Document rB20kbgMNXXrxyD02Qjem8R7

j4 iw Brit. J. iitdustr. Med{ % , 28, 293-295 -fcS -C(^5 Evaluation of the psychophysiological functions in humans exposed to trichloroethylene M. SALVINI, S. BINASCHI, and M. RIVA1 Institute of Preventive Medicine for Workers and Applied Psychology, University of Pavia, Italy Salvini, M., Binaschi, S., and Riva, M. (1971). Brit. J. industr. Med., 28, 293-295. Evaluation of the psychophysiological functions in humans exposed to trichloroethylene. To provide data on the psychophysiological efficiency of human beings exposed to solvent vapour currently used in the industry the effects of trichloroethylene (TCE)were evaluated by exposing six male universitystudents to an average vapour concentration of llOp.p.m. for two 4-hour exposures, separated by a 1^-hour interval. Each subject was examined on two different days, on one day undertaking a set of tests in an atmosphere contaminated with TCE vapours and on another day in a `control' atmosphere which did not contain TCE. On each of the two days two sets of test were performed at 8.30 a.m. and at 6 p.m. The following tests were performed: perception test with tachistoscopic presentation, Wechsler Memory Scale, complex reaction time test, and manual dexterity test. A crossed scheme analysis was used. In all the tests performed a statistically very significant decrease in per formance ability was seen; the greatest decrease occurred during the more complex tests. The suggested TLV for TCE (100 p.p.m.) appears to be very ciose to the average concentration capable of interfering with psychophysiological efficiency, even in the absence of other undesirable subjective and objective manifestations. Experiments performed on experimental animals to psychomotive efficiency (Stopps and McLaughlin, ascertain the effects of trichloroethylene (TCE) 1967). This conclusion may be questioned on two vapour have shown that this substance interfered with their psychophysiological efficiency (Grandjean and Battig, 1964). grounds: firstly, all of Stopps's experiments were performed for a limited period, not comparable to the 8-hour working day; secondly, the results are of Recently, experiments have been conducted to somewhat limited value because only one human find whether the same phenomenon occurs in being was exposed. humans. In one experiment, a human subject was Therefore, to provide more realistic and reliable exposed to four concentrations of TCE for 2 hours information on the psychophysiological efficiency of 45 minutes. The results indicated that at the TLV of human beings exposed to solvent vapours currently TCE (100 p.p.m., as recommended by the American used in industry, a research programme was initiated Conference of Governmental Industrial Hygienists, to evaluate the effects on six persons exposed to TCE 1967), no significant effects occurred in human at an atmospheric concentration of 110 p.p.m. for 'Research Laboratory Star Food Co. Ltd., Milan. Address requests for reprints to: Istituto di Medicina Preventiva del Lavoralon, 24, via Boezio - 27100 Pavia (Italy;. 8 working hours. Methods The effects of TCE were evaluated by exposing six male 293 si 33936 294 M. Salvini, S. liinaxclii, anil M. Riva university students, between 20 and 22 years of age, to an average vapour concentration of I lOp.p.m.and fluctuations between 90 p.p.m. and 130 p.p.m. TCE was periodically atomized into the test room to maintain the desired concentration. The air was analysed at regular intervals by gas-chromatography. The temperature, humidity, and ventilation rates were kept constant (dry bulb temperature 20CC; relative humidity 45%). Details of the experimental method arc similar to those given in the companion paper (Salvini, Binaschi, and Riva, 1971). During each exposure the following tests were applied (for details, sec the companion paper); 1. Perception test with lachistoscopic presentation (exposure lime 1/20 sec) - to evaluate the extension of the perceptive field, the span of perception, and the organ izing capacity of stimuli in space; 2. H'eclisler Memory Scale - to evaluate immediate memory and the perceptive field extension; 3. Complex reaction time - to evaluate the time lapse between different visual stimuli and the correct psychomotive response and the regularity between stimuli and response intervals. Manual dexterity tests involving the right, left, and both hands simultaneously were also conducted. From an objective clinical standpoint, no dis turbances in motor functions, co-ordination, equi librium or behaviour patterns were observed after two 4-hour exposures to TCE. A slight sense of dizziness coincided with the maximum fluctuations in TCE concentrations. During these periods some transient eye irritation was observed. All the test subjects complained about the odour of TCE. In all the tests performed there was a statistically significant decrease in performance ability; the greatest decrease occurred during the more complex experiments (Tables 1 to 5). TABLE 2 Immediate Memory Test - Analysis of Variance SSQ D.F. S' F Trichlorocthvlcnc (TCE) 462-68 1 462-6S 27-41' Mental fatigue (MF) 85-58 1 85-58 5-51 TCE x MF 216-74 1 216-74 12-84' Learning (L) 293-88 1 293-88 17-41' L x MF 160-53 16053 9-51' Subjects (S) 347-75 5 69-55 4-12 S x FM 116 5 23-20 1-37 Error 135-0! 8 16-88 `p < 0-05 *p < 0-01 *p < 0 001 TABLE 3 Complex Reaction Times (Speed of Responses) Analysis of Variance SSQ D.F. S' F Trichloroethylene (TCE) Mental fatigue (MF) TCE x MF Learning (L) L x MF Subjects (S) S x MF Error 119-72 77-04 127 37 87-71 46-44 162-80 105 36-68 1 1 1 1 1 5 5 8 119-72 77-04 127-37 87-71 46-44 32-45 21 4-58 26-14* 16-82' 27-8!5 19-15* 10-14' 7*111 4-59 'p < 0 05 *p < o-oi 1 p < o 001 TABLE 4 Complex Reaction Times (Regularity of Responses) - Analysis of Variance SSQ D.F. S' F Table 1 Perceptive Test - Analysis of Variance Trichloroethylene (TCE) Mental fangue (MF) TCE a MF Learning (L) L > MF Subjects (S) S x MF Error SSQ D.F. S' F 2S-12 1 2S-I2 27-84' 2-54 1 2-34 2-32 15-81 1 15-SI 15-65' 35-02 35-02 34-671 15-75 15-75 15-59' 38-60 5 7-72 7-641 15-10 5 3-02 2-99 8-11 8 1-0! 'p < 0 05 >p < o-oi jp < o-ooi SSQ = sum of square about the mean D.F. = aegrecs of freedom S' = estimate of variance F -- Sncdecor's variance ratio Trichloroethvlene (TCE) 132-54 1 132-54 12-41' Mental fatigue (MF) 19-65 1 19-65 1-S4 TCE x MF 22-86 1 22-86 2-04 Learning (L) 18-48 1 18-48 1-73 L x MF 8-76 8-76 0-S2 Subject (S) 108-95 5 21-79 2-04 S x MF 101-45 5 20-29 1-90 Error 85-41 8 10-68 'p < o-o i Discussion Our results indicate that the suggested TLV for trichloroethylene(100p.p.m.)appears to be very close to the average concentration capable of causing significant decrements in the functions essential to the safety of workers performing industrial operations. i SL 033937 Variance F 8 27-41* S 5-51 '4 12-84* S 17 41* . * 9-51* 5 4-12 `.0 1-37 *8 ponses) - F "2 26-14* uj 16-S2* 7 27-Sl3 1 19-15* 'rA 10-14* 15 7-11' 4-59 iS TY OF :e F 54 12-41* b5 1-84 86 2-04 as 1-73 76 0-82 "*9 '2-04 29 1-90 6S TLV for : very close of causing ssential io industrial Evalimiioit of the psychophysiological functions in humans exposed to trichloroethylene 295 TABLE 5 Manual Ability and Dexterity - Analysis of Variance (a) Right hand Trichloroethylene Learning Subjects Error SSQ D.F. J* F 480-11 1 480-11 25-47* 173-61 173-61 9-211 295-95 5 59-19 3-14 75-42 4 18-85 (6) Left hand Trichloroethylene Learning Subjects Error 83-39 37-79 401-85 14-51 1 1 5 4 83-39 37-79 80-37 3-63 23-80* 10-41 * 22-14* (f) Right and left hands Trichloroethylene 71-88 Learning 68-88 Subjects 30S-65 Error i 10-51 1 1 5 4 71-88 68-88 61-73 2-63 27-33* 26-19* >3-47* *P < 0-05 *P < 0 01 Ai first it was thought that these experiments could not be regarded as representative because of the complaints and reactions of the students about the odour of TCE. These reactions were considered psychological in nature because the students were never before exposed and therefore not accustomed to the odour of TCE. Neverthless, it was not known if and to what degree this factor affected the test results. For this reason, the experiment was repeated using as the subjects six workmen who regularly work with TCE and other solvents. The results of the experiments with workers confirmed the con clusions already drawn from the results with students and summarized in Tables 1 to 5. Conclusion Two 4-hour exposures, separated by a I j-hour interval, to trichloroethylene at an average con centration oT 110 p.p.m., with fluctuations ranging from 90 p.p.m. lo 130 p.p.m,, caused a statistically significant reduction in efficiency of both students and workers in performing various psychophysiological tests. The reduction in efficiency is particularly significant in those tests involving perceptive dis crimination. Therefore, it is possible that a TLV of 100 p.p.m. for trichloroethylene may result in interference with the psychophysiological efficiency of a man with executive or technical responsibilities even in the absence of other undesirable subjective and objective manifestations. References Grandjean, E., and Battig. K. (1964). Le spectre des effets du trichlorethylene sur le comportement du rat. Arch. int. Pharmacodyn., 147, pp. 333-350. Horvath, M., Frantik, E., and Michalovd, C. (1964). The research of higher nervous functions in occupational health. Proc. XIV int. Congr. occup. Hlth Madrid, 1963, vol. H, pp. 93-105. Excerpta nice. Int. Congr. Ser. No. 62. Lyubhna, E. I. (1961), Some methods used in establishing the maximum allowable concentrations. Pure appl. Chem., 3, 109-113. Salvini, M., Binaschi, S., and Riva, M. (1971). Evaluation of the psychophysiological functions in humans exposed to the threshold limit value of 1,1,1-tnchloroethane. Brit.J. industr. Med., 28, 286-292. Stopps, G. and McLaughlin, M. (1967). Psychophysio logical testing of human subjects exposed to solvent vapors. Amer. industr. Hyg. Ass.J.,2%, 43-50. Received for publication March 21, 1970. 033938 Six