Neurophysiological findings among workers occupationally exposed to styrene

Ninety-six male workers occupationally exposured to styrene in 24 plants producing reinforced polyester plastic products were studied neurophysiologically. The mean age of the subjects was 29.6 +/- 7.4 years, and the duration of the exposure varied from 6 months to 14 years (mean 5.0 years). Mandelic acid concentration in the urine (mean of five values determined during five consecutive weeks) was used as the measure of exposure. The individual means of the mandelic acid concentrations varied from 7 to 4,715 mg/dm3 (median 808 mg/dm3). Neurotoxic effects of styrene exposure upon the central nervous system were revealed by abnormalities in the EEG. The overall prevalence of abnormal EEGs was 24% (23 out of 96), which is higher than that found among a normal population (p less than 0.05). Abnormal EEGs were found in one-third of the subjects with relevant styrene exposure (mandelic acid concentration over 700 mg/dm3), while low-level styrene exposure did not increase the prevalence of normal EEGs above that found in a normal population. Nerve conduction velocity measurements performed on 40 subjects did not reveal any definite relationship between neuropathy and styrene exposure. The EEG examination is useful in the investigation of the neurotoxic effects of styrene. Whenever a possibility exists of excessive styrene exposure or beginning poisoning, the workers should be submitted to an EEG examination.     

Surveillance of early neurotoxic dysfunction

Surveillance of early neurotoxic alterations was undertaken in 3 reinforced plastics plants, with a view to preventive intervention. Using a longitudinal study design, exposure parameters (environmental styrene in the respiratory zone of each worker and end-shift mandelic acid (MA)) and neurobehavioral performance (Neurobehavioral Core Test Battery and Field Assessment: Sensory Tests), were assessed at time zero (T0); recommendations were made to reduce exposure at jobsites with the highest risk. Reassessment was made two years later (T2). Complete exposure data was available for 118 workers at T0; 75 were still employed at T2; of these, 57 (76%) returned for testing. Those who returned had more seniority (p < 0.001) and higher MA (p < 0.01) and styrene (p < 0.05) levels at T0 than the others. Analyses, performed on the T0-T2 differences, showed improvement in exposure parameters in Plant 3, where lower levels were observed at T2 for styrene (p < 0.05) and MA (p < 0.001). workers in Plant 3 (n = 29) performed better (p < 0.05) at T2 for short term memory, perceptuo-motor speed, motor precision and manual dexterity; they reported more vigor (p < 0.05) and less anger (p = 0.07). This was not the case for the workers from the other plants. Generally, the T0-T2 difference in MA was associated (Spearman's Rho) with differences in color vision (p < 0.001), simple reaction time (mean and standard deviation), digit span forward, tension, fatigue and the number of symptoms (p < 0.05); aiming precision showed a similar tendency (p < 0.10). These findings suggest that group surveillance of early nervous system changes for jobs with exposure to neurotoxins, using a sensitive neurofunctional test battery, may be useful for preventive intervention.     

Metabolic interferences in subjects occupationally exposed to binary styrene-acetone mixtures

OBJECTIVE: To investigate the excretion of styrene metabolites (mandelic acid, MA, and phenylglyoxylic acid, PGA) in workers employed in plastic manufacturing to verify the possible influence of coexposure to acetone on styrene metabolism. METHODS: This study was carried out on 50 workers employed in 3 factories producing polyester buttons. The workers were divided into three groups according to three different levels of acetone exposure. The trend of excretion for metabolites was examined during and after work shifts. Styrene and acetone were monitored on Thursday during the entire work shift by passive dosimeters placed on the lapel of the workers' uniforms, desorbed by carbon disulfide, and analyzed by gas chromatography. Biological monitoring was performed by determination of the urinary metabolites of styrene in urine samples collected on Thursday at the middle and the end of the work shift. MA and PGA were determined by a high-pressure liquid chromatographic method. RESULTS: The styrene concentrations ranged between 16 and 439 mg/m3, and in ten samples they exceeded the TLV-TWA (213 mg/m3). The acetone concentration ranged between 15 and 700 mg/m3 (TLV-TWA 1780 mg/m3), with the mean value being 208 mg/m3. During cleaning operations higher exposures to acetone demonstrated, with concentrations ranging between 500 and 3400 mg/m3. The amounts of MA and PGA determined at the end of workshifts did not significantly differ between the groups with different levels of acetone coexposure. Analysis of variance (ANOVA) between the groups confirmed that MA and PGA excretion did not significantly differ, although the metabolite values measured on the "morning of the day after" appeared higher in those groups with high levels of acetone exposure and were related to the average airborne concentrations of the solvent. In addition, the range and degree of correlation between styrene in air and biological levels of metabolites were modified by coexposure to acetone. CONCLUSIONS: Our data demonstrate that amounts of MA and PGA did not differ in groups with different levels of acetone exposure, but when the acetone air concentration increased the degree of correlation between styrene and MA and PGA decreased. Furthermore, coexposure to acetone levels similar to those described herein may hamper the use of urinary metabolites for the assessment of exposure to styrene, especially on an individual basis.     

The therapeutic focus in significant sessions of master therapists: a comparison of cognitive-behavioral and psychodynamic-interpersonal interventions

This study was designed to test the hypothesis that bright light (BL) can have a stimulating effect on vigilance even in the absence of suppression of melatonin secretion and that this effect can be detected when measured in subjects with low vigilance levels. Seven normal subjects were exposed to bright-white light (BL group) and seven to dim-red light (DL group) on 2 consecutive days, each following a night of 4-h sleep restriction. The light treatment was administered in the late morning, between 0900 and 1330 hours. Salivary melatonin measurements indicated that BL did not suppress melatonin secretion or induce circadian phase shifts. The effects of the two treatments were compared on validated measures of daytime vigilance: immediate effects were evaluated on subjective alertness during the light treatment, whereas short-term (0.5-10.5 h) and long-term (20.5-34.5 h) carryover effects were measured on subjective alertness, daytime sleep latencies (DSL), and psychomotor performance. After two nights of sleep restriction, subjective alertness and daytime sleep latencies decreased significantly, but there was no effect of the light treatment. BL treatment did not affect global performance, but there was an effect on the strategy used by the subjects, as shown by faster reaction times and increased percentage of errors in the BL group. It was concluded that daytime BL exposure did not have a stimulating effect on our measures of vigilance even in sleep-deprived subjects but that it may increase physiological arousal and affect the subjects' behavior in some specific performance tasks.     

Increase in neuropsychiatric symptoms after occupational exposure to low levels of styrene

The results of this study suggest that exposure to styrene below the current Swedish permissible exposure limit of 20 ppm induces neurotoxic effects expressed as an increased number of neuropsychiatric symptoms. Twenty men exposed to styrene at a plastics factory participated. The reference group included 20 non-exposed men matched for age, working schedule, and physical work load. Exposure to styrene during one workday was assessed by personal air monitoring and biological monitoring. To evaluate the physical work load the pulse(heart) rate was measured. One week before the study each man completed a neuropsychiatric symptom questionnaire containing 16 items. Also 17 questions regarding acute symptoms of local irritation and symptoms of the central nervous system were presented after the psychometric tests were performed. The tests were simple reaction time, colour word vigilance, and symbol digit. A follow up with regard to the symptoms among the exposed men was done after their summer vacation, about two to five weeks after their last exposure. The mean eight hour time weighted average (TWA) concentration of styrene in air, measured by passive dosimetry was 8.6 ppm (range 0.04-50.4 ppm). The exposed men had significantly more symptoms than the referents although there were no significant differences for the psychometric tests. At the follow up the exposed men reported fewer symptoms. This study indicates that symptoms are earlier indicators of adverse effects than complex tests and underlines the importance of regular follow up of people exposed to styrene (and probably organic solvents in general).     

Controlled Visuomotor Preparation Deficits in Attention-Deficit/Hyperactivity Disorder.

To the best of the authors' knowledge, there are no published reports on visuomotor preparation in attention-deficit/hyperactivity disorder (ADHD). This is unfortunate, because research suggests that ADHD is an output-related deficit, and suboptimal execution of tasks may be the result of incomplete visuomotor preparation. The authors compared 19 children with ADHD with 124 healthy and 120 pathological controls in terms of their performance (speed, speed variability, and accuracy) on the finger precuing test, a test measuring (automatic and controlled) visuomotor preparation. The data implied that children with ADHD have an impaired ability to engage in effortful, controlled visuomotor preparation activities. Fast, automatic response preparation was not affected by ADHD. In addition, children with ADHD showed more variability in overall test performance than other children. No group differences were found in response accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in white blood cells of workers occupationally exposed to styrene

Styrene-7,8-oxide (SO), the major in vivo metabolite of styrene, is a genotoxic compound and a potential carcinogenic hazard to occupationally exposed workers. The aim of the present work was to investigate the ability of styrene exposure to induce formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in white blood cells (WBC) of boatbuilders occupationally exposed to styrene. The study of these adducts was conducted to see if styrene exposure can cause oxidative damage of DNA. The 8-OHdG/10(5) dG ratio from 17 styrene-exposed workers showed significant increases (mean +/- SD, 2.23 +/- 0.54, median 2.35, P < 0.001) in comparison to the controls (1.52 +/- 0.45, median 1.50). However, 11 out of 17 workers who were between the ages of 32 and 60 years and had been occupationally exposed to styrene for > 10 years showed higher 8-OHdG/10(5) dG ratios (2.31 +/- 0.62, median 2.37) in comparison to 6 workers with < 6 years of occupational styrene-exposure (2.11 +/- 0.36, median 2.05; P > 0.05, no significant difference between the two groups of workers). The studies presented here provide an indication that styrene exposure can result in oxidative DNA damage.     

Evaluation of workers exposed to elemental mercury using quantitative tests of tremor and neuromuscular functions

Workers exposed to metallic mercury vapor were subjects for tremor, EMG, and psychomotor tests. Regression analysis revealed statistically significant trends in these test results related to workers' urine mercury histories. Effects were subclinical, functionally insignificant and most associated with those workers whose urine mercury had exceeded 0.5 mg/L in the previous year. In agreement with previous reports, effects were reversible upon reduction of mercury exposure.     

Effects of testosterone on locomotor performance and growth in field-active northern fence lizards, Sceloporus undulatus hyacinthinus

BACKGROUND: Short-term exposures to increased CO2 concentrations in breathing air up to 5% are assumed to have only negligible behavioral effects. In the present study it was examined to what extent prolonged exposures to moderately elevated levels of CO2 in the ambient air affect human performance. METHOD: During two phases of 26 d of confinement in a diving chamber a group of four subjects was exposed to two different levels of CO2 (0.7% and 1.2%). Cognitive, visuo-motor, and time-sharing performance were assessed repeatedly before, during, and after the exposure by means of a task battery including grammatical reasoning, memory search, unstable tracking, and dual tasks. In addition, subjective workload and mood ratings were collected. A second group of four subjects served as a control group who performed the different tasks on the same 26-d time schedule without being exposed to confinement and elevated CO2. RESULTS: During exposure to 0.7% CO2 only tracking performance was slightly disturbed compared with baseline levels, whereas performance of the control group remained stable. The time course of this effect suggested that it was related to chamber adaptation rather than to increased levels of CO2. During exposure to 1.2% CO2, tracking performance again was significantly impaired. In contrast to the lower exposure condition, the time course of this effect appeared to be related to the CO2 load and covaried with a loss of subjective alertness. CONCLUSIONS: The study indicates that at least visuomotor performance might be affected by CO2 concentrations in the ambient atmosphere as small as 1.2% if subjects are chronically exposed to these concentrations in a confined environment. The strength of these effects, however, does not appear to be of operational relevance.     

Exposure to styrene and mortality from nervous system diseases and mental disorders

Chronic low-dose exposure to solvents has been associated in epidemiologic studies with chronic neurotoxicity, but the evidence is not consistent. Styrene causes acute disturbances in the central and peripheral nervous systems. To determine if exposure to styrene may contribute to chronic diseases of the central nervous system, the authors examined mortality from nervous system diseases, mental disorders, and suicide in relation to styrene exposure in an international historical cohort study. The cohort involved 35,443 workers employed during 1945-1991 in the reinforced plastics industry, where high exposures to styrene occur. Indicators of exposure were reconstructed through job histories and environmental and biologic monitoring data. Poisson regression was used for internal comparisons. Mortality from diseases of the central nervous system (27 deaths) increased with time since first exposure, duration of exposure, average level of exposure, and cumulative exposure to styrene. A quadratic model described best the dose-response shape for cumulative exposure and duration of exposure with the highest risks at around 300 ppm-years and 5 years, respectively, and a subsequent decrease in risk in the highest exposure categories. Mortality from epilepsy increased monotonically with all styrene exposure indicators, while associations for degenerative diseases of the central nervous system were generally weaker. Mortality from mental disorders and suicide decreased with increasing duration of exposure and cumulative exposure, while there was no trend with time since first exposure and average exposure to styrene. These findings suggest that, in addition to the known acute effects, exposure to styrene may contribute to chronic diseases of the central nervous system.     

Influence of feed restriction in primiparous lactating sows on body condition and metabolic parameters

Bearing in mind a great diffusion of electromagnetic fields (EMF) with power-line frequency (in Poland-50 Hz) both in the occupational and communal environments, it is not surprising that possible health effects related to this exposure evoke much interest. Electromagnetic fields may affect the circulatory and nervous systems because of theoretical probability that electric impulses, generated by external electric and magnetic fields, may disturb their functions. For this reason we have decided to evaluate the functioning of the circulatory system in persons occupationally exposed to power-line frequency electromagnetic fields by employing the most up-to-date methods facilitating the in-depth diagnosis of the circulatory system and neurovegetative mechanisms. The work presented focused on the evaluation of electrocardiographic changes. The study covered 63 workers of the transforming and distributing stations, aged 22-67 years (median 39 +/- 10), employed under exposure for 2-43 years (median 15 +/- 10). The control group consisted of 42 workers of radio link stations, aged 23-65 years (median 30 +/- 14), employed in the similar system but not exposed to EMF, with employment duration of 1-42 years (median 13 +/- 4). All persons were subject to general medical examinations, resting ECG, and 24 h Holter monitoring. In addition, the level of exposure in individual workplaces was estimated following the measurements of the intensity of electric and magnetic fields. In workers of electromagnetic stations an increased risk for electrocardiographic disturbances was revealed. Under conditions of exposure to electric fields, observed in stations where workers were employed, the risk was increased by 10%.     

Visual search performance in children rated as good or poor attenders: The differential impact of DAT1 genotype, IQ, and chronological age.

Attention-deficit/hyperactivity disorder (ADHD) is characterized by poor attention to detail, poor attention maintenance, and variability throughout task performance. The authors used a quantitative trait loci approach to assess the association between the dopamine transporter (DAT1) high-risk genotype, cognitive performance (visual search and vigilance), and ADHD symptoms in a community sample of boys 6-11 years of age. The potential confounding effects of IQ and chronological age were also investigated. Results demonstrate that accuracy in target detection, not speed, distinguishes poor attenders from good attenders. The authors speculate that the measure of performance (e.g., time and false alarms) may be critical in detecting attentional weaknesses. In contrast, DAT1 gene, known to be associated with the behavioral symptoms of ADHD, was unrelated to visual search or vigilance performance, although it was related to ADHD symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting symptomatic distress in emergency services personnel.

This study identified predictors of symptomatic distress in emergency services (EMS) personnel exposed to traumatic critical incidents. A replication was performed in 2 groups: 154 EMS workers involved in the 1989 Interstate 880 freeway collapse during the San Francisco Bay area earthquake, and 213 counterparts from the Bay area and from San Diego. Evaluated predictors included exposure, social support, and psychological traits. Replicated analyses showed that levels of symptomatic distress were positively related to the degree of exposure to the critical incident. Level of adjustment was also related to symptomatic distress. After exposure, adjustment, social support, years of experience on the job, and locus of control were controlled, 2 dissociative variables remained strongly predictive of symptomatic response. The study strengthens the literature linking dissociative tendencies and experiences to distress from exposure to traumatic stressors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender-related variation in transfusion practices

Upper airway symptoms in workers employed in the manufacture of wood products using ultraviolet radiation curing or acid curing of surface coating have been reported. In this study, workers were divided into groups according to exposure: (1) UV-surface coating line, (2) acid curing surface coating line, (3) finishing processes of UV-cured acrylate coated products, (4) finishing processes of of both UV- and acid cured coated wood products, and (5) control group. The workers were examined with nasal lavage in order to investigate inflammatory signs (ECP, tryptase, albumin and microscopy with cell differential counting). UV-line workers and finishers had significantly increased levels of ECP in nasal lavage. There was a positive correlation between exposure time and ECP and albumin levels. Workers with general nasal complaints and atopics had increased levels of ECP. In this study there were findings indicating an inflammatory process in the nasal mucosa in workers exposed to UV radiation curing multifunctional acrylate coatings. The findings indicate an unspecific inflammation and, therefore, a correlation between occupational exposure to acrylate coatings and nasal inflammation seems probable.     

Assessment of early psychic dysfunctions due to metallic mercury

The aim of the study was to find the most sensitive psychological test battery, useful for evaluation of the earliest dysfunctions in workers exposed to metallic mercury (Hg). To assess the above mentioned disorders, six tests of interference and four tests of motor reactions were applied. The examinations were performed in 44 male workers exposed to Hg in the process of acetic aldehyde synthesis. The control group was matched for sex, age and educational level. The obtained results showed that in the detection od early dysfunctions of the nervous system, psychological tests of interference are more useful than test of the motor reactions. This toxicological test battery can be recommended for monitoring workers exposed to metallic mercury.     

An evaluation of digital subtraction radiography for assessment of changes in position of the mandibular condyle

OBJECTIVES: This study evaluated the mortality experience of workers from the styrene-butadiene rubber industry. Concerns about a possible association of 1,3-butadiene and styrene with lymphohaematopoietic, gastrointestinal, and lung cancers prompted the investigation. METHODS: A retrospective follow up study was conducted of 15,649 men employed for at least one year at any of eight North American styrene-butadiene rubber plants. Analyses used standardised mortality ratios (SMRs) to compare styrene-butadiene rubber workers' cause specific mortalities (1943-91) with those of the United States and Ontario general populations. RESULTS: On average, there were 25 years of follow up per subject. The standardised mortality ratio (SMR) was 87 (95% confidence interval (95% CI) 85 to 90) for all causes of death combined and was 93 (95% CI 87 to 99) for all cancers. There was an excess of leukaemia (SMR 131, 95% CI 97 to 174), restricted to hourly workers (SMR 143, 95% CI 104 to 191). For causes of death other than leukaemia, SMRs were close to or below the null value of 100. Results by work area (process group) were unremarkable for non-Hodgkin's lymphoma, multiple myeloma, and stomach cancer. Maintenance workers had a slight increase in deaths from lung cancer, and certain subgroups of workers had more than expected deaths from cancer of the large intestine and the larynx. CONCLUSION: This study found an excess of leukaemia that is likely to be due to exposure to butadiene or to butadiene plus other chemicals. Deaths from non-Hodgkin's lymphoma, multiple myeloma, and stomach cancer did not seem to be related to occupational exposure. The excess deaths from lung cancer among maintenance workers may be due in part to confounding by smoking, which was not controlled for, and in part to an unidentified occupational exposure other than butadiene or styrene. Increases in cancer of the large intestine and larynx were based on small numbers, did not seem to be due to exposure to butadiene or styrene, and may be chance observations.     

The application of the concise exposure index to repetitive movement tasks of the upper limbs in various production settings: preliminary experience and validation

A summary of eight investigations is presented, which were carried out using standardised methods, for the purpose of quantifying exposure to tasks involving repetitive movements of the upper limbs, as well as quantifying the prevalence of Work Related Musculo Skeletal Disorders of the upper limbs in groups of exposed workers. A total of 462 exposed workers were examined, and the study also took into account the data pertaining to a matched control group comprising 749 workers not exposed to any specific occupational risk. Regarding the quantification of exposure to increased risk, use was made of a Concise Index (OCRA), proposed by the Authors in a previous publication. The data resulting from the eight investigations were used for the study of measurements and models of association among the exposure variables (mainly represented by the OCRA index), as well as the effect variables represented by the prevalence of the various WMSDs of the upper limbs taken both individually and jointly. Significant associations were reported between the OCRA index and an effect indicator represented by the prevalence of all the WSMDs of the upper limbs, calculated on the number of upper limbs at risk. When a logarithmic conversion of the relative exposure (OCRA) and injury indices was carried out, a simple linear regression model resulted which seems to provide a satisfactory predictive performance of the risk of WMSDs of the upper limbs, based on the exposure index. The study confirmed the efficacy of various other models designed to predict effects based on multiple linear regression functions, in which the independent variables are represented by both the OCRA exposure index and by parameters relative to the breakdown by sex and age of the groups of exposed workers.     

Application of the concise exposure index (OCRA) to tasks involving repetitive movements of the upper limbs in a variety of manufacturing industries: preliminary validations

A summary of eight investigations is presented, which were carried out using standardized methods, for the purpose of quantifying exposure to tasks involving repetitive movements of the upper limbs, as well as quantifying the prevalence of work-related musculoskeletal disorders (WMSDs) of the upper limbs in groups of exposed workers. A total of 462 exposed workers were examined, and the study also took into account the data pertaining to a matched reference group comprising 749 workers not exposed to any specific occupational risk. Regarding the quantification of exposure to increased risk, use was made of a concise index (OCRA index), proposed by Occhipinti, in this issue. The data resulting from the eight investigations were used for the study of measurements and models of association among the exposure variables (mainly represented by the OCRA index), as well as the effect variables represented by the prevalence of the various WMSDs of the upper limbs taken both individually and jointly. Significant associations were reported between the OCRA index and an effect indicator represented by the prevalence of all the WSMDs of the upper limbs, calculated on the number of upper limbs at risk. When a logarithmic conversion of the relative exposure (OCRA) and injury indices was carried out, a simple linear regression model resulted that seems to provide a satisfactory predictive performance of the risk of WMSDs of the upper limbs, based on the exposure index. The study confirmed the efficacy of various other models designed to predict effects based on multiple linear regression functions, in which the independent variables are represented by both the OCRA exposure index and by parameters relative to the breakdown by gender and age of the groups of exposed workers.     

Residual cognitive dysfunctioning at 6 months following coronary artery bypass graft surgery

Neuropsychological testing is a sensitive method for quantitative assessment of cognitive dysfunctioning following cardiopulmonary bypass (CPB). However, the methodological problems associated with this method, such as learning effects due to repeated testing and the effects of distress on test performance, have often been underestimated. In this study, these confounding effects were controlled for by including the spouses of patients, exposed to the same potential stress effects associated with the operation, as a nonsurgical control group. The experimental group consisted of 63 patients (40-75 years) undergoing elective coronary artery bypass graft (CABG) surgery. A battery of standardized neuropsychological tests was administered to both groups 2 weeks preoperatively and 1 week, 1 month, and 6 months postoperatively. Statistical testing of inter-group differences in preoperative to postoperative changes in test performance revealed the following results: (1) For immediate memory and learning, in general test scores showed the same time course for both groups. (2) For recent memory, patients' scores showed a significant deterioration at 1 month after CABG surgery compared with the scores of spouses. This effect had not completely disappeared at 6 months postoperatively. (3) For attention and psychomotor speed as well as verbal fluency, patients' scores had deteriorated significantly at 1 week after surgery, with incomplete recovery at 6 months. These negative cognitive effects were not related to the patients' ages or CPB parameters (duration of CPB, aortic cross-clamp time, mean flow and arterial pressure during CPB and aortic cross-clamping, and minimum nasopharyngeal temperature). No differences in self-ratings of mood over time were found between the patients and spouses. The results indicate that, when adequately controlling for the effects of learning and distress, some cognitive functions are still impaired at 6 months after CABG surgery.     

The effect of occupational exposure to metallic mercury on selected parameters of hemostasis

The group investigated comprised 60 workers under conditions of chronic exposure to metallic mercury vapours (mean exposure duration--9.3 yrs; mean age of subjects--38.5 yrs). The control group was composed of 24 non-exposed persons (mean age--39.9 yrs). The workers exposed were divided into three groups according to the air concentration of metallic mercury vapours at the workpost, group A--0.15-0.17 mg/m3, group B--0.03-0.08 mg/m3 and group C--0.02-0.03 mg/m3. The workers qualified for the study did not receive any medication containing acetylsalicylic acid derivatives, and did not consume alcoholic drinks for few days prior to the study. Persons with the diagnosis or the history of blood disorders, venous or arterial thrombosis as well as those with diabetes and hyperlipidaemia were excluded from the study. The haemostasis assessment was based on the results of laboratory tests, PLT, TBT, ACT, APTT, HTCT, INR and Fg, AT III, alpha 2 M, FDP, and FM concentrations. The comparison of the exposed and control groups revealed a statistically significant decrease in ACT and AT III concentrations. When particular groups under exposure were compared with one another and the controls, the increased INR and Fg concentrations were found in group A. Moreover, this group showed an increased platelet count, as well as decreased TBT and alpha 2 M concentrations. However, the differences between the groups were statistically insignificant. The results of the study indicated that chronic exposure to mercury may impair haemostasis and lead to hypercoagulability. The latter may result from the deficiency of natural coagulation inhibitors.