[Evaluation of the biological exposure test "CS2 in urine"]

The necessity of integration of biological exposure tests, for example the BET "CS2 in urine", is shown in connection with the activities of the works doctor in order to evaluate the individual health risk of the exposed workers. The possibilities on principle for the tests are discussed Topical biological threshold limit values for CS2 in urine on the base of validity studies are presented. In addition a special intervention regime.

Accumulation of carbon disulphide metabolites

Biological monitoring for carbon disulphide (CS2) exposure performed using the iodine-azide test (IAT) and 2-thiothiazolidine-4-carboxylic acid (TTCA) test in urinalysis of workers with high exposure to CS2 (112-142 mg/m3, n = 34), workers with low exposure (4-7 mg/m3, n = 16), and non-exposed university workers (n = 10). Pre-shift and post-shift urine specimens were collected on three consecutive days in the exposed and for only one day in the non-exposed. According to the findings the specificity and the sensitivity seem to be low for the IAT and high for the TTCA test. Contrary to a previous report all pre-shift urine samples showed negative IATs. The TTCA test was positive in pre-shift urine even after 32 to 63.5 h without exposure, and values tended to increase during consecutive days of exposure in highly exposed workers. The possible health implications of these findings should be further investigated.

Special nerve functions and colour discrimination in workers with long term low level exposure to carbon disulphide

Certain functions of the peripheral and autonomic nervous systems, and colour discrimination were examined in 45 workers (mean age 49; mean exposure to carbon disulphide (CS2) 20 years) and 37 controls (mean age 48). Conduction velocity and refractory period of the peroneal and sural nerves were determined. The conduction velocity of the slower fibres of the peroneal nerve was measured by means of an improved method that makes use of the refractory period. Function of autonomic nerves was assessed by measuring the variation in heart rate during rest, during deep breathing, and during isometric muscle contraction. Colour discrimination was evaluated by the Lanthony desaturated test. Individual cumulative exposure to CS2 was calculated on the basis of exposure in the past and individual job history. Mean cumulative exposure was 165 ppm-years. The peroneal nerves of exposed workers showed a decrease (-1.0 m/s) in conduction velocity of the slow fibres and a prolongation (0.1 ms) of the refractory period (mean 1.6 ms) compared with controls. These effects were related to cumulative exposure. No impairment of function of the sural nerve or of colour discrimination was found. The muscle heart reflex was decreased in the exposed group, but this was not related to cumulative exposure. This study has established more firmly that a decrease in conduction velocity of slow motor fibres occurs at low levels of exposure to CS2. Extrapolation of the results suggests that small effects may occur after 40 years of exposure to concentrations below the present threshold limit value (10 ppm).

[Serum proteins levels of school children in areas with variable air pollution, especially by carbon disulfide (CS2)]

Within an epidemiological transversal study concerning the effect of CS2 immissions on the health state of school children during 1987/1988, 340 9 to 10 years old children (198 exposed, 142 non-exposed) have been investigated. From a venous blood sample 12 serum proteins have been determined, among other determinations. From these 12 immunological parameters, relating the mean concentrations of them in connection to the two different areas 7 were significantly different, 2 probably different, and 3 had no differences (T-test). These results are discussed in connection with other data from the literature.

Carbon disulfide exposure and neurotoxic sequelae among viscose rayon workers

In Norway's only viscose rayon plant, carbon disulfide (CS2) concentrations in ambient air usually were between 30 and 50 mg/m3 during the first 23 years of production. From 1970/1971 until the factory was closed in 1982, corresponding values were 10-25 mg/m3. Through all of these years, high peak exposures of CS2 and H2S occurred. In 1986, 16 of the 24 men still at work in 1982 and with at least 10 years' experience in the spinning room agreed to participate in this study. Clinical neurological examination demonstrated abnormalities in 15; neuropsychological tests showed impairments of probable organic origin in 14. Thirteen had cerebral atrophy demonstrated by cerebral computed tomography (CT). Electromyography (EMG) was abnormal in six, neurography in 11. Regional cerebral blood flow measurements indicated flow asymmetries in eight, whereas Doppler investigation of the extracranial carotid and vertebral arteries, electroencephalography (EEG), and evoked response investigations were mostly normal. Based on these results and the exposure data, a diagnosis of CS2-induced encephalopathy was reached in eight workers; another six had an encephalopathy in which CS2 exposure was regarded as a partial cause. Correspondingly, seven had a neuropathy probably caused by CS2 exposure alone; in three others, CS2 was found to be the partial cause of a neuropathy. This indicates that long-term, relatively moderate exposure to CS2 in association with high peak exposures to CS2 and H2S involves a substantial risk of developing neurotoxic disease.

Carbon monoxide, carbon disulfide, lead and cadmium--four examples of occupational toxic agents linked to cardiovascular disease

A variety of industrial agents to which large segments of the population are exposed have been linked to the development of cardiovascular disease. These toxic agents, which include carbon monoxide, carbon disulphide, lead, and cadmium, are produced by a wide variety of industrial processes and so are ubiquitous in the modern industrial environment. Although the mechanisms by which such toxins may contribute to cardiovascular disease are not well defined, there are at least four possible theories that have received clinical and experimental support. The postulated mechanisms by which such toxins may play a role in vascular disease are: (1) an increase in blood pressure; (2) an increase in the levels of blood cholesterol and/or an induction of lipid accumulation in vessel walls; (3) an induction of a lipid peroxidation process thereby increasing the tendency of blood clotting; and (4) a promotion of a mutation in the arterial cell wall.

[Evaluation of the health status of workers exposed to carbon disulfide]

The investigation included 134 workers from a viscose rayon factory who were exposed to average concentrations of carbon disulphide exceeding MAC values (x = 119.3 mg/m3) for more than 75% of their working hours. Workers' chronic morbidity from carbon disulphide exposure was analysed over a three-year period, and results were compared with those for a control group of the same age but with a shorter exposure duration. The percentage of ill workers and the prevalence rate were both similar to those of the control group. However, as concerns the specific morbidity caused by carbon disulphide exposure, toxic polyneuropathy was present only among the exposed workers. In that group hypertension too reached a higher prevalence rate, statistically significant, although both groups consisted of younger workers of similar age. The prevalence of other diseases was comparable, possibly because of the selection bias, and the healthy worker effect. Owing to that effect workers with the most distinct symptoms had been removed from their jobs and, consequently, excluded from examinations. That could have been a reason for underestimating exposure effects.

Work environment and cardiovascular diseases. A short review of the literature

The main purpose of this short review has been to present and evaluate the epidemiological evidence on CVD and environmental factors at work. It is indeed a difficult task to compare the scientific evidence in relation to the above mentioned risk factors. In some areas we find many studies, but with low overall methodological quality (noise is an example), while in others there are few, but good studies (e.g. carbon disulphide and nitroglycerine/glycol). We have to realize that in empirical sciences there is no such thing as a final proof. It would be easy if science dealt with what we know, while religion dealt with what we believe. It is more realistic however to say that science deals with what we believe we know, while religion deals with what we know we believe. Keeping this in mind the following classification of risk factors in the work environment seems to be well justified: Very probable causal relationships: Physical inactivity at work Nitroglycerine/nitroglycol Carbon disulphide Probable causal relationships: Monotonous high-paced work Shift work Noise Cobalt Arsenic Lead Possible causal relationships: Passive smoking Heat Dinitrotoluene Organophosphates Antimony Electromagnetic waves and fields No causal relationships: Cadmium Carbon monoxide One of the important questions raised by a list of this kind is whether we know enough to act, that is to use this knowledge in a preventive effort. Some might argue that we should wait until we have harder evidence. Another position would be that in many situations we have to act without such hard evidence. In my view fear of making mistakes should not prevent us from acting. If we always choose to wait until the evidence is 100% convincing, we will be very likely to make many - and often serious - mistakes.

Study of the effects of simultaneous exposure to noise and carbon disulfide on workers' hearing

The aim of this study was to explore the effects of simultaneous exposure to noise and carbon disulfide on workers' hearing and balance. The study was conducted by interviews and by audiometric and balance tests on workers in a rayon factory in the city of São Paulo, Brazil (n = 258). The workers studied had a history of exposure both to excessive noise levels (86-89 dBA) and to excessive levels of carbon disulfide (89.92 mg/m3). The percentage of hearing loss found was much higher than expected for this occupational activity, which reinforced the possible connection between the exposure to noise and carbon disulfide.

Mortality in the US rayon industry

A retrospective cohort study was undertaken of the mortality of men exposed to carbon disulfide in the US rayon industry. The cohort consisted of 10,418 men employed between 1957 and 1979. Deaths to mid-1983 were ascertained by the Social Security Administration and the National Death Index. Total mortality in the group was slightly lower than that of the comparable US population. There was no significant difference in overall mortality between the 4,448 employees who had held jobs with the greatest potential for exposure to carbon disulfide and the 3,311 workers who had no exposure. However, there was an excess of deaths from arteriosclerotic heart disease among the potentially most heavily exposed (242 deaths observed, 195.6 expected). An excess of deaths from suicide (29 observed, 18.8 expected) was seen in only one of the four plants.

Neurotoxic and neurobehavioral effects of organic solvents on the nervous system

Organic solvents have been widely used in industry for decades, and there has been constant concern about their toxic effects on the central and peripheral nervous systems. In this chapter the effects are reviewed and particular attention is paid to the reported clinical effects of long-term exposure.

Application of the Minnesota Code in evaluating electrocardiographic features of ischemic heart disease in patients exposed to carbon disulphide

We examined 81 men exposed for a long time to carbon disulphide (CS2) and tested the possible electrocardiographic (ECG) changes of ischemic heart disease (I.H.D.). The subjects were examined twice in two years. In order to make the ECG evaluation more objective, the Minnesota Code was applied. Two obligatory ECG examinations and only one submaximal effort test were carried out. For comparative evaluation, the control group was examined once. We proved that, in spite of the accepted opinion concerning the atheromatous action of CS2, this compound does not cause ECG symptoms of I.H.D. in a higher percentage of exposed persons. It also does not cause any significant increase in I.H.D. symptoms in dynamic ECG observations.

Extrapyramidal and other neurologic manifestations associated with carbon disulfide fumigant exposure

Three groups of pesticide-exposed grain workers from three different work facilities experienced chronic central and peripheral nervous system dysfunction that appeared to be exposure related. The grain inspectors, malt laboratory workers, and grain elevator workers displayed higher prevalence rates of atypical parkinsonism, cerebellar signs, hearing loss, and sensory changes than would be expected in a nonneurologic control population. The 21 self-selected patients included in this report exhibited cogwheel rigidity in 80% (17/21), decreased associated movements in 71% (15/21), distal sensory shading in 62% (13/21), intention tremulousness in 52% (11/21), resting tremulousness in 48% (10/21), and nerve conduction abnormalities in 44% (7/16). Carbon disulfide, a major component of the fumigant mixtures used, has been associated in the rayon industry, since the 1930s, with similar neurologic symptoms.

Exposure to carbon disulphide and ischaemic heart disease in a viscose rayon factory

The cohort of viscose rayon workers previously described by Tiller et al has been reconstructed and followed up to the end of 1982. The pattern of mortality at ages 45 to 64 for the extended period 1950-82 is similar to that described by Tiller et al for 1950-64. The spinners, the workers most heavily exposed to carbon disulphide, have a significantly higher mortality from all causes than the least exposed group. The excess mortality is largely accounted for by ischaemic heart disease (IHD) for which the spinners have an SMR of 172. When mortality is related to an exposure score in the same group, both all cause (p less than 0.01) and IHD (p less than 0.001) mortality increase with increasing exposure level. When this analysis is repeated covering all ages these trends become much less strong and only that for IHD remains significant (p less than 0.05). Over the age of 65 there is a tendency for mortality to decline with increasing exposure. This is contrary to expectation under the usual hypothesis that carbon disulphide promotes atherosclerosis. Instead it suggests that carbon disulphide has some type of reversible, direct cardiotoxic or thrombotic effect. This is supported by the findings that there is a strong trend (p less than 0.01) for IHD mortality to increase with increasing exposure in the previous two years. Further, both IHD (p less than 0.001) and total (p less than 0.01) mortality show highly significant trends with exposure among current workers but no such trends among workers who have left the industry.

Conduction velocity in slower motor fibres

Measuring conduction velocity in slower fibres (CVSF), through a partial antidromic block (Hopf-Seppäläinen method), allows estimating the dispersal of conduction velocity in motor fibres by the difference between the maximal motor conduction velocity (MCV) and CVSF. Investigations performed in workers exposed to medium concentrations of carbon disulphide show difference between MCV and CVSF as providing a more sensitive indicator for early diagnosis of peripheral neuropathies than MCV.

Effects of toxic chemicals on the reproductive system. Council on Scientific Affairs

In an effort to make physicians more aware of the hazards of the workplace to pregnant workers, the Council on Scientific Affairs' Advisory Panel on Reproductive Hazards in the Workplace prepared this third and final report reviewing the effects of chemical exposure. A total of 120 chemicals were considered for reviews based on an estimation of their imminent hazard, ie, widespread use and/or inherent toxicity. Following a brief introduction, which sets out general principles, clinical applications, and aids to the recognition of a human teratogen, the report presents reviews and opinions for three representative chemicals. Information concerning the remaining 117 compounds is available upon request.

Effects of intervention on the cardiovascular mortality of workers exposed to carbon disulphide: a 15 year follow up

The cardiovascular mortality of a cohort of 343 Finnish men exposed for at least five years to carbon disulphide (CS2) in a viscose rayon plant has been monitored prospectively from 1967 to 1982. The results from the first five years of follow up in 1972 showed a 4.7-fold excess mortality for ischaemic and other heart diseases (ICD A83-A84) compared with a comparable reference cohort of paper mill workers. After 1972 a preventive intervention programme instituted at the rayon plant included removing all workers with coronary risk factors from exposure. Thus only 19% of the exposed cohort continued to be exposed in 1977 compared with 53% in 1972. Moreover, exposure levels were reduced after 1972 in compliance with the set hygienic standard of 10 ppm. These measures were reflected in a normalisation of the risk of cardiovascular death; the relative risk was 1.0 in the period after the intervention (1 July 1974 to 30 June 1982), whereas it had previously been 3.2 (from 1 July 1972 to 30 June 1974). The risk of a fatal heart attack remained at 11.6% throughout the 15 year follow up period (95% confidence limits 8.5%-15.4%) among the exposed compared with 7.8% (5.3%-11.2%) among the unexposed. The entire risk difference of 3.8% was accumulated during the first seven years of follow up. Thus we can estimate that 59 CS2-related cardiovascular deaths would have occurred during the next eight years (instead of the actual 19 deaths) had there been no preventive action. Calculations yielded a preventive fraction of 68%.

Environmental validation of the homocystine theory of arteriosclerosis

It has been proposed that elevated concentrations of homocystine in vascular tissue could cause arterial damage leading to arteriosclerosis. This theory is indirectly supported by research in the area of environmental toxicology, which has revealed that carbon monoxide and carbon disulfide, agents whose prolonged exposure is known to result in the development of arteriosclerotic changes, induced vitamin B6 deficiency states which predictably lead to a homocystinuria-like state. Such information provides strong indirect support of the controversial homocystine theory of arteriosclerosis.

Neurophysiological and psychological disorders and occupational exposure to organic solvents

A number of reports, particularly from Scandinavian countries, claim that painters and workers in other trades in which prolonged occupational exposure to organic solvents may occur develop a type of mental illness characterized principally by impairment of memory and co-ordination and some deterioration of personality. The condition, called 'organic solvent disease', is recognized as a cause of premature retirement and is classed as an occupational disease in certain countries. The conclusions of these reports have been contested and the existence of such a disease entity has been questioned. The publications reporting adverse neurological, neurophysiological and psychological disorders in solvent-exposed workers, and the methods used to determine adverse effects, have therefore been evaluated. In addition, data from animal behavioural studies have been examined but were found to have little or no to have little or no relevance to the reported human disease. The human data indicate that, of the solvents studied, only CS2 provided clear evidence of neurotoxic damage detectable by clinical and pathological examination as well as by neurophysiological measurements (e.g. nerve conduction velocity and nerve action potentials) or neuropsychological techniques (e.g. Rorschach inkblot test and WAIS intelligence tests). In the case of several other solvents and mixtures of solvents commonly used in industry, the evidence of CNS impairment, based principally on the response to questionnaires and the results of neuropsychological and neurophysiological examinations was questionable. A critical evaluation of the reliability of these methods in detecting minor deviations from normal and of their ability to provide acceptable evidence of CNS dysfunction or damage leaves little doubt that these methods are of value in investigating personality, intelligence and memory in the clinical examination of individual patients. However, evidence indicates that they are not suitable for use in epidemiological studies, principally because the variability of response in normal individuals is ill-defined and insufficiently investigated. The same conclusion was arrived at in evaluating the contribution of electroencephalography, computerized axial tomography scanning and other electrophysiological examinations to the diagnosis of brain changes in groups of solvent-exposed and unexposed workers. Furthermore, the personality changes identified (by neuropsychological tests) in painters and other workers exposed to solvents could well be produced by ageing, exposure to lead or mercury, excessive alcohol intake, psychoactive drugs or the ordinary stresses of everyday life.(ABSTRACT TRUNCATED AT 400 WORDS)

Chest pain in rubber chemical workers exposed to carbon disulphide and methaemoglobin formers

A cross sectional prevalence study of chest pain in 94 rubber chemical workers exposed to carbon disulphide (CS2) and methaemoglobin forming aromatic amines was carried out. The purpose of the study was to determine whether the prevalence of chest pain or coronary heart disease (CHD), or both, in exposed individuals exceeded that of a group of non-exposed individuals from the same plant. Cardiovascular, smoking, and occupational histories were obtained. Blood pressure, height, weight, serum cholesterol, and fasting blood glucose were measured. Resting electrocardiograms (ECGs) were obtained on all study participants, as were exercise stress tests on selected exposed individuals. Matching eliminated important known risk factors for coronary artery disease. Both chest pain and angina were significantly related to exposure, controlling for age and cigarette smoking. This association was not dependent on duration of exposure as defined by 10 or more years of employment in the department of interest. CHD as defined by angina, a history of myocardial infarction, or a coronary ECG or a combination of these occurred more frequently among exposed workers. The number of abnormal ECGs in the exposed group was twice that in the control group, but the difference was not statistically significant. Age rather than exposure appeared to be the important variable associated with raised blood pressure. Neither biological measures of exposure nor ECGs showed an acute effect of workplace exposures on the myocardium. Possible additive or multiplicative effects of individual chemical agents could not be evaluated. Appropriate modification of medical surveillance of rubber chemical workers with exposure to CS2 and aromatic amines is warranted.

An epidemiological study on carbon disulfide angiopathy in a Chinese viscose rayon factory

To assess long-term vascular effects of occupational carbon disulfide (CS2) exposure, we examined 376 exposed and 325 unexposed Chinese workers with a medical and work-history questionnaire, a chest-pain questionnaire, blood pressure and blood cholesterol measurements, routine urinary tests, monochromatic fundus photography and other tests. Data from 354 exposed and 177 age- and sex-matched reference workers were evaluated. Personal exposure monitorings were performed simultaneously with a passive dosimeter using gas chromatography. Monochromatic fundus photography revealed no CS2-retinopathy characterized by microaneurysms and/or small dot hemorrhages, and no effects of CS2 on blood pressure and blood cholesterol were found. These negative results may have been due to the low daily exposure averages, which varied between 0.01 and 12.8, with a mean of 1.5 ppm. The present study suggested that the no-effect level of CS2 exposure on the development of retinopathy was around 2 ppm (8-h time weighted average), and the absence of adverse CS2 effects among the workers studied supported the current standard for occupational CS2 exposure of 10 mg m-3 in China.

A neurophysiological study among Chinese CS2-exposed workers

A neurophysiological study was carried out to examine peripheral neurotoxicity of extremely low levels of CS2, that is, less than 2 ppm (TWA-8hr) among Chinese viscose rayon workers. From the subjects who participated in a 1981 cross-sectional medical survey, 70 male workers exposed to CS2 and age-matched unexposed workers were randomly selected for the present neurophysiological examination. The conduction velocities of motor, sensory and slower motor fibres of the right ulnar nerve were measured using the same methods as those in the study by Seppäläinen (1974). Skin temperature was measured at the middle of the volar surface of the right forearm with a Thermistor thermometer. According to an earlier occupational hygiene survey in the plant, current personal exposures determined by a passive dosimeter method were very low; the average of daily exposure of 7 jobs studied was 1.45 ppm (range 0.2-5.0). Past and current area sampling data also suggested that occupational hygiene conditions regarding CS2 exposure in the plant had been extremely good for the previous 6 years. The present neurophysiological study clearly showed that significant reduction in the conduction velocities of motor and slower motor fibres of the ulnar nerve was detected as a consequence of chronic exposure to low levels of CS2. In the previous cross-sectional medical survey, no retinopathy was found among Chinese workers exposed to CS2 at this level. These results suggested that an effect of CS2 on the peripheral nerve would appear earlier than that on the retina.