Reports of Completed Research Projects
Identification of carcinogen-haemoglobin adduct in benzidine exposed
workers
Our
earlier findings on the workers exposed to benzidine (BZ) and BZ based
dyes revealed that exposure status and excretion pattern of benzidine
metabolites were strongly correlated with the level of DNA benzidine
adducts in exfoliated urothelial cell. Further, in an attempt to examine
haemoglobin (Hb) adducts, the blood samples were collected from 33 exposed
subjects (15 subjects exposed to benzidine and 18 subjects exposed to
benzidine based dyes e.g. Direct Black 38) and 15 control subjects matched
on age, sex and socio-economic status. These samples were processed and
shipped to NCI, NIH,USA on dry ice (-700C) for the analysis of
acetylated benzidine-Hb adduct level.
The
haemoglobin content was precipitated from the blood samples by alkaline
hydrolysis. After the conventional procedure of extraction and cleanup,
the samples were derivatized with heptaflurobutyric anhydride (HFBA). The
sample were analyzed by capillary GC equipped with mass detector operating
in negative chemical ionization mode with CH4 as reactant gas
(ion source 2500C, electron energy 2400C) selected
ion monitoring.
The mean age of control group (N=15), benzidine dye exposed
group (N=18) and benzidine exposed group (N=15) was 26.5
± 5.1, 23.8
± 3.7 and 23.3
± 4.1 years respectively. The
findings revealed that the haemoglobin adducts of acetylated benzidine
were non-detectable in the control subjects. However, it was present at
relatively low level in benzidine dye exposed workers (1.56
± 1.06 ngAcBz/100mgHb) and at a
very high level among benzidine exposed workers (27.99
± 13.67 ngAcBz/100mgHb).
Comparatively Hb adduct content was about 18 times higher in BZ exposed
workers than BZ dye exposed workers. Thus, the findings indicate the
usefulness of this technique in screening of subjects from high risk
population groups exposed to benzidine and other related aryl amines used
in industrial settings.
Assessment of Work Environment and Health Status of
Employees of Southern Iron and Steel Company Limited, Mecheri, Tamil Nadu
(Siscol)
The objectives of
the study were to assess the dust concentrations of working environment of
the Plant and to correlate them with health status of the workers. Hence,
a detailed environmental-cum-medical surveillance study was carried out.
Dust sampling was carried out with a dust monitoring equipment. Ambient
air temperature was measured with dry bulb thermometers. Sound pressure
levels were measured with a sound level meter. Clinical examination was
carried out through a standardised questionnaire. Hearing acuity was
assessed with an audiometer.
It was observed that the RPM values were 1.78mg/m 3 in Blast
Furnace Section (BF), 1.46 mg/m3 in Energy Optimisation furnace
(EOF), 1.27 mg/m3 in Ore yard, 0.69 mg/m3 in
Continuous Casting Machine (CCM), 0.52 mg/m3 in Sintering Plant
and 0.32 mg/m3 in Administration section. This shows that the
Blast Furnace Section was the dustiest among all the sections. The average
concentration of silica dust (7.68mg/m3) in Sintering Plant
well exceeded the TLV of 4.09g/m3 .
The ambient air temperature was measured to be as high as 30.05-36.2°C
during tapping operation and 26.5-30.7°C
without tapping operation against the recommended limit of exposure of
25.9°C.
The noise level also exceeded the recommended limit of 90 dBA in
turbo-blower (96.9 dBA), turbogenerator (92.3 dBA), and compressor area
(92.3 dBA) of the power plant.
High blood lead levels were observed in 26.6% workers (160-428mg/dl)
of the EOF Section, and in 20% workers (100-358mg/dl)
in Blast Furnace Section against the permissible level of 300mg/dl
(Biological Exposure Index). Interestingly, 42.85% of control subjects
were also observed to have Pb-B levels above the permissible level because
of the fact that the administrative section is located opposite to the
Petrol Filling Station inside the factory premises and also the high
frequency of vehicles passing through the road in front of the
administrative section.
The common morbidity pattern observed were: refractive errors (2.2-19.4%),
joint pain (2.3-12.5%), pterygium (2.9-4.6%) and chronic bronchitis
(1.4-2.9%).The prevalence of hearing impairment was observed in 10 out of
29 subjects (34.5%) in maintenance and mechanical section, 14 out of 44
subjects (31.0%) in CCM, 22 out of 75 subjects (29.0%) in BF and 3 out
of 11 subjects (27.3%) in Sintering Plant. It is suggested that audiometry
should be carried out periodically as an intervention programme
Health Surveillance of
Workers Exposed to Chromium in a Chemical Industry
Chromium occurs in environment in
different forms. The respiratory tract in human beings is a major target
organ of inhalation exposure to chromium compounds. Workers exposed to Cr
(VI) compounds may develop asthma, nasal perforation and other signs of
respiratory distress. Therefore, a study was undertaken on environmental
and biological monitoring of chromium to assess the health consequences
among the workers exposed to chromium in a chemical industry.
A complete health check up
of 176 exposed and 30 control subjects was conducted. Blood and urine
samples were collected for estimation of chromium levels as well as
relevant biochemical parameters. Sixty-one semen samples were collected
from exposed subjects to find out the effect of chromium on human sperm.
Environmental monitoring
of chromium at different places in industrial premises revealed that the
level of chromium was highest at filtration unit (27.9-82.3
mg/m3) followed by
storage (5.7-76.6 mg/m3)
and furnace area (10.5-49.3 mg/m3).
The lowest level of chromium (3.6-4.9 mg/m3)
was found at office premises. The above result shows that chromium level
in the industry was lower than the prescribed TLV of 500
mg/m3.
The mean blood Cr level
in exposed workers (6.41 mg/100
ml) was considerably high as compared to the control subjects (2.96
mg/100 ml). A total of 22 cases
(16 in furnace staff, 4 in supervisory staff and 2 in maintenance staff)
with nasal perforation were observed with no such cases in control
subjects. Biochemical parameters, like glucose, cholesterol, serum
protein, creatinine, SGPT showed insignificant alterations in the exposed
group compared to control subjects.
The data of semen analysis of Cr. exposed workers revealed that sperm
concentration was below 20 million/ml (lower than normal value) in semen
of the ten (16.3%) out of the 61 subjects studied. The sperm motility and
sperm viability were below 50% in three and six subjects respectively out
of the 59 subjects studied. The data of the seminal pH indicated that
58.8% subjects were in the normal range ( 7.2-8.0; reported by WHO).
However a considerable number of cases i.e. 39.2% showed the higher pH
value than the normal range. Recently, Harraway et al. (Am. J. Obstetrics
& Gynecol. 182, 1045, 2000) also reported a consistently higher pH value
in normal semen as well as in abnormal characteristic semen as compared to
reported normal range by WHO. Further the detailed analysis of the
parameters is in progress.
Interaction Effects of Noise, Illumination and Time of Day
on Human Work Performance
The ubiquitous presence of
noise in industry may be potential enough to cause adverse health
consequences. Furthermore, illumination levels lower than those needed
could reduce productivity and enhance risk to health and safety of
workers. Human activity is also guided by the "Time of Day". In the shop
floor all these three stresses could influence work performance. The
objective of this study was, therefore, to examine whether the combined
effects of noise, illumination and " time of day" had greater effects in
human functions than the independent effects of either of these factors. A
part of the experiment carried out under quiet condition was reported in
2001. The findings of the experiment, now concluded, are presented here.
A group of 64 young
healthy male human subjects, unexposed to occupational noise, with normal
hearing and vision, was administered a battery of six psychological tests
viz. DORN, memory, letter cancellation, hand precision, card sorting and
digit symbol. These tests were identified following ILO recommendations
related to behavioural effects due to physical hazards. The subjects were
allocated to two equal groups (Group A and Group B) of 32 each. Subjects
of group A worked under quiet condition (60 dB), while those of Group B
worked under noise condition (100 dB). The subjects of Group A was further
divided into 4 equal sized groups. Group 1 worked under low illumination
level (350 lx) during forenoon (1000-1200h) followed by afternoon
(1500-1700h) session, while those of Group 2 worked in the reverse order
of afternoon-forenoon sessions. The subjects of Group 3 and Group 4 worked
similarly under high illumination level (700 lx). The subjects of Group B
worked in the same order as those of Group A.
The psychological test
scores of all the subjects under each illumination level were pulled
together for statistical analysis. The test scores were analyzed into
three components: speed, accuracy and error. Speed was expressed as either
the time taken in performing the task or the total number of attempts.
Accuracy was taken to be as the ratio of number of correct attempts to the
total number of attempts. While error scores were in terms of proportion
of the total number of errors to the total number of attempts. However,
the error score in `card sorting` was taken to be the number of cards
wrongly sorted out as the speed score was in terms of time taken. The
accuracy scores and error scores were transformed into arcsine square root
for the best fit of the data to normality. A three way lay out (2x2x2)
analysis of variance (ANOVA), with repeated measure, was employed to
determine the main and interaction effects of noise.
The ANOVA showed that the
interaction effects of noise and illumination were statistically
appreciable reflecting that with the rise in illumination level (700 lx)
the speed of performance in DORN test increased under noise condition than
in quiet condition. However, the accuracy scores deteriorated under noise
condition at 100 dB than that under quiet condition at 60 dB. The times of
day effect was not significant on memory (forward) but was appreciable on
memory (backward), suggesting superior performance (Mean 6.57) during
afternoon than in the forenoon (Mean 4.26). In card sorting test (by face
value), noise or illumination did not have any considerable influence on
the speed of performance or error scores although the interaction of noise
in combination with the illumination reached statistical significance on
the latter. This illustrates the fact that the error rates were
significantly increased with the noise at high illumination level. In card
sorting test (design configuration), the interaction effects of noise x
illumination x time of day, did reflect statistical significance, although
the independent effects were absent, nor were the interaction effects of
any of these two factors significant. The error scores increased
significantly under noise condition during forenoon, which however
decreased with the rise in illumination level in the afternoon . In the
letter cancellation test significant slowing of response rate occurred in
noise condition (Figure 3a), while progressive improvement in performance
was reflected under increased illumination level. The significant combined
effect of noise x illumination x time of day, shows decrements in accuracy
of performance during forenoon under noise condition, which was found to
improve with the rise in illumination level during afternoon. In the hand
precision test the significant interaction effects of these three factors
indicate that the rate of decline in accuracy scores under high
illumination level was more pronounced under high noise condition during
afternoon compared to that in quiet condition. In the digit symbol test
the significant interaction effect indicate degradation in accuracy score
at high illumination level both under noise and quiet condition in the
afternoon with the deterioration being greater under noise condition.
Thus it may be suggested
that the interaction effects of the noise, illumination and time of day
were demonstrable on the speed, accuracy and error scores in some of the
psychological tests employed in this investigation.