Use of organic solvents in large research institutions in Japan
Environ Health Prev Med
Use of organic solvents in large research institutions in Japan
Yasuhiro Nagasawa 0 1
Hajime Samoto 0 1
Hirohiko Ukai 0 1
Satoru Okamoto 0 1
Kenji Itoh 0 1
Takaaki Hanada 0 1
Ai Kanemaru 0 1
Yoshinari Fukui 0 1
Satoshi Kojima 0 1
Jiro Moriguchi 0 1
Sonoko Sakuragi 0 1
Fumiko Ohashi 0 1
Shiro Takada 0 1
Takuya Kawakami 0 1
Masayuki Ikeda 0 1
0 Y. Nagasawa H. Samoto H. Ukai S. Okamoto K. Itoh T. Hanada A. Kanemaru Y. Fukui S. Kojima F. Ohashi S. Takada T. Kawakami M. Ikeda (&) Kyoto Industrial Health Association (Main Office) , 67 Nishinokyo-Kitatsuboicho, Nakagyo-ku, Kyoto 604-8472 , Japan
1 J. Moriguchi S. Sakuragi Kyoto Industrial Association (Mibu Office) , 4-1 Mibu-Shujaku-cho, Nakagyo-ku, Kyoto 604-8871 , Japan
Objectives Laboratories in research institutions use organic solvents in research and development. Nevertheless, the types of solvents in use have been seldom reported. This study was initiated to elucidate types of organic solvents used in large research institutions in Japan, with a focus on possible different use among research fields. Methods In 2010-2011, 4517 laboratories in seven large research institutions were visited. In accordance with legal stipulations, air in each laboratory was collected in polyvinyl fluoride bags and analyzed by direct injection into a gas-chromatograph for 47 types of organic solvents. In evaluation, the laboratories were grouped by 5 research fields, i.e., agriculture, biology, medicine, natural science, and technology and engineering. Results Types of organic solvents commonly used in research activities were not diverse. Those commonly used were chloroform and 1,2-dichloroethane out of 7 Group 1 organic solvents (with high toxicities); 6 organic solvents, i.e., acetone and methyl alcohol in general, ethyl acetate, hexane and toluene in technology and engineering laboratories; and xylenes in medical fields out of 40 Group 2 organic solvents (with relatively low toxicities). Judging from solvent vapor concentrations, work environments in more than 99 % of laboratories were considered adequate. Nevertheless, use of chloroform in high-performance liquid chromatography (HPLC) resulted in inadequate environments in 30 laboratories (0.7 %). Conclusions Organic solvents commonly used were not very diverse. Work environments in research laboratories were generally good, but the environment with use of chloroform in HPLC analysis remained yet to be improved.
laboratory; Chloroform; Organic solvents; Research; Unmixed solvents; Xylenes
Under Industrial Safety and Health Law [
administrations of national and public research institutions
(including universities) in Japan are responsible for
maintenance of healthy environment. For this purpose, the law
stipulates that the environment in workrooms including
research laboratories should be monitored in accordance
with procedures legally defined [
]. The enforcement has
produced a valuable opportunity so that the exposure to
chemicals in research institution laboratories should be
monitored and improvement should be conducted when the
exposure does not meet with the legal standards.
Organic solvents are among the chemicals widely used in
many laboratories across various fields of natural sciences.
Nevertheless, information on the solvent use has been
reported only on limited occasions and usually as a simple
compilation of solvent names [
] with no further details
such as use prevalence. In the present study, seven large
research institutions were studied for solvent use in
laboratories. Efforts were made to identify characteristic (if any)
solvent types subject to the fields of science. A preliminary
report based on a small-scale survey was previously
published . The results of surveys in succeeding years on an
expanded scale will be presented in this article.
Materials and methods
Laboratories and organic solvents surveyed
Seven large institutions were surveyed during the 1-year
period from 1 October 2010 until 31 September 2011. In
total, 4517 laboratories were visited. A laboratory was
typically in the size of 4 m 9 6 m with about 3 m to the ceiling,
and usually accommodated 1?2 researchers. Some
laboratories were, however, larger in size to accommodate up to 30
people, e.g., for the practice of post-graduate students.
According to scientific research fields, the laboratories were
classified into five groups, i.e., agricultural sciences (to be
abbreviated as AGR), biological sciences (BIOL; excluding
medicine), medicine (MED), natural sciences (SCI
excluding AGR, BIOL and MED) and technology and engineering
(T&E), although there were several borderline cases.
The Order [
] and the Ordinance [
] define the types of
organic solvents to be analyzed. Namely, 7 solvents of high
toxicity are defined as Group 1 solvents, and another 40
solvents of relatively low toxicity are defined as Group 2
solvents (Table 1). In addition, the Order and the
Ordinance identify 7 solvents (mostly of petroleum origin) as
Group 3 solvents, but these 7 solvents were not taken in
this analysis because they are mixtures by nature of poorly
defined multiple organic solvents, not fit for quantification
by gas-chromatography. Benzene, the most popular solvent
in the past, is regulated under separate ordinance [
because this solvent is a human leukemogen [
excluded from the present survey.
Sampling of laboratory air, analyses for organic
solvents, and evaluation
The protocol for solvent vapor measurement was as
previously detailed [
]. In short, 10 L of air was sampled in
polyvinyl fluoride bags at 5 or more crosses of a
hypothetical grid (with, e.g., up to 3 m apart between 2 grid
lines) set in each laboratory as defined by regulation [
It should be added that air sampling was conducted when
the research activities were actually on. The air samples in
the bags were brought to the laboratory in Kyoto Industrial
Health Association and were analyzed by direct injection
into FID-gaschromatography instruments equipped with a
25-m-long capillary column (for qualification purpose) or
on a 2.5-m-long packed column (for quantification) .
The results of analysis for solvent vapor concentrations
(n C 5) were calculated for geometric means (GMs) and
geometric standard deviations (GSDs) as representative
parameters, and the parameters were evaluated in reference
to Administrative Control Levels (ACLs [
]; for ACL
value of each organic solvent, see Table 1) to classify the
cases into 3 classes of Administrative Control Class 1 (the
well-controlled environment), Class 2 (the environment
that needs further improvements) and Class 3 (the
environment which requires immediate and sufficient
]) after the following equations:
Class 1 when log ACL [ log GM ? 1.645[(logGM)2 ?
Class 3 when log ACL \ log GM ? 1.151[(logGM)2 ?
Class 2 between the 2 levels.
By definition, 5 and 50 % of the organic solvent
concentrations in the workroom air would exceed ACL in
Class 2 and Class 3, respectively. The regulation [
requests repeated measurements on 2 consecutive days, and
a constant of 0.084 was empirically added for the cases of
1-day measurement to make the conditions more strict [
It should be noted that the visit to each laboratory was on
1 day in the present study. In case more than 2 solvents
were detected, the additiveness formula of RMi/ACLi
(where Mi and ACLi are measured concentration and ACL
for solvent i, respectively) was employed in place of
measure for an individual solvent [
Chi square test was employed to detect possible significant
difference in distribution; p \ 0.01 was taken as a cut-off
point for statistical significance. When the number of cases
in a cell was five or less, v2 test was considered not
applicable. Such cases were identified as ?na? in the tables.
Number of laboratories as classified by research fields,
and solvent use
When a total of 4517 laboratories were grouped by the five
research fields of AGR, BIOL, MED, SCI and T&E, the
numbers of laboratories in MED, SCI and T&E were in
excess of 1000, whereas those in AGR and BIOL were
around 600 (Table 2). Each of the laboratories in the five
research fields were further classified by the groups of
organic solvents used, i.e., those with Group 1 solvents
only, those with Group 2 solvents only, and those with
Group 1 and 2 solvents together. In addition, those with
Group 1 solvents were counted irrespective of the use of
Group 2 solvents in combination (Table 2).
It turned out that, over all, the use of Group 1 solvents
was in less than 10 % of total laboratories (i.e., 9.6 %)
whereas the use of Group 2 solvents only was common
(74 %). When evaluated by research fields, the use of
Group 1 solvents only were less prevalent in SCI and T&E
laboratories (169/2242 = 7.5 %; two research fields of the
Fig. 1 Number of types of
organic solvents detected in
laboratories of various fields of
science The left-most five
columns for each solvent
number group are (from left to
right) for agriculture (AGR),
biology (BIOL), medicine
(MED), natural science (SCI),
and technology and engineering
(T&E). The right-most thick
columns are for use in
enterprises (cited from Ref.
]). Note that cases with 8?13
solvents are summed up
Number of solvents
lowest prevalence) than in others (i.e., AGR ? BIOL ?
MED; 265/2275 = 11.6 %: p \ 0.01 by v2 test) whereas
the use of Group 2 solvent was more prevalent in SCI
laboratories (941/1089 = 86.4 %; the research field of the
highest prevalence) than in others (i.e., AGR ? BIOL ?
MED ? T&E, 2385/3428 = 69.6 %: p \ 0.01 by v2 test).
Similarly, the use of Group 1 solvents with or without
Group 2 solvents was significantly less prevalent in SCI
laboratories (148/1089 = 13.6 %; the least prevalent) than
in other fields (i.e., AGR ? BIOL ? MED ? T&E,
1043/3428 = 30.4 %; p \ 0.01 by v2 test).
Typical use of organic solvents in research laboratories
was as a single, unmixed solvent (Fig. 1). Observation of
practice in laboratories showed that each researcher used
one solvent in one process. When 2 or more types of
organic solvents were detected in laboratory air, it was
usually as the results of 2 or more researchers working with
different solvents in one room, or one researcher used 2 or
more different types of solvents in sequence. Typical cases
were observed in large T&E laboratories for practice of
undergraduate students where multiple solvents were
Group 1 solvents frequently used
The names of 5 Group 1 solvents actually detected (out of a
total of 7) are listed in Table 3; the other 2 Group 1
solvents (i.e., 1,2-dichloroehylene and
1,1,2,2-tetrachloroethane) were never detected as to be described later. Among
the 5 solvents, chloroform had a high prevalence (26 %),
being highest in AGR laboratories (34 %; p \ 0.01 for
difference from others) but was also high in T&E
laboratories (29 %; p \ 0.01) and in other fields in general
([13 %). The typical use was as a component in the mobile
phase in high-pressure liquid chromatography (HPLC).
Very often, the HPLC instrument was too bulky to be
accommodated in a local exhaust chamber. The second
most common was the use of 1,2-dichloroethane, being
highest in T&E (3.7 %; p \ 0.01) among the 5 fields. It
was not possible to identify specific use of this solvent.
Use pattern of Group 2 solvents
The use prevalence of the 40 Group 2 organic solvents is
summarized in Table 4. Among 40 Group 2 organic
solvents, acetone and methyl alcohol were most often used
throughout all fields ([30 %) and in T&E in particular
(48 % for acetone and 35 % for methyl alcohol in T&E).
The major use was for rapid drying of an inside wall of a
EG Ethylene glycol
na, v2 test is not applicable, because the number in a cell (or some cells) is less than 5
a Percentage over the number of laboratories surveyed
Solvents of limited use in laboratories
Among the 7 Group 1 and 40 Group 2 solvents, some
solvents were not detected or detected only on limited
occasions. They are listed in Table 5. It was made clear
that 2 Group 1 solvents and 11 Group 2 solvents were
never detected in laboratory air (the top half in Table 5). In
addition, 3 Group 1 and 15 Group 2 solvents were found
only rarely (i.e., in the prevalence of less than 1 %; the
bottom half in Table 5).
Distribution of Class 2 and Class 3 environments
When classified in terms of adequate (Class 1) and
inadequate (Class 2 and Class 3) work environments, it was
evident that, over all, a majority ([99 %) of laboratories
were in Class 1 irrespective of research fields (Table 6).
Nevertheless the environments in 32 laboratories in total
were identified as inadequate, i.e., Class 2 or Class 3.
Further breakdown of the cases revealed that the Classes 2
and 3 prevalence was significantly (p \ 0.01) higher in
T&E (1.7 %) as compared with other fields (0.4 %) (the
top two-thirds in Table 6), whereas no significant
difference was observed between biological and chemical
laboratories (p [ 0.10) (the bottom one-third in Table 6).
Perusal of the records for each laboratory disclosed that
chloroform was detected in 30 cases out of 32 Class 2 and
Class 3 laboratories, either as the only one solvent or in
copresence of other solvents. In remaining 2 laboratories,
high concentration of hexane (Class 3 laboratory) or
dichloromethane (Class 2) was detected as a sole solvent.
The present survey disclosed that types of solvents
commonly used in research laboratories appear to be not very
diverse, being only 2 Group 1 solvents (i.e., chloroform
and, to a lesser extent, 1,2-dichloroethane; Table 3) and a
few Group 2 solvents (acetone and methyl alcohol in
general, and ethyl acetate, hexane, and toluene in T&E, and
xylenes in MED in particular; Table 4). With regard to use
pattern, typical use of solvents in research laboratories was
as unmixed. This makes a sharp contrast to solvent use in
factories (or industrial plants) where, e.g., ink for printing
or paints for surface treatment contain more than one
solvent as liquid components [
18, 21, 22
]. The patterns of
distribution are illustrated for visual understanding in
Fig. 1, showing that a combination of 3?6 solvents are
often observed in factory air (a thick broken line), in
contrast to single solvent use in research laboratories (thin
glass or plastic container. In addition, methyl alcohol was a
common component of a mobile phase in HPLC analysis.
Dichloromethane was used in T&E (16 %) for extraction
purpose. Ethyl acetate (21 %), hexane (27 %) and toluene
(21 %) were also often used in T&E, but no specific use
could be identified. In contrast, the frequent use of xylenes
in MED (23 %) was unique as this solvent was specifically
used for removal of paraffin in the process of histology
a As defined by the Regulation (Ref. 7: for details, see the ??Materials and methods??): Class 1, those with adequate environment; Class 2 and
Class 3, those with inadequate environment
b % over total laboratories (i.e., n = 4517)
c % over total laboratories in each field
d AGR ? BIOL ? MED ? SCI
e The difference of AGR ? BIOL ? MED ? SCI from T&E is significant (p \ 0.01)
f Biological; AGR ? BIOL ? MED: Chemical; CSI ? T&E
g The difference between the ?Biological? group and the ?Chemical? group is insignificant (p [ 0.10)
The environment in research laboratories (with more
than 99 % in Class 1) was generally better than the
environment in factories (e.g., 87 % in Class 1 [
Nevertheless, the presence of 32 laboratories with Class 2 or
Class 3 environments apparently deserves attention. The
perusal of individual cases suggests that Class 2 or Class 3
environments were usually in association with use of
chloroform in a mobile phase in HPLC. While most part of
the analytical system in a HPLC equipment was made
leakage-free, the loose connection of the tube (for
discharge of the waste mobile liquid phase) with a waste
liquid container (usually a large glass bottle) is a source of
leaking chloroform vapor. While the fundamental solution
might be a development of a chloroform-free mobile phase
for HPLC analysis or a move of the HPLC instrument into
an exhaust chamber, installation of air suction pipe very
close to the leaking point may contribute to reduce the
Organic solvent use in research laboratories outside of
Japan have been reported only on limited occasions. Often,
only the fact that workers in laboratories were exposed to
organic solvents was mentioned but no further details were
given (e.g., Zhu et al. [
]; Zibrowski et al. [
et al. [
] studied pregnancy outcome of university
laboratory employees and reported that the employees were
exposed to acetone, benzene, chloroform,
dichloroethane, dichloromethane, ethyl alcohol, ethyl ether, methyl
alcohol, phenol, petroleum ether and toluene. Taskinen
et al. [
] also studied pregnancy outcome of laboratory
workers (it was not clear if the laboratories were for
research purpose). The solvents used included acetone,
acetonitrile, carbon tetrachloride, chloroform, cyclohexane,
dichloromethane, ethyl acetate, ethyl alcohol, heptane,
isopropyl alcohol, methyl alcohol, petroleum benzine,
toluene, 1,1,1-trichloroethane, trichloroethylene, white spirit,
and xylenes. Varella et al. [
] reported on mutagenicity of
urine of workers in organic chemistry laboratories. Solvents
the subjects worked with were diverse, but included
acetone, acetonitrile, benzene, dichloromethane, ethyl acetate,
ethyl alcohol, hexane and methyl alcohol. Substantial
commonalities with present results (Tables 3, 4) can be
observed in solvent types reported by Axelsson et al. [
Taskinen et al. [
] and Varella et al. [
], but no data on
prevalent use were given in these reports. Thus, it was not
possible to make a comparison on use prevalence. In
contrast, use of xylenes in histology laboratories were reported
by Gunson et al. [
] and Purdie et al. [
], suggesting that
xylenes are commonly used in histopathology laboratories
in medical fields, as in the present cases (Table 4). In
addition, Herpin et al. [
] reported that laboratory
technicians in charge of ?anatomy sample preparation for
microscopic analysis? were exposed to toluene and ethyl alcohol.
A major limitation of the present analysis is the fact that
the target analytes were limited to 47 organic solvents
under organic solvent-related regulations ([
3, 4, 12
see Table 1). Thus, those under separate regulation (e.g.,
benzene, as previously discussed) or newly coming-up
organic solvents (such as 1-bromopropane, a surrogate for
2-bromopropane, as 2-bromopropane has a potent toxic
effects on reproductive systems both in men and women
]) were not taken into consideration. Secondly, all
research institutions visited in this survey were large in
size. Although the work environments surveyed were
generally good, it is not clear if this conclusion can also be
applied to small-sized research institutions.
Scale-dependent difference in work environments may exist among
research institutions, as observed in production factories
]. Another limitation is short-term and changing nature
of research activities. Quite different from production
workplaces, the activities in a research laboratory are
generally for a short time period. For example, one series
of HPLC analyses may be terminated within a few hours,
and may not be repeated on the next day, although the
exposure to xylenes in a histology department in a clinical
facility may be repeated almost day-by-day as far as
clinical activities continue. The strategy of the present survey
could not take such changing exposure into consideration.
In conclusions, survey in large research institutions
revealed that only 26 types out of 47 legally designated
organic solvents were commonly used in research
laboratories. In the large research institutions, the work
environments in more than 99 % of research laboratories were
adequately controlled. Nevertheless, the environments with
leakage of chloroform vapor from HPLC facilities
remained yet to be improved.
Acknowledgments Thanks are due to the administration and the
staff of Kyoto Industrial Health Association for their interest in and
support to this work.
Conflicts of interest The authors declare that they have no conflicts
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