Surfactant protein-D and exposure to bioaerosols in wastewater and garbage workers.

PURPOSE: Bioaerosols and their constituents, such as endotoxins, are capable of causing an inflammatory reaction at the level of the lung-blood barrier, which becomes more permeable. Thus, it was hypothesized that occupational exposure to bioaerosols can increase leakage of surfactant protein-D (SP-D), a lung-specific protein, into the bloodstream. METHODS: SP-D was determined by ELISA in 316 wastewater workers, 67 garbage collectors, and 395 control subjects. Exposure was assessed with four interview-based indicators and by preliminary endotoxin measurements using the Limulus amoebocyte lysate assay. Influence of exposure on serum SP-D was assessed by multiple linear regression considering smoking, glomerular function, lung diseases, obesity, and other confounders. RESULTS: Overall, mean exposure levels to endotoxins were below 100 EU/m(3). However, special tasks of wastewater workers caused higher endotoxin exposure. SP-D concentration was slightly increased in this occupational group and associated with the occurrence of splashes and contact to raw sewage. No effect was found in garbage collectors. Smoking increased serum SP-D. No clinically relevant correlation between spirometry results and SP-D concentrations appeared. CONCLUSIONS: These results support the hypothesis that inhalation of bioaerosols, even at low concentrations, has a subclinical effect on the lung-blood barrier, the permeability of which increases without associated spirometric changes.

Hepatitis E, Helicobacter pylori and peptic ulcers in workers exposed to sewage: a prospective cohort study.

BACKGROUND: Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV). OBJECTIVES: To assess the incidence of clinical hepatitis E and peptic ulcers and the seroconversion rate of antibodies to H pylori and HEV in workers with and without sewage exposure. METHODS: 332 workers exposed to sewage and a control group of 446 municipal manual workers (61% participation rate) entered a prospective cohort study with clinical examination and determination of antibodies to H pylori and HEV (immunoglobulins G and A or G and M, respectively). Survival curves were examined with log rank tests and Cox regressions. Travelling to endemic areas, socioeconomic level, age, country of childhood, number of siblings, and personal protective equipment were considered as the main confounding factors. RESULTS: Incidence of clinical hepatitis E was not increased in sewage workers. One peptic ulcer and three eradications were recorded in sewage workers compared with no peptic ulcers and 12 eradications in control workers. Incidence rates of approximately 0.01, 0.10, and 0.15 seroconversion/person-year for hepatitis E, H pylori IgG and H pylori IgA, respectively, were found in both exposed and non-exposed workers. Survival curves did not show an increased risk in sewage workers and no association with any exposure indicator was found. Sensitivity analyses did not alter these results. CONCLUSIONS: Sewage does not appear to be a source of occupational infection by H pylori or HEV in trained sewage workers with personal protective equipment working in a region with good sanitation.

[Corneal and conjunctival findings in systemic silver intoxication]. / Corneale und conjunctivale Befunde bei systemischer Argyrose.

BACKGROUND: Chronic silver intoxication is a rare disease and therefore the typical ocular findings may be missed. Based on a case with severe intoxication, the clinical and histological findings as well as the prognosis in argyria are presented. HISTORY: A 33-years-old-employee of a battery production plant developed a biopsy proven systemic argyria. On slit lamp examination the conjunctiva showed a dark, blue-grey discoloration in the areas of the tear flow and the small conjunctival arteries. Diffuse silver deposits were noticed on the level of Descemet's membrane without endothelial damage. Silver deposits were also visible in the trabecular meshwork. Chemical reaction of the silver particles upon exposure to UV light results in irreversible tissue discoloration. Without options for an effective treatment, early diagnosis and prevention of overexposure are most important. CONCLUSIONS: The typical ocular findings in systemic argyria are helpful in occupational medicine for establishing the correct diagnosis.

Clara cell protein and surfactant protein B in garbage collectors and in wastewater workers exposed to bioaerosols.

OBJECTIVES: Inhalation of bioaerosols has been hypothesised to cause "toxic pneumonitis" that should increase lung epithelial permeability at the bronchioloalveolar level. Serum Clara cell protein (CC16) and serum surfactant protein B (SPB) have been proposed as sensitive markers of lung epithelial injury. This study was aimed at looking for increased lung epithelial permeability by determining CC16 and SPB in workers exposed to bioaerosols from wastewater or garbage. METHODS: Subjects (778 wastewater, garbage and control workers; participation 61%) underwent a medical examination, lung function tests [American Thoracic Society (ATS) criteria], and determination of CC16 and SPB. Symptoms of endotoxin exposure and several potential confounders (age, gender, smoking, kidney function, obesity) were looked for. Results were examined with multiple linear or logistic regression. RESULTS: Exposure to bioaerosols increased CC16 concentration in the wastewater workers. No effect of exposure on SPB was found. No clue to work-related respiratory diseases was found. CONCLUSIONS: The increase in CC16 in serum supports the hypothesis that bioaerosols cause subclinical "toxic pneumonitis", even at low exposure.

Hepatitis E, Helicobacter pylori, and gastrointestinal symptoms in workers exposed to waste water.

BACKGROUND: Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV). AIMS: To assess the prevalence of clinical hepatitis E (HE) and peptic ulcer disease as well as the seroprevalence of antibodies to H pylori and HEV in workers with and without sewage exposure and to look for symptoms due to exposure to endotoxin. METHODS: In the first year of a prospective cohort study 349 sewage exposed workers and 429 municipal manual workers (participation: 61%) underwent a complete medical examination. Travelling to endemic areas, socioeconomic level, age, country in which childhood was spent, and number of siblings were considered as the main confounding factors. RESULTS: Peptic ulcer disease and clinical HE did not occur more often in workers exposed to sewage. Prevalence of antibodies to HEV was 3.3% and overall prevalence of IgG antibodies to H pylori was 42% with large differences between subgroups. Logistic regression did not show an increased risk of seropositivity or antibodies to parietal cells in sewage exposed workers, but disentangling the effect of exposure from that of confounders was extremely difficult. No increase of symptoms due to exposure to endotoxin was found in sewage workers, with the exception of diarrhoea. CONCLUSIONS: No clear increased risk of infection by H pylori or by HEV in workers exposed to sewage was found in this cross-sectional study, but these results need to be confirmed by follow up.

[Hepatitis E and exposure to waste water]. / Hepatitis E und Abwasserkontakt.

Hepatitis E virus (HEV) is found in waste water which represents a route of infection. However, the risk for sewage workers is unknown. Thus, we aimed at determining the prevalence of anti-HEV antibodies in sewage workers from the Canton of Zurich. The anti-HEV antibodies evaluated in 288 subjects with exposure to sewage and 306 controls, a total of 594 subjects. Overall, twenty-two (3.7%) subjects had anti-HEV, the seroprevalence was similar in those exposed and controls. The most important risk factor, travelling in endemic areas, was lacking in two workers, who both were exposed to sewage. A follow up study in the population will soon give further evidence on the incidence rate.

[Lung diseases in persons exposed to waste disposal dust]. / Lungenerkrankungen bei müllstaubexponioertem Personen.

The current cohort study in the canton of Zurich is investigating respiratory diseases in waste collectors. Therefore, a clinical history was taken and lung function tests and measurement of the Clara cell protein concentration were carried out. The first results show no elevation of the prevalence of asthma or other lung diseases in waste collectors. Compared with control subjects, waste collectors have a lower forced expiratory volume in the first second and a higher mean Clara cell protein concentration. The prevalence of cardiovascular risk factors such as smoking, obesity and arterial hypertension which are not caused by the occupation is high. Indeed, about 50% of all participants are hypertensive.

[Must caries be completely removed?]. / Muss Karies vollständig entfernt werden?

Changes in restorative techniques and the development of new restorative materials have allowed the use of more conservative cavity preparations. Important questions are: What are the consequences of incomplete removal of caries-affected dentin? What are the bond strengths of adhesives to demineralized enamel and dentin? The non-invasive management of carious lesions with intact tooth surfaces in a manner that will bring about some remineralization offers a viable and superior alternative to conventional restorations. The bond strengths of adhesives to demineralized enamel seem to be similar to that on normal enamel. None of the modern filling technologies can guarantee the arrest of the carious process. The complete removal of the infected dentin is, however, still necessary irrespective of the restorative material used.

Hepatitis A in workers exposed to sewage: a systematic review.

OBJECTIVES: To assess whether the scientific literature supports the hypothesis that workers exposed to sewage are at higher risk of hepatitis A (HA). METHODS: All original papers reporting epidemiological studies published in English, French, or German which reported on the risk of HA infection in workers exposed to sewage were eligible. They were identified by several methods and each original paper was assessed independently with a checklist by two people. Studies were classified according to the strength of their design. Non-eligible studies were also examined to assess the impact of publication bias. If the risk estimates diverged widely, causes for heterogeneity were assessed. A distinction was made between seroprevalence studies based on subclinical HA (defined only by the presence of anti-HA antibodies) and clinical HA. RESULTS: 17 eligible studies were identified. No indication of an increased risk of clinical HA could be found. For seroprevalence the studies with the strongest design suggested a slightly increased risk of subclinical HA with an odds ratio (OR) <2.5. Heterogeneity was considerable and precluded a meta-analysis. Considering non-eligible studies would still decrease the OR. CONCLUSIONS: The systematic review does not confirm an increased risk of clinical HA in workers exposed to sewage. An increased risk of subclinical HA cannot be excluded but the association between seropositivity and exposure to sewage was not strong and became still weaker if publication bias was taken into account.

[Dental knowledge and evaluation of school dental care by school graduates in Berne canton]. / Zahnbewusstsein und Stellenwert der Schulzahnpflege bei Schulabgängern im Kanton Bern.

In 1996, a letter was written to 401 High-School level graduates of 20 randomly selected schools in the canton of Berne, Switzerland. Out of these 401, 343 individuals could be interviewed and subsequently be given a clinical examination comprising a plaque revealing test. The average plaque index was 70%. The assessment of the questionnaires showed a comprehensive basic dental knowledge of the students so that reasonable care of their teeth could be expected. Whereas almost everyone used a toothbrush regularly, flossing fell short in the majority of the cases. Outside the class-rooms, concentrated F-preparations were hardly used systematically. Besides parents and the family, dentists and specifically trained auxiliaries (school dental health assistants, SDHA) were found to play a central role in the mediation of theoretical knowledge and in the practical instruction of oral hygiene procedures. They received mostly good grades by the students for their work. The regular teaching staff, however, fell clearly behind the SDHAs. In spite of the obviously big influence on the youth, the dentists play only an insignificant role in some places. Overall, the students consider dental health education as relatively important placing it on the same level as sex education. Since SDHAs do not visit the classes during the last five years any longer, teaching of dental prophylaxis has been reduced in many communities to fluoridation with concentrated F-preparations. Negative consequences such as uncertainty regarding tooth brushing techniques, handling dental floss and questions as to oral hygiene behavior after leaving school have already been registered. With the academic year 2000/01 one visit by an SDHA to the upper level classes (last five years) was reintroduced. This tepid reaction by the Bernese education authority to a massive weakening of public dental health promotion will hardly suffice to keep up the remarkable level of dental prevention reached over the past decades, let alone to warrant substantial progress. The study has also demonstrated that the acquisition of knowledge is based on repetitive efforts. This is the fundamental reason for systematic monitoring and re-instruction of dental hygiene procedures also during the last five classes of mandatory scholarity.

[The operating microscope in dental general practice]. / Das Operationsmikroskop in der zahnärztlichen Allgemeinpraxis.

The great advantages of using a stereoscopic operating microscope in endodontics and especially in endodontic surgery are being increasingly advocated in postgraduate training courses and numerous publications. Widely underestimated, however, is the fact that this tool may open new horizons to almost all dental specialities and will improve ergonomics of the dental work place. Moreover, the superb images may contribute some pleasure to the daily dental work and stress. All this makes the clinical stereoscope interesting also for the general practice of dentistry. The purpose of this paper is to report about several years of practical experience with the "scope" in general dentistry. Technical aspects are discussed as well as the possibilities of use. Practical hints regarding the type of scope and the technique of its use are given in order to lower the barrier of entrance into this new era of doing dental work.

Long-term obturation quality using noninstrumentation technology.

The aim of the study was to evaluate and compare the sealing quality of hand- or vacuum-obturated root canals after hand instrumentation or noninstrumentation cleansing. A total of 60 single-rooted teeth were divided into six comparable groups. The root canals of three groups were instrumented with the balanced-force technique and obturated with gutta-percha condensation. The remaining teeth were cleansed and filled using noninstrumentation technology and the same sealers as with hand instrumentation (AH Plus, Apexit, Pulp canal sealer EWT). After aging the quality of coronal seal was assessed with a dye penetration method after perfusion with the dye under vacuum. The results of this study indicated superior sealing of the machine-filled roots (noninstrumentation technology), compared with laterally condensed conventionally filled root canals.

Renal effects of low-level environmental cadmium exposure: 5-year follow-up of a subcohort from the Cadmibel study.

BACKGROUND: The clinical relevance of renal effects of cadmium in people exposed in the environment remains uncertain. This study examined the evolution of renal effects observed in a population exposed to cadmium in the environment. METHODS: 208 men and 385 women surveyed in 1985-89 (Cadmium in Belgium study [Cadmibel]; baseline) were re-examined on average 5 years later (Public health and environmental exposure to cadmium study [PheeCad]; follow-up). Urinary and blood cadmium and markers of renal tubular dysfunction and glomerular effects were measured. The association between cadmium body burden and renal factors was examined by multivariate logistic and linear regression. FINDINGS: In men, mean urinary cadmium excretion and blood cadmium concentration measured at follow-up were 7.5 nmol/24 h (SD 1.9) and 6.1 nmol/L (2.2), reductions of 16% and 35% from baseline, respectively. In women, the corresponding values were 7.6 nmol/24 h (1.9) and 7.8 nmol/L (2.1), reductions of 14% and 28% from baseline. No indication of progressive renal damage was found and the overall results suggest that the effects of low environmental exposure to cadmium on the kidney are weak, stable, or reversible. INTERPRETATION: Subclinical renal effects that have been reported in Belgium in patients with increased cadmium body burden are not associated with progressive renal dysfunction and most likely represent non-adverse manifestations.

Interleukin 1 alpha hematological examination in mechanics exposed to low benzene concentrations.

OBJECT: To examine the hypothesis of Renz and Kalf relative to the involvement of interleukin 1 alpha (IL-1 alpha) in the development of anemia in benzene-exposed workers. According to this hypothesis, benzene inhibits the cleavage of the IL-1 alpha precursor (proIL-1 alpha) to mature IL-1 alpha and the lack of this cytokine is responsible for benzene-induced bone marrow suppression. This inhibition of the processing of proIL-1 alpha is attributed to an inhibition of calpain. METHOD: Selection of a population of mechanics exposed to low levels of benzene from fuels, assessment of usual exposure and lifetime exposure duration, and measurements of concentrations of workplace-air benzene and urinary benzene metabolites. Determination of IL-1 alpha concentrations was done by a whole-blood assay after lipopolysaccharide stimulation and a hematological examination was carried out. Statistical analysis considered several possible confounding factors, particularly smoking and drinking habits. DESIGN: Cross-sectional study. RESULTS: The level of exposure of the mechanics to benzene from fuels was mostly well below 1 ppm. IL-1 alpha production was not decreased in mechanics exposed to benzene from fuels, and no correlation between IL-1 alpha concentrations and red blood cell counts appeared. With the exception of a slight decrease in red blood cell counts in mechanics, no hint of a toxic effect of exposure on hematological parameters was found. CONCLUSIONS: The hypothesis of Renz and Kalf could not be confirmed. Although the low level exposure of the study population and methodological factors are possible explanations, it cannot be excluded that the hypothesis of Renz and Kalf is not generalizable to benzene-exposed humans. Presently, one cannot advise the measurement of IL-1 alpha production for biological effect monitoring of workers exposed to low concentrations of benzene.

Hematopoietic and lymphatic malignancies in vehicle mechanics.

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

Relationships between smoking habits, smoking-associated hematological changes, and urinary benzene metabolites.

It has been suggested that benzene metabolites might be good indicators of smoking. Moreover, benzene could stimulate the neutrophil lineage while depressing the lymphocytic and erythroid lineages, possibly by an interference with cytokines. The effect on the neutrophil lineage could explain the smokers' leukocytosis, the mechanism of which is presently unknown. Therefore, the usefulness of benzene metabolites as indicators of smoking was compared to that of cotinine and thiocyanate, and the relationships between benzene metabolites, the hematological parameters of smokers, and interleukin 1 alpha production were examined. The results show that benzene metabolites are not better indicators of smoking status than cotinine or thiocyanate. Furthermore, it seems unlikely that the smokers' leukocytosis is benzene induced.

Biological monitoring of vehicle mechanics and other workers exposed to low concentrations of benzene.

It has been suggested that the threshold limit value (TLV) for the time-weighted average (TWA), of benzene be lowered because of its possible leukemogenic effect at low exposure concentrations. This requires the development of new methods of biological monitoring. In this cross-sectional study the diagnostic power of blood and breath benzene and of urinary phenol, catechol, hydroquinone, S-phenylmercapturic acid, and muconic acid were compared in a population of 410 male workers exposed to benzene in garages, in two coke plants, and in a by-product plant. Benzene exposure was assessed by personal air sampling (charcoal tube and passive dosimeter). In all, 95% of the workers were exposed to less than 0.5 ppm benzene. According to the multiple regression equation, the muconic acid and S-phenylmercapturic acid concentrations detected in nonsmokers exposed to 0.5 ppm benzene were 0.3 mg/g and 6 micrograms/g, respectively (range 0.2-0.6 mg/g and 1.2-8.5 micrograms/g, respectively). With muconic acid very few false-positive test results were found, and this determination remained reliable even around a cutoff level of 0.1 ppm benzene. Moreover, the diagnostic power of this test proved to be good even when diluted or concentrated urine samples were not excluded. S-Phenylmercapturic acid (S-PMA) also performed fairly well. Blood and breath benzene as well as urinary phenol (PH) and hydroquinone (HQ) were clearly less suitable biomarkers than muconic acid (MA). Catechol (CA) was not associated with occupational benzene exposure. According to the results of biological monitoring, the skin resorption of benzene from gasoline or other fuels seems negligible. Correlation, multiple regression, and likelihood ratios consistently showed that MA and S-PMA concentrations were fairly good indicators of benzene exposure in the 0.1- to 1-ppm range, even in a population comprising both smokers and nonsmokers. PH, HQ, CA, and blood and breath benzene were less suitable, if at all, in the same exposure range.