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The role of the occupational physician in the private sector is changing. Fewer large corporations maintain medical departments following the 'downsizing' trend of the late 1980's and early 1990's and those that do have extensively redefined the duties of the corporate medical director, often extending these duties to include responsibility for environmental health. Occupational medical services for employees previously covered by in-house services are now often provided by outsourcing. The private practice of occupational medicine has become the major growth area of the specialty in both the US and Canada. These trends have been driven primarily by economic imperatives and new management philosophies; the trend may have gone too far and a 'rightsizing' correction may be in progress. However, it is not clear that corporations in general are deriving the greatest value they can from their physicians or that the current generation of senior managers is utilizing its health professionals as effectively as they might. This is in part because the training, qualifications and capabilities of occupational physicians are not well understood. At least as important, however, is persistent confusion over desirable and appropriate roles that obscures the potential contribution of the medical professional within a management structure. We suggest that the greatest value in occupational medical services may be in the anticipation of risk related to health issues and the flexibility this gives the organization to manage the problem.

As population health programs, environmental health services differ fundamentally from other forms of health service delivery. At a time when the health sector is striving for integration, the incorporation of these unique services into the delivery system presents a unique challenge to policy makers and administrators across the country. The University of Alberta recently completed a comprehensive review and redesign of locally governed and delivered environmental health protection services in Alberta. This paper outlines the key issues and unique features surrounding the delivery of environmental health services and presents the study team's suggested approach to addressing these issues.

The effect of thrombopoietin (TPO) on the functional activity of surface alpha IIb beta 3 (GPIIbIIIa) was investigated in both primary human megakaryocytic cells, derived from peripheral blood CD34+ cells, and HEL hematopoietic cell line. TPO (100 ng/mL) induced a sixfold to ninefold enhancement of adhesion of both primary megakaryocytic and HEL cells to plates coated with either fibrinogen or fibronectin and a parallel increase of immunoreactivity to the PAC1 monoclonal antibody (MoAb) and fluorescein isothiocyanate-fibrinogen, both of which recognize an activated state of alpha IIb beta 3. The enhanced adhesion to fibrinogen or fibronectin was mediated by the Arg-Gly-Asp (RGD) recognition sequence of alpha IIb beta 3, as it was abolished by pretreatment of cells with saturating concentrations of RGDS peptide. A MoAb specific for the alpha IIb beta subunit of alpha IIb beta 3 also inhibited cell attachment to fibrinogen or fibronectin, while MoAb to anti-alpha v beta 3 or anti-alpha 5 integrins were completely ineffective, clearly indicating that alpha IIb beta 3 participates in this association. A role for PI 3 kinase (PI 3-K) in the TPO-mediated increase in alpha IIb beta 3 function in megakaryocytic cells was suggested by the ability of the PI 3-K inhibitor wortmannin (100 nmol/L) and antisense oligonucleotides directed against the p85 regulatory subunit of PI 3-K to completely block the TPO-induced increase in alpha IIb beta 3 integrin activity upon TPO stimulation. The modulation of adhesiveness to extracellular matrix proteins containing the RGD motif mediated by TPO likely plays a physiologic role in megakaryocytopoiesis, as pretreatment of CD34+ cells with RGDS or anti-alpha IIb MoAb significantly reduced the number of megakaryocytic colonies obtained in a fibrinclot semisolid assay.

An important part of the new thinking about asthma is control of preventable risk factors, air pollution among them. The epidemiological evidence that ground-level ozone, in particular, is an important risk factor for provoking asthmatic attacks is strong. however, the evidence that it increases the prevalence of asthma overall, or mortality from asthma at levels frequently encountered in the developed world is lacking. The mechanism of airway response to ozone may be complex, involving modification of the atopic response to an antigen, rather than simple inflammation. Likewise, there may be many complexities in assessing the mechanism of association between exposure to air pollution and airways exposure, including susceptibility states, comorbidity from respiratory disorders, tolerance, and the attack rate for common viral infections. Some jurisdictions have proposed to use the frequency of asthmatic episodes as a means to set air pollution standards. The current state of the art, for many of these same reasons, does not support this. Progress will require mechanistic as well as population based research and broader thinking in the analysis of available data. Two hypotheses that especially require critical testing are age-dependent sensitization as a risk factor for asthma, and gradient-threshold response to irritant exposures.

Canada and Poland share many demographic and economic characteristics: both countries are relatively large, urbanised, historically dependent on extractive industries, and comparable in population. The principal differences reflect their recent histories and economic systems. We compare the development of occupational medicine in each country and the historical forces that shaped the specialty in each country. We describe certain features of the Canadian occupational health system that may be of interest and propose a program of scientific cooperation for mutual benefit.

Background Due to the high toxicity of anticancer drugs and their low therapeutic index, any errors in anticancer drug treatment can cause serious injury, even at approved doses. For this reason it is necessary have some national guidance to prevent errors during anticancer treatment. Purpose To prevent errors in anticancer drug treatment, the Ministry of Health has developed a specific Recommendation addressed to healthcare workers (physicians, pharmacists and nurses). Materials and Methods A working group consisting of pharmacists, oncologists, nurses, psychologists and patients representatives was set up. The same format of Recommendations made by MoH for Patient Safety was followed. Results The Recommendation is addressed to Regions, Health facilities, clinical risk managers, healthcare workers; it finds application inside the Medical Oncology and Haematology Units of private and public hospitals, inside hospital pharmacies and at the patient’s home. The Recommendation is to protect patients needing anticancer drug treatments. Highlight: the hospital should provide working instruments and develop a procedure including all instructions for proper anticancer drug management. They also have to: draw up a Patient Safety Training Plan, promote communication and integration among health professionals, provide accurate and complete information to patients and their families, consider the psychological and emotional state of patients and give detailed indications for the delivery of drugs at discharge. Conclusions The Recommendation is a reference for health professionals involved in handling anticancer drugs, providing information about the patient’s objectives and expected benefits from treatment. The document provides guidance aimed at preventing errors that can occur during anticancer drug treatment and includes recommendations encouraging the promotion of clinical governance. A verification of this Recommendation is expected soon. Many experts gave their suggestions to facilitate its implementation. No conflict of interest.

This book is a long-overdue history of air pollution in Los Angeles. It will be a helpful reference for anyone interested in this long, fascinating, and seminal story, which is central not only to ...

Hydrogen sulphide (H2S) is the primary chemical hazard in natural gas production in 'sour' gas fields. It is also a hazard in sewage treatment and manure-containment operations, construction in wetlands, pelt processing, certain types of pulp and paper production, and any situation in which organic material decays or inorganic sulphides exist under reducing conditions. H2S dissociates into free sulphide in the circulation. Sulphide binds to many macromolecules, among them cytochrome oxidase. Although this is undoubtedly an important mechanism of toxicity due to H2S, there may be others H2S provides little opportunity for escape at high concentrations because of the olfactory paralysis it causes, the steep exposure-response relationships, and the characteristically sudden loss of consciousness it can cause which is colloquially termed 'knockdown.' Other effects may include mucosal irritation, which is associated at lower concentrations with a keratoconjunctivitis called 'gas eye' and at higher concentrations with risk of pulmonary oedema. Chronic central nervous system sequelae may possibly follow repeated knockdowns: this is controversial and the primary effects of H2S may be confounded by anoxia or head trauma. Treatment is currently empirical, with a combination of nitrite and hyperbaric oxygen preferred. The treatment regimen is not ideal and carries some risk.

This is the first round in a series of surveys conducted in Fort McMurray as part of the Fort McMurray Demonstration Project in social marketing. This component of the survey was intended to focus on the most prominent group of employed workers in the community and to compare their patterns of response with the community as a whole. Respondents to the survey were overwhelmingly male (96%), married (72.9%) and living in households of two to five persons (87.9%). They were predominantly aged 30-44 (55%) and graduates of high school (53.5%). Younger male workers (below age 30) were more likely to have a high school diploma (78.3%) or some additional technical or vocational training (21.7% compared to 12.5% overall) and to be unmarried or separated. Attitudes toward safety-related behaviours were stronger than for respondents from the community as a whole. Approximately 70-100% of all age groups and both sexes showed strong agreement with attitudes involving child car seats and the unacceptability of drinking and driving. These attitudes include strong advocacy of vigorous enforcement of occupational health and safety standards. However, they showed a variability similar to the community as a whole in behaviour at home compared to work, generally reporting more consistent use of personal protection on the job than in their own homes, particularly hearing protection. Even so, they were much less likely to perform stretching and warm-up exercises prior to exertion than community residents in general. The potential may exist to transfer the technology and attitudes from workplace health and safety to community safety. One possible strategy to accomplish this is to involve workers in this industry directly in community initiatives. This strategy may be generalizable to any community in which there are major employers who place a heavy emphasis on risk control and occupational health and safety.

Preventive medicine is an exciting specialty that is often blocked in its progress by internal conflicts and external obstacles. We can all change this state of affairs. I present and compare definitions of important terms to clarify the discussion. Structural problems of the specialty include, among others, fragmentary representation, unfocused academic departments, lack of control over professionalization, and specialty identification, particularly with respect to occupational medicine. A set of suggested solutions to these problems include these actions: (1) federate the leading organizations into a coalition for organizational strength, without sacrificing their individual identities; (2) define the core content of the specialty once and for all by the mechanism of consensus-driven competency-based learning objectives; (3) build stronger bridges to clinical specialties other than family medicine, particularly to internal medicine; (4) restructure academic departments to form a preventive medicine unit as such, encouraging health care research and community medicine to connect principally with family medicine departments; (5) rethink specialty certification, including a model defining a knowledge and skills set in defined modules, which would be combined in various ways to support flexible specialty certification; and (6) integrate occupational medicine with preventive medicine generally by exploring issues of common interest and building closer institutional ties when the opportunity arises. These and other ideas might be discussed by the leadership of the principal public health and prevention organizations at a "summit" meeting, but some group must take the initiative to champion the cause. Medical Subject Headings (MeSH): preventive medicine, future, definitions, specialty certification, community medicine, population medicine.

Acute toxic inhalation by irritant, and particularly oxidant, gases has until recently been considered to be no more complicated conceptually than a chemical burn of the epithelial surface. More recently, however, toxic inhalation has been appreciated to be a complex process involving biochemical, morphological and functional changes which are quantitatively similar, although inducible by different agents. Recent advances in pulmonary pathophysiology, inhalation toxicology, and particularly endothelial biology have clarified the events occurring at the moment of, and immediately following, exposure to oxidant gases. Studies of the pathophysiologic mechanisms associated with toxic inhalation by oxidant gases have been relatively static, however. Implications of recent findings in related fields illuminate the pathophysiology of toxic inhalation. Several principal speakers in this workshop are collaborating in an effort to develop a research facility for the study of toxic inhalation injury. This would be an international registry to serve as a teaching and research facility for documentation of cases of occupational and environmental toxic inhalation, considered as lung injury resulting from the inhalation of a toxic substance in a workplace setting or an uncontrolled release affecting residents of a community. The registry, as proposed, would encourage submissions by clinicians and institutions of a data set on each patient and on each incident; the registry would further encourage long-term follow-up of subjects and documentation of residual effects.

Because of their occupational exposure to a variety of toxic agents, fire fighters may be at risk for a number of exposure-related diseases. We reviewed the current literature on disease risk among fire fighters to compare findings and to infer magnitude of risk. A standard mortality ratio (SMR) of 200 is equal to an attributable risk of 100% of expected, sufficient to justify presumption in most workers' compensation systems that accept this. We therefore concentrated on risks that approach or exceed an SMR of 200 or an equivalent risk estimate, bearing in mind that confidence intervals around these estimates are wide. Based on the criteria for presumption of occupational risk, we suggest the following conclusions with respect to general presumption of risk: (1) Lung cancer: There is evidence for an association but not of sufficient magnitude for a general presumption of risk. (2) Cardiovascular. There is no evidence for an increased risk of death overall from heart disease. Sudden death, myocardial infarction, or fatal arrhythmia occurring on or soon after near-maximal stress on the job are likely to be heart related, but such "heart attacks" occurring away from work cannot be presumed to be work related. (3) Aortic aneurysm: The evidence is incomplete for an association, but if an association does exist, it would probably be of a magnitude compatible with a general presumption of risk. (4) Cancers of the genitourinary tract, including kidney, ureter, and bladder: The evidence is strong for both an association and for a general presumption of risk. (5) Cancer of brain: Incomplete evidence strongly suggests a possible association at a magnitude consistent with a general presumption of risk. (6) Cancer of lymphatic and hematopoietic tissue: By group, there is some evidence for both an association and a general presumption or risk. However, the aggregation is medically meaningless. We therefore recommend a case-by-case approach. (7) Cancer of the colon and rectum: There is sufficient evidence to conclude that there is an association but not that there is a general presumption of risk. (8) Acute lung disease: Unusual exposures, such as exposure to the fumes of burning plastics, can cause severe lung toxicity and even permanent disability. This does not appear to result in an increased lifetime risk of dying from chronic lung disease. Language: en

Occupational health services in China occupy a much more central role in public life than they do in North America. The Communist ideology on which the People's Republic was built, and which it almost alone today defends, places an idealized concept of the worker at the centre of the economic, social and political system. The present system in China is a parallel, institutionally separate system of medical care and research on occupational disorders that is in some ways better provided for with resources than the general healthcare system. One of the issues facing China today is how to turn the priorities of this vast, elaborate and incompletely developed system of occupational health care away from the provision of medical care to workers made ill from workplace exposure and towards prevention of the exposures that made them ill in the first place. The prevalence of smoking and the intensity of passive smoke exposure in Chinese workplaces make this exposure one of the most deadly occupational hazards seen. This problem of health promotion can probably only be effectively approached in China by worksite programmes but these are not apparent.

General patterns of injury in the Alberta workplace are reflected in figures from the Workers' Compensaton Board, which reliably enumerates acute injuries but not necessarily chronic musculoskeletal conditions. Roughly one-quarter of these injuries are to the back and neck. The absolute number of injuries is of interest in terms of the overall problem of injury in the workplace, but the rate of injury is used to set priorities for intervention among industries. The injury rate identifies industries at greatest risk given the size and activity of their workforce. Using rates, industries can be classified as high or low risk. Over time, claim rates for the major industrial sectors have been fairly stable. Rates from 1987 and 1988 were used in setting provincial government initiatives to control injury frequency and severity and are examined in this report. Construction is clearly a high-risk industry. It involves many trades and operations that have an inherently high risk. The situation is different for the manufacturing sector. This also has a very high injury experience. However, unlike construction, the risk is concentrated in one sub-industry- meat and poultry packing. As a single sector, oil and gas has a low risk. When the industry is broken down into its component functions, however, the oil and gas exploration, drilling and servicing components are clearly out of line with the rest of the sector. Risk is highly concentrated in these sub-industries. Data from Alberta confirm that smaller employers generally have a higher injury risk than larger employers. However, smaller businesses are the norm in many high-risk industries in the province, such as servicing wells, wildcatting, cutting timber, and small-scale construction. Ideas about what causes injuries change over time. An approach to injury control borrowed from epidemiology and public heath has been accelerating since the 1980s. Safety professionals try to find common factors among unrelated injury trends, then look for solutions to common causes. This approach accepts risks as inevitable but manageable and accommodates the idea of unified management of injury, loss, liability, costs, and exposure to risk. This is the philosophy towards which Alberta seems to be moving. It is suggested that, in the past, safety was not considered to be as much a societal value as it is today, and that risk-taking behaviour was more widely tolerated as a cultural norm

In 1993, I served as consultant to a Canadian government agency with responsibility for the characterization of chemical hazards. The work was divided into three tasks: (1) an extensive review of present priorities within the agency, (2) a survey of recognized experts to determine perceived "gaps" in the coverage of research on chemical hazards, and (3) preparation of a set of recommendations. The 23 perceived gaps identified by the expert panel cluster into three general groups: existing projects designed to protect the health of Canadians, practical solutions to concrete problems, and robust methods for dealing with chemical mixtures and generalizable research methodology. A specific set of priorities was recommended to the agency and several procedural changes were proposed: encouragement of working partnerships, a mechanism for ongoing review of priorities, and consideration of alternatives to dedicated research projects, such as emphasizing behavioral rather than toxicological studies on tobacco smoke. A research management system was also proposed based on a matrix organization in which accountability is not divided but which features research-driven cross-program interdisciplinary colloquia within the agency. The general approach and specific findings in this study may be useful in clarifying issues in the management of other, similar agencies.

We studied the responses of leaders in a suburban community in western Canada near Edmonton, Alberta, that was affected by a false allegation of increased cancer risk. In 1986, a cancer agency responded to community concerns by conducting a study of cancer incidence (1979-1983) and reported elevations on the order of 25 per cent over expected for most sites. Reanalysis of these data several months later revealed an error in the population figure used to calculate the rates. Correction brought the rates into line with Alberta as a whole and comparable to those for other communities surrounding Edmonton. We interviewed elected and appointed public officials in one affected community as well as non-official community leaders and realtors to determine their subjective impression regarding the effect of the incident on their communities and to rule out alternative explanations for the drop in housing prices in association with the incident we have reported elsewhere. Their narrative responses were particularly interesting and articulate, and are quoted at length. Their collective perceptions appear to confirm the impression of a profound impact on the community, reflected in housing prices, and attribute at least part of the impact to the disclosure that a high official in the community was afflicted by cancer. Most felt that there remained a great deal of latent concern in the community and at least some felt that a subsequent public issue involving transmission line rights-of-way near the community reactivated this latent concern.

By incorporating the principles of occupational medicine into their practices, physicians can better help those patients with job-related disorders and can improve the management of patients whose non-work-related conditions have implications for their employment. This article focuses on occupational history, physical examination skills, investigation of work sites, risk assessment, screening and surveillance, fitness-to-work evaluations and disability assessment, administration, prevention, health education and general communication, and ethical issues.

Occupational exposure to hydrogen sulfide (H2S) and the medical management of H2S-associated toxicity remains a problem in the sour gas industry and some other industrial settings. The acute effects of exposure to H2S are well recognized, but accurate exposure-response data are limited to acutely lethal effects, even in animal studies. Odor followed by olfactory paralysis and kerato-conjunctivitis are the characteristic effects of H2S at lower concentrations. H2S-induced acute central toxicity leading to reversible unconsciousness is a “knockdown”; it is controversial whether repeated or prolonged knockdowns are associated with chronic neurologic sequelae but the evidence is suggestive. Knockdowns can be acutely fatal as a consequence of respiratory paralysis and cellular anoxia. Pulmonary edema is also a well-recognized acute effect of H2S toxicity. Human studies of sublethal exposure with satisfactory exposure assessment are almost nonexistent. There are indications, poorly documented at present, of other chronic health problems associated with H2S exposure, including neurotoxicity, cardiac arrhythmia, and chronic eye irritation but apparently not cancer. Rigorous and comprehensive studies in the sour gas industry are difficult, in part because of confounding exposures and uncertain end points.

Interpretation of longitudinal trends in asthma incidence, prevalence, and mortality must assume consistency in the diagnostic criteria used by clinicians. This review samples the textbook and clinical literature on clinical recognition and diagnosis of asthma from Laënnec (1819) to the National Asthma Education Program (1991), which introduced as a standard for clinical care a set of diagnostic criteria based on laboratory confirmation. There is great consistency among authors in descriptions of the cardinal diagnostic criteria of asthma as episodic dyspnea punctuating periods of normal breathing, generally associated with expiratory wheezing and prolonged expiration. In contrast, there is much greater variation in the formal definitions or explanations of the presumed pathophysiology of the disorder. It is much more difficult to document the actual diagnostic criteria used by practicing clinicians in the past, but these findings indicate a high degree of consistency over 172 years in what was taught and was considered acceptable practice. The literature on asthma contains several medical classics, a few gems of insight, and some unusual authors; some of these are noted in the discussion, as is the strong tradition of reciprocity in American and British medicine.

Environmental risk management is facing a crisis. The number of recognized environmental hazards has clearly outstripped the resources available to do detailed studies on each or to establish effective control measures for each on an individual basis. Some method of prioritizing environmental hazards is required that does not involve detailed and individualized quantitative risk assessment. An alternative approach that has gained favour in recent years has been "risk comparison", as sponsored by the U.S. Environmental Protection Agency and as applied in several American states and local communities. Risk comparison is an approach that involves expert panels and the interested public in a consultative and iterative process leading to widespread agreement, if not consensus, on the relative rankings of often disparate environmental hazards. An outline of steps in the process formulated by the Northeast Center for Comparative Risk at the Vermont Law School is presented with commentary regarding its applicability to the Canadian scene. Implicit tradeoffs in risk comparison are also explored, including emphasis on categorical hazards v. media quality, magnitude of hazard v. population affected, ecological integrity v. human health, social concern v. scientific assessment, and novel v. familiar hazards. In practice, risk comparison is a process-oriented and often tedious approach, but it represents one way out of the current conundrum in dealing with environmental hazards.

Environmental and occupational epidemiology are in the tradition of "critical science." Critical science is a mode of science in which scientific methods are used to critique the adverse consequences of technological development. Critical science should be explicitly recognized as a paradigm in interdisciplinary research. It is the "mode" in which environmental and occupational epidemiology function and the role that these and related disciplines play in society. As the feedback to society on the performance of technology, critical science has assumed a major role in modern society by providing an acceptable critique of technological development. The close association between scientific research and technology of the last three and one-half centuries has been the exception to the historical rule. Intelligent guidance of technology in modern society makes public participation and education in scientific, biomedical, and technical affairs imperative. Critical science in its interdisciplinary dimension is imperative to this public process. Truly interdisciplinary work can only be accomplished when the disciplinary underpinnings are strong and when individual investigators are encouraged to pursue their individual priorities. Critical science is no exception and requires encouragement of skepticism on the part of the investigator toward conventional assumptions.

Mortality from asthma has been reported to be increasing in recent years in many countries, including Canada. Alberta, and the prairie provinces generally, appear to have an excess of deaths from asthma compared to other provinces. We studied mortality from asthma and from chronic obstructive pulmonary disease (COPD) generally in Alberta between 1927 and 1987 using a data set compiled and recorded from Alberta Vital Statistics to describe birth cohorts' age-specific mortality rates. We also present the distribution of deaths in the years since 1987. There was a clear and sustained increase in mortality from COPD since 1950 after age 40 but no evidence to support the proposition that deaths from asthma were increasing in recent years; more recent data from Alberta Vital Statistics show no sustained increase since 1987, either. There was great variability from year to year and sporadically increased rates in a given year that were not sustained. These transient increases were observed particularly among females aged 10-14, 15-19, and 25-29 and among males aged 15-19, 25-29, and 80-84; however, there were also comparable decreases in asthma mortality of similar magnitude during the same time period in different age groups or in the other sex in the age group 10-14. We conclude that there is no excess of deaths from asthma over those expected by historical trends in Alberta at the present time but that the smoking-related epidemic of deaths from COPD continues unabated. The "smoothness" and consistency of the mortality trends suggest that physicians certifying deaths from these causes are using implicit diagnostic criteria that have not changed abruptly.

The mortality experience of firefighters has been an active topic of investigation. Collateral toxicological evidence suggests that certain causes of death are likely to be associated with firefighting: lung cancer, heart disease, and obstructive pulmonary disease. To date there has not been a clear and consistent demonstration of excess risk due to occupational exposure for these outcomes, but certain other cancers, including genitourinary, colon and rectum, and leukemias, lymphomas, and myeloma, appear to be consistently elevated. A major unproven hypothesis is that risk increased following the introduction, in the 1950s, of combustible plastic furnishing and building materials known to generate toxic combustion products. Mortality by cause of death was examined for two cohorts totalling 3,328 firefighters active from 1927 to 1987 in Edmonton and Calgary, the two major urban centers in the province of Alberta, Canada, examining associations with cohort (before and after the 1950s) and years of service weighted by exposure opportunity. The study attained 96% follow-up of vital status and over 64,983 person-years of observation, yielding 370 deaths. Mortality from all causes was close to the expected standardized mortality ratio (96; 95% confidence limits (CL) 87, 107) as was that for heart disease (110; 95% CL 92, 131), and neither was statistically significant at the p < 0.05 level (N.S.). Excesses were observed for all malignant neoplasms (127; 95% CL 102, 155, p < 0.05) and for cancer of lung (142; 95% CL 91, 211, N.S.), bladder (315; 95% CL 86, 808, N.S.), kidney and ureter (414; 95% CL 166, 853, p < 0.05), colon and rectum (161; 95% CL 88, 271, N.S.), pancreas (155; 95% CL 50, 362, N.S.) and leukemia, lymphoma, and myeloma (127; 95% CL 233, N.S.); obstructive pulmonary diseases (157; 95% CL 79, 281, N.S.). Fire-related causes showed a marked excess (486; 95% CL 233, 895, p < 0.01), but external causes overall showed a marked excess (486; 95% CL 233, 895, p < 0.01), but external causes overall showed a significant deficit (66; 95% CL 49, 87, p < 0.05). The lung cancer excess was confined to Edmonton; there was no consistent association with duration of employment, exposure opportunity, or cohort of entry (before or after the 1950s) except that the highest risk was observed among Edmonton firefighters with over 35 weighted years. The excess of cancers of the urinary tract was observed mostly among firefighters entering service after 1950, appeared to increase with length of service and exposure opportunity, and was observed in both cities. An occupational association with heart disease and chronic pulmonary disease is not supported in this study on this population. An effect on lung cancer is not obvious, but may be present in the highest exposure group; a weak effect for lung cancer confounded by stronger effects cannot be ruled out. Associations of firefighting with cancers at genitourinary sites and with fire-related injury are strongly suggested in this population. © 1993 Wiley-Liss, Inc.

Urban bus drivers are exposed to a variety of discomforts and physical hazards associated with their occupation. We obtained death certificates for 99 per cent of 219 decreased members of the Amalgamated Transit Union Local 596 of Edmonton, Alberta, and conducted a proportionate mortality study against the distribution of all deaths among men in the province of Alberta, standardized by age and year of death. We found a highly significant excess from undetermined accidents due to gas (proportionate mortality ratio (PMR) 3761, based on 3 cases; p less than 0.003), which may bear a relationship to an elevation observed for suicide due to gas, which failed to achieve statistical significance (PMR 242, based on 2 cases). Collateral evidence suggests that this excess may include misclassification of some suicides. Gas inhalation as an instrument of suicide may be suggested by familiarity with vehicle exhaust. No other excess achieved statistical significance. Several causes of death showed elevated PMRs of relatively modest magnitude; elevations in PMR for lung cancer (PMR 154) and chronic obstructive pulmonary disease (PMR 176) suggest a mutual association with smoking.

Repetitive strain injuries include a group of disorders that most commonly develop in workers using excessive and repetitious motions of the neck and upper extremity. A careful occupational history, physical examination and specific diagnostic maneuvers can help distinguish these musculoskeletal injuries from rheumatologic diseases, psychologic disorders, acute joint or tendon inflammation from other causes and single-event traumatic sprains and strains. Repetitive strain injury may be manifested by cervical syndrome, tension neck syndrome, thoracic outlet syndrome and frozen shoulder syndrome. Common injuries involving the elbow, wrist and hand include epicondylitis, carpal tunnel syndrome and ulnar nerve entrapment. Conservative treatment consisting of rest, application of ice or heat and anti-inflammatory drugs is usually effective, but the injury may take weeks or months to resolve. Modifications in the workplace can prevent many of these injuries and may be required to prevent reinjury after the patient returns to work.

The Canadian province of Alberta is a major world producer of oil and gas. It is therefore vested in issues of air quality and health, which are in turn driven by fossil fuel combustion. The scientific community within the province provides the capacity to address these issues and in order to remain current needs to be actively engaged in research. Air quality is generally very good in Alberta. The reason to support a scientific capacity is to better address economic and ecological sustainability for the future of a province that is economically dependent on fossil fuels. However, the history of air quality studies in the province is mixed.

Two suburban communities in western Canada, with a combined population of 52,000, were affected by a false allegation of increased cancer risk. In 1986, a cancer research agency responded to community concern by conducting a study of cancer incidence (1979 to 1983) and reported elevation on the order of 125% of expected for most sites. Reanalysis of these data several months later revealed an error in the population figure used to calculate the rates. Correction brought the rates into line with Alberta as a whole and comparable to other communities surrounding Edmonton. National media reported the cancer excess but did not report the correction. A Joint Advisory Committee convened at the time by the Minister responsible was a valuable resource for public education. This case study may be useful in the instruction of students and as an example of clerical errors that can indirectly affect an otherwise useful study. Residents of two nearby communities in northern Alberta became concerned about an apparently elevated rate of cancer among adults in their area. Many speculated on an association with the concentration of refineries in eastern Edmonton and petrochemical facilities outside the city in one of the communities. In 1986, the responsible provincial agency conducted a preliminary study of cancer incidence in the area compared to Alberta as a whole. The findings were summarized in a draft document which became widely circulated, although it was never intended to be the definitive report. It was "leaked" from a high government office and became the basis for numerous news stories. A reanalysis of these data revealed that the population figure used to calculate the combined cancer rates for the two communities was valid only for one of them and not the two combined. Correction of this mistake brought the calculated rates into line with those for Alberta as a whole. The original error was shown to be one of interpreting a confusing set of tables that lacked specific instructions and is not likely to be repeated. The original study is now invalidated. Reference to its findings should be made only as it has affected recent local history and public concern. There is certainly no evidence for a serious chemical threat to the health of residents of the area today in the present study and no suggestion of an occupational or environmental factor at work in the past.

Numerous chemicals are used in various processes of the oil and gas industry: drilling, cementing, completion, stimulation, and production. The number and the complexity of composition of process chemicals has increased greatly over the last three decades. The occupational hazards of exposure to these agents has received little attention. We reviewed the various processes in the industry, the type of chemicals used in each process, and some of their characteristics. We placed emphasis on those for which significant toxicity has been established or is suspected, and those for which there is incomplete information on their chemistry and health hazards. This report is intended to form a basis for a more complete survey of the process chemicals, and to draw attention to the possibilities for toxic exposure resulting from use of these agents in the oil and gas industry. The ultimate objective is to promote the safe use of these agents in the industry.

Comparatively little attention has been given to the health implications of global ecological changes on human health, with the exception of concern over ozone depletion leading to an increased frequency of ultraviolet irradiation-induced skin cancer and cataracts. The implications for human health of five large-scale ecological disruptions were explored: climate change (greenhouse effect), ozone depletion, acid precipitation, transregional pollution, and demographic changes. Limitations of presently available data and the uncertainty of current interpretations of apparent trend is emphasized. Rigorous assessment of the effects of these changes and the response required from public health professionals is needed. This overview provides a point of departure.