Sixty years on: the price of assembling military gas masks in 1940

BACKGROUND

Between 1940 and 1944 military gas masks with filter pads containing 20% crocidolite were assembled in a Nottingham factory.

METHODS

Records supplied by the late Professor Stephen Jones were of 1154 persons, mainly women, who had worked in the factory during this period; they included many deaths from mesothelioma. A systematic effort was therefore made to establish causes of death for the whole cohort.

RESULTS

Of 640 employees with full name and sex recorded, 567 (89%) were traced. Of these, 491 had died, including 65 from mesothelioma, though only 54 were certified as such. After exclusion of these 54, standardised mortality ratios were significantly raised for respiratory cancer (SMR 2.5) and carcinomatosis (SMR 3.2). The pattern of mortality in the remaining 514 employees without full identification was similar, but a low tracing rate (40%) did not justify their further analysis. The first death from mesothelioma was in 1963 (22 years after first exposure) and the last in 1994, whereas a further 5.0 cases would have been expected between 1996 and 2003 (p = 0.0065).

CONCLUSION

These findings in a cohort followed over 60 years after brief exposure to crocidolite confirm a high and specific risk of mesothelioma (28% peritoneal) and perhaps of lung cancer some 20-50 years later. The statistically significant absence of further mesothelioma cases during the past eight years suggests that crocidolite, though durable, is slowly removed.

Incidence by occupation and industry of work-related skin diseases in the United Kingdom, 1996–2001

BACKGROUND

Work-related skin disease is common but few cases are documented in statutory reports or disability systems. Voluntary reporting by specialist physicians provides more complete information.

AIMS

To summarize incidence rates of work-related skin diseases reported by consultant dermatologists and occupational physicians, with emphasis on contact and allergic dermatitis by occupation and industry.

METHODS

Cases reported in 1996-2001 to the EPIDERM and OPRA national surveillance schemes were analysed by causal agent, occupation and industry, with incidence rates calculated against appropriate denominators.

RESULTS

Average annual incidence rates based on data from dermatologists were 97 per million overall, 74 for contact dermatitis and 14 for neoplasia. The corresponding rates for occupational physicians were 623 overall, 510 and 2, respectively. For infective disease, the rates for occupational physicians were 28 compared to 2 for dermatologists. Contact dermatitis was most frequently attributed to rubber chemicals, soaps and cleaners, wet work, nickel and acrylics; most cases of contact urticaria were attributed to rubber chemicals or foods and flour. The pattern of incidence rates by occupation and industry was complex, but correlated with the probable type of exposure. Rates of contact dermatitis were highest among skilled workers in the petrochemical and rubber and plastic manufacturing industries, with machine operators and technical workers in metal and automotive industries also at increased risk. High proportions of cases attributed to rubber chemicals were in nurses and technicians in the health and social services.

CONCLUSIONS

These findings identify jobs and types of work where contact with causal agents is common and potentially preventable.

Incidence by occupation and industry of acute work related respiratory diseases in the UK, 1992-2001

AIMS

To summarise incidence rates and epidemiological characteristics of new cases of work related respiratory disease reported by specialist physicians in thoracic and occupational medicine, with particular reference to occupation, industry, and causal agents for asthma, inhalation accidents, and allergic alveolitis.

METHODS

Cases reported 1992-2001 to the SWORD and OPRA national surveillance schemes, in which almost all UK chest and occupational physicians participate, were analysed by age, sex, cause, occupation, and industry, with incidence rates calculated against appropriate denominators.

RESULTS

Excluding diseases of long latency, infrequently seen by occupational physicians, the distribution of diagnoses in the two specialties was similar, but with rates generally much higher in occupational than chest physicians. Occupational asthma was responsible for about 25% of cases overall, affecting mainly craft related occupations and machinists, and most often attributed to isocyanates, metals, grains, wood dusts, solders, and welding fume. These same occupations were those at highest risk from inhalation injuries, most frequently caused by irritant gases, vapours, and fume. Among medical technicians and nurses, however, glutaraldehyde and latex were the main causes of occupational asthma. Allergic alveolitis was seldom reported, with almost all cases in agriculture, forestry, and fishing.

CONCLUSION

During the 10 year period studied, there were few changes in level of reported incidence, apart from some decline in occupational asthma and inhalation injuries. These results and their implications should be distinguished from much higher estimates of asthma made worse by work derived from population surveys, based on prevalence rather than incidence, and self-reported symptoms rather than diagnoses made by specialist physicians. Even so, the reported incidence of new cases of acute respiratory illness caused by work remains substantial.

The radiological properties of a novel lung tissue substitute

Lung phantoms have been manufactured using commercially available, polyurethane foam products. Some of these materials are no longer available; therefore, a new lung tissue substitute was developed. The elemental composition and radiological properties of the new lung tissue substitute are described in this paper. Because the lung tissue substitute will be used to manufacture phantom lungs that will be used to evaluate chest counting systems, it is necessary to know the radiological properties of the material. These properties must be compared with reference materials and materials that have been used for lung phantoms in the past. The radiological properties of interest include the electron density, mean excitation energy, electron stopping power and photon mass attenuation coefficients. In all these properties, the calculated values for the new lung tissue substitute closely matched the calculated values of ICRU Publication 44 lung tissue. Good agreement was also found when the new lung tissue substitute was compared with the Griffith lung tissue substitute described by the ICRU. The new material was determined to be an excellent lung tissue substitute.

Asbestos, asbestosis, and lung cancer: a critical assessment of the epidemiological evidence

The question of whether lung cancer can be attributed to asbestos exposure in the absence of asbestosis remains controversial. Nine key epidemiological papers are reviewed in a point/counterpoint format, giving the main strengths and limitations of the evidence presented. Of the nine papers, two concluded that asbestosis was necessary and seven that it was not. However, the study design, nature and circumstances of exposure and method of analysis of the studies differed considerably, and none was considered definitive. It is concluded that, because of the relative insensitivity of chest radiography and the uncertain specificity of findings from histological examinations or computed tomography, it is unlikely that epidemiology alone can put either the strict scientific or practical medicolegal questions beyond doubt. It is probable that the issue may depend critically on asbestos fibre type, an aspect not so far addressed.

Mortality in a cohort of vermiculite miners exposed to fibrous amphibole in Libby, Montana

BACKGROUND

Fibrous tremolite is a widespread amphibole asbestiform mineral, airborne fibres of which constitute an environmental hazard in Libby, Montana, northern California, and elsewhere.

AIMS

To determine excess risk from lung cancer, mesothelioma, and all-cause mortality in a cohort of men exposed to tremolite, but no other form of asbestos.

METHODS

Mortality by certified cause and various measures of exposure to tremolite and related amphibole fibres was assessed in a cohort of 406 vermiculite mineworkers in Libby, Montana, employed before 1963 and followed until 1999.

RESULTS

Total deaths were: lung cancer 44 (SMR 2.40), non-malignant respiratory disease (NMRD) 51 (SMR 3.09), all causes 285 (SMR 1.27); included among the total were 12 deaths ascribed to mesothelioma (4.21% of all deaths). Adjusted linear increments in relative risks (per 100 f/ml.y), estimated by Poisson regression, were: lung cancer (0.36, 95% CI 0.03 to 1.20), NMRD (0.38, 95% CI 0.12 to 0.96), and all deaths (0.14, 95% CI 0.05 to 0.26).

CONCLUSIONS

The all-cause linear model would imply a 14% increase in mortality for mine workers exposed occupationally to 100 f/ml.y or about 3.2% for a general population exposed for 50 years to an ambient concentration of 0.1 f/ml. Amphibole fibres, tremolite in particular, are likely to be disproportionately responsible for cancer mortality in persons exposed to commercial chrysotile, but to what extent cannot be readily assessed.

Dose limits for man do not adequately protect the ecosystem

As has been noted by both of our participants, it is interesting to see that their views approached agreement during the course of the debate. This is not altogether unexpected since the topic is on that has many facets. It is fair to say that protecting man is an appropriate starting point for the protection of other more, or less, radiosensitive life forms sharing the planet with us. That there may be special situations requiring attention has been recognized by both of our participants. That the ICRP recognizes the need for further work on this topic is encouraging for ourselves as well as the 'bugs and bunnies'.

Pyogenic liver abscess

BACKGROUND

A current assessment of liver abscesses should allow for better understanding of the pathogenesis of the disease and improve the effectiveness of diagnosis and treatment. Amebic liver abscess occurs more commonly than pyogenic liver abscess on a worldwide basis. However, in the United States, pyogenic liver abscess predominates. The purpose of our study was to evaluate the etiology, management, morbidity, and mortality of all patients admitted to our medical center with diagnoses of pyogenic liver abscess between 1983 and 1996.

METHODS

A retrospective chart review was performed on all patients admitted to our medical center, Louisiana State University Medical Center, Shreveport, with diagnoses of pyogenic liver abscess.

RESULTS

Twenty patients were admitted with diagnoses of pyogenic liver abscess. The subjects were 65% (13/20) male and 65% (13/20) African-American and had an average age of 52 years. The most common presenting symptoms were fever and pain. The most common physical finding was right upper-quadrant tenderness. The most common etiologies of pyogenic liver abscesses were cryptogenic, trauma, and biliary, while portal vein was the source for only 10% of the cases. The right lobe of the liver was involved in 95% of the cases, and 70% of these liver abscesses were solitary. Computed tomography (CT)-and ultrasound-guided percutaneous drainage were performed in 85% (17/20) of patients with liver abscesses. One patient was treated by open drainage, three patients were treated with antibiotics alone, and three patients did not respond to aspiration and catheter placement, which subsequently required open drainage. The culture results were as follows: 50% were gram-negative organisms, 25% were gram-positive organisms, 10% were anaerobic organisms, and 15% of the abscess were sterile. Sixty percent of the positive abscess cultures were polymicrobial.

CONCLUSIONS

CT scan- and ultrasound-guided percutaneous drainage of pyogenic liver abscesses were safe and effective methods of treatment. The right lobe of the liver was involved in 95% of cases. Although no one species predominated, gram-negative bacteria were the most common organism cultured, and 60% of the abscesses were polymicrobial. There was no in-house mortality in this review.