[Mesothelioma and acceleration]

INTRODUCTION

Taking a publication by Berry in 2007 (3) as a cue, this paper presents in didactic form the topic of acceleration of events as a consequence of a harmful exposure and extends the proposed approach to the case of the asbestos-mesothelioma relationship.

METHODS

Berry's approach was applied to lung cancer and mesothelioma data.

RESULTS

The effects of the acceleration of events are presented as a function of age at onset in exposed subjects, relative risk, scale factor, in addition to age and geographical variability of the relationship between age and mesothelioma rates.

DISCUSSION

The discussion regards the general characteristics of the method of acceleration, its meaning and interpretation, and the difficulties associated with its application in the context of diseases with low occurrence; the conditions, applicability constraints, and specific results in the case of mesothelioma; the epidemiologic meaning of acceleration and the difficulties of its extension to individual subjects.

III Italian Consensus Conference on Malignant Mesothelioma of the Pleura. Epidemiology, Public Health and Occupational Medicine related issues

The III Italian Consensus Conference on Pleural Mesothelioma (MM) convened on January 29th 2015. This report presents the conclusions of the 'Epidemiology, Public Health and Occupational Medicine' section. MM incidence in 2011 in Italy was 3.64 per 100,000 person/years in men and 1.32 in women. Incidence trends are starting to level off. Ten percent of cases are due to non-occupational exposure. Incidence among women is very high in Italy, because of both non-occupational and occupational exposure. The removal of asbestos in place is proceeding slowly, with remaining exposure. Recent literature confirms the causal role of chrysotile. Fibrous fluoro-edenite was classified as carcinogenic by IARC (Group 1) on the basis of MM data. A specific type (MWCNT-7) of Carbon Nanotubes was classified 2B. For pleural MM, after about 45 years since first exposure, the incidence trend slowed down; with more studies needed. Cumulative exposure is a proxy of the relevant exposure, but does not allow to distinguish if duration or intensity may possibly play a prominent role, neither to evaluate the temporal sequence of exposures. Studies showed that duration and intensity are independent determinants of MM. Blood related MM are less than 2.5%. The role of BAP1 germline mutations is limited to the BAP1 cancer syndrome, but negligible for sporadic cases. Correct MM diagnosis is baseline; guidelines agree on the importance of the tumor gross appearance and of the hematoxylin-eosin-based histology. Immunohistochemical markers contribute to diagnostic confirmation: the selection depends on morphology, location, and differential diagnosis. The WG suggested that 1) General Cancer Registries and ReNaM Regional Operational Centres (COR) interact and systematically compare MM cases; 2) ReNaM should report results presenting the diagnostic certainty codes and the diagnostic basis, separately; 3) General Cancer Registries and COR should interact with pathologists to assure the up-to-date methodology; 4) Necroscopy should be practiced for validation. Expert referral centres could contribute to the definition of uncertain cases. Health surveillance should aim to all asbestos effects. No diagnostic test is recommended for MM screening. Health surveillance should provide information on risks, medical perspective, and smoking cessation. The economic burden associated to MM was estimated in 250,000 Euro per case.

[Health expenditures for cases of pleural mesothelioma]

Through the study of 65 cases of probable pleural mesothelioma currently under discussion in 4 criminal trials in the Lombardy Region, who died between 2002 and 2015, this study aimed to provide economical information regarding the health expenditures sustained by the Regional Health Service (RHS) for providing hospitalization, outpatient services and drugs to such patients. Health information regarding the services provided for the cases under study were electronically retrieved from the RHS information system. For each pleural mesothelioma case the costs (on average) were about 67,000 euros, 37,000 of which were spent after the date of diagnosis. Drugs formed the largest part of health expenditure (about 37,000 euros per person). Per capita expenditures showed a peak near (before and after) the date of diagnosis, rising when approaching the date of death and with increasing age of the patient, and did not vary with survival time. This information, reported for the first time in detail in this paper, will be useful for out-of-court agreements and for setting up reimbursement schemes, and describe per capita expenditures which are higher than estimations proposed in recent criminal trials in Italy and to those reported in the international literature.

[Pier Luigi Viola and vinyl chloride: notes that were never published]

The name and work of Pier Luigi Viola (1917-1985) are unequivocally connected with the history of the discovery of the toxic effects of vinyl chloride, cancer in particular. A biography and a bibliography of Professor Viola are still lacking but his work is well documented; equally well known is his professional career as an occupational physician who spent his entire working life as an employee of one single industrial group, Solvay; his work was dedicated firstly to taking care of the health of the workers of the Corporation and not only in Italy, and secondly to organizing the occupational health departments of all Solvay's establishments in Italy. This positive connection between occupational physician and scientist has recently been challenged in certain historical reconstructions of the discovery of vinyl chloride's carcinogenicity: in particular, these reconstructions (which we do not consider to be coherent with the facts) depict Viola as in constant conflict with his employer. As crucial support to this view are offered on the one hand a statement by Viola, in 1980, that "At the basis of every discovery there is frequently the poetical imagination of a researcher who is always alone in facing the difficulties of the research, difficulties that rise up against him like a wall reaching up to the sky"; and on the other the supposed failure to find some of Professor Viola's notes which should reflect his spiritual testimony, and from which should emerge "the suffering, the torments, and the pressures of that initial period". The true history is very different: the notes do exist: they were personally delivered to one of the authors (PB) by Viola's widow a few months after his death; they are in fact the first pages of a planned book on vinyl chloride that Viola never actually succeeded in writing. In these pages Viola developed some personal reflections from which it is clear that he was conscious of having been in the centre ofa fantastic adventure in the field of scientific research in which he also played the principal role; there is no mention whatsoever of any conflict or contrast between Viola and Solvay. In fact, the backdrop to this story reflects the typical dynamics of scientific research. The article continues with the publication of Viola's handwritten notes: in this way the supposed "mistery of the missing notes" is solved.

[Acroosteolysis in PVC autoclave cleaners: history of an occupational disease]

OBJECTIVES

This paper examines the history of an occupational disease which has now disappeared: acroosteolysis of manual tank cleaners in the production of polyvinyl chloride (PVC), which is a rare disease characterized by destructive alterations of the distal phalanges of the hands.

METHODS

All the available literature on this disease was examined. The history of acroosteolysis was studied within the general framework of the history of the discovery of adverse health effects of exposure to vinyl chloride, and this history was studied up to the end of the 1960's.

RESULTS

The disease was observed for the first time in mid-1963 in Belgium (Jemeppe) in a chemical plant operated by Solvay, and affected two workers whose job was the manual cleaning of vessels used for the polymerization of vinyl chloride; similar cases occurred in almost all PVC production plants all over the world, but not in the plants where the main activity was the production of vinyl chloride monomer (VCM). Little more than one hundred cases are described in the scientific literature, and this number increases by a few dozen if we consider known but unpublished cases. These figures confirm the rarity of the disease, which peaked at the end of the 1960's and disappeared during the 1970's, probably due to the complete elimination of manual reactor cleaning. Observation of the disease lasted no more than fifteen years and the disease was not replicated in experimental conditions on animals.

DISCUSSION

The disease was clinically characterized, had a short latency (from several months to several years), was rare and unequivocally linked to the manual cleaning of PVC polymerization tanks. However many questions still remain open: the period when the disease first appeared (many years after the start of PVC production in the world), the etiology of the disease (the most accredited hypothesis considers three concomitant factors: a chemical factor--one of the many substances used during polymerization, and particularly vinyl chloride monomer, a physical factor--microtraumas of the fingers during manual cleaning, individual susceptibility), the pathogenetic mechanism (in particular: the role of skin, respiratory, or digestive system, as entrance door), a method (or test) to screen subjects potentially predisposed to the disease. In our view acroosteolysis of manual tank cleaners in PVC production is an occupational disease which is distinct from "vinyl chloride disease" as identified by Viola (1974).

[La Medicina del Lavoro: 100 volumes]

With these pages La Medicina del Lavoro starts its 100th volume, so we have yet another historical occasion to celebrate the oldest occupational health journal in the world that is still publishing. Over the last few years we have had many occasions to celebrate, for example several anniversaries of the Journal (the 80th volume in 1989, 90 years in 1992, 100 years in 2001); the centenary of the foundation of the Clinica del Lavoro "Luigi Devoto" of Milan in 2001; the celebration of the 300 years' anniversary of the publication of De Morbis Artificum Diatriba by Bernardino Ramazzini, and we obviously hope to continue for many years to come in this positive outlook. One hundred volumes makes for a very large collection, with the highs and lows ofthe Journal's history (here we mean the variations in number of pages and physical size of the Journal). It is thanks to the Editors-in-chief(there have been very few so we can cite them all: Luigi Devoto, 1901-1936; Luigi Preti, 1936-1941; Enrico Vigliani, 1943-1992; e Vito Foà, 1992 to the present); the contributors who in various ways and with varying degrees of commitment but always with an exceptional personal participation, that it has been possible to reach 100 volumes, starting with C. Moreschi who, along with Luigi Devoto, was the first and sole editor at the Journal's foundation; up to the present extended and impressive editorial board; the printers (from the first. Tipografia Cooperativa, Via dei Molini in Pavia, to the latest: Casa Editrice Mattioli in Fidenza); the sponsors, including the most evident who, via advertising (rather limited as a matter offact), directly gave information about themselves, but also those who have often been or are behind the scenes, ensuring fundamental support which is not visible; content. articles, news, events, reports, ideas, opinions, photographs, tables, numbers... etc, which are really impossible to sum up. But the true collection which, for obvious reasons, cannot be individually named, consists of the people and the ideas that have enriched the history of the Journal in its over 100 years of existence. And the subscribers, above all, who by their almost anonymous presence have been the true guarantors of the Journal's ife. And of course the contributors who with their articles have consigned a part of their lives to history. Starting from 1925 we counted nearly 11.000, a really grand number. It would be wonderful if we could invite them all to a hypothetical (and impossible) grand convention to simply say "Thank you, your contributions will not be forgotten". There have been 100 volumes but in actual fact the Journal is more than 100 years old. It was founded in Pavia in 1901 as Il Lavoro-Rivista di fisiologia, clinica ed igiene del lavoro, and between 1901 and 1910 only three volumes were published, then, due to the difficulties during the First World War and the immediate post-war years, there were no issues in 1916, 1918 and 1919. Issues finally became regular in 1920 with volume 11; from that moment on not one issue was missed and the Journal even got through the Second World War without interruptions. In 1925, with volume 16, it took on the name that still distinguishes it to-day: La Medicina del Lavoro, "the official standard bearer of a work of enormous scientific, social and political content" as Luigi Devoto presented the event at the time. The first few years of the Journal were difficult ones (with only three volumes published in 10 years) to the effect that events such as the First International Congress on Occupational Diseases (Milano, 1906), the foundation of the International Commission for Occupational Health (1906), the First National Italian Congress on Occupational Diseases (Palermo, 1907), and above all the inauguration of the Clinica del Lavoro in Milano (20 March, 1910) are not reported in the Journal, which by 1911 had resumed publication but had moved to Milan. Many years have passed since those first three volumes and in the meantime we have moved on to another century and another millenium: this brings new opportunities, new responsibilities, new perspectives, new objectives, but also new subscribers, new contributors, new authors, and new topics. We would like to conclude by repeating the undertaking made "20 volumes ago": The Editorial Board wishes to thank everyone and take the opportunity to renew our unfaltering commitment to work well by ensuring our full respect for authors and readers so as to contribute, via the pages of La Medicina del Lavoro, to spreading love and knowledge of our discipline.

[A simple method for risk assessment and its application to 1,3-butadiene]

BACKGROUND

This paper presents a risk assessment exercise applied to 1,3-butadiene, a probable carcinogenic agent, in the context of the activity of the Scientific Committee on Occupational Exposure Limits (SCOEL) of the European Commission. Data on cumulative exposures and relative risks for leukaemia in humans were derived from the open literature.

METHODS

A variety of excess relative risk models were applied taking into consideration, in a life-table fashion, mortality from leukaemia by age.

RESULTS

As an example of the outcome of the method, results are presented for a 1 ppm exposure (each year) lasting for a working lifetime. They show that in a population of 1,000 adult males experiencing mortality rates similar to those of the 1981 male population of England and Wales, occupational exposure to 1 ppm of 1,3-butadiene for each year of a working life (40 years between the age of 20 and 65) will cause from 0 to 7.1 extra leukaemia deaths between the age 20-85 years, in addition to the 5.1 leukaemia deaths expected to occur in the absence of exposure to 1,3-butadiene. A summary of the estimates, in terms of excess leukaemia deaths, obtained for 0.1 ppm, 0.2 ppm, 0.5 ppm, 1.0 ppm, 2.0 ppm, 5.0 ppm, and 10 ppm of exposure (each year) is also presented.

CONCLUSIONS

The method can be applied to predict the risk of carcinogenic agents for which dose-response data exist and no health-based limit value can be established. Results are consistent with those of previous risk assessments based on similar assumptions

Effect of shift work on body mass index: results of a study performed in 319 glucose-tolerant men working in a Southern Italian industry

OBJECTIVE

To examine the influence of shift work on metabolic and cardiovascular risk factors in subjects working in an industry sited in Apulia, Southern Italy.

DESIGN

Cross-sectional study of metabolic effects of shift work in glucose tolerant workers in a chemical industry in southern Italy.

SUBJECTS

The subjects included 319 glucose tolerant male individuals, aged 35-60 y.

MEASUREMENTS

Anthropometric parameters (body mass index (BMI) and waist-to-hip ratio (WHR)), fasting concentrations of glucose, insulin, and lipids (total cholesterol, HDL-cholesterol, triglycerides), the sum of glucose levels during 75 g-oral glucose tolerance test (Sigma-OGTT), and systolic and diastolic blood pressure (SBP and DBP, respectively).

RESULTS

The prevalence of obesity was higher among shift workers compared to day workers, whereas body fat distribution was not different between the two groups. Shift workers had higher BMI than day workers, and shift working was associated with BMI, independently of age and work duration. Shift workers had significantly higher SBP levels, which were independently influenced by BMI, but not by shift work, thus suggesting that the difference in SBP may well be mediated by the increased body fatness.

CONCLUSION

In workers of an industry sited in Southern Italy, shift work may be directly responsible for increased body fatness and is indirectly associated with higher blood pressure levels and some features of metabolic syndrome.

[Causality link in criminal law: role of epidemiology]

This paper focusses on the role of epidemiology in demonstrating causality in criminal trials of toxic tort litigation. First of all, consideration is given of the specificity of the criminal trial and of the role of the epidemiologist as expert witness. As a second step the concept of causality is examined separating general from specific (individual level) causality. As regards general causality, strategies based on some criteria (example: Bradford-Hill criteria) are contrasted with approaches that do not consider causality a matter of science but one of health policy; and specific methods frequently used (meta-analysis, risk assessment, International Boards evaluation,....) are discussed, with special reference to the adoption of high-level standards and to the context of cross-examination. As regards individual level causality the difficulties of the epidemiologic approach to such evaluation are stressed, with special reference to topics like expected value, attributable risk, and probability of causation. All examples are taken from Italian court trials. A general comment on the difficulties of using the criminal trial (dominated by the "but for" rule) for toxic tort litigation and on the opportunity to switch to trials (civil, administrative) with less stringent causal rules ("more probable than not") is offered, with a consideration also of what are called "class actions".

[Occupational epidemiology: from analysis of the apparent to investigation of the unknown]

This paper, as a contribution for the centenary celebration of the establishment of the "Clinica del Lavoro Luigi Devoto" in Milan (Italy), presents a brief 30 year history of the activities of its Department of Occupational Epidemiology. Studies and methodological contributions that characterized the first decade of activity are presented and grouped under the heading of analysis of known health effects. The second decade was dominated by the studies and activities that originated from the Seveso accident (dioxin), with an initial interest towards molecular epidemiology, which became increasingly relevant during the third decade when we addressed topics like melanoma, lung cancer, and benzene, in addition to dioxin. More traditional occupational approaches were not dismissed and cohort mortality studies are currently under way (textile dyeing and finishing industry, sulfuric acid, tetrafluoroethylene). Pros and cons of the epidemiologic approach are discussed in the context of occupational health and the strength of its methodological apparatus is suggested as a fundamental tool for studying adverse occupational health effects. In contrast, it is stressed how occupational epidemiology has been poorly used in the application of law 626/94. Considering that contemporary epidemiology is much more inclined towards the discovery of new work-related risks (electromagnetic fields, air pollution) than the description of known health effects, the paper suggests that occupational epidemiology enlarge its interests: people and environment outside the factories might be good candidates for study.

Health effects of dioxin exposure: a 20-year mortality study

Follow-up of the population exposed to dioxin after the 1976 accident in Seveso, Italy, was extended to 1996. During the entire observation period, all-cause and all-cancer mortality did not increase. Fifteen years after the accident, mortality among men in high-exposure zones A (804 inhabitants) and B (5,941 inhabitants) increased from all cancers (rate ratio (RR) = 1.3, 95% confidence interval (CI): 1.0, 1.7), rectal cancer (RR = 2.4, 95% CI: 1.2, 4.6), and lung cancer (RR = 1.3, 95% CI: 1.0, 1.7), with no latency-related pattern for rectal or lung cancer. An excess of lymphohemopoietic neoplasms was found in both genders (RR = 1.7, 95% CI: 1.2, 2.5). Hodgkin's disease risk was elevated in the first 10-year observation period (RR = 4.9, 95% CI: 1.5, 16.4), whereas the highest increase for non-Hodgkin's lymphoma (RR = 2.8, 95% CI: 1.1, 7.0) and myeloid leukemia (RR = 3.8, 95% CI: 1.2, 12.5) occurred after 15 years. No soft tissue sarcoma cases were found in these zones (0.8 expected). An overall increase in diabetes was reported, notably among women (RR = 2.4, 95% CI: 1.2, 4.6). Chronic circulatory and respiratory diseases were moderately increased, suggesting a link with accident-related stressors and chemical exposure. Results support evaluation of dioxin as carcinogenic to humans and corroborate the hypotheses of its association with other health outcomes, including cardiovascular- and endocrine-related effects.

[The epidemiologist in the courtroom: various arguments to start a discussion]

This paper focusses on some topics peculiar to the presence of the epidemiologist in the courtroom and suggests an initial inventory of questions that might be addressed. Epidemiology and law have peculiarities that must be recognized but a specific collaboration between these expertises is necessary. First of all, it is important to admit that scientific discussion is different from courtroom discussion: some simple examples give an idea of the different ways in which the discussion may proceed in each of the contexts and of the difficulties in using traditional epidemiologic tools. Secondly, the concept of general causality (whether an agent can cause a disease) and specific causality (whether an agent did cause a plaintiff's disease) are briefly reviewed, and the role of epidemiology in addressing both question is discussed. The last point regards the use of epidemiologic methodology in the courtroom context, with particular reference to errors, study design, and literature evaluation: a minimum set of criteria for quality assessment is requested.

[Liver angiosarcoma in humans: epidemiologic considerations]

A review of the available literature on angiosarcoma of the liver in an epidemiologic perspective shows that this cancer is rare (0.5-2.5 cases every 10,000,000 persons). It escapes current mortality statistics; it presents peculiar diagnostic difficulties even when histologic material is scrutinized by panels of pathologists; it occurs in both gender at every age (also in children); estimated latency is long (10-40 years, in occupational cases) or very long (60 years and above, in non-occupational cases). Thorotrast, arsenic, and vinyl chloride monomer are frequently listed as risk factors but, along with other substances (steroids, hemochromatosis, diethylstilbestrol, phenelzine, urethane, cyclophosphamide, oral contraceptives) they contribute to explaining the occurrence of no more than 20% of the published cases. Focussing on subjects exposed to vinyl chloride monomer, the published cases were all males aged 35-75 years, with an average latency of 22 years (range 10-40), in jobs with a potential for a high, or very high exposure to VCM (mainly as autoclave cleaner) started before 1970, and limited to a small number of factories. No evidence of a relationship between environmental (non occupational) exposure to VCM and angiosarcoma of the liver emerges from the available literature. We conclude that in more than 25 years of research, apart from the case of vinyl chloride, the etiology of this type of cancer has remained unchanged and largely unknown.

[Bernardino Ramazzini. Ante litteram epidemiologist]

Bernardino Ramazzini, born in Carpi in 1633 and deceased in Padua in 1714, is universally renowned father and founder of occupational health. This paper will present Bernardino Ramazzini under a different perspective, and will show that during his scientific career he continuously maintained the attitude of a modern epidemiologist. Reviewing all his scientific papers, and many papers commenting his activity, we present four major areas in which Ramazzini expressed in a direct and convincing way his epidemiologic culture: the epidemiologic constitutions and the work done mainly on physical subjects while he was in Modena; the general architecture of his most important book (De Morbis Artificum Diatriba); the first full description of an episode of environmental pollution which occurred in Finale Emilia in 1689 (in his book this episode is reported in the chapter describing the diseases of chemicals); the opening lectures of some academic years he gave while he was teaching, mainly, in Padua. To our knowledge the epidemiological attitude of Bernardino Ramazzini is not recognized yet in epidemiology textbooks.

Prevalence and histologic features of transfusion transmitted virus and hepatitis C virus coinfection in a group of HIV patients

BACKGROUND

A recently identified DNA transfusion-transmitted virus has been associated with post-transfusion non-A to G hepatitis.

AIM

To determine the prevalence of transfusion-transmitted virus in patients with human immunodeficiency virus infection. Its clinical role in the pathogenesis of liver disease was also evaluated in patients with transfusion-transmitted-virus hepatitis C virus coinfection compared with those with hepatitis C Virus infection alone.

PATIENTS AND METHODS

We evaluated 312 HIV-hepatitis C virus coinfected patients (225 males, 87 females). All underwent screening for transfusion-transmitted virus DNA using a nested polymerase chain reaction technique. In some transfusion transmitted virus-DNA positive patients, we performed a phylogenetic analysis. In 56 patients (20 transfusion-transmitted-virus-hepatitis C virus and 36 hepatitis C virus alone), liver biopsy was collected.

RESULTS

The prevalence of transfusion-transmitted virus was 113/312 (36%). The genotype distribution was similar to that reported in other studies. No difference in liver histology was found between the two groups.

CONCLUSION

Transfusion-transmitted virus infection is common in human immunodeficiency virus patients. We found no histologic differences between liver biopsy specimens from patients coinfected with transfusion-transmitted virus plus hepatitis C virus compared with those infected with hepatitis C virus alone. Transfusion-transmitted virus is not clearly associated with a distinct liver injury.

[Bernardino Ramazzini and "Medicina del Lavoro"]

Three hundred years after the first edition of Ramazzini's "De Morbis Artificum Diatriba", this paper reviews all the articles on the work of the great Master of Carpi that have been published over a century in the ninety volumes of "La Medicina del Lavoro". Since the first issue of the journal in 1901, many authors have submitted papers which revisited and commented on the work of Ramazzini, particularly in anniversary years (1914, the anniversary of his death, 1933 and 1983, anniversaries of his birth), but only Luigi Devoto was capable of fully understanding the methodology introduced by Ramazzini, transforming it into practical applications which he listed in ten fundamental actions. Mainly for this reason and considering that Ramazzini had been practically ignored for two centuries, it was decided to consider the Devoto period as the "true Ramazzini era". The death of the founder of the journal in 1935 marked the unexpected beginning of a long silence, lasting up to 1983, during which not one paper on Ramazzini was published in "La Medicina del Lavoro". It is concluded that a comparison between the diseases described by Ramazzini and those of to-day is of no practical use and that a tribute to Ramazzini is simply necessary in recognition of his contribution to the birth and development of occupational medicine, but is nonetheless insufficient. What is also needed, following in the footsteps of the founder of this journal and of the Clinica del Lavoro of Milan, is to reinterpret Ramazzini's methods in modern terms in the perspective of the ten actions he proposed, bearing in mind that possibilities exist to-day whereby his efforts can be completed and further enlarged in terms of practical applications.

Mortality study in an Italian oil refinery: extension of the follow-up

This article present the results of the extension of the follow-up of a cohort of workers employed in an Italian oil refinery. 1,583 workers employed in 1949-1982 in a northern Italy oil refinery plant were followed-up for mortality as of May 31, 1991. Environmental measurements documented potential exposure to benzene. Standardized mortality ratios (SMR) and their 95% confidence intervals (95% CI) were calculated using as references national (1949-1968) and regional mortality rates (1969-1991). Elevated mortality from lymphoma (seven deaths, SMR 190, 95% CI 76-391) and leukemia (eight deaths, SMR 225, 95% CI 97-443) was observed. No consistent trends by length of employment or time since first exposure were apparent. Nonetheless, the excess risk was particularly and significantly increased among workers with 15 or more years of employment, and 30 or more years since first employment. The findings of elevated mortality from leukemia and lymphoma are in agreement with those of other oil refinery studies. Chance, confounding, or other biases might have played a marginal, if any, role in determining the results. Exposure to benzene is a biologically plausible explanation.

[Minor and major work accidents in a Puglia business in the food sector: a 10-year study]

At present no official data are available for those occupational accidents which, according to current law, are not subject to notification to the Italian National Institute for Insurance of Occupational Accidents (INAIL) and which are conventionally called "minor" accidents. They can be divided into accidents with prognosis from 1 to 3 days (franchises) and accidents which do not cause absence from work (medications). The already mentioned lack of data, which is not confined to Italy, is reflected in the small number of articles published in Italian and international journals. Also information regarding the possible relationships between "minor" accidents and the life habits of injured workers, are rare. The aim of this study was to provide detailed data on the characteristics of the different kinds of occupational accidents occurring in a food factory in Apulia, southern Italy, from 1985 to 1994, as well as to verify whether any relationship existed between the different types of occupational accidents and the consumption of cigarettes and alcohol by injured workers. The company's accident register yielded data on injuries which caused absence from work; the nursing service register provided information about accidents which did not determine absence from work; personal health documents gave details of worker life habits; and the company pay roll showed the amount of "worked hours". "Minor" accidents represented 70% of all accidents occurring during the ten year period studied. "Blue collars" had more frequent and serious occupational injuries, in comparison with "technical employees". "Minor" accidents, and especially "medications", occurred more frequently during one-shift work than during three-shift work. As work seniority increased, the number of "major" accidents decreased and number of accidents without absence from work rose. Contusions were the most frequent lesions and were responsible for the majority of the 3 kinds of accidents. "Medications"" together with injuries notified to INAIL ("major" accidents), mostly involved upper limbs; "franchises" were mostly head interested. About 50% of all causes of occupational accidents were mainly associated with unsafe environmental and working situations, whereas the remaining 50% were mainly associated with unsafe behaviour by workers. Heavy smokers showed a higher frequency of "major" accidents. As alcohol consumption rose, she did number of accidents with absence from work. "Minor" accidents, particularly the "medicated" ones, represented the greatest part of occupational injuries. All the considered causes and circumstances contributed to determine the different kinds of accidents. Thereby, it appears necessary for prevention purposes to obtain information about any kind of injury in the different manufacturing sectors. Finally, it seems dutiful to inform workers about the relationships between life habits and occupational accidents.

[Seveso. Dioxin: an example of environmental medicine. Epidemiologic data as guidelines for health programming]

The 1976 dioxin accident in Seveso, Italy, represented a major environmental health problem for the population of the surrounding territory and a challenge for the entire regional area and the health and scientific institutions. The role of occupational health and of epidemiology in the incident investigation and management is discussed. Of major relevance was the consideration of all the different component factors of the interested environment, from chemical pollution to cultural attitudes and psycho-social stressors. Scientific research was helpful in elucidating the incompletely known toxic effects of dioxin and the complex mechanism of cancer induction by this widespread pollutant of our industrialized environments. The experience gained in Seveso was also useful in prompting national and international legislation concerning major industrial accidents, and the lessons learned contributed to the content of this legislation. Preparedness to these events requires mapping of the potential sources of these accidental occurrences and the monitoring of the social and health characteristics of the possibly affected populations. In the Lombardy Region, the numerous epidemiological investigations performed and the expertise implemented for the study and the control of the accident consequences, formed the basis on which the Regional Epidemiology Surveillance System established.

Respiratory mucus transportability is impaired in foundry workers: a longitudinal study

Mucus transportability impairment can prolong the permanence of occupational inhalable noxae within ciliated airways. A reliable, non-invasive indicator of mucus transportability is the Normalized Frog Palate Transport Rate (NFPTR). The aim of this 3-year prospective study was to compare NFPTR between a group of 166 foundry workers (E) and a group of 133 power plant workers (NE). In the first and third years of the study, workers underwent: clinical examination, spirometry, NFPTR, chest radiography. In both plants, environmental concentrations of respiratory irritants were well below the limits set by the American Conference of Governmental Industrial Hygienists. Both groups were homogeneous for age and smoking habits. Mean NFPTR was significantly lower in E than in NE in the first and third years of the study, and in smokers in comparison with non-smokers, at the end of the follow-up. NFPTR impairment was significantly associated with occupational exposure in the first and third years of the study. In the third year, a decline in NFPTR was associated with exposure, smoking habits, FVC and FEV1/FVC.100. At the end of the study, the means of FVC, FEV1 and PEF were significantly lower in E. No cases of pneumoconiosis were observed. In this study, low doses of foundry respiratory irritants were associated with impairment of mucus transportability; the consequent slowing of mucociliary clearance increased internal doses of foundry airborne noxae.

[Carcinogens and the Law 626/94: examples of application related to Title VII]

This paper is aimed at describing the state of the art with respect to the application of law 626/94, particularly with reference to the activities connected with the use of carcinogens at the workplace. To understand what is going on and what practical activities have been established we found it useful to look for practical examples in the field of carcinogenic risk assessment. We interviewed many colleagues and experts in a non-random sample of situations, and this paper briefly describes the methodological problems encountered and some specific results emerging from eight experiences. The examples described regard both large and small factories, in different fields of activity (chemical and pharmaceutical industries, transport, power production, ...), with different attitudes and traditions with regard to carcinogenic risk assessment, and also with different specific results in terms of risk evaluation. Two among the eight examples reported directly involved the activities performed by private consultants or territorial Public Services active in the field of prevention. The paper concludes with the indication of the problems encountered in the collection of information and with the suggestion that such experiences should be freely presented in the literature, thus offering an opportunity of public discussion and evaluation.

Models of interaction between metabolic genes and environmental exposure in cancer susceptibility

Polymorphic metabolic genes that confer enhanced genetic susceptibility to the carcinogenic effects of certain environmental carcinogens act according to a type 2 interaction between genetic and environmental risk factors. This type of interaction, for which the gene has no effect on disease outcome by itself but only modifies the risk associated with exposure, must be treated differently from other types of gene-environment interaction. We present a method to analyze different dose effects often seen in studies involving these genes. We define a low exposure-gene effect, when a greater degree of gene environment interaction appears at lower doses of exposure (the interaction follows an inverse dose function), and a converse high exposure-gene effect, when the interaction increases as a function of dose. Using a standard logistic regression model, we define a new term, alpha, that can be determined asa function of exposure dose in order to analyze epidemiological studies for the type of exposure-gene effect. These models are illustrated by the use of hypothetical case-control data as well as examples from the literature.

Dioxin exposure and non-malignant health effects: a mortality study

OBJECTIVE

To investigate, in a population heavily exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the possible unusual occurrence of diseases other than cancer.

METHODS

Five year extension of the follow up of the cohort involved in the Seveso accident. Soil measurements identified three exposure zones: (A) highest contamination, (B) substantial, and (R) low but higher than background contamination. Blood TCDD measurements, although limited in number, confirmed zone exposure ranking. The 15 year mortality in the exposed cohort was compared with that of a large population in the surrounding non-contaminated territory. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated with Poisson regression techniques.

RESULTS

The already noted increased occurrence of cardiovascular deaths was confirmed, in particular in zone A, among males for chronic ischaemic heart disease (five deaths, RR 3.0, 95% CI 1.2 to 7.3), and among females for hypertensive disease (three deaths, RR 3.6, 95% CI 1.2 to 11.4) and chronic rheumatic heart disease. Novel findings were the increase of chronic obstructive pulmonary disease, most notably among males in zone A (four deaths, RR 3.7, 95% CI 1.4 to 9.9) and females in zone B (seven deaths, RR 2.4, 95% CI 1.1 to 5.1); and from diabetes, which was significantly increased in females in zone B (13 deaths, RR 1.9, 95% CI 1.1 to 3.2). In zone R, chronic ischaemic heart disease (males and females), hypertension (females), and diabetes (females) showed less pronounced, although significant excesses.

CONCLUSIONS

As well as high TCDD exposure, the accident caused a severe burden of strain in the population. Both these factors might have contributed to the noted increased risks (in particular, circulatory and respiratory). The cardiovascular and immune toxicity of TCDD, as well as its complex interaction with the endocrine system, might be relevant to the explanations of these findings. These results, although not conclusive, concur with previous data in suggesting cardiopulmonary and endocrine effects in humans highly exposed to TCDD.

Gene--environment interactions in the application of biomarkers of cancer susceptibility in epidemiology

Metabolic susceptibility genes are important determinants of individual susceptibility to the effects of environmental carcinogens. These genes follow the form of 'type 2' gene-environment interaction, whereby the polymorphic genetic risk factor functions only in the presence of an environmental exposure. Two different effects of carcinogen dose have been observed for these genes. Sometimes, increasing dose leads to a decreasing interaction, so that cases with the genetic risk factor have lower exposures than those cases without it. Other examples of a direct dose effect, whereby increasing exposure leads to increased interaction, have also been described. We propose a model based on multiple logistic regression to assess the nature of the dose effect in this type of gene-environment interaction. This model allows for distinction between these two dose effects, and other effects such as protective or non-interactive effects of environmental and genetic risk factors.

Why and how to control for age in occupational epidemiology

In occupational epidemiology, the need to consider the age factor properly influences the choice of study design and analytical techniques. In most studies, age is viewed as a potential confounder. Age is strongly associated with end points of interest in occupational epidemiology (diseases, physiological characteristics, doses of xenobiotics, etc), but to measure age as a confounder it must be associated with the exposure under study. When the exposure of interest is time related-for example, duration of employment, time since first exposure, cumulative exposure-a strong intrinsic association with age can be anticipated, and age will behave as a (usually strong) confounder. When occupational exposures without a direct relation with age-for example, job, department, type of exposure-are evaluated, the degree and direction of confounding bias cannot be anticipated. Control of the confounding effect of age can be accomplished in the design phase of a study by way of randomisation, restriction, and matching. Randomisation is seldom viable in occupational settings. Restriction is rarely used in the case of age. Matching is often used in a case-control study as a method to increase the study efficiency, but it must be followed by proper matched or stratified analysis. Options for age adjustment in the analysis phase involve stratification and regression methods. In longitudinal studies the modified life table analysis is used to take into account the fact that subjects cross categories of age as the study proceeds. Stability of relative measures of effect over age strata favoured the greater use of relative risks than risk differences. In the presence of effect modification the influence of age should not be eliminated; its interaction with exposure should be explicitly considered.

Dioxin exposure and cancer risk: a 15-year mortality study after the "Seveso accident"

Dioxin (2,3,7,8-tetrachlorodibenzo-para-dioxin, or TCDD) is a powerful carcinogen in experimental animals, whereas the evidence in humans is limited. We examined cancer mortality from 1976 to 1991 among residents of Seveso, Italy, which was highly contaminated after an industrial accident. The area was divided into zones with decreasing exposure to dioxin (A = highest, B = lower, R = lowest). The population of a surrounding noncontaminated area was used as a reference group. Zone A was small (11,516 person-years); in that zone, we saw a moderate increase in mortality from digestive cancer among women [relative risk (RR) = 1.5; 95% confidence interval (CI) = 0.5-3.5]. In zone B, we also saw excesses at digestive sites (83,610 person-years), 10 years after the accident. Women had an increased mortality from stomach cancer (RR = 2.4; 95% CI = 0.8-5.7), and men had increased mortality from rectal cancer (RR = 6.2; 95% CI = 1.7-15.9). Hematologic neoplasms were increased. The highest risks were seen in zone B for leukemia in men (RR = 3.1; 95% CI = 1.3-6.4), multiple myeloma in women (RR = 6.6; 95% CI = 1.8-16.8), and Hodgkin's disease in both genders (RR = 3.3; 95% CI = 0.4-11.9 in men; and RR = 6.5; 95% CI = 0.7-23.5 in women). Soft tissue sarcoma was elevated only among zone R males (256,408 person-years; RR = 2.1; 95% CI = 0.6-5.4). We found no increase for all-cancer mortality or major specific sites (for example, respiratory among males, breast among females). The specific excesses that we observed were not explained by bias or confounding, and their association with dioxin exposure is plausible. The follow-up is continuing.

[Ordinary epidemiology: pleural mesothelioma and asbestos]

This paper describes a practical experience which took place in a Health District of the Lombardy Region (Northern Italy). This experience was motivated by the publication, on a newspaper, of the results of an epidemiological study which reported the nationwide geographical distribution of the mortality data for pleural mesothelioma during the period 1980-1987. The presence of excesses of pleural mesothelioma cases in two municipalities of Health District captured the attention of some field operators which decided to start working on the topic. Using all information available in the District all cases of pleural mesothelioma occurring during the period 1978-1993 in the two municipalities were identified; possible sources of both occupational and environmental asbestos exposure in the area were identified; and the next-of-kin of the cases was interviewed so as to gain information on the history of possible exposure to asbestos of the cases. For thirteen (out of seventeen) deaths the next-of-kin accepted to be interviewed and for them results are reported: the information presented describes gender, smoking habits, and an evaluation of the potential for exposure to asbestos both of occupational and environmental origin. We discuss the value importance of the experience, with particular emphasis on: a) the routine activities of the Services participating in the study; b) the resources employed; c) the use of epidemiological methods and tools; d) the primary prevention activities originated in the area; e) the personal motivations hat such experiences are capable to convey.

Minimal immunological effects on workers with prolonged low exposure to inorganic mercury

OBJECTIVES

This study was carried out to investigate possible immunological changes in workers with prolonged low exposure to inorganic mercury in a fluorescent light bulb factory.

METHODS

29 immunological variables were examined in 34 workers with prolonged low level exposure to inorganic mercury (exposed workers) and 35 unexposed workers as the controls. The selected indicator of mercury exposure was concentration of mercury in the urine (U-Hg), which declined progressively from 36.0 micrograms/l in 1978 to 6.0 micrograms/l in the study year 1994.

RESULTS

None of the exposed workers had ever shown signs of either acute or chronic inorganic mercury toxicity or had shown any form of hypersensitivity. The only changes found in the exposed workers, compared with the controls, were a reduction of the cells that express cluster differentiation (CD25,(T activation antigen (Tac antigen))) and concentrations of tumour necrosis factor-alpha (TNF-alpha) in serum. However, the decrease of cells that express CD25 was unrelated to occupational exposure and was, in all likelihood a chance finding. Conversely, the decline in serum TNF-alpha was closely associated with occupational exposure. However, no dose-response relation was found between U-Hg and TNF-alpha concentrations; nor were TNF-alpha concentrations affected by cumulative occupational exposure to inorganic mercury in over 20 years.

CONCLUSIONS

Tentatively, we suggest that reduced serum TNF-alpha concentrations might be indicative of an in vivo functional defect of the monocyte macrophage system in this particular group of workers even though they were clinically asymptomatic.

Cancer mortality among man-made vitreous fiber production workers

We have updated the follow-up of cancer mortality for a cohort study of man-made vitreous fiber production workers from Denmark, Finland, Norway, Sweden, United Kingdom, Germany, and Italy, from 1982 to 1990. In the mortality analysis, 22,002 production workers contributed 489,551 person-years, during which there were 4,521 deaths. Workers with less than 1 year of employment had an increased mortality [standardized mortality ratio (SMR) = 1.45; 95% confidence interval (CI) = 1.37-1.53]. Workers with 1 year or more of employment, contributing 65% of person-years, had an SMR of 1.05 (95% CI = 1.02-1.09). The SMR for lung cancer was 1.34 (95% CI = 1.08-1.63, 97 deaths) among rock/slag wool workers and 1.27 (95% CI = 1.07-1.50, 140 deaths) among glass wool workers. In the latter group, no increase was present when local mortality rates were used. Among rock/slag wool workers, the risk of lung cancer increased with time-since-first-employment and duration of employment. The trend in lung cancer mortality according to technologic phase at first employment was less marked than in the previous follow-up. We obtained similar results from a Poisson regression analysis limited to rock/slag wool workers. Five deaths from pleural mesothelioma were reported, which may not represent an excess. There was no apparent excess for other categories of neoplasm. Tobacco smoking and other factors linked to social class, as well as exposures in other industries, appear unlikely to explain the whole increase in lung cancer mortality among rock/slag wool workers. Limited data on other agents do not indicate an important role of asbestos, slag, or bitumen. These results are not sufficient to conclude that the increased lung cancer risk is the result of exposure to rock/slag wool; however, insofar as respirable fibers were an important component of the ambient pollution of the working environment, they may have contributed to the increased risk.

Relationship between prevalence rate ratios and odds ratios in cross-sectional studies

BACKGROUND

Cross-sectional data are frequently encountered in epidemiology and published results are predominantly presented in terms of prevalence odds ratios (POR). A recent debate suggested a switch from POR, which is easily obtained via logistic regression analysis available in many statistical packages, to prevalence rate ratios (PRR). We thought it useful to explore the mathematical relationship between PRR and POR and to evaluate the degree of divergence of the two measures as a function of the prevalence of disease and exposure.

METHODS

With the use of some algebra and the common definitions of prevalence of the disease (Pr(D)), prevalence of the exposure (Pr(E)), PRR, and POR in a 2 x 2 table, we have identified a useful formula that represents the mathematical relationship between these four quantities. Plots of POR versus PRR for selected values of Pr(D) and Pr(E) are reported.

RESULTS

Mathematically speaking the general relationship takes the form of a second order curve which can change curvature and/or rotate around the point POR = PRR = 1 according to the values of Pr(D) and Pr(E), with POR being always further from the null value than is PRR. The discrepancies are much more influenced by variations in Pr(D) than in Pr(E).

CONCLUSIONS

We think that the choice between POR or PRR in a cross-sectional study ought to be based on epidemiological grounds and not on the availability of software tools. The paper offers a formula and some-examples for a better understanding of the relationship between PRR and POR as a function of the prevalence of the disease and the prevalence of the exposure.

Effects of HIV seropositivity and drug abuse on cognitive function

Fifty-eight HIV-positive drug abusers and 22 HIV-positive nondrug abusers at stages II-III and IV of the Centers for Disease Control classification were evaluated neuropsychologically. The study confirmed previous findings that drug abuse has a negative influence on cognitive function. It also emerges that seropositivity affects cognitive function, although the poor performance of group II-III patients compared to group IV may be explained by factors related to seropositivity (anxiety and panic) rather than the disease itself. It is concluded that disease-related factors probably determine cognitive performance in the earlier stages of HIV infection.

[Analysis of correlated data in occupational medicine: examples with binary data]

In a previous paper in this Journal we presented and discussed examples of analysis of correlated data when the response variable was continuous and normally distributed (the measurement of exposure to a toxic substance was the case in point). In this paper we extend the analysis and the discussion to take into account categorical (binary) variables (described in terms of proportions or odds); to favour the comprehension of the analogies (and discrepancies) between the two contexts we have fully developed an example that mimics the situation presented in the previous paper. Marginal, conditional, random effects and transitional models for correlated data are introduced in practical terms; the meaning of the different estimates obtained are interpreted for epidemiological purposes; the disadvantages of not considering correlation in the analysis are explained and the complexities connected to this type of analysis are fully appreciated. It is concluded that correlated data are very frequently encountered in occupational settings and that an appropriate analysis is necessary. This analysis requires sophisticated computer programs and statistical expertise, particularly in the case of categorical data.

Lung cinescintigraphy in the dynamic assessment of ventilation and mucociliary clearance of asbestos cement workers

OBJECTIVES

To verify in vivo whether lung cinescintigraphy confirms the effect of asbestos on the patency of the smallest airways and on the efficiency of mucociliary clearance in asbestos cement workers.

METHODS

39 male subjects were examined: 30 asbestos cement workers and nine workers never exposed to occupational respiratory irritants. All subjects had a chest radiograph (International Labour Organisation (ILO) 1980); standard questionnaire on chronic bronchitis; spirometry; arterial blood gas analysis; carbon monoxide transfer factor (TLcosb); pulmonary O2 and CO2 ductances (DuO2, DuCO2); electrocardiogram; and lung cinescintigraphy after radioaerosol inhalation for the measurement of mucociliary clearance time in vivo in the smallest ciliated airways and for the assessment of radioaerosol deposition in alveoli (alveolar deposition index).

RESULTS

Apart from nine non-exposed subjects, the 30 asbestos cement workers were so classified on the basis of chest radiography: nine of them as healthy exposed, 10 with pleural plaques, and 11 with asbestosis. The four groups had similar ages, work seniority, and smoking habits. Exercise dyspnoea was significantly more frequent in asbestos cement workers. Lung function variables of workers with effects related to asbestos were significantly lower than the other two groups. The PaO2, TLcOsb and DuO2 mean values were significantly lower in exposed workers than non-exposed. The mean PacO2 value was significantly higher in the asbestosis group than in the other three groups. Workers with effects related to asbestos showed a significantly lower alveolar deposition index and a significantly higher mucociliary clearance time than the other two groups. Subjects with asbestosis showed similar differences from those with pleural plaques.

CONCLUSIONS

Lung cinescintigraphy confirms in vivo the effects of asbestos on bronchiolar and alveolar patency and on efficiency of mucociliary clearance in the smallest ciliated airways. Finally, lung cinescintigraphic variables are able to discriminate workers with asbestosis from those with pleural plaques.

Cytochrome P4501A2: enzyme induction and genetic control in determining 4-aminobiphenyl-hemoglobin adduct levels

Cytochrome P4501A2 (CYP1A2) activity may be related to bladder cancer risk through metabolic activation of aromatic amines, such as 4-aminobiphenyl (ABP), to reactive intermediates that can form DNA and hemoglobin (Hb) adducts. In the context of a study on smoking and bladder cancer risk, 97 healthy male volunteers were investigated. CYP1A2-dependent N-oxidation activity was measured using a molar ratio of urinary caffeine metabolites [(paraxanthine + 1,7-dimethyluric acid)/caffeine] obtained between the fourth and fifth h after drinking a standardized cup of coffee. N-Oxidation activity was induced by blond tobacco smoke, meat consumption the dinner before the test, or more than four cups of coffee a day. The regular use of medication appeared associated with a decrease in N-oxidation levels. Age and alcohol consumption were not related with CYP1A2 activity. A polymorphic distribution of the CYP1A2 and N-acetyltransferase-2 (determined by the caffeine metabolite ratio 5-acetylamino-6-formylamino-3-methyluracil:1-methylxanthine) phenotypes was examined in relation to susceptibility to ABP-Hb adduct formation. Rapid oxidizers and subjects with the combined slow acetylator-rapid oxidizer phenotype showed the highest ABP-Hb adduct levels at a low smoking dose. Blond tobacco smokers exhibited higher adduct levels compared with black tobacco smokers, after adjustment for the quantity of cigarettes smoked. At the highest levels of smoking exposure, no major difference in ABP-Hb adduct levels was found among the different combinations of CYP1A2 and N-acetyltransferase-2 phenotypes. In a subset of only 45 available samples, no association was seen between the ABP-Hb adduct levels and the glutathione S-transferase M1 genotype.

[The concept of risk and its estimation]

The concept of risk, in relation to human health, is a topic of primary interest for occupational health professionals. A new legislation recently established in Italy (626/94) according to European Community directives in the field of Preventive Medicine, called attention to this topic, and in particular to risk assessment and evaluation. Motivated by this context and by the impression that the concept of risk is frequently misunderstood, the present paper has two aims: the identification of the different meanings of the term "risk" in the new Italian legislation and the critical discussion of some commonly used definitions; and the proposal of a general definition, with the specification of a mathematical expression for quantitative risk estimation. The term risk (and risk estimation, assessment, or evaluation) has mainly referred to three different contexts: hazard identification, exposure assessment, and adverse health effects occurrence. Unfortunately, there are contexts in the legislation in which it is difficult to identify the true meaning of the term. This might cause equivocal interpretations and erroneous applications of the law because hazard evaluation, exposure assessment, and adverse health effects identification are completely different topics that require integrated but distinct approaches to risk management. As far as a quantitative definition of risk is of concern, we suggest an algorithm which connects the three basic risk elements (hazard, exposure, adverse health effects) by means of their probabilities of occurrence: the probability of being exposed (to a definite dose) given that a specific hazard is present (Pr(e[symbol: see text]p)), and the probability of occurrence of an adverse health effect as a consequence of that exposure (Pr(d[symbol: see text]e)). Using these quantitative components, risk can be defined as a sequence of measurable events that starts with hazard identification and terminates with disease occurrence; therefore, the following formal definition of risk is proposed: the probability of occurrence, in a given period of time, of an adverse health effect as a consequence of the existence of an hazard. In formula: R(d[symbol: see text]p) = Pr(e[symbol: see text]p) x Pr(d[symbol: see text]e). While Pr(e[symbol: see text]p) (exposure given hazard) must be evaluated in the situation under study, two alternatives exist for the estimation of the occurrence of adverse health effects (Pr(d[symbol: see text]e)): a "direct" estimation of the damage (Pr(d[symbol: see text]e) through formal epidemiologic studies conducted in the situation under observation; and an "indirect" estimation of Pr(d[symbol: see text]e) using information taken from the scientific literature (epidemiologic evaluations, dose-response relationships, extrapolations, ...). Both conditions are presented along with their respective advantages, disadvantages, and uncertainties. The usefulness of the proposed algorithm is discussed with respect to commonly used applications of risk assessment in occupational medicine; the relevance of time for risk estimation (both in the term of duration of observation, duration of exposure, and latency of effect) is briefly explained; and how the proposed algorithm takes into account (in terms of prevention and public health) both the etiologic relevance of the exposure and the consequences of exposure removal is highlighted. As a last comment, it is suggested that the diffuse application of good work practices (technical, behavioral, organizational, ...), or the exhaustive use of check lists, can be relevant in terms of improvement of prevention efficacy, but does not represent any quantitative procedure of risk assessment which, in any circumstance, must be considered the elective approach to adverse health effect prevention.

[Work-related accidents in minors in Lombardy]

Work-related injuries in children and adolescents represent a negative indication of more general inequities of the society in which events occur. Their characteristics are not well described, particularly in Italy, and this paper is aimed at highlighting some fundamental aspects of these injuries. The case in point is represented by the injuries that received compensation and occurred in the Lombardy Region (Italy) between 1984 and 1989 and involved people under the age of eighteen. The injuries occurring in the same period and area in workers over eighteen were used for comparison. Work related injuries in minors were more frequent in crafts activities than in industry, but their gravity (in terms of deaths or permanent consequences) was lower than in the corresponding adult workers. Ninety percent of the events in young workers occurred in males, in each age category, and about 5% of the cases pertains to very young workers (less than 15 years). Cuts/lacerations are the most frequent type of lesion (49.9%) and the hands represent the site most frequently involved (55.5%). The great majority of the observed injuries pertains to a limited number of economic activity sectors: about 75% of the cases occurred in ten sectors. Metal manufacturing, construction and machine production scored first, with interesting correlations with the same sectors in adult workers. Ten specific occupations represent over fifty percent of the cases, with mechanics and bricklayers at the top. The description of the accident in terms of mode of occurrence and the agents involved was less informative and not specific.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV infection and drug use: influence on cognitive function

OBJECTIVE

To examine the involvement of cognitive function in HIV-seropositive drug users (DU) in a pre-AIDS state.

DESIGN

Fifty-six HIV-positive DU were prospectively evaluated. They belonged to groups II, III and IV (subgroups A, C2 and E) of the 1987 Centers for Disease Control and Prevention classification, with anamnesis negative for neurological pathology. HIV-negative DU (n = 19) and non-DU (n = 27) were used as controls. Infection with HIV and use of toxic drugs were considered variables of influence on cognitive function.

METHOD

Subjects underwent neuropsychological evaluation by tests designed to explore cortical and subcortical function.

RESULTS

HIV-positive DU showed worse performance scores at the psychometric tests than HIV-negative non-DU, but there was no difference when compared with HIV-negative DU. Ex-DU showed better performance than active DU. No difference with regard to degree of disease evolution was observed among HIV-positive individuals (i.e., groups II and III versus group IV).

CONCLUSIONS

There was no evidence of cognitive deficits in HIV-positive individuals in non-AIDS phases to indicate early involvement by HIV at the cerebral level. Progression of the disease, prior to the AIDS phase, did not determine a worsening of intellectual performance. Instead, cognitive function was affected by the chronic and current use of toxic substances. In HIV-positive DU, a decline in cognitive function was found to be attributable to the chronic use of toxic substances rather than HIV infection.

[Analysis of correlated data: problems and examples in industrial medicine]

In occupational health we are frequently faced with data that are not independent, but to recognize the lack of such an independence is not yet a common practice. To help researchers in the field to treat correlated data in a proper way this paper has two aims: to highlight practical situations in which the data are not independent and to show the main differences between a statistical analysis which does consider the correlation appropriately and one which doesn't. As to the first aim, four typical examples are discussed: repeated measurements in the same subject (e.g., cells in which the number of sister chromatid exchanges is counted); health effects observed in multiple organs (e.g., visual impairment in both eyes); evaluation of prevention programs (e.g., exposure assessment to styrene before and after environment remediation); longitudinal studies of health effects (e.g., changes over time of pulmonary function parameters). With respect to the second aim a practical exercise is described completely. Measurements of exposure to a toxic substance in two different departments before and after environment remediation are evaluated with statistical tools which both do and do not consider the correlation between such measurements. Differences in the results obtained, with particular reference to indices of variability (e.g., standard errors), point toward the need of analysing correlated data with appropriate statistical tools that take correlation into account.

[Mucociliary clearance and respiratory function in foundry workers]

The aim of the study was to establish whether changes occur in respiratory function, particularly mucociliary clearance, among second fusion smeltery workers. The research covered 93 male smelters employed in steel forming and casting and 116 male workers of an electric power station, considered as non-exposed. Physiological, pathological and occupational histories of all subjects under study were available. An ECCS respiratory symptoms questionnaire was administered to all subjects ad the two groups also underwent a general medical examination, a spirometry and a chest X-ray. During the medical examination sputum was collected from the subjects to measure mucus transport rate on frog palate, expressed as Normalised Frog Palate Transport Rate (NFPTR). For the environmental research, dust, fumes and gas samplings were taken either at a fixed station or by means of personal dosimeters. Environmental research revealed very low concentrations of respiratory irritants (total dust: 0.2-6.8 mg/m3; respirable dust: 0.1-4.9 mg/m3; total silica: < 2-15.5%; respirable silica: < 0.004-0.3 mg/m3; iron: 0.008-0.085 mg/m3; chromium and manganese: < 0.001 mg/m3; fumes and gases: well below the TLV. The two groups were homogeneous with regard to age and smoking habits. Exposed workers showed rales, dyspnoea and spontaneous phlegm more frequently than non-exposed workers. NFPTR alterations were checked in 49 out of 81 exposed and in 18 out of 81 non-exposed subjects (chi squared = 22.9; p < 0.001). Stratification of the results according to smoking habits further confirmed the strong association between occupational exposure and NFPTR alterations. Smelters showed significantly lower mean NFPTR values compared to non-exposed subjects; also, the mean value of NFPTR in the exposed was below 0.70, which is considered the lowest individual limit in normal subjects. The only variable which explains a large part of the variability of NFPTR is past work in a smeltery rather than in an electric power station. The spirometries showed that only the mean PEF values were significantly lower among the exposed. Stratified analysis of the results according to smoking habits in the two groups revealed a close association between smeltery work and reduction of PEF to under 80% of the ECCS 1983 theoretical values, independently of smoking habits. We also compared the mean PEF values, both as measured values and as percent values of the ECCS 1983 theoretical values, stratified for occupational exposure and smoking; the results again showed that differences between these mean values were mainly due to current or past work in the foundry.(ABSTRACT TRUNCATED AT 400 WORDS)

[Mortality rate and its statistical properties]

The rate is an epidemiologic measure which has a widespread use in describing the occurrence of diseases. In this paper, with a didactic approach, the definition of the mortality (morbidity) rate is introduced following two ways of reasoning: firstly, in the context of survival analysis, as an instantaneous conditional probability of failure (either disease or death) (instantaneous risk) and, secondly, as a traditional measure of rapidity of change in time. We then proceed to highlight the differences, in terms of definition, interpretation, and application, between the concepts of rate and risk. As a next step the statistical properties of the rate are explored and it is explained why the variability of the measure is simply associated with the numerator (events) and not with the denominator (person-times) of the rate. In this context the Poisson distribution is commonly considered the probability distribution which better describes the statistical variability of the observed events, and examples of such a distribution are presented. When the number of deaths is sufficiently elevated the Poisson distribution can be adequately approximated by the Gauss distribution, which is simpler and in common use in occupational medicine, and formulas are presented to compute mean and variance of the rate in this situation. When the number of deaths is small a suggestion is made of making a log transformation of the rate (or of the deaths) before using the Gauss distribution: formulas are proposed for this situation, too. As a practical application of the statistical properties presented and as a concluding example, a confidence interval for the rate is computed. Numerical and graphical comparisons of the results deriving from the use of different formulas are described.

[Minor injuries: little known aspects of occupational accidents]

This paper is aimed at describing and characterizing occupational injuries which do not receive compensation (minor injuries), and at evaluating the differences between compensated and non compensated injuries with reference to type and site of the lesion. Data were collected in a car manufacturing plant and covered the period 1984-1991. Information regarding all kinds of occupational accidents were extracted, following a standardized procedure, from different paper forms compiled by health personnel within the factory (physicians and nurses). Due to the large amount of information registered, a sampling scheme was adopted which considered the same three months every two years, previously selected to cover the entire observation period (1984-85, 1987-88, 1990-91). In addition, to evaluate che adequacy of the sampling procedures for the compensated injuries only, the resulting sampled distributions of the relevant variables were compared with the totality of the injuries. 7,299 events occurred in the sampled months, which corresponded to 652.59 occupational accidents per million hours worked: 8.97% of them caused absence from work lasting more than three days (compensated cases), 3.59% caused a less than three workday loss (LTTWL cases), and the great majority (87.44%) did not cause any absence from work (first aid cases). The frequency index of the total number of accidents did not change over time, but the three categories of injuries did change: for example, first aid cases had their maximum frequency during the middle period (with a peak of 93.21% in March 1987) and their minimum during the last period (73.28% in June 1991). An opposite pattern occurred for accidents which caused absence from work. Type and site of the lesions differed among the three categories of occupational accidents. For example, cuts/lacerations were observed in 48% of first aid cases, 30% of compensated cases, and 15% of LTTWL cases. On the contrary, injuries due to extraneous bodies and contusions which were the most frequent category for LTTWL cases with, respectively, 28% and 25% of the cases, represented only 10% and 13% of first aid cases. With respect to the site of the lesion, hands had the highest frequency index both for first aid (56%) and compensated (39%) cases, and eyes were most affected (36%) among LTTWL cases. With respect to compensated injuries, a notable correspondence of the distributions of the relevant variables between the sample and the whole population was evident, also when considering separate individual subperiods.(ABSTRACT TRUNCATED AT 400 WORDS)

[Variations over time in the accident rate in an automobile manufacturing plant]

This paper describes some characteristics of occupational injuries occurring in a car manufacturing plant during the period 1984-1991. Data regarding all kinds of injuries (not only those which received compensation) were extracted from records compiled by health personnel within the factory according to a sampling scheme that considered the same three months every two years. In addition, all injuries which caused absence from work lasting more than three days were evaluated (without sampling). To compute frequency indexes, the number of hours worked each month/year were obtained. Roughly 650 occupational injuries per million hours worked occurred in the whole population without appreciable changes over time: about 90% of the events did not cause absence from work. For two-thirds of the injuries that caused absence from work, the absence lasted more than three days. More than 50% of the injuries involved the hands; the eyes and arms followed with lower percentages. Cuts/lacerations comprised 45% of all injuries, followed by contusions and foreign bodies. Over time, the frequency index of foreign bodies in the eyes diminished, whereas muscular disorders increased, mainly in the last period. Compensated injuries were particularly elevated in the final period and lowest in the middle: this pattern is attributable only to events with temporary consequences. The increase in the incidence of injuries in the last period was observed in all categories of duration of absence but the decrease of incidence in the middle period concerned only events with shorter duration (less than fourteen days' absence). These trends can be partially attributed to the changes in health management within the factory (recognition and first aid) which occurred in the time period considered. Some combinations of site and type of lesion (i.e., foreign bodies in the eyes) showed a decrease over time both for index of frequency and mean duration of absence; others had a particular pattern: decrease in frequency and increase in mean duration of absence in the middle period, followed by an opposite pattern in the last period (i.e., cuts/lacerations of the hands); some others showed a decrease both for frequency and duration of absence (sprains/strains of the vertebral column muscles).

Cancer in a young population in a dioxin-contaminated area

An industrial accident in Seveso, Italy, in 1976, caused contamination of the residential community with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We investigated cancer occurrence in the first post-accident decade (1977-1986) among nearly 20,000 subjects aged 0-19 years. People who left the area were actively followed with a 99% follow-up rate. For reported cancer cases confirmation was obtained through consultation with original medical records. Two ovarian cancers were observed versus none expected. A suggestive increase was seen for Hodgkin's lymphoma (relative risk [RR] = 2.0; 95% confidence interval [CI] = 0.5-7.6). Myeloid leukaemia showed a clear, but not statistically significant increase (RR = 2.7; 95% CI = 0.7-11.4). The most prominent result concerned thyroid cancer, not just for the magnitude of the increase (two cases, RR = 4.6; 95% CI = 0.6-32.7), but also for its consistency with experimental findings and previous observations in humans. Any conclusive interpretation would be premature because of the short time since initial exposure, ecological definition of exposure status, and limited number of events.