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Annals of Work Exposures and Health, 2017, 1–10
doi: 10.1093/annweh/wxx080
Original Article
Original Article
Occupational Exposure to Inhalable Manganese
at German Workplaces
Benjamin Kendzia1, Rainer Van Gelder2, Tobias Schwank2,
Cornelia Hagemann2, Wolfgang Zschiesche1, Thomas Behrens1, Tobias
Weiss1, Thomas Brüning1†, and Beate Pesch1*†
Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of
the Ruhr University Bochum (IPA), Bochum, Germany; 2Institute for Occupational Safety and Health of the
German Social Accident Insurance (IFA), Sankt Augustin, Germany
1
*Author to whom correspondence should be addressed. Tel: +49-(0)234-302-4536; fax: +49-(0)234-302-4505; e-mail pesch@ipa-dguv.de
Equally contributed.
†
Submitted 14 March 2017; revised 19 July 2017; editorial decision 22 August 2017; revised version accepted 4 September 2017.
Abstract
Due to mounting evidence of neurotoxic effects of manganese (Mn) already at low concentrations,
occupational exposure limits (OELs) have been adopted. We analyzed 5771 personal measurements of inhalable manganese (Mn) together with information on sampling conditions and job
tasks from the German exposure database Messdaten zur Exposition gegenüber Gefahrstoffen am
Arbeitsplatz (MEGA) to assess exposure levels in welders and other occupations between 1989 and
2015. Geometric means (GMs) of exposure to Mn were estimated for various occupational settings
adjusted for 2-h sampling duration and analytical method, centered at 2009. Measurements below
the limit of quantification (LOQ) were multiply imputed. The median concentration was 74 µg m−3
(inter-quartile range 14–260 µg m−3) in welders and 8 µg m−3 (inter-quartile range <LOQ–31 µg m−3)
in other occupations. Every third measurement was higher than 100 µg m−3, 20% exceeded 200 µg
m−3, and 5% of welders inhaled concentrations ≥1000 µg m−3. GMs >100 µg m−3 were observed in gas
metal and flux-cored arc welders and in shielded metal arc welders using consumables of high Mn
content (>5%). Tungsten inert gas welding, laser welding and working in other occupations such as
foundry worker, electroplater, or grinder were associated with GMs <10 µg m−3. A shorter sampling
duration was associated with higher Mn concentrations. High-emission welding techniques require
protective measures to cope with adopted OELs. Results of this study are useful to assess cumulative Mn exposure in community-based studies on neurotoxic effects.
Keywords: manganese; modelling; occupational exposure; welding
© The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.
2
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX
Introduction
Mounting evidence of neurotoxic effects prompted a
review of exposure to manganese (Mn) that was carried
out for a comprehensive Criteria Document on adopting occupational exposure limits (OELs; Levy, 2005).
The largest use of metallic Mn is in steel production to
improve firmness, formability, and corrosion resistance
(Postle et al., 2015). Mn is also added to nonferrous
alloys. Most welding consumables contain up to 6%
Mn. Furthermore, Mn compounds are used in paints
and zinc-carbon and alkaline batteries, and permanganates are powerful oxidizers.
Due to reports on neurotoxic effects of Mn concentrations at low doses, standard-setting committees and
governmental bodies reduced OELs for airborne Mn
(Bevan et al., 2017). In 2013, the American Conference
of Governmental Industrial Hygienists (ACGIH) lowered the threshold limit value (TLV) for inhalable Mn to
100 µg m−3 and for respirable Mn to 20 µg m−3 (ACGIH,
2011, 2013). In 2015, German OELs were reduced to
20 µg m−3 for respirable Mn and to 200 µg m−3 for inhalable Mn (http://www.baua.de/de/Themen-von-A-Z/
Gefahrstoffe/TRGS/TRGS-900.html). However, the
relation between Mn concentrations in respirable and
inhalable particles of metal fumes may vary by setting
and has been studied in parallel in few studies only. In
welding fumes, most of Mn was respirable (Pesch et al.,
2012; Jeong et al., 2016).
Personal exposure to Mn varies widely between and
within different industrial settings (Levy, 2005). The
technological process, Mn content of materials, workplace conditions, and protective measures may influence
the concentration of Mn in the breathing zone of workers as could be quantified for welders (Pesch et al., 2012).
Several job tasks can hardly comply with these OELs, for
example gas metal arc welding (GMAW) (Wallace et al.,
2001; Flynn and Susi, 2010; Pesch et al., 2012; Taube,
2013). In high-exposure circumstances such as welding
with high-emission techniques in confined space, powered air-purifying respirators may be needed reduce Mn
to levels below OELs (Lehnert et al., 2014).
So far, estimates of exposure to Mn were usually
based on few measurements in selected industrial settings (Levy, 2005). Large exposure databases have been
established in many countries, which could be mined to
assess personal exposure to Mn (Flynn and Susi, 2010;
Peters et al., 2012). These databases compile personal
measurements since the 1980s, where measurements
in the respirable particle fraction are limited. Here, we
took advantage of a large number of personal measurements of inhalable Mn compiled in the German database
‘Messdaten zur Exposition gegenüber Gefahrstoffen am
Arbeitsplatz’ (MEGA) along with ancillary information
on the sampling conditions, analytical methods, and
technological processes (Stamm, 2001; Gabriel et al.,
2010; Pesch et al., 2015; Kendzia et al., 2017). The
analysis of these measurements serves for several aims,
for example to publish reports on exposure levels at
German workplaces and in connection with the chemical safety assessment of REACH (Gabriel et al., 2010).
Our objective was to estimate exposure to Mn in a
variety of job tasks and industrial settings in order to
evaluate compliance with OELs and to provide quantitative data for the exposure assessment within the
framework of research on neurotoxic effects in community-based studies. Our results were used to calculate
cumulative exposure to Mn of metal workers enrolled
in the Heinz Nixdorf Recall Study (HNRS, https://www.
uni-due.de/recall-studie/) to estimate neurotoxic effects
(Casjens et al., 2017).
Materials and Methods
Measurements of inhalable Mn
The concentrations of inhalable Mn were obtained
from the exposure monitoring and measurement system (MGU) of the Institute for Occupational Safety and
Health (IFA) of the German Social Accident Insurance
(DGUV) compiled in the exposure database MEGA
as previously reported for an analysis of hexavalent
chromium (Cr(VI)) and nickel (Ni) (Pesch et al., 2015;
Kendzia et al., 2017). The measurements were carried
out by technicians of the Employer’s Liability Insurance
Associations (Berufsgenossenschaften) based on standard operating procedures and a computer-assisted
data documentation of the measurements and ancillary
information. For example, the Mn content of welding
consumables is shown in the material safety data sheet.
Here, this analysis was based on 5771 personal measurements collected between 1989 and 2015 together with
data on the sampling duration, analytical method, and
occupational setting, including information on the welding technique and materials.
The measurements were performed with a GSP sampler operating at a flow rate of 3.5 l min−1 according to
the standard EN 481 to capture inhalable particles in the
breathing zone of workers (EN 481, 1993). Workplace
samples were analysed at the central laboratory at IFA
by means of atomic absorption spectrometry (AAS),
reflection X-ray fluorescence (TXRF), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX3
(ICP-OES). Concentrations below the limit of quantification (LOQ) were documented by their individual LOQs,
which mainly depend upon the analytical method, pump
flow rate, and duration of sampling.
Assessment of occupational exposure to
manganese
Job titles were coded in MEGA according to the German
classification of occupations (Bundesanstalt für Arbeit,
1988). We assigned measurements according to the
information on job title, more detailed job tasks and
occupational settings to predefined at-risk occupations
of a supplemental questionnaire applied in the second
follow-up of HNRS to investigate neurotoxic effects.
The modelling of exposure levels in these settings based
on the measurements corresponds to an approach that
has been applied to analyse Cr(VI) and Ni (Pesch et al.,
2015; Kendzia et al., 2017). We categorized welders by
major process and consumable material as major source
of airborne Mn (Pesch et al., 2012). We assigned a high
Mn content if welding consumables contained >5%.
We considered the contents of aluminium (Al), Cr, or
Ni in settings with Mn ≤5% as follows. High Al means
a content usually higher than 95%. Next, we classified
consumable electrodes as stainless steel if the Cr or/and
Ni content exceeded 10%. Otherwise, electrodes were
classified as mild steel. In case of techniques not using
consumables, this classification was applied to the base
material.
Metal workers comprised torch cutters, electroplaters, foundry workers, steel workers, grinders, metal
mixer, blast-furnace workers, solderers, rolling-mill
workers, scrap-metal workers, and sinters. We included
metal workers and all other occupations with measurements of Mn in the category ‘non-welders’.
Statistical analysis
All calculations were performed with the statistical software SAS, version 9.4 (SAS Institute Inc., Cary,
NC, USA). We modelled exposure to Mn according to
the methods applied to measurements of Cr(VI) and Ni
(Pesch et al., 2015; Kendzia et al., 2017). In brief, the
fraction of measurements below the LOQ and selected
percentiles were used to describe the distribution of
inhalable Mn, in particular the median, inter-quartile
range (IQR), 90th, and 95th percentile. Measurements
below the LOQ were multiply imputed with 10 runs
(Lotz et al., 2013). We defined an interval where the
lower bound was set to zero and the upper bound was
set to the specified LOQ and postulated that the probability distribution of concentrations within this interval
(0 to LOQ) depends on all measurements above LOQ.
For 10 imputation runs, we applied mixed regression
models and adjusted the log-transformed Mn concentrations for occupational setting, calender year (mediancentered at 2009), analytical method, and duration of
sampling:
ln (Mn) = Intercept + β × Occupational setting + β × Year
1
2
+ β × Analytical method + β × ln (Duration ) + ε .
3
4
For welders, we additionally implemented the welding technique and consumable material with regard to
the occupational setting. Following, point estimates
of all runs were combined with PROC MIANALYZE.
We estimated geometric means (GMs) of exposure to
Mn for the median duration of sampling (2 h) for the
various occupational settings. Adjusted R2 was estimated
for goodness-of-fit of the respective regression models
(Harel, 2009).
Results
Table 1 presents the characteristics of 5771 personal
measurements of inhalable Mn. The median of all concentrations was 35 µg m−3 (IQR 6–180 µg m−3). Major
analytical method was ICP-MS, especially in more recent
years. We observed a halving of the concentrations from
1989 to 2015 based on all measurements. Low-emission
welding technologies such as tungsten inert gas welding (TIG) or laser welding were more frequently used in
more recent years (data not shown). Sampling duration
was mostly 2 h. Individual LOQs ranged from 0.0015 to
67 µg m−3 (data not shown).
Table 2 and Fig. 1A and B shows the distribution of
inhalable Mn in welders (n = 3985) and other occupations. Median Mn concentrations were much higher in
welders (74 µg m−3; IQR 14–260 µg m−3) than in other
occupations (8 µg m−3; IQR <LOQ-31 µg m−3). About
5% of welders exceeded concentrations of 1000 µg m−3.
Flux-cored metal arc welding (FCAW) ranked highest (median 240 µg m−3; IQR 27–860 µg m−3), followed
by GMAW (median 130 µg m−3; IQR 35–340 µg m−3),
in particular when welding mild steel. Also, a high Mn
content of the consumables in shielded metal arc welding (SMAW) can result in concentrations >100 µg m−3
(median 110 µg m −3; IQR 46–835 µg m −3). Mn concentrations < 20 µg m−3 were mostly measured in TIG
welding (median 8 µg m−3; IQR 4–21 µg m−3), plasma,
and laser welding. Also, all other metal workers had
median Mn concentrations <20 µg m−3 except torch cutters (median 28 µg m−3; IQR 8–74 µg m−3). For example,
foundry workers had a median value of 7 µg m−3 and
grinders presented on average with 11 µg m−3.
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX
4
Table 1. Distribution of personal measurements of inhalable manganese compiled in the German MEGA database
between 1989 and 2015.
Characteristics
N
Total
5771
Analytical method
AAS
1694
ICP-OES
665
ICP-MS
2529
X-ray fluorescence
883
Time of measurement [years]
1989 to <2005
1482
2005 to <2009
1297
2009 to <2012
1470
2012 to ≤2015
1522
Sampling time [hours]
<2
903
2 to <3
4054
3 to <4
537
≥4
277
N < LOQ (%)
P25 (µg m−3)
Median (µg m−3)
P75 (µg m−3)
P90 (µg m−3)
P95 (µg m−3)
14
6
35
180
500
880
16
13
9
22
10
14
4
7
58
67
23
29
250
260
140
130
650
700
400
430
1100
1200
680
810
17
14
10
13
10
8
6
4
55
46
28
21
270
210
140
120
740
560
410
350
1300
1000
700
610
11
14
17
12
20
6
4
4
110
30
20
21
400
160
130
110
1300
430
392
320
2600
710
800
500
AAS = atomic absorption spectroscopy; ICP-OES = inductively coupled plasma emission spectroscopy; ICP-MS = inductively coupled plasma mass spectroscopy;
LOQ = limit of quantification; P25 = 25th percentile; P75 = 75th percentile; P90 = 90th percentile; P95 = 95th percentile.
Table 3 depicts the adjusted effect estimates from
the regression model as factors modifying the average
exposure level. GMAW and ICP-MS served as reference
groups. Only welders applying FCAW had higher Mn
concentrations (exp(β) 1.51; 95% confidence interval
[CI]: 1.03–2.19) than GMAW. Welding with electrodes
of >5% Mn was associated with nearly 2-fold higher
Mn concentrations as compared to mild steel. AAS and
X-ray fluorescence did not differ from ICP-MS but ICPOES resulted in 1.42-fold higher concentrations. We
could not estimate a significant time trend between 1989
to 2015 when stratifying by setting and adjusting for
covariates. Mn concentrations were significantly higher
in exposure circumstances with a shorter sampling time.
Adjusted R2 was 0.42 (95% CI 0.40–0.44).
Table 4 presents GMs in these occupational settings
centered for the median year 2009 with adjustment for
the average sampling duration of 2 h. GMs >100 µg m−3
were estimated for GMAW using consumables of high Mn
content (201 µg m−3; 95% CI 138–291 µg m−3) and when
applying FCAW (115 µg m−3; 95% CI 79–168 µg m−3).
We estimated GMs >50 µg m −3 for all welders using
GMAW (78 µg m−3; 95% CI 72–84 µg m−3) and SMAW
with electrodes of high Mn content (84 µg m−3; 95%
CI 56–127 µg m −3). GMs <20 µg m −3 were estimated
for welding with Al, submerged arc welding with the
exception of electrodes of high Mn content. GMs <5µg
m −3 were observed in laser, plasma, and resistance
welding. Among the non-welding settings, GMs between
10–20 µg m −3 were estimated in torch cutters, blastfurnace workers, grinders, and metal mixers. All other
settings had lower GMs, for example foundry workers
(5 µg m−3).
Discussion
Mn is an essential additive for improving the hardness
of steel and is a major constituent of welding fumes,
besides a variety of other applications and exposure
circumstances (Postle et al., 2015). High exposure
to airborne Mn has been associated with neurotoxic
symptoms such as movement disorders (Olanow, 2004;
Lucchini et al., 2009). Here, we estimated occupational
exposure to inhalable Mn using 5771 personal measurements and ancillary data compiled in the German exposure database MEGA between 1989 and 2015. The data
distribution was skewed with a median of 35 µg m−3
and 880 µg m−3 as 95th percentile but welders had nearly
10-fold higher concentrations than other metal workers.
GMAW, FCAW, and SMAW with consumables of high
Mn content ranked highest with P95s >1000 µg m−3.
Following mounting evidence of neurobehavioral
dysfunctions already at lower doses, regulatory bodies
adopted OELs for Mn (Bevan et al., 2017). For inhalable Mn, ACGIH recommends 100 µg m −3 as TLV
(ACGIH, 2013), and Germany established an OEL at
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX5
Table 2. Distribution of personal measurements of inhalable manganese in occupations with anticipated exposure
(MEGA database, 1989–2015).
Occupation
Welder
Gas metal arc welding
Tungsten inert gas
welding
Shielded metal arc
welding
Flux-cored metal arc
welding
Laser welding
Submerged arc welding
Plasma welding
Resistance welding
Others or not specified
Non-welders
Torch cutter
Electroplater
Foundry worker
Steel worker
Grinder
Metal mixer
Blast-furnace worker
Solderer
Rolling-mill worker
Scrap-metal worker
Sinter
Other occupations
Welding material
N
N < LOQ
(%)
P25
(µg m−3)
Median
(µg m−3)
P75
(µg m−3)
P90
(µg m−3)
P95
(µg m−3)
Total
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Other content
Total
3985
2721
1418
342
68
47
846
529
8
3
2
5
29
2
2
18
14
35
53
20
<LOQ
40
34
4
74
130
180
50
10
113
130
8
260
340
410
135
30
400
320
21
610
690
890
380
73
1800
590
47
1100
1100
1400
620
150
2900
940
71
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Other content
Total
60
332
34
10
93
283
25
18
48
0
15
6
3
4
<LOQ
30
5
15
15
7
3
30
8
57
31
15
8
74
22
210
43
37
22
100
50
930
92
51
27
120
70
2200
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Other content
85
84
22
92
95
3
7
8
6
2
28
10
46
15
27
95
33
110
57
240
270
79
835
210
860
1200
180
3000
830
1678
2200
210
5300
1600
2293
47
36
27
103
144
1786
251
60
212
10
461
144
14
26
32
46
20
511
36
5
56
50
17
27
8
50
23
10
22
32
7
50
28
52
50
33
<LOQ
8
<LOQ
<LOQ
6
<LOQ
8
<LOQ
2
4
4
<LOQ
6
<LOQ
<LOQ
<LOQ
<LOQ
<LOQ
3
21
<LOQ
3
52
8
28
5
7
6
11
5
15
4
4
<LOQ
8
5
8
88
6
6
235
31
74
11
24
21
34
38
45
5
14
5
13
23
37
150
24
20
730
130
290
24
86
48
100
550
60
8
34
13
140
130
48
370
77
30
1100
370
630
45
190
66
280
830
240
18
69
20
320
350
LOQ = limit of quantification; P25 = 25th percentile; P75 = 75th percentile; P90 = 90th percentile; P95 = 95th percentile.
200 µg m−3 (http://www.baua.de/de/Themen-von-A-Z/
Gefahrstoffe/TRGS/TRGS-900.html). In our analysis of
measurements of inhalable Mn at German workplaces,
the 75th percentile of all measurements was 180 µg m−3,
34% exceeded 100 µg m−3, and 20% were >200 µg m−3,
mostly among welders. We observed a 50% reduction of
6
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX
Figure 1. (A and B) Density function of the concentrations of inhalable manganese among welders (left) and non-welders (right)
(MEGA database, 1989–2015).
exposure levels between 1989 and 2015, which may be
due to an increasing use of low-emission welding technologies such as TIG and laser welding as well as an
improvement of ventilation and local fume extraction at
the workplaces.
The distribution of Mn concentrations in an exposure database is influenced by the purpose of the measurements and, hence, the selection of settings for
monitoring workplace exposure. The MEGA database
documents a large data set of measurements from multiple purposes, including inspection, compliance, research,
and surveys. The majority of measurements was available for welders, where GMAW comprised 47% of all
concentrations of inhalable Mn. The median concentration was 74 µg m−3 in all welders, which corresponds to
73 µg m−3 as median among 230 welders of the German
study WELDOX using the same sampling device in the
breathing zone of the welders (Pesch et al., 2012). FCAW
was associated with the highest exposure levels among
all at-risk settings and frequently exceeded 200 µg m−3
(median MEGA: 240 µg m−3, WELDOX: 585 µg m−3).
An intervention study in a high-exposure setting with
FCAW demonstrated that Mn concentrations <20 µg m−3
could be achieved inside powered air-purifying respirators (Lehnert et al., 2014). GMAW of mild steel ranked
also high with a median concentration of 180 µg m−3 in
MEGA as well as in WELDOX. Inhalable Mn >100 µg
m−3 was measured in SMAW when using consumable
electrodes with Mn content >5%. TIG welding was
mostly associated with inhalable Mn <20 µg m−3, which
confirms observations in WELDOX and other studies
(Flynn and Susi, 2010; Pesch et al., 2012). New techniques such as laser welding resulted in even lower concentrations of inhalable Mn with GMs ≤2 µg m−3.
Exposure to inhalable Mn was on average lower
than 20 µg m−3 in most of the non-welding settings, like
in steel production. We found only minor differences
between average concentrations for certain occupations estimated with data compiled in MEGA and in
the US Chemical Exposure Health Database (CEHD,
https://www.osha.gov/opengov/healthsamples.html). For
example, median exposure of blast-furnace workers was
14 µg m−3 which is similar to the median of 13 µg m−3
from measurements compiled CEHD. Even lower averages were observed for several other settings, like scrapmetal workers (MEGA: 2 µg m−3, CEHD: 4 µg m−3).
The respirable mass concentration of particulate matter is a more suitable metric for neurotoxic effects of Mn,
which can enter the brain via blood (Baker et al., 2014).
However, only few measurements of respirable Mn were
available in MEGA or other databases. Whereas most
measurements of Mn compiled in MEGA were derived
from inhalable particulate matter, CEHD compiled measurements of Mn in total dust. Progress has been made
in defining size-specific sampling criteria, and the inhalable particle fraction has replaced ‘total dust’ (Levy,
2005). The relation between Mn determined in inhalable
versus respirable particulate matter may vary by setting
and other factors and has been estimated with a factor
of 5 (ACGIH) or 10 (Germany) for particle-size-specific
OELs. When preparing the comprehensive report on Mn
(Levy, 2005), only one study in the alloy production was
identified, which reported a ratio of 10 from side-byside measurements of Mn in the inhalable and respirable
fraction (Ellingsen et al., 2000). Newer studies found
lower ratios of around 2 for measurements in welding
fumes where Mn is mostly respirable (Pesch et al., 2012;
Jeong et al., 2016).
One strength of this modelling approach is the large
number of Mn concentrations in a wide range of job
tasks together with ancillary data about the measurements, workplaces, and welding techniques. In published studies, the Mn content of welding consumables
as major source of airborne Mn was rarely considered
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX7
Table 3. Influence of occupation, year of measurement, welding material, and sampling duration on the concentration
of inhalable manganese (MEGA database, 1989–2015).
Intercept
Welder
Gas metal arc welding
Tungsten inert gas welding
Shielded metal arc welding
Flux-cored metal arc welding
Laser welding
Submerged arc welding
Plasma welding
Resistance welding
Others or not specified
Welding material
Mild steel
Stainless steel
Al content >5%
Mn content>5%
Other or mixed content
Non-welders
Torch cutter
Electroplater
Foundry worker
Steel worker
Grinder
Metal mixer
Blast-furnace worker
Solderer
Rolling-mill worker
Scrap-metal worker
Sinter
Other occupations
Analytical method
AAS
ICP-OES
ICP-MS
X-ray fluorescence
Year of measurement [Ref = 2009]
Sampling time [log(h)]
95% CI
N
Exp(β)
5771
194
169–222
2721
529
283
95
47
36
27
103
144
1.00
0.10
0.42
1.51
0.03
0.24
0.02
0.02
0.28
0.09–0.13
0.33–0.53
1.03–2.19
0.01–0.04
0.13–0.44
0.01–0.06
0.01–0.03
0.20–0.38
1995
1096
137
96
2447
1.00
0.57
0.10
2.10
0.77
0.49–0.66
0.07–0.14
1.44–3.07
0.68–0.87
251
60
212
10
461
144
14
26
32
46
20
511
0.20
0.02
0.08
0.07
0.11
0.07
0.19
0.01
0.05
0.01
0.03
0.05
0.16–0.26
0.01–0.03
0.06–0.11
0.02–0.22
0.09–0.14
0.05–0.09
0.07–0.49
0.00–0.03
0.03–0.09
0.00–0.01
0.01–0.08
0.04–0.06
1694
665
2529
883
5771
5771
0.93
1.42
1.00
1.10
0.97
0.44
0.79–1.10
1.20–1.67
0.94–1.28
0.96–1.00
0.39–0.50
CI = confidence interval of Exp(β). R2 0.42 (95% CI = 0.40–0.44).
(Hobson et al., 2011). Facing the lognormal distribution of measurements at workplaces, GMs should be
preferred to present average exposure levels instead of
arithmetic means. A limitation of our analysis is the
duration of measurements which lasted usually 2 h. In
high-exposure settings, the sampler could be loaded with
particles even within a shorter time. As discussed in the
modelling of Cr(VI) concentrations with MEGA data,
we refrained from calculating 8-h shift estimates (Pesch
et al., 2015). For example, the measurements are commonly performed during the activity under evaluation,
for example when welding. However, the welding torch
does not burn during the whole shift.
The modelling of average exposure concentrations in
at-risk occupations is a pivotal step in exposure assessment. The information compiled in MEGA allowed
us to describe exposure patterns not only by welding technique but also for various types of electrodes.
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX
8
Table 4. Model-based estimates of the geometric means of occupational exposure to inhalable manganese predicted for
the year 2009 with adjustment for sampling time. (MEGA database, 1989–2015).
Occupations
Welding material
Welder
Gas metal arc welding
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Tungsten inert gas welding
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Shielded metal arc welding
Mild steel
Stainless steel
Al content >5%
Mn content >5%
Flux-cored metal arc welding
Laser welding
Submerged arc welding
Plasma welding
Resistance welding
Others or not specified
Non-welders
Torch cutter
Electroplater
Foundry worker
Steel worker
Grinder
Metal mixer
Blast-furnace worker
Solderer
Rolling-mill worker
Scrap-metal worker
Sinter
Other occupations
95% CI
(µg m−3)
N
Geometric mean
(µg m−3)
2721
1418
342
68
47
529
60
332
34
10
283
85
84
–
22
95
47
36
27
103
144
78
95
54
9
201
6
10
6
1
21
33
40
23
4
84
115
2
18
1
1
21
72–84
87–105
47–62
7–13
138–291
5–7
8–12
5–7
1–1
14–31
26–41
32–51
18–29
3–6
56–127
79–168
1–3
10–34
1–4
1–2
15–29
251
60
212
10
461
144
14
26
32
46
20
511
16
1
5
6
8
5
13
1
4
1
2
3
13–20
1–2
4–7
219
6–9
3–6
5–35
0–2
2–7
0–1
1–6
3–4
CI = confidence interval of geometric mean.
However, some information was not documented in former MEGA data, like the position of the sampler head
(inside or outside of a helmet) or the type of wire (solid
or flux-cored). In WELDOX, also the type of wire, efficiency of the local exhaust ventilation and welding in
confined space was assessed and could explain >70% of
the variance of respirable Mn together with the major
welding technique (Pesch et al., 2012). When assessing
exposure in large cohort or community-based studies,
the retrospective assessment of such detailed information is less feasible. We already used the estimates of this
analysis to calculate cumulative Mn exposure in welders
and other occupations for the investigation of neurotoxicity in a community-based study (Casjens et al., 2017).
A welding process exposure matrix was developed for
a cohort study among European welders where the job
axis was stratified by major technique and type of steel
(Gerin et al., 1993). Our former analysis of Cr(VI) and
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX9
Ni using MEGA data may improve this JEM (Pesch
et al., 2015; Kendzia et al., 2017). Mn can be an additional agent of such a matrix.
Conclusions
This analysis of a large data set of inhalable Mn aimed
at estimating average exposure levels in occupational
settings in Germany between 1989 and 2015. Welders
had a median value of 74 µg m−3 compared to 8 µg m−3
in other occupations. GMAW, FCAW, and SMAW frequently exceeded 100 µg m−3 and require protective measures to comply with OELs. We recommend collecting
information about the welding technique in addition to
the job title in community-based studies when estimating neurotoxic effects of Mn in welders.
Acknowledgements
We are grateful for access to concentrations of manganese compiled in the database MEGA of the Institute for Occupational
Safety and Health of the German Social Accident Insurance
(IFA), Sankt Augustin, Germany.
Conflict of interest
Authors from the Institute for Prevention and Occupational
Medicine (IPA) and Institute for Occupational Safety and Health
(IFA) work for the German Social Accident Insurance (DGUV).
The authors are independent from the DGUV in study design,
access to the collected data, responsibility for data analysis and
interpretation, and the right to publish.
References
ACGIH (Ed.). (2011) TLVs and BEIs, Threshold Limit Values
for Chemical Substances and Physical Agents and Biological
Exposure Indices. Cincinnati, OH: Signature Publications.
ACGIH (Ed.). (2013) Manganese, Elemental and Inorganic
Compounds: TLV(R) Chemical Substances. 7th edn
Documentation. Cincinnati, OH: Signature Publications.
Baker MG, Simpson CD, Stover B et al. (2014) Blood manganese as an exposure biomarker: state of the evidence. J
Occup Environ Hyg; 11: 210–7.
Bevan R, Ashdown L, McGough D et al. (2017) Setting evidence-based occupational exposure limits for manganese.
Neurotoxicology; 58: 238–48.
Bundesanstalt für Arbeit. (1988) Klassifizierung der Berufe:
Systematisches und alphabetisches Verzeichnis der
Berufsbenennungen. Nürnberg, Germany: Bundesanstalt für
Arbeit.
Casjens S, Pesch B, Robens S et al. (2017) Associations between
former exposure to manganese and olfaction in an elderly
population: Results from the Heinz Nixdorf Recall Study.
Neurotoxicology; 58: 58–65.
Ellingsen D, Bast-Pettersen R, Hetland S et al. (2000)
Health Survey of Individuals Exposed to Manganese in
Smelting Plants: A Cross Section Survey. Norway: Statens
Arbeidsmiloinstitutt (STAMI).
EN 481. (1993) Workplace atmospheres; size fraction definitions
for measurement of airborne particels: European Standard
EN 481. Brussels, Belgium: European Standardization
Committee.
Flynn MR, Susi P. (2010) Manganese, iron, and total particulate
exposures to welders. J Occup Environ Hyg; 7: 115–26.
Gabriel S, Koppisch D, Range D. (2010) The MGU - a monitoring
system for the collection and documentation of valid workplace exposure data. Gefahrstoffe - Reinhalt Luft; 70: 43–9.
Gerin M, Fletcher AC, Gray C et al. (1993) Development and
use of a welding process exposure matrix in a historical prospective study of lung cancer risk in European welders. Int J
Epidemiol; 22 (Suppl 2): 22–8.
Harel O. (2009) The estimation of R2 and adjusted R2 in incomplete data sets using multiple imputation. J App Stat; 36:
1109–18.
Hobson A, Seixas N, Sterling D et al. (2011) Estimation of particulate mass and manganese exposure levels among welders. Ann Occup Hyg; 55: 113–25.
Jeong JY, Park JS, Kim PG. (2016) Characterization of total and
size-fractionated manganese exposure by work area in a
shipbuilding yard. Saf Health Work; 7: 150–5.
Kendzia B, Pesch B, Koppisch D et al. (2017) Modelling of occupational exposure to inhalable nickel compounds. J Expo
Sci Environ Epidemiol; 27: 427–33.
Lehnert M, Weiss T, Pesch B et al.; WELDOX Study Group.
(2014) Reduction in welding fume and metal exposure of
stainless steel welders: an example from the WELDOX
study. Int Arch Occup Environ Health; 87: 483–92.
Levy LS. (2005) Occupational exposure limits: Criteria document for manganese and inorganic manganese compounds.
Leicester, UK: MRC Institute for Environment and Health,
pp. 285.
Lotz A, Kendzia B, Gawrych K et al. (2013) Statistical methods
for the analysis of left-censored variables. GMS Med Inform
Biom Epidemiol; 9: 1–9.
Lucchini RG, Martin CJ, Doney BC. (2009) From manganism
to manganese-induced parkinsonism: a conceptual model
based on the evolution of exposure. Neuromolecular Med;
11: 311–21.
Olanow CW. (2004) Manganese-induced parkinsonism and
Parkinson’s disease. Ann N Y Acad Sci; 1012: 209–23.
Pesch B, Kendzia B, Hauptmann K et al. (2015) Airborne exposure to inhalable hexavalent chromium in welders and other
occupations: Estimates from the German MEGA database.
Int J Hyg Environ Health; 218: 500–6.
Pesch B, Weiss T, Kendzia B et al. (2012) Levels and predictors
of airborne and internal exposure to manganese and iron
among welders. J Expo Sci Environ Epidemiol; 22: 291–8.
Peters S, Vermeulen R, Olsson A et al. (2012) Development of
an exposure measurement database on five lung carcinogens (ExpoSYN) for quantitative retrospective occupational
exposure assessment. Ann Occup Hyg; 56: 70–9.
10
Annals of Work Exposures and Health, 2017, Vol. XX, No. XX
Postle M, Nwaogu T, Upson S, et al. (2015) Manganese, The
Global Picture: A Socio Economic Assessment. Report for
the International Manganese Institute; Loddon, Norfolk, UK.
http://www.manganese.org/images/uploads/publications/
Manganese_SEA_-_Complete.pdf.
Stamm R. (2001) MEGA-database: one million data since 1972.
Appl Occup Environ Hyg; 16: 159–63.
Taube F. (2013) Manganese in occupational arc welding fumes–
aspects on physiochemical properties, with focus on solubility. Ann Occup Hyg; 57: 6–25.
Wallace M, Shulman S, Sheehy J. (2001) Comparing exposure
levels by type of welding operation and evaluating the effectiveness of fume extraction guns. Appl Occup Environ Hyg;
16: 771–9.
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