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Biomedical subjects

T L Guidotti

Publications and source records attributed to T L Guidotti.

At least 19 recordsLinked to original sources
PubMed1999

Zinc exposure in Chinese foundry workers.

BACKGROUND: Inhalational exposure to zinc oxide fumes is associated with metal fume fever, a self-limited but very uncomfortable condition closely resembling influenza. Very little is known regarding the toxicokinetics of inhaled zinc, making the interpretation of zinc measurements in serum and urine problematic. METHODS: Twenty workers in a zinc foundry in Baiyin, Peoples' Republic of China, were investigated with serial examinations by a physician, chest radiographs, and spirometry. Exposure assessment consisted of the measurement of zinc in serum, urine, and personal air samples. RESULTS: No cases of metal fume fever were observed during the study period despite exposures to as high as 36.3 mg/m3 over less than 4 hr. In addition, no radiographic or functional changes were noted. Serum zinc levels of all workers were within the reference range and did not correlate with external exposure measurements. However, elevations were noted in urinary zinc levels, which showed a significant association (Spearman's correlation coefficient = 0.47, P = 0.04) between exposure to zinc and urine zinc. CONCLUSIONS: These results provide exposure measurements for zinc at which workers demonstrate tolerance to the development of metal fume fever. Furthermore, they suggest that urine may be the preferred biological medium for the assessment of zinc exposure.

Adult↗
PubMed1999

Differential sensitivity of lung and brain to sulfide exposure: a peripheral mechanism for apnea.

Acute exposure to hydrogen sulfide (H2S) causes 4 dose-dependent responses: hyperpnea, unconsciousness or knockdown, apnea, and death. At present, scientific mechanisms for these effects are unknown, but inhibition of cytochrome oxidase in the central nervous system (CNS) by sulfide has been suggested. In this study, the premise of brain as target is examined by comparing peripheral with direct delivery of sulfide to brain. NaHS was administered to anesthetized Sprague-Dawley male rats, by femoral intravenous, or carotid intra-arterial injection. With apnea as the test, ED100 values of 0.6 and 3.0 mg kg(-1) were found for peripheral and direct delivery to brain, respectively. Peripheral delivery is 5 times as effective as direct delivery to the brain, and greater if the relative dilution factors are considered. Lidocaine, applied to the vagus, prevented apnea, so lung-brain transmission was essential. It was therefore concluded that the lung is the peripheral site of action. Hyperpnea increased in duration with dose. The carotid body, located distal to the arterial catheter, sensed the high doses of NaHS but did not trigger apnea. Intravenous infusion or intraperitoneal injection with NaHCO3 prevented hyperpnea, apnea, and death. The following conclusions are drawn: the carotid body is not implicated in NaHS-induced apnea, the lung and not brain harbors the primary site of action of H2S, and an afferent neural signal from the lung via the vagus induces the apnea. Finally, NaHCO3 appears to prevent toxicity from sulfide, and therefore H2S, by some unexplained mechanism. Practical emergency treatment for acute toxicity in the field may be possible.

Anesthesia↗
PubMed1998

Variability in the classification of radiographs using the 1980 International Labor Organization Classification for Pneumoconioses.

This study describes the extent of agreement in classification of chest radiographs using the International Labor Organization (ILO) classification among six readers from the United States and Canada. A set of 119 radiographs was created and read by three Canadian and three US readers. The two ratings of interest were profusion (scored from 0/- to 3/+) and pleural abnormalities consistent with pneumoconiosis (scored with the ILO system, then collapsed into a yes/no). We used a number of approaches to evaluate interreader agreement on profusion and pleural changes, determining concordance, observed agreement, kappa statistic, and a new measure to approximate sensitivity and specificity. This study found that five of six readers had good fair to good agreement for pleural findings and for profusion as a dichotomous variable (> or = 1/0 vs < or = 0/1) using the kappa statistic, while a sixth reader had poor agreement. We found that concordance, expressed as percent agreement, was higher for normal radiographs than for ones that showed disease, and describe the use of the kappa statistic to control for this finding. This analysis adds to the existing literature with the use of the kappa statistic, and by presenting a new measure for "underreading" and "overreading" tendencies.

Humans↗
PubMed1997

Occupational medicine in Canada in 1996.

Occupational medicine in Canada presents many paradoxes and anomalies. This paper outlines the history, status, and current direction of occupational medicine in the country, with an emphasis on the unusual features of the Canadian experience.

Accreditation↗
PubMed1997

The changing role of the occupational physician in the private sector: the Canadian experience.

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.

Attitude of Health Personnel↗
PubMed1997

Interpretation of the trace metal analysis profile for patients occupationally exposed to metals.

Trace element profile analysis detects and quantifies the presence of several metals simultaneously at low concentrations in the body. In occupational medicine, it may be used to monitor exposure or to evaluate suspected toxicity. Clinical interpretation is often difficult because, with the exception of lead and possibly cadmium, there is little firm information on toxicity thresholds. For these tests, the reference ranges typically reflect low levels of exposure in the general population and it is expected that workers handling metals in occupations such as welding and industries such as steelmaking will have higher levels. Interpretation requires some knowledge of the toxicokinetics of the metal of interest and the preferred medium for analysis for each: serum, whole blood or urine (preferably 24-hour collection). Trends are often more informative than concentrations at one time. Trace element values are reported together with a reference range which must be distinguished from the normal range of other clinical tests. As a practical matter, the greatest interpretation problems tend to be found with manganese because serum levels have a poor correlation with both recent exposure and neurological symptoms. Molybdenum and vanadium are often found to be elevated among workers exposed to metals who show no evidence of clinical illness. Interpretation of the trace element profile analysis overall when an elevation occurs generally requires close attention to the pattern of elevation, clinical context, absolute and relative magnitude of the elevation and knowledge of the exposure history.

Data Interpretation, Statistical↗
PubMed1997

Occupational medicine in Canada and Poland in the 1990s.

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.

Canada↗
PubMed1996

An international registry for toxic inhalation and pulmonary edema: notes from work in progress.

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.

Administration, Inhalation↗
PubMed1996

Considerations for regional health authorities in the provision of environmental health services.

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.

Alberta↗
PubMed1996

The Fort McMurray Demonstration Project in social marketing: health- and safety-related behaviour among oil sands workers.

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.

Adult↗
PubMed1996

Hydrogen sulphide.

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.

Animals↗
PubMed1995

Managing environmental research in a government agency: priorities in chemical hazards.

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.

Canada↗
PubMed1995

Occupational injuries in Alberta: responding to recent trends.

General patterns of injury in the Alberta workplace are reflected in figures from the Workers' Compensation 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Occupational↗
PubMed1995

Occupational health in China: 'rising with force and spirit'.

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.

China↗
PubMed1995

Occupational mortality among firefighters: assessing the association.

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.

Cardiovascular Diseases↗