[Cardiovascular risk factors and life and occupational stress among policemen]

BACKGROUND

Several studies have shown an association between work-related stress and risk factors for cardiovascular disease. ever, only a few studies concerned the police. The aim of this study was to assess the relationship between the general and work-related stress, and the functioning of the circulatory system in the police staff.

MATERIAL AND METHODS

The study group consisted of 126 policemen (aged 37.8 +/- 7.3 years), with average employment duration of 14.4 +/- 7 years. The study comprised the assessment of health status based on the medical examination and medical history of identified diseases, cardiovascular risk factors and symptoms, dietary habits, physical activity, intake of drugs, data on the family history, determinations of serum total cholesterol, HDL and LDL fractions, triglycerides, and fasting glycemia . The stress level was assessed using the Questionnaire for the Subjective Assessment of Work and Perceived Stress Scale.

RESULTS

On medical examination hypertension was found in 36% of the people under study. Chest discomfort was reported by 60% of the subjects. Average body mass index (BMI), serum cholesterol and LDI, were elevated (22.7 +/- 4.1, 222.6 +/- 41.7 mg/dl and 142.7 +/- 39.7 mg/dl, respectively). Mean triglyceride, HDL fraction and fasting glucose levels were normal in the whole group. The levels of general and occupational stress were 34.914.8 and 128.0+33.3, respectively, being higher than in other occupational groups. In the group with the highest level of stress, there were significantly more people with circulatory problems (81%), drinking strong alcohol at least once a week (27%), working in a 3-shift system (40.5%) and working overtime (44%).

CONCLUSIONS

The results show that the police are a group at high risk of developing cardiovascular diseases due to work-related stress.

Behavioral effects following repeated exposure to hexachloronaphthalene in rats

Polychlorinated naphthalenes (PCNs), including hexachloronaphthalene (HxCN), are widespread global environmental contaminants. Our experiments were aimed at assessing HxCN effects on motor behavior, long-term memory, pain sensitivity, magnitude of stress-induced analgesia, auditory function and sensorimotor gating, following repeated intragastric administration (28 days) of HxCN at 0.3 and 1.0 mg/kg body weight. Three weeks after the exposure termination, male Wistar rats were subjected to the neurobehavioral tests battery performed in the following order: open-field test, passive avoidance test, hot-plate test and acoustic startle response test. Repeated administration of HxCN induced disorders of motivational processes manifested by: anorectic effect caused by aphagia and adipsia; significantly reduced motor activity (hypokinesia); impaired long-term memory and acquired passive avoidance reaction; reduced pain threshold and shortened duration of anxiety reaction after pain stimulus (sensory neglect). Some of these neurobehavioral effects (impaired long-term memory, reduced pain threshold and stress-induced analgesia) were observed at 0.3 mgHxCN/kg body weight without any signs of overt toxicity. The outcome of our study shows that HxCN, like other compounds of the persistent organic pollutants (POPs) group, creates a potential risk of behavioral changes in the central nervous system in the general population as a result of environmental exposure.

Headspace measurements of irradiated in vitro cultured cells using PTR-MS

A pilot study was performed to evaluate a new concept for a radiation biodosimetry method. Proton transfer reaction-mass spectrometry (PTR-MS) was used to find out whether radiation induces changes in the composition of volatile organic compounds (VOCs) in the headspace of in vitro cultured cells. Two different cell lines, retinal pigment epithelium cells hTERT-RPE1 and lung epithelium cells A-549, were irradiated with gamma radiation at doses of 4 Gy and 8 Gy. For measuring the cell-specific effects, the VOC concentrations in the headspace of flasks containing cells plus medium, as well as of flasks containing pure medium were analyzed for changes before and after irradiation. No significant radiation-induced alterations in VOC concentrations in the headspace could be observed after irradiation.

The inflammatory response in lungs of rats exposed on the airborne particles collected during different seasons in four European cities

Epidemiological studies have reported associations of ambient particulate air pollution, especially particulate matter (PM) less than 10 μm with exacerbations of asthma and chronic obstructive pulmonary disease. In an in vivo model, we have tested the toxicity of urban airborne particles collected during spring, summer, and winter seasons in four cities (Amsterdam, Lodz, Oslo, and Rome) spread across Europe. The seasonal differences in inflammatory responses were striking, and almost all the study parameters were affected by PM. Coarse fractions of the urban particle samples were less potent per unit mass than the fine fractions in increasing cytokine [macrophage inflammatory protein (MIP)-2 and tumor necrosis factor (TNF)-α] levels and in reducing Clara-cell secretory protein (CC16) levels. This study shows that PM collected at 4 contrasting sites across Europe and during different seasons have differences in toxic potency. These differences were even more prominent between the fine and coarse fractions of the PM.

Discrimination of cancerous and non-cancerous cell lines by headspace-analysis with PTR-MS

Proton transfer reaction mass spectrometry (PTR-MS) has been used to analyze the volatile organic compounds (VOCs) emitted by in-vitro cultured human cells. For this purpose, two pairs of cancerous and non-cancerous human cell lines were selected:1. lung epithelium cells A-549 and retinal pigment epithelium cells hTERT-RPE1, cultured in different growth media; and 2. squamous lung carcinoma cells EPLC and immortalized human bronchial epithelial cells BEAS2B, cultured in identical growth medium. The VOCs in the headspace of the cell cultures were sampled: 1. online by drawing off the gas directly from the culture flask; and 2. by accumulation of the VOCs in PTFE bags connected to the flask for at least 12 h. The pure media were analyzed in the same way as the corresponding cells in order to provide a reference. Direct comparison of headspace VOCs from flasks with cells plus medium and from flasks with pure medium enabled the characterization of cell-line-specific production or consumption of VOCs. Among all identified VOCs in this respect, the most outstanding compound was m/z = 45 (acetaldehyde) revealing significant consumption by the cancerous cell lines but not by the non-cancerous cells. By applying multivariate statistical analysis using 42 selected marker VOCs, it was possible to clearly separate the cancerous and non-cancerous cell lines from each other.

The effects of low environmental cadmium exposure on bone density

Recent epidemiological data indicate that low environmental exposure to cadmium, as shown by cadmium body burden (Cd-U), is associated with renal dysfunction as well as an increased risk of cadmium-induced bone disorders. The present study was designed to assess the effects of low environmental cadmium exposure, at the level sufficient to induce kidney damage, on bone metabolism and mineral density (BMD). The project was conducted in the area contaminated with cadmium, nearby a zinc smelter located in the region of Poland where heavy industry prevails. The study population comprised 170 women (mean age=39.7; 18-70 years) and 100 men (mean age=31.9; 18-76 years). Urinary and blood cadmium and the markers of renal tubular dysfunction (beta(2)M-U RBP, NAG), glomerular dysfunction (Alb-U and beta(2)M-S) and bone metabolism markers (BAP-S, CTX-S) as well as forearm BMD, were measured. The results of this study based on simple dose-effect analysis showed the relationship between increasing cadmium concentrations and an increased excretion of renal dysfunction markers and decreasing bone density. However, the results of the multivariate analysis did not indicate the association between exposure to cadmium and decrease in bone density. They showed that the most important factors that have impact on bone density are body weight and age in the female subjects and body weight and calcium excretion in males. Our investigation revealed that the excretion of low molecular weight proteins occurred at a lower level of cadmium exposure than the possible loss of bone mass. It seems that renal tubular markers are the most sensitive and significant indicators of early health effects of cadmium intoxication in the general population. The correlation of urinary cadmium concentration with markers of kidney dysfunction was observed in the absence of significant correlations with bone effects. Our findings did not indicate any effects of environmental cadmium exposure on bone density.

Hydrophilic olive cake extracts: characterization by physicochemical properties and Cu(II) complexation

Disposed olive cake generates hydrophilic components that can be mobilized in the aquatic environment. This paper deals with the characterization of such components, isolated by alkaline extraction. It is shown that these substances possess properties very much resembling humic acid, including a substantial inventory of proton exchanging groups. Extraction and purification of the hydrophilic components from the disposed olive cake was performed by the standard approach for isolation of humic acids from solid sources, i.e. alternating alkaline dissolution and acid flocculation, leaving the purified extract in the protonated form. The purified sample was characterized by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Fourier Transform Infra Red Spectroscopy (FTIR), UV-vis, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Asymmetrical Flow Field-Flow Fractionation (AFFFF). The complex formation properties were investigated by potentiometry using Cu(II) ion selective electrode under atmospheric conditions at I=0.1M NaClO(4) (aqueous solution) and pH 6. The formation constant for the CuHA complex is found to be logbeta=5.3+/-0.4 which is close to the corresponding value (logbeta=5.2+/-0.4) obtained from similar investigations with the commercially available Aldrich humic acid (this study) and corresponding published values for various humic acids. Both, structural properties and complex formation data show that the olive cake extract has considerable similarities with humic acids from different sources, pointing towards potential similarities in environmental behavior and impact.

Independent prognostic factors in patients with liver cirrhosis

BACKGROUND/AIMS

Evaluation of the urgency of the liver transplantation in individual patients may help to prioritize patients at risk of death. Consequently we undertook the search for independent prognostic factors in patients with liver cirrhosis.

METHODOLOGY

The study group was composed of 219 patients with liver cirrhosis, treated in our Department, from 1996 to 2005. Patients' files were examined for details of physical findings, results of laboratory examinations, and patients' survival. Prognostic significance of 15 variables was analyzed. All prognostic factors which turned out to be statistically significant in univariate analysis were included in the Cox proportional hazard model.

RESULTS

Child-Turcotte-Pugh (CTP) score B (p<0.001; hazard ratio (HR): 13.33), CTP score C (p<0.001; HR=7.45), presence of hepato-renal syndrome (p<0.001; HR=3.54), history of esophageal bleeding (p=0.048; HR=1.63) and presence of peripheral edema (p=0.034; HR=1.61) were found to be independently associated with survival. Model of End-stage Liver Disease score, etiology of cirrhosis, sex, ascites, bacterial spontaneous peritonitis, encephalopathy, serum creatinine concentration, INR and serum bilirubin concentration were shown to be significantly associated with patients' prognosis, however not independently.

CONCLUSIONS

Analysis of presence of common clinical symptoms is crucial for evaluation of patients' prognosis.

Expression of tumour necrosis factor-related apoptosis-inducing ligand and caspase-3 in relation to grade of inflammation and stage of fibrosis in chronic hepatitis C

AIM

To assess whether the distribution of the recently described proapoptotic ligand, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), and the apoptosis effector, caspase-3 alters with the degree of inflammation and fibrosis present in liver biopsy specimens from patients with chronic hepatitis C virus infection.

METHODS AND RESULTS

Expression of TRAIL and caspase-3 was assessed immunohistochemically in liver biopsy specimens obtained from 89 adults with chronic hepatitis C. Expression of TRAIL in hepatocytes correlated inversely with stage of fibrosis (P = 0.001), classified according to the Scheuer score; expression of caspase-3 in hepatocytes correlated with grade of inflammation (P = 0.012). Expression of TRAIL in hepatocytes was not correlated with grade of inflammation (P > 0.05); expression of caspase-3 was not correlated with stage of fibrosis (P > 0.05). Maximum expression of proapoptotic TRAIL protein was observed in cases with low grade inflammation (G0) and low stage fibrosis (S1). Maximum expression of caspase-3 in hepatocytes was observed in cases with high grade inflammation (G3-4) and high stage fibrosis (S3), but not with liver cirrhosis (S4).

CONCLUSIONS

There is a significant decrease in TRAIL expression with increasing grade of inflammation, whereas caspase-3 expression is significantly increased with advanced fibrosis, short of cirrhosis.

Hematological effects of four ethylene glycol monoalkyl ethers in short-term repeated exposure in rats

This study was carried out to compare the hematological effects of 2-methoxyethanol (ME), 2-ethoxyethanol (EE), 2-isopropoxyethanol (IPE), and 2-butoxyethanol (BE) in short-term studies in rats. Male rats were subcutaneously treated with ME or EE at a dosage of 0, 1.25, 2.5 and 5.0 mM/kg in saline, 5 days per week, for 4 weeks. Other rats were exposed to IPE or BE at doses of 0, 0.25, 0.5, 0.75 and 1.25 mM/kg in the same manner. Administration of each chemical, except of ME, resulted in a time- and dose-dependent swelling of erythrocytes as evidenced by an increase in mean corpuscular volume (MCV). Subsequently, red blood cells (RBC), packed cell volumes (PCV), hemoglobin concentration (HGB), and mean cell hemoglobin concentration (MCHC) decreased. Furthermore, an increase in mean cell hemoglobin (MCH) and reticulocyte counts was observed. The onset of hemolysis induced by EE, IPE or BE was faster than after ME administration. While in rats exposed to ME hematological changes were strongly pronounced and progressively increased with exposure time beginning from the day 11, those in animals treated with EE were rather persisted at low constant level for all exposure period. In contrast, the rats exposed to IPE and BE demonstrated the dramatic hematological changes more pronounced in case of BE than IPE at the beginning of exposure (on day 4). Despite of exposure duration, these changes were regressed, although the decrease in RBC and MCHC and the increase in MCV and MCH in rats treated with highest doses of both compound (0.5, 0.75, and 1.25 mM/kg) were more persistent, probably due to selective hemolysis of the aged erythrocytes. In addition, significant leukopenia due to reduction of lymphocytes in rats exposed to ME was observed. In summary, this study demonstrated no tolerance to ME- and EE-induced intravascular hemolysis developed under these experimental conditions. On the contrary, tolerance to IPE- and BE-induced hemolysis in rats exposed to these compounds was prompted.

Expression of Bax, Bcl-xL and Bcl-2 proteins in relation to grade of inflammation and stage of fibrosis in chronic hepatitis C

AIMS

To determine the expression of regulators of apoptosis in chronic hepatitis C.

METHODS AND RESULTS

Expression of Bax, Bcl-xL and Bcl-2 proteins was assessed immunohistochemically in liver biopsy specimens obtained from 89 adults with chronic hepatitis C. Expression of Bax in hepatocytes correlated inversely with grade of inflammation (P < 0.001) and stage of fibrosis (P = 0.011), classified according to the Scheuer score; expression of Bcl-xL in hepatocytes did not correlate with grade of inflammation (P = 0.106) or stage of fibrosis (P = 0.078); maximum Bcl-xL expression was observed in grade 3 inflammation and stage 4 fibrosis. Expression of Bcl-2 protein in hepatocytes was present in only two cases (both with advanced disease); the expression of Bcl-2 protein in interlobular bile duct epithelial cells correlated with the grade of inflammation (P = 0.018), but not with stage of fibrosis (P = 0.154). The expression of Bcl-2 protein in lymphoid cells infiltrating portal zones and lobules did not correlate with grade of inflammation (P = 0.113) or stage of fibrosis (P = 0.815).

CONCLUSION

Major differences in expression of studied proteins were observed in relation to grade of inflammation and stage of fibrosis in chronic hepatitis C.

Does fecal diversion offer any chance for spontaneous closure of the radiation-induced rectovaginal fistula?

Analysis of the clinical course of patients with postirradiation rectovaginal fistula after fecal diversion. The studied group included 17 women with postirradiation rectovaginal fistula who underwent fecal diversion as a sole mode of treatment, between January 1987 and December 2002, in our department. All patients were subjected to radiotherapy due to cancer of the uterine cervix, administered 5-107 months before the fistula appearance (mean, 22.9 months). In 3 of 17 patients (18%), spontaneous closure of fistula was observed after 5, 6, and 9 months, respectively, from fecal diversion. Closure was confirmed by endoscopy. Length of follow-up after fecal diversion ranged from 0.5 to 122 months. The actuarial probability of spontaneous closure of postradiotherapy rectovaginal fistula was 0.24 at 9 months of follow-up and then remained stable thereafter. In conclusion, colostomy alone gives hardly a chance for closure of the postradiotherapy rectovaginal fistula. Additional surgical measures are necessary.

Glomerular basement membrane thinning in children: a morphometric assessment

OBJECTIVE

To develop our own procedures, allowing for a quick evaluation of glomerular basement membrane (GBM) thickness and to present a statistical classification of thin basement membrane disease (TBMD), minimal change disease (MCD), and IgA nephropathy (IgAN) cases.

STUDY DESIGN

Measurements were carried out with the aid of the original software for semiautomatic image analysis on biopsies from 31 children with TBMD, 51 with MCD, and 10 with IgAN.

RESULTS

The strongest statistically significant dependence between GBM thickness and age was observed in children with MCD below 5 years of age. There was no significant dependence between GBM thickness and age among patients with TBMD. The values of all analyzed parameters characterizing GBM thickness distribution in children with TBMD were significantly lower than those in patients with MCD and IgAN. A slight, statistically significant increase of some parameters was noted in children with IgAN in contrast to patients with MCD. The multivariate logistic regression model with three independent variables--quartile 1, quartile 3, and percentile 30--proved to be the most appropriate in differentiating between patients with TBMD and children with MCD or IgAN. The model allowed for correctly classifying 96.8% of patients with TBMD (30 of 31 children) and 98.4% patients from the MCD and IgAN groups (60 of 61 children). We failed to construct a similarly appropriate model for differentiating between patients with MCD and IgAN.

CONCLUSION

The introduction of morphometric and statistical methods to routine nephropathologic diagnostics represents true progress in very precise and quick assessment of GBM thickness.

Evaluation of Metabolic Control in Women with Gestational Diabetes Mellitus by the Continuous Glucose Monitoring System: A Pilot Study

OBJECTIVE

To evaluate the blood glucose concentrations in a group of women with gestational diabetes mellitus (GDM), by the use of a continuous glucose monitoring system (CGMS).

METHODS

Seven women with diet-controlled GDM (group G1), 5 with diet- and insulin-controlled GDM (group G2), and 7 healthy, pregnant women (group N) were included in the study. The treatment was adjusted on the basis of self-monitoring of blood glucose (SMBG). The self-monitoring was performed 4 times a day, with the goals of fasting blood glucose values of <90 mg/dL and postprandial (2 hours after each meal) values of <120 mg/dL. Then patients were submitted to a 72-hour period of use of the CGMS.

RESULTS

In the 3 study groups--N, G1, and G2, respectively--no significant differences were noted in individual study parameters, measured with the CGMS in regard to the following: mean 24-hour glycemia (85, 87, and 91 mg/dL), fasting blood glucose (79, 88, and 82 mg/dL), postprandial glucose (96, 97, and 105 mg/dL), mean glucose level during the night (77, 71, and 75 mg/dL), and area under the glycemia curve (281, 315, and 310). Moreover, no significant difference was found in the total duration of glycemia below 60 mg/dL (317, 300, and 370 minutes) or the duration of glycemia of more than 120 mg/dL (259, 225, and 394 minutes) in group N, G1, and G2, respectively. With use of the CGMS, however, in comparison with SMBG, a wider range of glycemic levels was observed in all 3 study groups: for the healthy, pregnant women, 41 to 194 mg/dL versus 61 to 151 mg/dL; for G1, 40 to 244 mg/dL versus 40 to 180 mg/dL; and for G2, 40 to 173 mg/dL versus 50 to 157 mg/dL.

CONCLUSION

The therapy, based on SMBG levels, when applied to the group of women with GDM, brought the glucose levels under effective control, with mean outcome values similar to those observed in the group of normal pregnant women. Nevertheless, using the CGMS, we detected long, asymptomatic periods of high and low blood glucose levels, both in the patients with GDM and in the unaffected pregnant women. The use of the CGMS for monitoring blood glucose profiles might be beneficial in this group of pregnant women.

Exacerbation of noise-induced hearing loss by co-exposure to workplace chemicals

BACKGROUND

: Numerous organic solvents applied in industry, like toluene, styrene, xylene and n-hexane have been demonstrated to impair hearing in animals. However, the effects of exposure to a given organic solvent and the interaction of noise and solvents on hearing in humans are still not fully recognized.

STUDY DESIGN

: The study was aimed to assess the effects of occupational exposure to solvents alone or in combination with noise on hearing in 1117 employees of yacht, ship, plastic, shoe, and paint and lacquer industry. These persons were exposed either to the mixture of organic solvents with xylene as the main component, or predominantly to styrene, or to the mixture of n-hexane and toluene. Detailed questionnaire data and pure-tone audiometry were compared with data of the reference group that included white collar workers, exposed neither to solvents nor noise and metal factory workers exposed to noise only. In all statistics, the confounding factors were recognized as gender, age, exposure to noise, and other variables occurring at a different rate in study and reference group.

RESULTS

: Odds ratio (OR) of hearing loss related with the particular exposure to chemicals was 2.4 (95%CI 1.59-3.74) in case of solvent mixture, 3.9 (95%CI 2.4-6.2) in case of styrene and 5.3 (95%CI 2.6-10.9) in case of n-hexane and toluene exposure. The odds of developing hearing loss substantially increased in the case of combined exposure to organic solvents and noise as compared to isolated exposure to each of these hazards. The highest OR (over 20-fold) was demonstrated in subgroups of subjects exposed simultaneously to noise and two ototoxic solvents (i.e. styrene and toluene or n-hexane and toluene). The mean hearing thresholds were significantly higher in the solvent-exposed groups than in the reference group. The differences in thresholds were observed at high frequencies in the solvent mixture- and n-hexane + toluene-exposed groups and at all frequencies in the styrene-exposed group. A positive linear relationship existed between exposure to solvents and hearing thresholds at high frequencies.

CONCLUSIONS

: The results of the study provide the epidemiological evidence that exposure to organic solvents in humans is associated with an increased risk of hearing loss. The simultaneous exposure to organic solvents and noise seems to enhance the hearing deficit if compared with isolated exposures.

Results of extracapsular dissection of pleomorphic adenoma of parotid gland

PURPOSE

Current opinion that extracapsular dissection is in fact a euphemism for enucleation prompted us to retrospectively identify all patients in whom the extracapsular dissection technique was used and to critically assess the value of this technique.

PATIENTS AND METHODS

The study includes all patients who underwent extracapsular dissection of parotid pleomorphic adenoma from 1979 to 2002 in our department (Department of Surgical Oncology, Medical University of Lodz, Poland). Ninety-eight cases were evaluated. Mean tumor diameter was 3.6 cm (range, 1.5 to 10 cm; median, 3 cm).

RESULTS

In 8 cases (8/98; 8.2%) local recurrence was observed. For the entire group, the probability of living 10 years without the recurrence of the disease was 0.58. The lowest probability of local recurrence was found in patients with tumors larger than 4 to 6 cm in diameter. In these cases, the extensiveness of resection was similar to superficial parotidectomy, which could explain the result. In 13 cases (13/98; 13.3%) capsular exposure was found and consequently microscopic disease was present at the excision margins. In 7 cases (7/98; 7.1%) capsular rupture took place during surgery. The persistent paresis of facial nerve was observed in 8 cases (8/98; 8.2%).

CONCLUSION

Extracapsular dissection of pleomorphic adenoma is a very demanding technique. Inevitable eventual clinical errors (eg, incomplete resection) lead to unacceptably high incidences of recurrences and complications. We do not advise this technique for the treatment of pleomorphic adenoma.

Acute exposure to 930 MHz CW electromagnetic radiation in vitro affects reactive oxygen species level in rat lymphocytes treated by iron ions

The aim of this study was to test the hypothesis that the 930 MHz continuous wave (CW) electromagnetic field, which is the carrier of signals emitted by cellular phones, affects the reactive oxygen species (ROS) level in living cells. Rat lymphocytes were used in the experiments. A portion of the lymphocytes was treated with iron ions to induce oxidative processes. Exposures to electromagnetic radiation (power density 5 W/m2, theoretical calculated SAR = 1.5 W/kg) were performed within a GTEM cell. Intracellular ROS were measured by the fluorescent probe dichlorofluorescin diacetate (DCF-DA). The results show that acute (5 and 15 min) exposure does not affect the number of produced ROS. If, however, FeCl2 with final concentration 10 microg/ml was added to the lymphocyte suspensions to stimulate ROS production, after both durations of exposure, the magnitude of fluorescence (ROS level during the experiment) was significantly greater in the exposed lymphocytes. The character of the changes in the number of free radicals observed in our experiments was qualitatively compatible with the theoretical prediction from the model of electromagnetic radiation effect on radical pairs.

Patients with Paget disease of nipple and with palpable mass in breast have unfavorable prognosis

Recent data indicate that in breast cancer patients the presence of Paget disease of the nipple may be related to poor prognosis. Therefore, we decided to assess long-term results of the treatment of such patients, and to assess the relationship between the physical and pathological findings and prognosis. The files of 60 patients with Paget disease of the nipple who were treated between 1977 and 2000 were analyzed retrospectively with respect to the results of physical and pathologic examinations, disease recurrence and survival. In 38/60 patients, the cancer was invasive. In 26/60 patients, palpable masses in the breast were diagnosed. The 5-year overall survival probability was 0.68; the probability was 0.82 for patients without palpable masses, 0.51 for those with palpable masses, 0.91 for patients without invasive cancer and 0.58 for patients with associated invasive cancer. In conclusions, patients with Paget disease of the nipple and with palpable mass in the breast had unfavorable diagnosis. The nature of all nipple changes should be explained as early as possible in order to diagnose the disease when no mass is palpable in the breast.

Effects of Coexposure to Noise and Mixture of Organic Solvents on Hearing in Dockyard Workers

Questionnaire and audiometric data of 701 dockyard workers (517 noise and organic solvent mixture-exposed and 184 noise-only-exposed) were referred to 205 control subjects not exposed to either noise or solvents. The odds ratio (OR) of hearing loss was significantly increased by approximately 3 times in the noise-only group and by almost 5 times in the noise and solvent group. A moderate effect of solvent ototoxicity, in addition to noise, was observed on hearing threshold at a frequency 8 kHz. ORs for hearing loss were 1.12 for each increment of 1 year of age, 1.07 for every decibel of lifetime noise exposure (dB-A), and 1.004 for each increment of the index of lifetime exposure to solvents. The results suggest an additive damaging effect of coexposure to noise and organic solvents to the auditory organ.

Epidemiology of occupational noise-induced hearing loss (ONIHL) in Poland

Noise-induced hearing loss is a major health risk worldwide. In Europe about 35 million people are exposed to detrimental noise levels (> 85 dB-A) in industrial plants, and occupational deafness is a leading occupational compensible disease in the all countries; it is an insidious slow process that develops over a period of approximately 10 to 20 years. Accordingly to the latest estimations, more than 650,000 workers (of a total 5 million employed in industry) are put at risk in Poland. Despite progress in engineering approaches for reducing noise in the work environment and in improving hearing conservation programs (both the technical and medical) the ONIHL still remains a common and costly disability. The aim of this study is presentation of the most recent data on the incidence of ONIHL in Poland in the years 1992-2002 considered to be a base for implementing the effective prophylactic activities. The analysed data were derived from the central state register which collects all cases of occupational diseases recognized in the country. The highest incidence was found in such key industrial branches as coal mining, iron and steel, metallurgical and transport equipment; majority of cases were observed in southern and western provinces, mainly in the Silesian district, known from the significant concentration of noisy enterprises. The most affected were those workers aged 50-59 years and exposed to noise for over 20 years. More than 30 new cases of ONIHL were identified in the years 1992-1998 annually per 100,000 employees, and with beginning 1999 the rate was significantly decreased to 10 cases in 2002. One may presume that it results from the set up of national program of hearing preservation introduced in 1999 with obligatory pre-employment and follow-up pure-tone audiometry, as well as with hearing screening by means of the otoacoustic emissions.

Immunohistochemical evaluation of P21ras and P53 proteins expression in human non-small-cell lung cancers

Human non-small-cell lung cancers (NSCLCs) of 48 patients were analyzed immunohistochemically to detect P21 ras and P53 proteins expression. The relationship between P21 ras and P53 proteins expression and clinicopathologic findings was also assessed. DAKO EnVision TM detection system was employed in the study. The P21 ras and P53 proteins expression was shown in 75% (36/48) and 33.3% (16/48) studied NSCLCs, respectively. In both cases the difference was significant when compared with adequate negative control. Simultaneous expression of both studied proteins was observed in all cases in which P53 expression was noticed. No significant association of P21 ras and P53 expression was found with age, histologic type, histologic grade, tumor size or lymph node metastasis of the studied NSCLCs. Therefore, our study suggests that P21 ras and P53 protein play a role in the pathogenesis of NSCLCs but they have no value as a prognostic markers in the case of lung cancers.

Suicidal ideation and suicide attempt in Polish adolescents: is it a suicidal process?

The objective of our study was to assess the prevalence and possible predictors of suicide attempts and ideation in the school population of adolescents in the city of Lodz.

METHOD

A self-administered anonymous questionnaire was distributed to a representative (random) sample of 1,663 students, aged 14 to 21 years. Adolescents reporting no suicide behaviour constitute the control group; characteristics of this group were compared to those of the group concerned, with exploration of the correlation between different variables in terms of relative risk, separately for suicidal ideation and suicide attempts.

RESULTS

About 31% of students reported suicidal ideation (SSI), and 8%--suicide attempts (SSA). Among the factors related to the highest relative risk of suicide attempts in the examined students and differentiated SSA and SSI, the most significant factor appeared to be previous psychiatric treatment and/or psychotherapy (OR = 9), run away from home (OR = 7), suicidal deaths among relatives and friends (OR = 6), drug abuse (OR = 5), and "fascination with death" (OR = 4).

CONCLUSIONS

There are separate predictors of suicide attempt and suicidal ideation in Polish adolescents. Suicidal ideation as a common phenomenon (occurring in every third pupil) probably should be included into the specificity of the puberty process and considered as a separate phenomenon from suicide attempt. The presence of previous psychiatric diagnosis is most strongly related to the occurrence of suicide attempts (including those repeated), but is not related to suicidal ideation.

Glutathione S-transferase M1 and P1 metabolic polymorphism and lung cancer predisposition

Individual susceptibility to different environmental agents is expected to be associated with alterations in metabolism of xenobiotics. Thus, genetic polymorphism of glutathione S-transferase (GST) can be recognized as a potential risk modifier in lung cancer development. The distribution of GSTM1 and GSTP1 genotypes was studied in a group of 138 diagnosed lung cancer patients and in 165 controls living in central Poland and RFLP-PCR technique was applied. The frequency of GSTM1 null genotype and GSTP1 Val single and duplicated alleles was similar among patients and controls. GSTM1 homozygous deletion was most prevalent in small-cell carcinoma groups (adjusted odds ratio (OR): 2.32, 95% confidence interval (CI): 0.98-5.52). In patients and controls, GSTM1A genotype was most frequent (34.1% vs. 37.0%). The estimated lung cancer risk for GSTM1 null, GSTP1 Ile/Val and GSTP1 Val/Val combined genotype was 1.44 (95% CI: 0.73-2.83), suggesting the absence of modifying effect of defective GSTM1 and GSTP1 alleles on lung cancer predisposition.

Ototoxic effects of occupational exposure to styrene and co-exposure to styrene and noise

Ototoxicity of styrene and the synergistic action of styrene and noise have been shown in rats. The respective data in humans are scarce and equivocal. This study evaluated the effects of occupational exposure to styrene and combined exposures to styrene and noise on hearing. The study group, comprised of 290-yacht yard and plastic factory workers, was exposed to a mixture of organic solvents, having styrene as its main compound. The reference group, totaling 223 subjects, included (1) white-collar workers, exposed neither to solvents nor noise and (2) metal factory workers, exposed exclusively to noise. All subjects were assessed by means of a detailed questionnaire and underwent otorhinolaryngological and audiometric examinations. Multiple logistic regression analysis revealed almost a 4-fold (or 3.9; 95% CI = 2.4-6.2) increase in the odds of developing hearing loss related to styrene exposure. The factors adjusted for were: age, gender, current occupational exposure to noise, and exposure to noise in the past. In cases of the combined exposures to styrene and noise, the odds ratios were two to three times higher than the respective values for styrene-only and noise-only exposed subjects. The mean hearing thresholds--adjusted for age, gender, and exposure to noise--were significantly higher in the solvent-exposed group than in the unexposed reference group at all frequencies tested. A positive linear relationship existed between an averaged working life exposure to styrene concentration and a hearing threshold at the frequencies of 6 and 8 kHz. This study provides the epidemiological evidence that occupational exposure to styrene is related to an increased risk of hearing loss. Combined exposures to noise and styrene seem to be more ototoxic than exposure to noise alone.

The excretion of 6-hydroxymelatonin sulfate in healthy young men exposed to electromagnetic fields emitted by cellular phone -- an experimental study

OBJECTIVES

It is quite likely that non-visible electromagnetic fields (EMF) may affect melatonin production. Some studies confirmed this hypothesis and showed that extremely low EMF altered pineal function in animals and humans. Thus, it is reasonable to suppose that EMF emitted by cellular phones may also influence secretion of melatonin. The present study sought to evaluate possible effect of the exposure to EMF emitted by cellular phone on 6-hydroxymelatonin sulfate (6-OHMS) excretion, which reflects melatonin levels in blood.

MATERIAL AND METHODS

The examined group consisted of 9 healthy males aged 19-29 years. The experiment was performed under controlled conditions (the light intensity-50 lx till midnight and 0 lx during night). Each person was examined twice: on a day without exposure (control day, C-day) and on a day with continuous exposure (60 min. exposure from cellular phone, frequency 900 MHz, pulsed with 217 Hz, pulse with 576 micros, SAR 1.23 W/kg, E-day). From 7 p.m. to 8 p.m. they used a cellular phone. The subjects did not know which day was E-day, and which was C-day. From 8 p.m. till midnight the subjects listened to music and than they slept till 7 a.m. next day. Urine samples were collected at 7 p.m., at midnight, and at 7 a.m. in the same way in C-day as in E-day. Sample were frozen for later ELISA analysis of 6-OHMS. The 6-OHMS ELISA kit from Immuno-Biological Laboratories (Hamburg) was used for measurement of 6-OHMS. The data were analysed using Wilcoxon matched-pairs signed-ranks test for each subject and for the whole group. We compared 6-OHMS level on the E-day and on the C-day separately for 3 time-points - 7 p.m., midnight, 7 a.m.

RESULTS

Mean 6-OHMS level in both experiments did not differ significantly for any of the respective time points. Circadian variations of 6-OHMS level were detected in all subjects.

CONCLUSIONS

The results of our investigation has demonstrated that EMF emitted by cellular phones has no distinct influence on the melatonin level.

Hearing loss among workers exposed to moderate concentrations of solvents

OBJECTIVES

It is known that some industrial organic solvents are ototoxic. This study was aimed at evaluating the hearing effects of a mixture of organic solvents alone or in combination with noise on employees in paint and lacquer enterprises. The concentration of solvents was below the occupational exposure limits (OEL) for most of the subjects.

METHODS

Altogether 517 subjects were divided into the following three groups: persons with no risk due to noise or organic solvent exposure at the workplace, workers exposed to organic solvents only, and workers exposed to both organic solvents and noise.

RESULTS

The relative risk (RR) of hearing loss in the solvent-only exposure group was significantly increased (RR 4.4 and RR 2.8 for noise exposure of < 80 dB-A and < 85 dB-A, respectively) in a wide range of frequencies (2-8 kHz). No additional risk in the solvent + noise exposure group was found (RR 2.8). Hearing thresholds were significantly poorer in a wide range of frequencies (1-8 kHz) for both groups exposed to solvents, when compared with the reference group. The mean hearing thresholds at frequencies of 2-4 kHz were poorer for workers exposed to solvents + noise than for the solvent-only group; this finding suggests an additional effect for noise. However, there was no correlation between hearing loss and the extent of solvent exposure.

CONCLUSIONS

The results indicate that occupational organic solvent exposure at moderate concentrations increases the risk of hearing loss, and the ototoxic effects should be considered when the health effects of exposed workers are monitored.

Nested case-control study of lung cancer among pulp and paper workers in relation to exposure to dusts

BACKGROUND

Numerous studies have indicated an increased risk of lung cancer in pulp and paper industry workers. In a 1990 survey, standardized mortality ratio (SMR) was found to be 122 (95% CI:96-153) for lung cancer in Polish male workers in the pulp and paper industry, and 166 (95% CI:95-270) among workers engaged in paper production.

METHODS

A nested case-control design within a cohort of pulp and paper workers was applied. Seventy-nine lung cancer cases and 237 "healthy" controls were selected from the cohort of 10,460 workers employed during the years 1968-1990, and observed until the end of 1995. Based on personnel files, occupational exposure was reconstructed by experts. Using a questionnaire, data on smoking habits were collected. ORs unadjusted and adjusted for smoking were calculated applying the model of conditional logistic regression.

RESULTS

Occupational exposure to inorganic dusts (kaolin, lime, cement, brick, grindstone) adjusted for smoking was a significant lung cancer risk factor, with a 4.0-fold risk (95% CI:1.3-12.6), and a dose-response by cumulative dose index. Among organic dusts only wood dust increased albeit insignificantly the risk for those exposed (adjusted for smoking OR = 2.1, 95% CI:0.9-4.9), but without dose-response relationship.

CONCLUSIONS

Exposure to occupational dust with relatively low content of silica, but at high concentrations may be considered as a factor increasing lung cancer risk. However, the observation made in this study should be viewed with caution as it was based on a small number of cases, and further evidence is needed to confirm or refute the authors' hypothesis.

[Quantitative evaluation for risk assessment of neoplasms caused by exposure to chemical substances]

This work is based on the assumption that work safety and hygiene inspectors or a work hygiene inspectors in sanitary and epidemiological station will not develop their own dose-response models on the basis of background data. They should be equipment with a tool allowing them to assess a given risk in the most simple way. Dose-response models for assessing cancer risk induced by carcinogenic chemicals are presented in the "Guidelines on health risk assessment of carcinogenic agents" published since 1995 by The Nofer Institute of Occupational Medicine in Łódź. Nevertheless, it seemed advisable to gather in one publication all models published thus far, and by adding relevant comments and necessary formulas for calculations, produce a simple set of practical rules of risk assessment. All models already published in Guidelines may be divided into two groups: linear and non-linear models. In addition, among linear models one may differentiate those for asbestos dust exposure because of different nature of the relationship between the extent of exposure and likelihood of cancer occurrence. The models are given in three tables under the following headings: linear models for 21 chemicals, non-linear models for 12 chemicals and linear models for asbestos. There are also included formulas that allow to convert dose into concentration and concentration into dose, and occupational exposure into equivalent exposure over the course of a lifetime, as well as conversion coefficients enabling the use of animal experiment results in the assessment of human risk.

Cardiovascular disturbances in workers exposed to carbon disulfide

According to literature data myocardial infarction was often the first noticeable effect of CS2 on the cardiovascular system. Therefore, a question arises whether earlier circulatory lesions are absent in CS2-exposed people, or they are present but are not detectable by the diagnostic methods used. The aim of our study has been to determine whether electrocardiological disturbances do occur in exposed people, and their association, if any, with the level of CS2 exposure. Modern diagnostic methods (resting and 24-h ECG, heart rate variability, late ventricular potential analysis, and long-term blood pressure monitoring) were used to answer this question. The examination comprised 177 male workers aged 24-66 years (44+/-12), employed under conditions of the exposure for 5-38 years (14+/-9), and 93 male workers non-exposed to CS2 aged 23-65 years (41+/-12). Results of our studies show that abnormalities in resting and/or 24-h ECG recordings occur significantly more frequently in people exposed to CS2 than in the controls. ECG abnormalities were found primarily among the workers with a long, over 20-year, period of exposure. The considerable coincidence between the questionnaire and ECG results was found (87% reported complaints were confirmed by ECG data). Therefore it seems that all CS2-exposed people reporting heart symptoms should be subjected to a detailed examination. The frequency of late ventricular potentials in CS2-exposed people was not higher than in the controls. It may indicate that the ECG disturbances observed in those people were associated with functional rather than organic changes. Results of long-term ABP monitoring did not show increased incidence of elevated blood pressure in the exposed group. As the levels of the risk factors of ischemic heart disease in the exposed and control groups were similar, it seems that exposure to CS2 was responsible for the significant changes in the circulatory system.

Mortality of workers at two asbestos-cement plants in Poland

To assess mortality rate among workers occupationally exposed to asbestos, cohort studies were carried out in two asbestos cement plants operating since the 1960s. Asbestos cement sheets for roofing and siding have been manufactured there, using mostly chrisotile, and since 1985 also crocidolite for pressure pipes. In all, the cohort comprised 3,220 workers, including 2,616 male workers. Subject to consideration were the workers employed for at least three months in the period between the onset of the production and 1980. The vital status of the subjects was traced up to 31 December 1991. The availability of the cohort was 96.8%. Workers' mortality was analysed using standardized mortality ratio (SMR). The reference group was the general population of Poland. In the male cohort, 385 cases of death were recorded. Statistically significant excess of mortality from large intestine cancer (7 cases, SMR = 264) and pleural mesothelioma (5 cases, SMR = 2846) was found. In male workers who died from pleural mesothelioma the work history ranged from 12 to 26 years. An excess mortality from pleural mesothelioma was also noted among the female workers (2 cases, SMR = 11,275). No malignant neoplasms of other locations produced significant excess mortality either in the male or female workers.

Time-of-flight secondary ion mass spectrometry of matrix-diluted oligo- and polypeptides bombarded with slow and fast projectiles: positive and negative matrix and analyte ion yields, background signals, and sample aging

Human angiotensin II, chain B of bovine insulin, and porcine insulin were determined by time-of-flight secondary ion mass spectrometry under impact of approximately 25 keV Xe+ and SF5+ ion beams and approximately 100 MeV 252Cf fission fragments. Matrix-embedded samples, dissolved in a large surplus of alpha-cyano-4-hydroxycinnamic acid, were prepared by nebulizer spray deposition, neat samples by the droplet technique. It is shown that the status of the sample can be assessed by evaluating the matrix-specific features of the mass spectra. The beneficial effect of matrix isolation was small for angiotensin but large for the insulin samples, which did not show parent peaks from neat material. Negative ion yields under SF5+ impact were up to a factor of 50 higher than with Xe+. For positive secondary ions, the enhancement was much smaller. The mass spectra produced by slow ion beams or fast fission fragments were qualitatively similar. Quantitative differences include the following: with fast projectiles the yields were about 10-30 times higher than with slow ions, but similar for negative ion emission under SF5+ bombardment; the analyte-to-matrix yield ratios were higher with slow ions and up to 250 times higher than the molar analyte concentration; for analyte ions the peak-to-background ratios were higher using slow projectiles; the fraction of carbon-rich collisionally formed molecular ions was much higher with fast projectiles. Sample aging in vacuum for up to five weeks strongly reduced the yield of protonated analyte molecules ejected by slow ion impact, but not of deprotonated species. Hence protonation seems to correlate with sample "wetness" or the presence of volatile proton-donating additives.

[Incidence of occupational diseases in Poland]

The paper is aimed at presenting the incidence of occupational diseases in Poland. The analysis was performed on the basis of the information included in 'occupational disease certificates'. All sanitary and epidemiological stations throughout the country are committed to send these certificates to the Central Register of Occupational Medicine in The Nofer Institute of Occupational Medicine in Lódź. The incidence of occupational diseases during the three recent years (1996-97-98) was the subject of a thorough analysis. In all, 11,318, 11,685 and 12,017 cases of occupational diseases, respectively were registered over those three years. The corresponding rates were 116.0, 116.9 and 117.3, respectively per 100,000 people employed. In 1998, diseases of the voice organ predominated (30.4%) of all occupational diseases) and they were followed by hearing impairment (28.2%), infectious and parasitic diseases (9.9%), pneumoconioses (8.2%), dermatoses (6.4%), vibratory syndrome (2.9%) and poisoning (2.5%). These disease categories constituted over 88% of all occupational diseases registered in that year. Diseases of the voice organ which showed the greatest growth dynamic were mainly diagnosed among teachers. Neither in the United States nor in the member states of the European Union, this pathology is included into the list of occupational diseases. In view of high rates of its incidence in our country it has become one of essential problems of occupational medicine. In Poland, particular attention is paid to infectious and parasitic diseases among which hepatitis occupies the first place (65%), mostly among health service workers. The decrease in hepatitis incidence observed in the 1990s has been due to an intensive vaccination programme in this group of workers. The incidence of occupational hepatitis became rather stable and accounted for 940 cases per year, however the incidence of hepatitic C increased at the same time. Lower rates of incidence of 'classic' occupational diseases, such as poisoning, pneumoconioses or vibratory syndrome are a positive observation. It is also interesting to note that the rate of occupational diseases diagnosed in advanced stage has also diminished. When analyzing occupational diseases one should bear in mind that the majority of pathologies already diagnosed result from long-term effect of exposure to harmful factors. In all, 93% of cases of occupational diseases emerged after a ten-year exposure. The highest rates, taking account of sections of activity, were found in mining and quarrying, health service, agriculture, hunting and forestry.

[Quantitative assessment of cancer risk following epidemiological studies]

The role of data derived from epidemiological studies in the quantitative assessment of cancer risk has been constantly growing. That results from the fact that epidemiological studies are performed directly on humans so that it is possible to avoid bias very often associated with methods of extrapolation between animals and humans. Moreover, a slow but continuous increase in the number of well designed epidemiological studies with results which can be used to estimate dose-response relationship is being observed. In this paper, the methodological foundations of cancer risk modelling on the basis of epidemiological studies are discussed, and the dose-response relationship based on epidemiological study carried out in an occupational cohort of workers employed in a pulp and paper plant was estimated. The epidemiological study was performed by the team of the Department of Epidemiology, The Nofer Institute of Occupational Medicine, Lódź. Lung cancer was adopted as the effect of occupational exposure. In oder to estimate the increase in cancer risk induced by occupational exposure, the risk for the whole occupational life was calculated by employing the methods of competitive risks, essential relative risks were modelled using Poisson means for data divided into groups, and a Cox proportional-hazards model was used for single data. The analysis indicated, that the data from epidemiological studies render it possible to carry out a more thorough investigation as compared to data obtained from animal experiments. As to the cohort under study, a certain effect of age at which workers enter into exposure on lung cancer risk was observed. A risk 'outfit' the workers bring in at the beginning of their employment is clearly visible in older age groups. A general conclusion drawn from the study may be formulated as follows: epidemiological studies play a major role in assessing the effect of working conditions on the increase in the morbidity risk, however, they are not a panacea for all the problems emerging in the cancer risk assessment in exposed persons. Therefore, information obtained from epidemiological and toxicological studies should supplement and reinforce one another, and data from both sources should be used to obtain the best possible characteristics of risk cancer in humans.

Hyposensitivity to amphetamine following exposure to chlorphenvinphos--protection by amphetamine preexposure

We investigated the effect of an acute exposure to chlorphenvinphos (CVP), an organophosphate anticholinesterase, on amphetamine-induced open-field locomotion in rats. CVP was administered in a single i.p. dose of 1.0 mg/kg (1/10 of the LD50). All animals were challenged with 1.0 mg/kg amphetamine (AMPH) three weeks after the CVP exposure, i.e. after a time sufficient for acetylcholinesterase recovery. Some rats were also given AMPH three weeks before the CVP exposure. In rats challenged with AMPH only once after the CVP exposure, AMPH-induced open-field locomotion was significantly reduced. Such an effect was not observed in rats given AMPH three weeks before the CVP exposure. The results suggest that a single CVP exposure may result in persistent dopaminergic hyposensitivity, and that an amphetamine pretreatment may protect the rat against this effect.

[The causes of increased risk for lung cancer in the pulp and paper industry workers. The effect of smoking and exposure to chemicals]

An analysis of mortality in a cohort of workers employed in the pulp and paper industry, carried out by the authors of this presentation several years ago, indicated an increase of 22% in the risk of mortality from lung cancer. This risk decreased by only 4% after taking account of smoking. The results obtained then were considered as sufficient to undertake further studies aimed at identifying specific occupational factors responsible for an increased risk for mortality from lung cancer in the population under study. The nested case-control study, in which cases (of lung cancer) and controls were selected from the same cohort observed earlier, was approved as the most suitable method for achieving the aforesaid aim. The study covered 79 cases of deaths from lung cancer confirmed by histological and cytological or radiological examinations, and 237 'healthy' controls matched in the ratio of one to three, taking into account gender, date of birth and date of employment. A group of experts carried out in-depth analysis of exposure to harmful factors in each case of death and in each control. Using a questionnaire, specially developed for this purpose, detailed data on smoking habits among persons under study were collected. Odds ratio was used as a measure of a relative risk for death from lung cancer. A crude relative risk and risk adjusted by eliminating the effect of smoking, applying the model of conditional logistic regression, were calculated for individual exposure factors. Smoking proved to be a significant causal factor responsible for the development of lung cancer in the cohort studied. That was evidenced by relative risk accounting for 12.9 for smokers in relation to non-smokers and an enhanced risk with the increasing number of cigarettes smoked daily, the number of smoking years and an accumulated dose. The study does not confirm a hypothesis that chemical factors specific of the pulp and paper industry exert a significant effect on the risk of death from lung cancer. Odds ratios, crude and adjusted for smoking, were lower than one in all distinguished categories of exposure.

[Application of BMD models in quantitative evaluation of carcinogenic risk]

The characteristics of the relationship between the exposure level and the incidence of harmful health effects is a general objective of assessing health risk related to chemical exposure. A real dose-response relationship, particularly for low doses, is usually unknown thus it can only be deduced on the basis of biological and statistical considerations. Low dose risk estimation requires extrapolation beyond the range of data observed. Nowadays, quantitative risk assessment encounters certain duality as linear models are mostly used in evaluation of environmental exposure, and nonlinear models are most frequently applied in occupational exposure. Bearing in mind that the assumption on the dose-response linear relationship is an apparent simplification built on our lack of knowledge of carcinogenic mechanisms, it seems that the proposal of the US Environmental Protection Agency (US EPA) to use benchmark dose methods (BMD) for exposure effects manifested by neoplasms, is the compromise between a conservative approach of the EPA towards risk modelling resulting from the limited knowledge of these mechanisms and lack of criteria for selection of nonlinear models. In the case of carcinogenic risk assessment, this solution involves the identification of so called 'cut off point' by applying relevant statistical models. The cut off point indicates the exposure level that contributes to the increase in risk by 10%, 5% or 1%. Another possibility is to use interspecies extrapolation methods for the cut of point modification, and then draw a line between the cut off point and the beginning of the system of co-ordinates. Since it is not feasible to apply a complete BMD methods for certain chemicals (e.g. bezo(a)pirene), not because of chemical properties, but due to insufficient experimental experience, it is proposed to use the method of sticking together a straight line and a curve in relation to a two-grade curve and not to its confidence limitation.

Cancer risk in workers of the pulp and paper industry in Poland. A continued follow-up

A mortality cohort study was undertaken among Polish pulp and paper workers. This paper concentrates on neoplasms mortality among men and women employed continuously for at least one year in the factory producing sulphate pulp, paper board and paper products. A retrospective observation carried out till 31 December 1995 covered 10,460 workers employed during the years 1968-1990. The cohort accessibility was 99%. Cancer risk was evaluated on the basis of standardized mortality ratio (SMR) calculated according to the person-years method. The general population of Poland was the reference population. The results of a 23-year cohort observation, published earlier, showed a lowered overall mortality from all causes and from all malignant neoplasms, and a significant excess of death from peritoneum and prostate cancer among pulp mill male subcohort. The conclusion was drawn that a 'young' cohort and relatively short follow-up period might have affected the results. The results presented in this paper, obtained after further five years of observation showed in the male cohort an excess of deaths from cancer of respiratory tract and peritoneum (lung SMR = 122, nasal cavities SMR = 587, peritoneum SMR = 562). An approximate correction for smoking habits resulted in only 4 decreased risk estimates for lung cancer, indicating a small positive confounding effect of smoking in this material. In female cohort an excess of brain cancer was found (SMR = 355). Only the excess mortality from cancers of nose, lung and peritoneum was coherent with the exposure to higher concentrations of wood dust, pulp, paper and board dust. It may support a hypothesis that these factors as well as dust pollutants, not yet identified in this study, may be considered as one of the risk factors contributing to the incidence of neoplasms of these sites.