PII: S0003-4878(99)00064-2
Ann. occup. Hyg., Vol. 44, No. 2, pp. 119±124, 2000
# 2000 British Occupational Hygiene Society
Published by Elsevier Science Ltd. All rights reserved
Printed in Great Britain.
0003±4878/00/$20.00
Exposure to Organic Solvents in the O€set Printing
Industry in Norway
KRISTIN SVENDSEN$* and KARI S. ROGNES%
$Department of Occupational Medicine, University Hospital of Trondheim, 7006, Trondheim,
Norway; %Local Labour Inspection, PB 4368, 7002, Trondheim, Norway
The purpose of this study was to document the conditions regarding solvent exposure at o€set
printing oces in Norway at present and to study the variation of exposure between printing
oce technologies.
Measurements were made at seven o€set printing oces. The measurements consisted of ®ve
to 10 whole day personal exposure measurements at each oce performed over a period of 2
months. Variables that may in¯uence the level of exposure were registered by the occupational
hygienist at the end of each measuring day using a check list. The in¯uence of the variables on
the ``additive factor'' was examined by linear regression analysis.
The main contributor to the ``additive factor'' was isopropanol. The exposure to isopropanol
sometimes exceeded the Norwegian TLV. The exposure decreased when a separate exhaust
ventilation was used. The exposure increased when the machine had automatic cleaning. The
variables automatic cleaning and separate exhaust ventilation explained 59% of the variation in
the ``additive factor''. The results of this study indicate that the most important source of
solvent exposure in printing oces at present is the moisturizer used in the printing machines.
We think it is worth giving attention to this exposure and making e€orts to reduce it. # 2000
British Occupational Hygiene Society. Published by Elsevier Science Ltd. All rights reserved.
Keywords: solvents; o€set printing; isopropanol; 2-propanol; exposure limit addition
INTRODUCTION
Since the late 1970 s the use of organic solvents in
the printing industry has been linked to acute intoxication and decreased performance in behavioural tests (Helle et al., 1980; Baelum et al.,
1982). Workers in this industry are also represented
in statistics of patients with the diagnosis ``chronic
brain dysfunction'' (Labour Inspection, 1999). In
the years 1978±79 exposure measurements were carried out at printing oces in Norway as part of a
project to study the impact of organic solvent exposure on the health of printing press operators
(Thorud and HaÊgensen, 1981). Di€erent kinds of
printing processes were investigated. Some of them
showed high exposure to organic solvents. The task
which led to the highest exposure at the printing
oces was the cleaning procedure where exposure
Received 5 March 1999; in ®nal form 24 May 1999.
*Author to whom correspondence should be addressed.
Tel.: +1-47-73-86-75-15; fax: +1-47-73-86-89-70; E-mail:
[email protected]
119
levels of 100±200 ppm toluene or 5±10 ppm toluene
and 50±100 ppm white spirit were measured.
Since the early 1980 s the printing industry has
made e€orts to reduce the exposure to organic solvents. Toluene, xylene and chlorinated hydrocarbons have been replaced by parans and
cycloparans with high boiling points, and to some
extent with water-based solvents and terpenes.
However, despite these improvements, exposure to
organic solvents is still present in the printing industry and we consider it of interest to assess the present exposure levels. One circumstance which might
confuse the situation, is that the solvents which are
in use today often have a faint odour. Therefore,
the conditions at the o€set printing oces in regard
to solvent exposure may seem acceptable to the
workers. Along with this substitution, general ventilation and local exhaust systems have also become
more common, and new printing machines, often
with automatic cleaning, have entered the market.
The purpose of this study was to document the
conditions regarding solvent exposure in o€set
printing oces at present and to study the variation
120
K. Svendsen and K. Rognes
of exposure between di€erent printing oce technologies.
The solvents used for cleaning in the o€set printing industries which were included in this study,
were mostly aliphatic hydrocarbons with boiling
points above 1508C. Some printing oces also used
more complex solvents consisting of aromatic
hydrocarbons and more volatile solvents for short
tasks.
METHODS
The study was performed as a collaboration
between the local Labour Inspection and the
Department of Occupational Medicine of the
University Hospital of Trondheim. Printing oces
to be included in the study were located by means
of the register of employers at the Labour
Inspection and by the telephone catalogue. In this
way, 12 printing oces in the city of Trondheim
were identi®ed as potential study objects, and all of
these were visited. The inclusion criteria for the
study was that the oces had to perform o€set
printing and no other printing processes. Of the 12
identi®ed printing oces there were seven which
ful®lled this demand and these were included in the
exposure measurements. The measurements consisted of ®ve to 10 whole day personal exposure
measurements at each oce, usually on two
workers with repetitions on each worker if possible.
The measuring days were chosen over a period of 2
months. In order to get as close to random
sampling as possible, and to avoid special arrangements on days when the measurements were performed, neither the workers nor the employers
knew on which days the measurements would be
made. The measurements were always made on the
day we had chosen, and all week days were
measured at each oce. An occupational hygienist
either from the Labour Inspectorate or from the
Department of Occupational Medicine spent the
®rst measuring day in each oce to learn the processes and to watch the working methods. On subsequent days, the occupational hygienist started and
®nished every measurement. At some of the printing
oces we also carried out some personal, short
time sampling for 30 min on the ®rst day of
sampling. This sampling time included the cleaning
of the machines.
The seven printing oces di€ered with regard to
the number of workers, the kind of printing machines, the types of solvents used for cleaning, the
size of the rooms and the types of ventilation system. The printing machines varied from small onecolour machines which had been in use since 1978,
to brand new four-colour machines with automatic
cleaning. Other variables which could in¯uence the
level of exposure were registered by the occupational hygienist at the end of each day using a
check list. These variables were; weekday, which
oce, which worker, size of the room, kind of
printing machine and kind of cleaning solvent. The
Table 1. Characterisation of printing presses and locations for the seven o€setprinting oces in the study
Oce
no
Type of press; name, year model, no of colours, cleaning system
Ventilation
Size of press
room m2
1
Roland 200, 1987, 2 colours, manual cleaning
Natural ventilation
200
2
Roland 20, 1994, 4 colours, automatic cleaning
Mechanical air
supply
800
Speedmaster CD 102, 1994, 4 colours, automatic cleaning
Heidelberg o€set, 1980, 2 colours, manual cleaning
100
3
Heidelberg o€set, 1994, 4 colours, manual cleaning
Balanced
mechanical
300
4
Roland 300, 1996, 4 colours, automatic cleaning
Balanced ventilation
and separate
exhaust ventilation
650
Ryobi 522, 1991, 2 colours, manual cleaning
W2GTO, 1980, 1 colour, manual cleaning
5
Heidelberg GTO, 1988, 2 colours, manual cleaning
Roland 200, 1994, 2 colours, manual cleaning
Outlet ventilation
120
6
Man Roland/Roland Record, 1988, 4 colours, manual cleaning
Balanced
mechanical
500
Balanced
mechanical
200
Heidelberg o€set ETO, 1978, 1 colour, manual cleaning
7
Heidelberg, 1983, 4 colours, manual cleaning
Heidelberg, 1981, 1 colour, manual cleaning
Exposure to organic solvents in the o€set printing industry in Norway
main cleaning solvent (including automatic cleaning) in all the oces was a mixture of aliphatic
hydrocarbons with a range of boiling points from
180±2708C. Occasionally, for few minutes each day,
other more volatile solvents containing aromatic
hydrocarbons, esters, or ketones were used.
Another source of solvent exposure in the printing
oces was the moisturizer used in the printing machines. This moisturizer contains approximately
10% of isopropanol. Characterization of the printing presses and locations for the seven o€set printing oces in the study are given in Table 1.
The whole day personal measurements were
sampled using passive dosimeters (3 M 3500, organic vapour monitor). Short time sampling was
performed using pumps (SKC 222-6DK3B) and
charcoal tubes (SKC Anasorb CsC Coconut
Charcoal 50/100 mg). All the samples were analyzed
at the Laboratory of the Labour Inspection in
Bergen, Norway, according to standard procedures.
Combined exposure to more than one solvent is
often expressed as an additive factor which is the
sum of the quotients between the measured concentration of a speci®c substance and the TLV of the
substances. If the additive factor is below one, the
combined TLV is not exceeded.
The statistical analysis of the data was performed
by means of the Statistical Package for the Social
Sciences (SPSS for MC Windows Release 6.0).
The in¯uence of the variables on the additive factor was examined by stepwise linear regression
analysis. The level of statistical signi®cance was set
to P < 0.05 for entering a variable and to P > 0.1
for removing a variable. Each model's explanatory
value was assessed through the coecient of determination (adjusted R2). The variables tested in the
model were: automatic cleaning of the machine,
separate exhaust ventilation above the engine, production year of the machine, and the size of the
work room.
The natural logarithm of the arithmetic mean of
the additive factor was used as the dependent vari-
121
able, since this transformation produces a multiplicative e€ect for each of the variables and the results
from the measurements were log-normally distributed.
RESULTS
The results from the whole day personal measurements are given in Tables 2 and 3. Table 2 shows
the levels of isopropanol, aliphatic hydrocarbons,
toluene, ``other solvents'' and the additive factor in
ppm as the arithmetic mean of the measurements
for each printing oce. The only other solvents
which were detected were n-butyl acetate, ethyl isobutyl ketone, ethanol and ethyl acetate. There were
substantial di€erences between the oces, in particular with regard to the concentration of isopropanol which was also the main contributor to the
additive factor. In Table 3 the results are given for
each worker. The exposure levels of isopropanol
varied from 0.8±100 ppm between the workers. The
levels of aliphatic and aromatic hydrocarbons were
low and varied from 0±4.7 ppm.
In Table 4 the results of the measurements are
presented according to the di€erent sampling strategies; personal whole day measurements, and personal short time measurements performed while
cleaning the machine with organic solvents. The
additive factor was highest for the personal whole
day measurements, while the level of aliphatic
hydrocarbons and toluene was highest for personal
sampling during the cleaning of the machines. Even
so, the main contributor to the additive factor in
these measurements was the measured concentrations of isopropanol. Neither the di€erence
between the additive factor nor the di€erences
between the levels of isopropanol for the two
sampling strategies were statistically signi®cant. For
the level of aliphatic hydrocarbons there was a statistically signi®cant di€erence between the short time
measurements, including cleaning of the machines
with solvents, and the full day measurements.
Table 2. Full day measurements of the concentration in ppm of organic solvents and ``additive factor'' for combined exposure in seven printing oces, arithmetic mean and standard deviation (SD). Geometric mean and GSD are given for
``additive factor''
Oce
1
2
3
4
5
6
7
Isopropanol
ppm
(SD)
Aliphatic
hydrocarbons
ppm (SD)
Toluene
ppm
(SD)
Other solvents
ppm (SD)
23.3
71.6
54.9
21.7
27.5
6.2
0.8
1.1
1.8
1.3
4.3
1.7
0.6
1.0
0.6
0.3
0
0.7
0.1
1.5
0.1
0.3 (0.1)
0
0
0
0
1.5 (3.0)
0.01 (0.03)
(10.7)
(33.7)
(3.1)
(7.1)
(27.5)
(2.8)
(0.4)
(0.5)
(0.8)
(0.4)
(1.5)
(0.9)
(0.4)
(0.5)
(0.3)
(0.2)
(0.6)
(0.03)
(2.3)
(0.1)
Additive factor
Number of
measurements
Arithmetic
mean
(SD)
Geometric
mean
(GSD)
0.29
0.77
0.57
0.30
0.34
0.15
0.03
0.28
0.69
0.57
0.30
0.22
0.12
0.02
(0.10)
(0.35)
(0.04)
(0.08)
(0.30)
(0.10)
(0.02)
(1.38)
(1.68)
(1.07)
(1.32)
(2.86)
(1.80)
(1.80)
5
11
5
7
9
10
10
122
K. Svendsen and K. Rognes
Table 3. Full day measurements of the concentration in ppm of organic solvents and ``additive factor'' for combined exposure for each worker in seven printing oces: arithmetic mean and standard deviation (SD). Geometric mean and
GSD are given for ``additive factor''
Person
Oce
Isopropanol
ppm (SD)
Aliphatic
hydrocarbons
ppm (SD)
Toluene
ppm (SD)
Other solvents
ppm (SD)
Additive factor
Arithmetic
mean
(SD)
Geometric
mean
(GSD)
Number of
measurements
1
1
23.3 (10.7)
1.1 (0.5)
0.6 (0.3)
0.3 (0.05)
0.29 (0.1)
0.28 (1.38)
5
2
3
4
2
2
2
40.6 (14.0)
91.2 (0.63)
100.6 (23.4)
1.1 (0.3)
1.7 (0.05)
2.6 (0.7)
0.4 (0.2)
0.4 (0.3)
0.2 (0.1)
0
0
0
0.45 (0.15)
0.98 (0.01)
1.08 (0.24)
0.43 (1.37)
0.98 (1.01)
1.06 (1.26)
5
2
4
5
6
3
3
52.1
55.6 (3.1)
1.0
1.4 (0.5)
0
0
0
0
0.54
0.58 (0.04)
0.54 (1.00)
0.58 (1.07)
1
4
7
8
4
4
25.2 (8.4)
19.1 (5.7)
4.7 (1.7)
4.0 (1.5)
0.7 (0.4)
0.7 (0.7)
0
0
0.35 (0.1)
0.28 (0.06)
0.34 (1.32)
0.27 (1.31)
3
4
9
10
5
5
15.8 (18.9)
50.8 (29.9)
1.5 (0.6)
2.1 (1.3)
0.1 (0.05)
0.09 (0.0)
0
0
0.22 (0.21)
0.59 (0.35)
0.15 (2.68)
0.53 (1.71)
6
3
11
12
6
6
5.9 (2.8)
6.4 (3.2)
0.4 (0.1)
0.8 (0.4)
0.4 (0.1)
2.7 (3.0)
0.1 (0.07)
3.0 (3.9)
0.09 (0.03)
0.20 (0.11)
0.08 (1.39)
0.18 (1.69)
5
5
13
14
7
7
0.8 (0.4)
0.8 (0.5)
0.9 (0.7)
1.0 (0.4)
0.1 (0.1)
< 0.1 (0.0)
0.2 (0.04)
0
0.03 (0.03)
0.03 (0.01)
0.02 (2.21)
0.02 (1.37)
5
5
Table 5 shows the results of the multiple regression analysis of the separate independent variables. The ®nal model which included the
independent variables ``automatic cleaning'' and
``separate exhaust ventilation'' explained 59% of
the variation in the additive factor. Automatic
cleaning of the machines increased the exposure
and separate exhaust ventilation decreased it. Table
6 shows the full day exposure levels of isopropanol
and additive factor for work with machines with
and without automatic cleaning. The correlation
coecient (Pearson) between isopropanol exposure
measurements and the additive factor was 0.96, P
< 0.01 in our measurements indicating that the
level of aliphatic and aromatic hydrocarbons contributes little to the additive factor.
3.5% of the full day samples showed results
above the TLV, and 50% of the samples showed
results below 30% of the TLV.
DISCUSSION
The result of these measurements show that
working with modern printing machines can
entail exposures to isopropanol up to and above
the Norwegian TLV which is 100 ppm. However,
the level of exposure varied to a great extent
between di€erent printing oces. For oces with
more than one type of machine there can also
be substantial di€erences between each worker.
The results also show that the type of machine
seems more important for the total exposure
level of organic solvents than the type of clean-
Table 4. Arithmetic mean for two di€erent sampling strategies; full day sampling, and sampling over 30 min during
cleaning of machines. Geometric mean and GSD are given for ``additive factor''
Strategy
Full day
During
cleaning,
short time
*
Isopropanol Aliphatic
Toluene
Other
ppm (SD)
hydrocarbons ppm ppm (SD) solvents ppm
(SD)
(SD)
28.9 (31.4)
13.3 (12.9)
1.6 (1.3)
4.1 (3.4)*
0.5 (1.1)
1.2 (2.3)*
0.3 (1.3)
0.1 (0.2)
Statistically signi®cantly di€erent from other results in the column.
Additive
factor
Arithmetic
mean
(SD)
Geometric
mean
(GSD)
0.35 (0.3)
0.28 (0.2)
0.19 (3.63)
0.21 (2.51)
Number of
measurements
57
13
Exposure to organic solvents in the o€set printing industry in Norway
123
Table 5. Multivariate regression models for natural logarithm of ``additive factor'' as a function of possible explanatory
variables in o€set printing oces
Coecient of determination
(adjusted R2)
Explanatory variables
Regression
coecient
Standard
error
P
value
0.18
0.29
0.59
Automatic cleaning
Sep. exhaust ventilation
Automatic cleaning and
sep. exhaust ventilation
1.44
ÿ 1.55
1.79
ÿ 1.81
0.39
0.31
0.28
0.24
0.006
< 0.001
< 0.001
< 0.001
ing solvent used. This can be explained by the
small variation between the chemical formulation
of the di€erent cleaning solvents used in this
study, and the fact that cleaning was performed
for only a few minutes each day.
Workers handling the machines with automatic
cleaning had the heaviest exposure regarding isopropanol concentration and the highest additive
factor.
The results of the present study showed that
3.5% of the full time samples showed additive
factor above 1 and thus exposure above the
TLV. In a previous study performed in 1978,
17.5% of the samples showed results above the
TLV at that time (Thorud and HaÊgensen, 1981).
In the present study 50% of the full time
measurements showed levels below 30% of TLV
which is the same fraction as in 1978. There is
however, an important di€erence in that di€erent
solvents contribute to the exceeding of the TLV.
The dominating solvents 20 years ago were white
spirit (Stoddard solvent) and toluene, both with
a 1978 TLV of 100 ppm. Today the exposure to
those solvents has diminished, and the solvent
which contributes most to the additive factor is
now isopropanol, for which there is a 1998 TLV
in Norway of 100 ppm. Another interesting feature is that the mean additive factor for personal
sampling during cleaning of the machines, did
not exceed the mean of the additive factor for
full time sampling. This is probably because the
workers who did manual cleaning of the machines worked with machines with less isopropanol emission. Even though the level of aliphatic
and aromatic hydrocarbons was somewhat higher
during cleaning, this contributed only slightly to
the additive factor.
Isopropanol has a known e€ect on the central
nervous system (CNS) and is irritating to mucous
membranes. When used in combination with chlorinated solvents, isopropanol reinforces their e€ect
on the liver. Results of animal studies have also
shown that isopropanol in itself is approximately
twice as intoxicating to the CNS as ethanol (IPCS,
1990). Because ethanol retards the elimination of
isopropanol and the two substances are both CNS
depressants, the interaction between them may
increase the CNS e€ect of either agents (IPCS,
1990).
Isopropanol metabolizes to acetone (Brugnone
et al., 1983) which is eliminated through urine
and the lungs. Recent studies indicate that
acetone could have e€ects both on the central
and peripheral nervous system (Mitran et al.,
1997). Studies of workers complaints from isopropanol exposure are rare.
In 1990 a few measurements were made at an
o€set printing oce where the levels of isopropanol were reported to be between 6 and 36 ppm
(Karlsson et al., 1990). At that oce the workers
complained of mucous membrane irritation, headache and fatigue, possibly re¯ecting a systemic
e€ect of exposure even at that level.
In our investigation, the levels of aliphatic and
aromatic hydrocarbons were low at all the
oces. It seems that all the cleaning solvents
used at these printing oces at present give low
levels of exposure to solvents.
The results of this study indicate that the most
important source of solvent exposure at o€set printing oces at present is the moisturizer used in the
printing machines which contains approximately
10% of isopropanol. The most modern machines
with automatic equipment gave the highest solvent
exposure. These were big machines with large surfaces covered with moisturizer. As the level of iso-
Table 6. Exposure levels of isopropanol and ``additive factor'' for working with machines with and without automatic
cleaning for full day sampling. Arithmetic mean and standard deviation (SD). Geometric mean and GSD are given for
``additive factor''. (The di€erences are statistically signi®cant)
Concentration of isopropanol ppm (SD)
With automatic cleaning
Without automatic cleaning
64.3 (40.4)
20.4 (22.0)
Additive factor
Arithmetic mean (SD)
Geometric mean (GSD)
0.72 (0.4)
0.26 (0.2)
0.61 (1.87)
0.14 (3.52)
124
K. Svendsen and K. Rognes
propanol varies substantially depending on the
di€erent types of machines and ventilation, is it dif®cult to assess exposure at printing oces without
taking measurements at each particular oce. As
the exposure to isopropanol may be high we ®nd
that there is a need for such exposure assessment
and to strive for a reduction when necessary.
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