后期（P<0.001）;TSH及TT4水平不受青春发育分期的影响（P>0.05）。多重线性回归分析及多因素logistic回归分析结果一致,青春发育与TT3和FT3水平呈负相关。PDS总分每增加1分,TT3和FT3水平在模型1中分别减少0.067 nmol/L和0.170 nmol/L,在模型2中分别减少0.065 nmol/L和0.162 nmol/L;相较于青春期前期者,青春期后期者具有较低的TT3和FT3水平（模型1：OR=0.337,95% CI：0.173～0.658;OR=0.283,95% CI：0.144～0.557;模型2：OR=0.306,95% CI：0.155～0.605;OR=0.263,95% CI：0.132～0.524）。结论 青春发育与女性甲状腺形态及功能状况存在关联。青春发育越成熟,甲状腺容积越大,结节越易发生,TT3及FT3水平越低。     

童年期虐待经历与青春期抑郁症状的前瞻性关联

目的 探讨童年期虐待经历与青春期抑郁症状的前瞻性关联。方法 于2013年5月方便选取安徽省蚌埠市3所小学,根据知情同意原则,对参加研究的3～4年级学生进行身高、体重测量,同时开展问卷调查,其中学生问卷包括童年期受虐待经历（情感、躯体和性虐待）和抑郁症状等;父母问卷包括父母学历和家庭经济条件等信息。2017年3月进行随访。基线抑郁症状采用儿童抑郁量表评价,随访期抑郁症状采用《心境与情绪问卷》评价。建立多因素二分类非条件logistics回归模型,分析童年期虐待经历与青春期抑郁症状的前瞻性关联。结果 2013年基线调查1 172名学生,4年后随访1 021名（87.1%）。基线童年期虐待经历报告完整的学生为1 126名,其中躯体、情感和性虐待报告率分别为12.8%（144/1 126）、11.1%（125/1 126）和10.9%（123/1 126）。基线与随访期抑郁症状报告率分别为7.0%（82/1 172）和12.3%（126/1 021）。logistic回归结果表明,调整基线抑郁症状、随访时年龄、性别、独生子女、家庭经济状况、父母离婚、BMI分类后,童年期情感虐待经历（OR=1.86,95% CI：1.03～3.36;P=0.039）和躯体虐待经历（OR=2.37,95% CI：1.39～4.03;P=0.001）增加青春期抑郁症状发生风险。结论 童年期情感虐待和躯体虐待可能增加青春期抑郁症状发生的风险。     

陕西省新生儿体表先天畸形的影响因素分析

目的 探讨陕西省新生儿体表先天畸形的影响因素。方法 采用分层多阶段随机抽样方法,通过问卷调查2010-2013年陕西省孕满28周且结局明确的育龄妇女及其生育子女的相关信息,采用多因素logistic回归分析新生儿体表先天畸形的影响因素。结果 多因素logistic回归分析结果显示,妊娠期肝内胆汁淤积症（OR=21.76,95%CI：4.46～106.25）、不良孕产史（OR=11.88,95%CI：9.14～15.45）、家族出生缺陷史（OR=6.15,95%CI：2.66～14.23）、双胎（OR=5.74,95%CI：3.34～9.86）、母亲为工人（与其他职业比,OR=2.47,95%CI：1.30～4.68）或农民（与其他职业比,OR=1.91,95%CI：1.14～3.20）、产检<4次（与产检>7次者比,OR=1.84,95%CI：1.28～2.64）、职业危险暴露（OR=1.74,95%CI：1.26～2.42）、母亲来自关中地区（与陕北地区者比,OR=1.65,95%CI：1.20～2.28）、母亲居住农村（OR=1.75,95%CI：1.13～2.71）、围孕期使用药物（OR=1.64,95%CI：1.26～2.13）是体表先天畸形的危险因素,而母亲围孕期服用铁剂（OR=0.46,95%CI：0.21～0.99）是体表先天畸形的保护因素。结论 母亲来自关中地区、农村、农民或工人、不良孕产史、家族出生缺陷史、双胎、产检<4次、职业危险暴露、使用药物、妊娠期患肝内胆汁淤积症可能增加新生儿体表先天畸形的罹患风险。     

江苏省心血管病高危人群颈动脉斑块流行及影响因素分析

目的 了解颈动脉斑块（CP）在江苏省心血管病高危人群中的流行概况及相关影响因素。方法 2015-2016年依托中国心血管病高危人群早期筛查与综合干预项目,以江苏省6个项目点筛查出的11 392名心血管病高危人群作为研究对象,进行问卷调查、身体测量、实验室检测以及颈动脉彩色超声检测,探讨CP的流行概况,对CP发生的影响因素进行多因素logistic回归分析。结果 研究对象年龄为（59.4±8.9）岁,男性4 821例（42.3%）。颈动脉异常5 971例（52.4%）,其中颈动脉内中膜增厚1 782例（15.6%）,CP 3 811例（33.5%）,颈动脉狭窄378例（3.3%）。高龄（OR=2.253,95%CI：2.127~2.386）、城市居民（OR=2.622,95%CI：2.375~2.895）、高血压（OR=1.439,95%CI：1.195~1.732）、吸烟（OR=1.441,95%CI：1.259~1.650）、脉压差增大（OR=1.270,95%CI：1.198~1.347）、FPG升高（OR=1.109,95%CI：1.059~1.161）、LDL-C/HDL-C升高（OR=1.225,95%CI：1.164~1.288）增加心血管病高危人群发生CP的风险,女性（OR=0.558,95%CI：0.494~0.630）、高BMI（OR=0.948,95%CI：0.904~0.994）、较高的文化程度（OR=0.708,95%CI：0.531~0.945）和较高的家庭年收入（OR=0.773,95%CI：0.669~0.894）则降低其风险。结论 江苏省超一半心血管病高危人群颈动脉异常,高血压、高血糖、高血脂和吸烟是相关影响因素。     

苏州市社区建成环境与居民体力活动的关联分析

目的 了解苏州市居民体力活动水平,探索社区建成环境与居民体力活动的关联。方法 2017年采用多阶段整群随机抽样方法抽取苏州市25~64岁常住人群进行面对面调查,采用国际体力活动量表长卷（IPAQ-L）评估居民体力活动水平,采用居民环境步行量表简表（NEWS-A）评价社区建成环境主观感知。结果 苏州市居民过去1周总体力活动水平M=3 610.42 MET-min/w,以工作相关体力活动水平为主,交通、家务及休闲相关体力活动水平较低。控制社会人口学因素后,公共服务可及性与社区居民的总体力活动水平呈负相关（OR=0.522,95%CI：0.329~0.830）,场所设施多样性与工作相关体力活动水平呈负相关（OR=0.701,95%CI：0.492~0.999）,步行和自行车道设施与工作相关体力活动水平呈正相关（OR=1.603,95%CI：1.004~2.559）;交通安全与交通相关体力活动水平呈负相关（OR=0.642,95%CI：0.416~0.990）;住宅密度与休闲相关体力活动水平呈正相关（OR=1.001,95%CI：1.000~1.002）;此外,社区美观与舒适的主观感知程度越高,工作、交通、家务及总体力活动水平越高（OR=1.889,95%CI：1.176~3.033;OR=1.671,95%CI：1.120~2.495;OR=1.775,95%CI：1.143~2.756;OR=1.593,95%CI：1.079~2.350）。结论 完善步行道和自行车道设施、提高社区的美观和舒适程度对于增加居民体力活动有重要作用。     

2015年我国35岁及以上高血压患者社区健康管理与高血压治疗控制情况分析

目的 了解2015年我国≥ 35岁高血压患者的社区健康管理及高血压治疗控制情况并探索其影响因素。方法 利用2015年中国成人慢性病与营养监测项目收集的问卷调查及体格测量等信息,以乡镇卫生院（社区卫生服务中心）或以上级别医疗卫生机构医生诊断为高血压的≥ 35岁的患者为研究对象,对样本进行复杂加权后,分析其一般特征、高血压社区健康管理情况及高血压治疗控制情况。结果 共纳入高血压患者23 974名,经复杂加权后,我国≥ 35岁高血压患者的社区健康管理率为54.10%（95%CI：51.02%~57.17%）,社区规范管理率为45.72%（95%CI：42.93%~48.51%）;高血压治疗率为88.16%（95%CI：87.00%~89.31%）,控制率为22.67%（95%CI：21.25%~24.09%）,治疗控制率为27.76%（95%CI：26.09%~29.42%）。多因素分析结果显示,城市和农村年龄≥ 65岁（OR=1.40,95%CI：1.05~1.87;OR=3.11,95%CI：2.22~4.36）、按医嘱服药（OR=2.15,95%CI：1.46~3.15;OR=1.35,95%CI：1.13~1.62）、进行血压监测（OR=2.34,95%CI：1.88~2.90;OR=3.10,95%CI：2.72~3.53）的高血压患者更愿意接受高血压社区健康管理;文化程度大专及以上（OR=0.51,95%CI：0.39~0.66）、适量饮酒（OR=0.69,95%CI：0.57~0.84）或过量饮酒（OR=0.73,95%CI：0.58~0.92）的城市高血压患者接受社区高血压管理的情况不佳。城市和农村超重（OR=0.74,95%CI：0.61~0.91;OR=0.83,95%CI：0.71~0.98）、肥胖（OR=0.54,95%CI：0.45~0.65;OR=0.67,95%CI：0.54~0.83）的高血压患者血压控制情况较差,按医嘱服药（OR=4.58,95%CI：3.16~6.63;OR=2.84,95%CI：2.18~3.69）的高血压患者的血压控制状况较好。地处中部（OR=0.74,95%CI：0.61~0.89）、过量饮酒（OR=0.72,95%CI：0.54~0.97）的城市高血压患者血压控制情况较差,合并其他慢性疾病（OR=1.22,95%CI：1.04~1.44）、参加高血压社区规范管理（OR=1.29,95%CI：1.06~1.58）的城市高血压患者血压控制情况较好;地处中、西部地区（OR=0.71,95%CI：0.58~0.87;OR=0.62,95%CI：0.47~0.80）、适量饮酒（OR=0.81,95%CI：0.67~0.98）、人均每日食盐摄入量>6 g （OR=0.80,95%CI：0.69~0.93）的农村高血压患者血压控制情况较差,进行血压监测（OR=1.38,95%CI：1.18~1.61）的农村高血压患者血压控制情况较好。结论 我国≥ 35岁高血压患者社区健康管理情况较之前有所改善,但是高血压控制情况距离相关政策指标还有一定差距。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

The occurrence of antimicrobial substances in toilet,sink and shower drainpipes of clinical units: A neglected source of antibiotic residues

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference.To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02?μg·L^?1 to a maximum of 79?mg·L^?1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.