![Emission factor of VOC species under He and O2 conditions (source: [37]).](https://www.researchgate.net/publication/390514688/figure/fig2/AS:11431281404834403@1745664706985/Emission-factor-of-VOC-species-under-He-and-O2-conditions-source-37_Q320.jpg)
![Emission factor of VOCs at different temperatures (source: [37]).](https://www.researchgate.net/publication/390514688/figure/fig3/AS:11431281405041778@1745664707355/Emission-factor-of-VOCs-at-different-temperatures-source-37_Q320.jpg)
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Academic Editor: Xin-Gui Li
Received: 7 March 2025
Revised: 31 March 2025
Accepted: 2 April 2025
Published: 4 April 2025
Citation: Gao, Y.; Xue, Y.; Sun, C.; She,
L.; Peng, Y. Emission Characteristics of
Volatile Organic Compounds from
Material Extrusion Printers Using
Acrylonitrile–Butadiene–Styrene and
Polylactic Acid Filaments in Printing
Environments and Their Toxicological
Concerns. Toxics 2025,13, 276.
https://doi.org/10.3390/
toxics13040276
Copyright: © 2025 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license
(https://creativecommons.org/
licenses/by/4.0/).
Review
Emission Characteristics of Volatile Organic Compounds from
Material Extrusion Printers Using Acrylonitrile–Butadiene–
Styrene and Polylactic Acid Filaments in Printing Environments
and Their Toxicological Concerns
Yuan Gao 1, Yawei Xue 1,2, Chenyang Sun 2,3,4,5, Luhang She 2,3,4,5 and Ying Peng 2,3,4,5,*
1Instrumentation and Service Center for Science and Technology, Beijing Normal University,
Zhuhai 519087, China; yuan.gao@bnu.edu.cn (Y.G.); 202321180070@mail.bnu.edu.cn (Y.X.)
2Research and Development Center for Watershed Environmental Eco-Engineering, Advanced Institute of
Natural Sciences, Beijing Normal University, Zhuhai 519087, China; 15893863095@163.com (C.S.);
15764410923@163.com (L.S.)
3State Key Laboratory of Wetland Conservation and Restoration, School of Environment,
Beijing Normal University, Beijing 100875, China
4Key Laboratory of Coastal Water Environmental Management and Water Ecological Restoration,
Guangdong Higher Education Institutes, Beijing Normal University, Zhuhai 519087, China
5Zhuhai Key Laboratory of Coastal Environmental Processes and Ecological Restoration,
Beijing Normal University, Zhuhai 519087, China
*Correspondence: pengying@bnu.edu.cn
Abstract: The utilization of 3D printing releases a multitude of harmful gas pollutants,
posing potential health risks to operators. Materials extrusion (ME; also known as fused
deposition modeling (FDM)), a widely adopted 3D printing technology, predominantly
employs acrylonitrile–butadiene–styrene (ABS) and polylactic acid (PLA) as printing mate-
rials, with the respective market shares of these materials reaching approximately 75%. The
extensive usage of ABS and PLA during the ME process leads to significant volatile organic
compound (VOC) emissions, thereby deteriorating the quality of indoor air. Nevertheless,
information regarding the emission characteristics of VOCs and their influencing factors,
as well as the toxicological impacts of the printing processes, remains largely unknown.
Herein, we thoroughly reviewed the emission characteristics of VOCs released during
ME printing processes using ABS and PLA in various printing environments, such as
chambers, laboratories, and workplaces, as well as their potential influencing factors under
different environmental conditions. A total of 62 VOC substances were identified in cham-
ber studies using ABS and PLA filaments; for example, styrene had an emission rate of
0.29–113.10
µ
g/min, and isopropyl alcohol had an emission rate of 3.55–56.53
µ
g/min.
Emission rates vary depending on the composition of the filament’s raw materials, ad-
ditives (such as dyes and stabilizers), printing conditions (temperature), the printer’s
condition (whether it has closure), and other factors. Additionally, we reviewed the tox-
icological concerns associated with hazardous VOC species commonly detected during
the ME printing process and estimated cancer and non-cancer risks for users after long-
term inhalation exposure. Potential health hazards associated with inhalation exposure
to benzene, formaldehyde, acetaldehyde, styrene, and other substances were identified,
which were calculated based on concentrations measured in real indoor environments. This
study provides valuable insights for future research on the development of ME printing
technologies and offers suggestions to reduce VOC emissions to protect users.
Toxics 2025,13, 276 https://doi.org/10.3390/toxics13040276
Toxics 2025,13, 276 2 of 16
Keywords: 3D printing environment; material extrusion; FDM; acrylonitrile–butadiene–
styrene; polylactic acid; emission characteristics; toxicological concern
1. Introduction
Globally, 3D printing development has been growing rapidly in recent years, and its
global market value increased to USD 14 billion in 2020 from USD 7.4 billion in 2017 [
1
].
This figure is predicted to reach USD 56 billion in 2027 [
2
,
3
]. These trends point toward
the increasing importance of 3D printing technology in our daily lives, which has been
widely used in many industries—for example, manufacturing, building, aerospace and
medical devices, and environmental research, as well as common applications in offices,
small workplaces, and homes [4–7].
Material extrusion (ME) printing is a commonly used 3D printing technology due to
its ease of operation and the diversity of its printing materials [
8
]. More importantly, ME
printers reduce the cost of creating basic proof-of-concept models and simple prototyping
substances in small-scale indoor environments such as homes, studios, and small offices.
For example, some small companies have used this technology and saved as much as
50% on their tooling costs. The consumption of filaments for ME printing is increasing
annually, with a compound annual growth rate of approximately 23.3% of the total market
figures [
9
,
10
]. Previous reports have demonstrated that various harmful indoor pollutants,
e.g., volatile organic compounds (VOCs) such as styrene, acetaldehyde, and acetone, are
primarily emitted from the printing of raw materials (for example, polymer and thermo-
plastic material) and secondarily from the process of 3D printing (for example, heating) [
11
].
Additionally, the increase in the use of printing composite materials is related to the increase
in the number of volatiles. Some
in vitro
cell experiments and human and animal exposure
experiments have shown evidence of pollutants induced by 3D printing and adverse health
impacts [
12
]. Furthermore, individuals who work with 3D printers for more than 40 h per
week are more likely to report respiratory-related asthma or allergic rhinitis [13].
Direct and indirect toxic effects in individuals under occupational exposure to synthetic
polymers of ME printing have been observed in previous studies, such as asthma, chronic
obstructive pulmonary disease, allergic rhinitis, and DNA damage [
13
–
16
]. ME printing
filaments are made from plastic, and some contain metal and ceramic materials [
17
–
19
].
Plastic was the largest segment in the production of 3D printing filaments, which includes
acrylonitrile–butadiene–styrene (ABS), polylactic acid (PLA), nylon, polyvinyl alcohol
(PVA), polycarbonate (PC), and high-density polyethylene (HDPE). Due to the outbreak
of COVID-19, there is a high demand for medical devices and medical applications, i.e.,
swabs, face masks, and ventilator splitters, all of which can be produced using ME printing
with plastic filaments [
19
]. As mentioned in the 2021 3D printing industry report, over 50%
of the 3D printing materials consumed in China are plastic materials. Among plastics, ABS
and PLA filaments are the two most widely used types, accounting for 75% of the market.
However, these materials are often not fully pure. For instance, talc is commonly added
to improve printability, and additives in these materials may further increase particles
and VOC emissions. With the widespread application of ME printing technology in
offices, households, and for domestic purposes, it is of great importance to understand the
characteristics of ME printers that use ABS and PLA filaments, as well as their associated
toxicological concerns. Concerns about particulate and VOC emissions during the ME
3D-printing process and their health impacts have attracted much attention over the
years [
12
,
20
–
35
]. However, there is currently a lack of systematic reviews regarding the
consumption of ABS and PLA in ME printer emissions, which hinder our understanding
Toxics 2025,13, 276 3 of 16
of VOC emissions and secondary formation pollutants, as well as evaluating the potential
risks to the environment.
Therefore, this review summarizes the recent progress in studies on the emission
characteristics of VOCs released from ME printers using ABS and PLA filaments in various
settings, including chambers and workplaces (such as household, educational, and small
business environments), over the past decade. Meanwhile, the potential influencing factors
of VOC emissions are discussed, and the potential indoor health impacts of hazardous VOC
species released from ABS and PLA filaments are also reviewed. In total, over 150 studies
were found by searching the following keywords in different online platforms (i.e., Google
Scholar and Web of Science): FDM 3D printing, ABS, PLA, emission of volatile organic
compounds, hazards, occupational exposure, and risk assessment. The inclusion criteria for
choosing publications were as follows: (1) contain a discussion on the VOC emission values
from ABS and PLA printing process; (2) contain a discussion about the toxicology of long-
term exposure; (3) not workshop and conference papers; and (4) published in the English
or Chinese language. We excluded publications that were duplicates and those that did not
meet the above criteria. The aim of this study was to understand the potential emission
characteristics of harmful chemicals, the influencing factors (e.g., environment parameters
and the setup of printers) of emissions of harmful chemicals, and toxicology effects from
exposure to harmful chemicals through a comparison of the emitted VOC pollutants during
the ME printing process with ABS and PLA filaments. This study provides suggestions and
recommendations for the safe development and application of ME printing technology.
2. VOC Measurement and Emission Characteristics of ABS and
PLA Filaments
According to the literature, VOCs have been collected and analyzed in different ways.
Typically, total volatile organic compounds (TVOCs) are measured using a photoionization
detector (PID) as concentrations in parts per billion (ppb). Mendez et al. (2017) used the real-
time PID method to measure TVOC value in a 0.18 m
3
stainless steel chamber and concluded
that VOCs were traceable pollutants [
36
]. The individual VOCs most often used Tenax
®
sorbent tubes or canisters and analyzed with gas chromatography–mass spectrometry (GC-
MS). Some studies used DNPH cartridges and analyzed them using a high-performance
liquid chromatography-UV detector (HPLC-UV) to identify oxygenated VOCs (OVOCs).
Recently, the Proton Transfer Reaction–Mass Spectrometry (PTR-MS) technique has been
used for on-line VOC measurement [
30
]. Potter et al. (2019) [
37
] discussed VOC emissions
under different temperature situations in mass per printed filament (
µ
g/g). The VOC
emission concentration was measured in real indoor environments, expressed in units
with the unit of mass emitted per volume (
µ
g/m
3
). For example, the TVOC values were
216.5–317.7
µ
g/m
3
for ABS filaments in a printing room and university laboratory [
38
,
39
].
The dominant VOCs species reported in the real indoor environment were sebacic acid, 3-
methylbut-2-enyl propyl ester, decane, styrene, 2-amino-2-oxo-acetic acid, N-[3,4-dimethyl],
ethyl ester, and nonanal, and the concentration ranged from 3.0 to 23.0
µ
g/m
3
[
38
–
40
].
These dominant species were mostly OVOCs, which may indicate that the emitted VOCs
were being oxidized in the real indoor environment, where the concentration of oxidants
(i.e., O3and OH) were likely significant under the light sources.
The VOC emission rate is an important parameter for determining the emission charac-
teristics of different filaments. In most of the chamber studies, the emission rate of VOCs was
discussed in terms of the mass emitted per unit time (
µ
g/min). Tables S1 and S2 summarize the
emission rates of different VOC substances from ABS and PLA filaments [
21
,
35
,
36
,
39
,
41
–
50
].
A total of 36 types of VOC, including hydrocarbons, ketones, aldehydes, alcohols, aliphatic
hydrocarbons, carboxylic acids, esters, siloxanes, and other compounds, were identified
Toxics 2025,13, 276 4 of 16
from the emissions when ABS filaments were used as the printing material. The range of
these substances varied from 0.01
µ
g/min to around 113.0
µ
g/min (Table S1). The predom-
inant VOC species identified was styrene, with emission rates ranging from 0.3
µ
g/min
to 113.0
µ
g/min, depending on the filament brands, printers, and experiment conditions
employed. For example, the emission rates of styrene were reported as 33.5
µ
g/min and
113.0
µ
g/min when using white ABS filaments in two different printer brands, FlashForge
(China)and MakerBot (U.S.A), respectively [
44
]. Stefaniak et al. (2017) [
41
] compared the
emission of four color ABS filaments in the same ME printer, and the highest emission was
observed in the nature color filament (9.0
µ
g/min). The comparative emission value was
determined for red ABS filament to be 8.5
µ
g/min, and its emission rate was also shown
to be a relatively high value in other studies [
21
,
37
,
50
,
51
]. Ethylbenzene emerged as the
second most abundant VOC species, with emission rates varying between 0.2
µ
g/min and
5.4
µ
g/min. The relatively high values were found when using white (5.4
µ
g/min) and
red (4.8
µ
g/min) color filament [
39
,
41
–
47
]. The VOC substances mentioned above exhibit
toxicity and are associated with significant adverse health effects [
12
]. Styrene, which has a
strong smell, may affect the central nervous system and has been assessed as being possibly
carcinogenic to humans (Group 2A) by the International Agency for Research on Cancer
(IARC). Ethylbenzene is listed as a possible carcinogen by the IARC, causing adverse effects
in the kidneys and testicular tissue [52].
According to Table S2, the emission of VOC substances from PLA filaments is quite
different, with the emission value relatively low compared to the emission from ABS
filaments. Methyl methacrylate, isopropyl alcohol, lactide, and acrylic acid dimers were
reported as primarily emitted from PLA filaments [
12
]. A total of 37 VOC substances were
reported, with emission rates ranging from 0.1 to 56.5
µ
g/min. Isopropyl alcohol, acrylic
acid dimmer (1,4-dioxane-2,5-dione, 3,6-dimethyl-), ethanol, and hexanal were identified
as the main VOC species in previous chamber studies [
39
,
44
,
48
]. The highest emission rate
(median value of 14.8
µ
g/min) was detected for isopropyl alcohol, which has been reported
as a byproduct of polylactic acid depolymerization. PLA is a biodegradable filament made
from renewable organic materials, including corn starch or sugarcane. According to Floyd
et al. (2017) [
47
], PLA-based filaments primarily emit d-limonene and acrylic acid, where
acrylic acid dimer may form lactic acid via dehydration and subsequent dimerization.
Furthermore, the human body can naturally produce or eliminate lactic acid, and PLA has a
relatively low operating temperature, resulting in reduced VOC emissions [
53
]. D-limonene
may potentially prevent some cancers. Consequently, PLA-based filaments are likely safer
than ABS-based filaments. However, according to the literature, the emission of VOC
substances is not limited to acrylic acid and d-limonene; many more VOC species were
identified, which is summarized in Table S2 [
21
,
39
–
41
,
44
,
46
,
48
–
50
]. It is also worth noting
that the emission of ethanol and octanal from PLA filament reported in many studies is
mainly related to the process of print-bed production preparation [54].
In summary, styrene, a typical primary pollutant, is the most common pollutant
emitted from the use of ABS filaments. However, the reported emission rates of styrene
exhibit substantial variability across the studies. The emission rates of pollutants from
PLA filaments are relatively low, and the most common pollutants emitted are secondary
pollutants. In addition, out of the 63 VOCs identified in each filament, only 10 VOC species
were consistently detected in both filaments (Figure 1), including isopropyl alcohol, ethanol,
and hexanal, among others. Emissions of ethanol, acetaldehyde, and acetone were reported
in most studies, suggesting that they may serve as additives and product intermediates of
the filaments [
21
]. The VOC species mentioned above may be secondary pollutants formed
during the printing process, but the formation mechanisms are not well understood, so
further studies are needed.
Toxics 2025,13, 276 5 of 16
Toxics 2025, 13, x FOR PEER REVIEW 5 of 16
intermediates of the filaments [21]. The VOC species mentioned above may be secondary
pollutants formed during the printing process, but the formation mechanisms are not well
understood, so further studies are needed.
Figure 1. VOC species emissions from PLA and ABS filaments (n ≥ 3).
3. Potential Influences of VOC Emission from ABS and PLA Filaments
In general, the emission of VOCs is closely related to the chemical composition of the
filaments. For example, ABS is synthesized by polymerizing styrene and acrylonitrile in
the presence of polybutadiene, which can undergo decomposition into styrene, butadiene,
and acrylonitrile under high-temperature conditions [55–57]. Therefore, styrene, acrylo-
nitrile, and polybutadiene have been reported to be the primary pollutants emied from
ABS filaments [20]. Styrene has consistently been reported to be the predominant VOC
emied from ABS filaments across numerous studies [21,37,41,43,50,51,58–61]. Further-
more, apart from styrene, ethylbenzene, acetone, and acetaldehyde have been identified
as the predominant VOCs emied. This is aributed to the formation of these three com-
pounds through the thermal degradation of filament monomers [21].
To fulfill various requirements of 3D-printed products, additives such as dyes, plas-
ticizers, and stabilizers are commonly incorporated into filaments [21,22,51,62]. However,
the incorporation of these additives in ABS filaments has an impact on the emissions of
gaseous pollutants. For example, Poer et al. (2019) [37] compared VOC emissions from
ABS filaments and ABS filaments with carbon nanotubes (which are additives that can be
used in 3D printers to produce conductive electrical components), and the results showed
a decrease in styrene emissions and an increase in the formation of α-methyl styrene in
the presence of carbon nanotubes [37]. In addition, benzaldehyde, a hazardous pollutant,
exhibited an upward trend in its values due to surface interactions [21,63], as adsorbed
oxygen on the surface can increase the oxidation capacity. Furthermore, the addition of
ABS filaments may also contribute to the formation of toxic particles. For instance, Zhang
et al. (2017, 2018) [64,65] found that the mass spectra of ABS-emied particles exhibited
various compositions that differed from those of the raw filament material monomers,
apparently due to the presence of a minor unknown filament additive, leading to particle
formation [25,27,64–68].
Regarding PLA, acrylic acid is expected to be the predominant emission [47], but it
has not been detected in many studies because acrylic acid readily forms other com-
pounds. The dominant VOC species reported were identified as the major ones listed in
Table S2. While various studies have identified complex VOC species [26,39,49,59–61,69–
Figure 1. VOC species emissions from PLA and ABS filaments (n≥3).
3. Potential Influences of VOC Emission from ABS and PLA Filaments
In general, the emission of VOCs is closely related to the chemical composition of the
filaments. For example, ABS is synthesized by polymerizing styrene and acrylonitrile in the
presence of polybutadiene, which can undergo decomposition into styrene, butadiene, and
acrylonitrile under high-temperature conditions [
55
–
57
]. Therefore, styrene, acrylonitrile,
and polybutadiene have been reported to be the primary pollutants emitted from ABS
filaments [
20
]. Styrene has consistently been reported to be the predominant VOC emitted
from ABS filaments across numerous studies [
21
,
37
,
41
,
43
,
50
,
51
,
58
–
61
]. Furthermore, apart
from styrene, ethylbenzene, acetone, and acetaldehyde have been identified as the predom-
inant VOCs emitted. This is attributed to the formation of these three compounds through
the thermal degradation of filament monomers [21].
To fulfill various requirements of 3D-printed products, additives such as dyes, plasti-
cizers, and stabilizers are commonly incorporated into filaments [
21
,
22
,
51
,
62
]. However,
the incorporation of these additives in ABS filaments has an impact on the emissions of
gaseous pollutants. For example, Potter et al. (2019) [
37
] compared VOC emissions from
ABS filaments and ABS filaments with carbon nanotubes (which are additives that can be
used in 3D printers to produce conductive electrical components), and the results showed
a decrease in styrene emissions and an increase in the formation of
α
-methyl styrene in
the presence of carbon nanotubes [
37
]. In addition, benzaldehyde, a hazardous pollutant,
exhibited an upward trend in its values due to surface interactions [
21
,
63
], as adsorbed
oxygen on the surface can increase the oxidation capacity. Furthermore, the addition
of ABS filaments may also contribute to the formation of toxic particles. For instance,
Zhang et al. (2017, 2018) [
64
,
65
] found that the mass spectra of ABS-emitted particles exhib-
ited various compositions that differed from those of the raw filament material monomers,
apparently due to the presence of a minor unknown filament additive, leading to particle
formation [25,27,64–68].
Regarding PLA, acrylic acid is expected to be the predominant emission [
47
], but it
has not been detected in many studies because acrylic acid readily forms other compounds.
The dominant VOC species reported were identified as the major ones listed in Table S2.
While various studies have identified complex VOC species [
26
,
39
,
49
,
59
–
61
,
69
–
73
], there
is limited information available regarding their emission or secondary formation process.
Inkinen et al. (2011) [
74
] reviewed the possible origins and effects of lactic acid monomers
and lactide on the formation of PLA products. They reported that the precursor of PLA,
lactic acid fermentation broth, contains many different impurities, such as glycerid, succinic,
formic, fumaric, puryvic, methanol, ethanol, butanol, methyl, ethyl, and butyl lactates.
These impurities in chemical compounds may be present in PLA products, contributing
Toxics 2025,13, 276 6 of 16
to VOC emissions during or after the 3D printing process. Meanwhile, the additives of
PLA filaments also impact the emissions of gaseous pollutants. Floyd et al. (2017) [
47
]
discovered a higher emission rate of TVOCs when using bronze-PLA filaments compared
to pure PLA filaments, which was attributed to the presence of additives. The varied
filament brands likely contain different impurities and additives, resulting in variations in
VOC emissions and differences in trace components within the bulk material. Therefore,
defining the purity of filament is a crucial step to ensure the biodegradability and safety
of PLA filaments. Hence, further research is needed to understand the chemical reactions
occurring during or after the printing process when using PLA filaments.
Table 1summarizes the individual VOC emissions from the same-colored ABS filament
using different printers in an environmentally controlled chamber. Here, we chose red
filaments as an example because more data were available. A total of 21 VOC species were
reported, with concentrations ranging from 0.4 to 912.8
µ
g/m
3
. The identified VOC species
varied with different printers. Only two VOCs were detected in three printers: styrene
and ethylbenzene; acetophenone was measured in two printers. One interesting finding
observed in the three studies (carried out in 2016, 2017, and 2019) was a significant reduction
in the emission concentrations of styrene, ethylbenzene, and acetophenone [
41
,
43
,
44
]. In
addition, the number of emitted VOC species also decreased. Davis et al. (2019) [
21
]
compared emission rates of TVOC by using five commercial ME printers from various
manufacturers, revealing a range of emission rates between 9.0 and 18.2
µ
g/min. Davis,
Stefaniak, and others used the same method to measure the emission rate of TVOCs in 1 m
3
and 0.5 m
3
stainless steel chambers using different ME printers, with the emission rates
ranging from 13.9
µ
g/min to 59.2
µ
g/min [
21
,
71
]. These results suggest that the printing
brand is the other main factor affecting VOC emissions. However, it is still unclear whether
the evolution of 3D printers and filaments will result in a reduction in VOC emissions.
The VOC analysis methods used in the studies were also inconsistent, which might have
introduced bias into the measurement data. Therefore, future studies should be carried
out to identify the effects of printing materials and printers by utilizing standardized
experimental procedures.
Table 1. VOC species emissions from red ABS filaments.
µg/m3Printer 1 aPrinter 2 bPrinter 3 c
styrene 912.8 237.1 17.0
ethylbenzene 59.9 6.6 13.0
acetophenone 61.5 2.0
benzene 0.4
acetaldehyde 7.7
isopropyl alcohol 108.1
ethanol 39.9
acetone 31.5
xylene 3.0
benzaldehyde 6.0
c14(tetradecane) 2.0
acetic acid 3.0
phenol 1.0
Toxics 2025,13, 276 7 of 16
Table 1. Cont.
µg/m3Printer 1 aPrinter 2 bPrinter 3 c
hexadecane 2.0
toluene 40.4
hexanal 70.5
octanal 41.4
nonanal 39.7
1-butano 39.5
benzenemethanol, alpha.,
alpha.-di 44.8
alpha.-pinene 42.2
Remark:
a
LulzBot Mini (U.S.A) (extruder temp: 240
◦
C, bed temp: 110
◦
C);
b
MakerBot 2x (extruder temp: 230
◦
C,
bed temp: 110 ◦C); cZortrax (Poland) (extruder temp: 240 ◦C, bed temp: 80 ◦C); [41,43,44].
The emissions of volatile organic compounds (VOCs) from ME printers that utilize ABS
and PLA may also be influenced by environmental conditions, particularly in facilitating
the secondary generation of VOCs. For example, benzaldehyde and acetaldehyde are
typical oxygenated volatile organic compound (OVOC) species that can be emitted both
primarily and secondarily. In the literature, benzaldehyde and acetaldehyde have been
detected in ME printing processes using ABS and PLA filaments, which may imply the
existence of VOC secondary formation during the printing process. A study by Potter
et al. (2019) [
37
] showed that 3D printing under O
2
conditions emitted more VOC species
than the printing process under He conditions (Figure 2), which supports the existence of
secondary formation during the 3D printing process. However, the secondary formation or
degradation of carbonyl compounds during the printing process is not fully understood, as
only 4-oxopentanal, a carbonyl compound, was reported by [41].
Toxics 2025, 13, x FOR PEER REVIEW 7 of 16
hexadecane
2.0
toluene
40.4
hexanal
70.5
octanal
41.4
nonanal
39.7
1-butano
39.5
benzenemethanol, alpha., alpha.-di
44.8
alpha.-pinene
42.2
Remark: a LulzBot Mini (U.S.A) (extruder temp: 240 °C, bed temp: 110 °C); b MakerBot 2x (extruder
temp: 230 °C, bed temp: 110 °C); c Zortrax (Poland) (extruder temp: 240 °C, bed temp: 80 °C);
[41,43,44].
The emissions of volatile organic compounds (VOCs) from ME printers that utilize
ABS and PLA may also be influenced by environmental conditions, particularly in facili-
tating the secondary generation of VOCs. For example, benzaldehyde and acetaldehyde
are typical oxygenated volatile organic compound (OVOC) species that can be emied
both primarily and secondarily. In the literature, benzaldehyde and acetaldehyde have
been detected in ME printing processes using ABS and PLA filaments, which may imply
the existence of VOC secondary formation during the printing process. A study by Poer
et al. (2019) [37] showed that 3D printing under O2 conditions emied more VOC species
than the printing process under He conditions (Figure 2), which supports the existence of
secondary formation during the 3D printing process. However, the secondary formation
or degradation of carbonyl compounds during the printing process is not fully under-
stood, as only 4-oxopentanal, a carbonyl compound, was reported by [41].
Figure 2. Emission factor of VOC species under He and O2 conditions (source:[37]).
Furthermore, previous studies have demonstrated that the operational temperature
is a key influencing factor in the emissions of VOCs from ABS ME printing, with higher
temperatures promoting greater VOC production. For example, the TVOC emission rates
were found to be 557, 567, and 716 µg/min at a 220 °C, 240 °C, and 260 °C nozzle temper-
ature, respectively [75]. The dominant species, styrene and ethylbenzene, exhibited ap-
proximately threefold increases when the temperature was raised from 200 °C to 300 °C
Figure 2. Emission factor of VOC species under He and O2conditions (source: [37]).
Furthermore, previous studies have demonstrated that the operational temperature is
a key influencing factor in the emissions of VOCs from ABS ME printing, with higher tem-
peratures promoting greater VOC production. For example, the TVOC emission rates were
Toxics 2025,13, 276 8 of 16
found to be 557, 567, and 716
µ
g/min at a 220
◦
C, 240
◦
C, and 260
◦
C nozzle temperature,
respectively [
75
]. The dominant species, styrene and ethylbenzene, exhibited approximately
threefold increases when the temperature was raised from 200
◦
C to 300
◦
C [
37
]. Moreover,
elevated temperatures of up to 300
◦
C resulted in the detection of additional VOC species,
such as acetophenone and alpha-methyl styrene (Figure 3).
Toxics 2025, 13, x FOR PEER REVIEW 8 of 16
[37]. Moreover, elevated temperatures of up to 300°C resulted in the detection of addi-
tional VOC species, such as acetophenone and alpha-methyl styrene (Figure 3).
Figure 3. Emission factor of VOCs at different temperatures (source: [37]).
Sunlight is another environmental condition that affects the emissions of VOC spe-
cies. For example, many studies have reported the emission rates or concentrations of sty-
rene, but only a few studies have identified acrylonitrile and polybutadiene emissions
from 3D printing (Tables S1 and S2). Based on the literature, the lack of data on acryloni-
trile and polybutadiene emission rates or concentrations is aributed to the emission of
secondary products formed during the printing process (resulting from the formation or
degradation of primary pollutants). Acrylonitrile is a compound that readily volatilizes in
air and can be easily degraded by photooxidation processes [57], while the photooxidation
products derived by polybutadiene can result in the formation of hydroxyl, carboxyl, ke-
tone, and epoxy groups of VOCs [76–79]. Moreover, a study conducted by Vance et al.
(2017) [58] discovered the absence of peaks for styrene and acrylonitrile in the Raman
aerosol spectra, suggesting that these aerosols were not the result of volatilization but ra-
ther likely originated from the VOC photooxidation process. Another example is carbonyl
compounds, which can be formed directly through chemical reactions during the printing
process or indirectly via ozonolysis of alkene [80,81].
In the above comparisons, the filament composition, printing conditions, and envi-
ronmental parameters (e.g., sunlight) are the main factors that influence the emissions of
VOCs. In order to reduce emissions in a real 3D printing environment, specific mitigation
measures may include adjusting the printing temperature (in the range of 200–250 °C),
minimizing photo-oxidation in the printing environment, or decreasing gas-phase free
radical concentrations through a catalytic filtration system.
4. Toxicological Concerns
Previous studies have reported that exposure to 3D printer emissions can induce po-
tential toxic effects in humans or animals, such as respiratory symptoms, inflammation,
oxidative stress responses, and cardiovascular impacts [13–15,82,83]. Moreover, similar
results were found in in vitro studies; rat alveolar macrophages and human bronchial
Figure 3. Emission factor of VOCs at different temperatures (source: [37]).
Sunlight is another environmental condition that affects the emissions of VOC species.
For example, many studies have reported the emission rates or concentrations of styrene,
but only a few studies have identified acrylonitrile and polybutadiene emissions from 3D
printing (Tables S1 and S2). Based on the literature, the lack of data on acrylonitrile and
polybutadiene emission rates or concentrations is attributed to the emission of secondary
products formed during the printing process (resulting from the formation or degradation
of primary pollutants). Acrylonitrile is a compound that readily volatilizes in air and can
be easily degraded by photooxidation processes [
57
], while the photooxidation products
derived by polybutadiene can result in the formation of hydroxyl, carboxyl, ketone, and
epoxy groups of VOCs [
76
–
79
]. Moreover, a study conducted by Vance et al. (2017) [
58
]
discovered the absence of peaks for styrene and acrylonitrile in the Raman aerosol spectra,
suggesting that these aerosols were not the result of volatilization but rather likely origi-
nated from the VOC photooxidation process. Another example is carbonyl compounds,
which can be formed directly through chemical reactions during the printing process or
indirectly via ozonolysis of alkene [80,81].
In the above comparisons, the filament composition, printing conditions, and envi-
ronmental parameters (e.g., sunlight) are the main factors that influence the emissions of
VOCs. In order to reduce emissions in a real 3D printing environment, specific mitigation
measures may include adjusting the printing temperature (in the range of 200–250
◦
C),
minimizing photo-oxidation in the printing environment, or decreasing gas-phase free
radical concentrations through a catalytic filtration system.
4. Toxicological Concerns
Previous studies have reported that exposure to 3D printer emissions can induce
potential toxic effects in humans or animals, such as respiratory symptoms, inflammation,
Toxics 2025,13, 276 9 of 16
oxidative stress responses, and cardiovascular impacts [
13
–
15
,
82
,
83
]. Moreover, similar
results were found in
in vitro
studies; rat alveolar macrophages and human bronchial ep-
ithelial cells demonstrated a significant reduction in cell viability and a significant increase
in intracellular reactive oxygen species induced by PLA and ABS ME printer emissions [
84
].
Farcas et al. (2022) [
85
] found that after 24 h of exposure to ABS filaments, normal human-
derived bronchial epithelial cells showed a significant increase in proinflammatory markers,
including IL-12p70, IL-13, IL-15, IFN-
γ
, TNF-
α
, IL-17A, VEGF, MCP-1, and MIP-1
α
. In con-
trast, Uribe-Evheverria and Beiras (2022) [
86
] proved that the PLA filament was harmless to
Paracentrotus lividus larvae. However, the presence of additives, such as in the plasticizers,
in the filaments has toxic effects.
Common hazardous VOC species detected from the ME printing process using ABS
and PLA filaments include (but are not limited to) respiratory irritants (toluene and xylenes),
asthmagens and strong irritants (styrene), and carcinogens (toluene, benzene, formalde-
hyde, acetaldehyde, xylene, and isopropyl alcohol). Table S3 summarizes toxicological
data of the frequently detected VOC species from FDM 3D printing that uses ABS and
PLA materials, including IARC carcinogenicity classifications, inhalation unit risk (IUR)
and the reference concentration (RfC) from the Integrated Risk and Information System
(IRIS), OELs from Occupational Safety and Health of the German Social Accident Insurance
(IFA), and permissible exposure limits (PELs) from OSHA. In the case of 3D printing with
ABS, the main volatile compounds generated during printing are styrene and ethylben-
zene. Styrene was found to be released from ABS pellets and formed, resulting from the
thermal depolymerization of ABS [
54
]. Acute exposure to styrene can irritate the eyes and
respiratory tract and affect the central nervous system, causing depression symptoms such
as dizziness and headaches. Long-term exposure may lead to liver damage, peripheral
neuropathy, and endocrine problems [
54
], and styrene has been classified by the IARC
as a Group 2A possible human carcinogen [
87
,
88
]. The main toxic mechanism involves
the metabolic formation of styrene-7,8-oxide, which binds to DNA and induces mutations
while simultaneously generating reactive oxygen species (ROS) that trigger oxidative stress
and cellular structural damage. Byrley et al. (2020) [
22
] reported that styrene mass concen-
trations (0.4 mg/m
3
and 0.8 mg/m
3
for 3 min and 5 min samples, respectively) emitted
from ABS pellets were close to the EPA IRIS RfC value for inhaled exposure of styrene
(1.0 mg/m
3
). Ethylbenzene has been identified in most ABS studies. Acute exposure
to ethylbenzene can irritate the eyes and respiratory tract and affect the central nervous
system, causing depression symptoms, such as dizziness and headaches [
54
]. Long-term
exposure may lead to abnormalities in liver and kidney function, and it has been classified
by the IARC as a Group 2B possible human carcinogen [
87
,
89
]. The main toxic mechanism
involves liposolubility, which disrupts the integrity of cell membranes, and its metabolites
(such as phenylacetaldehyde) consume glutathione, triggering oxidative stress and DNA
damage. Other common VOC species found in ME printing that uses ABS include toluene,
acetaldehyde, xylene, and benzene (Table S3). All of these substances are considered toxic
and harmful to human health. It is also worth considering substances such as acetone or
ethanol, which can be detected as process emissions and from the residues after cleaning
the print bed. Besides toluene, acetone, and acetaldehyde, other hazardous compounds,
including isopropyl alcohol, are commonly detected in PLA printing (Table S3). Isopropyl
alcohol is considered an air pollutant due to its high toxicity to the ecological system and
carcinogenicity to human health; it is harmful to the central nervous system, eyes, nose,
throat, and lungs [
88
]. The acute effects of exposure to high concentrations of acetonitrile
include irritation of mucous membranes; however, the concentrations detected in the ME
printing process using PLA were much lower than the recommended safe exposure limits
(70 mg/m
3
in OSHA TWA) [
90
]. This finding indicates that laboratory workers were not
Toxics 2025,13, 276 10 of 16
at risk of acute toxicity effects, but further studies should be conducted on the effects of
prolonged exposure to acetonitrile concentrations.
Furthermore, various VOC species can be directly emitted or form secondary pollu-
tants through the printing process, thereby increasing the impact on human health. The
level of VOC emissions can be significantly enhanced, leading to higher human exposure
risks [
12
]. Based on VOC substances measured in the indoor printing environment (e.g.,
the laboratory and printing room), the worst-case values of 15 hazardous compounds were
selected for potential health risk assessment of targeted individuals (Table 2). The chronic
daily intake and lifetime hazardous cancer risk are determined by the frequency, dura-
tion, and activity patterns of inhalation exposure. The equations and details of inhalation
exposure parameters are listed in the Supplementary Materials (Table S4). As shown in
Table 2, the cancer risk for 3D printing workers ranged from 1.79
×
10
−6
(acetaldehyde) to
2.11
×
10
−4
(ethylbenzene). Although ethylbenzene is less commonly detected in
3D printing environments, benzene, ethylbenzene, acetaldehyde, and formaldehyde
are carcinogenic to humans when inhaled. The total cancer risk was estimated to be
2.40
×
10
−4
(larger than 10
−6
), which is considered a potential carcinogenic concern. For
VOC substances that are not defined as carcinogenic compounds but have a health im-
pact, the hazard quotient (HQ) is introduced, and its calculation equation is provided in
Table S4, Equation (S2). If the calculated HQ is <1, there is no adverse health effect. Accord-
ing to Table 2, the HQ values for individual VOC species are below 1; when we sum up the
individual HQ values, it amounts to 1.2567, indicating that the health impact of long-term
exposure to non-carcinogenic VOC substances released during the ME printing processes
using ABS and PLA in various printing environment cannot be ignored. Furthermore,
regarding the 15 hazardous compounds, most of them are regulated under occupational
exposure standards. However, in terms of indoor air quality management, while acetalde-
hyde has specific regulatory limits in indoor air management standards in China and Japan,
six substances—benzene, formaldehyde, toluene, o/p-xylene, ethylbenzene, and styrene—
have individual regulatory limits in management documents concerning indoor air quality
(VOC emissions and exposure) in Europe, the United States, and China. Acetone, butanone,
acetic acid, and isopropyl alcohol may be included in the overall control of TVOCs (total
volatile organic compounds). Notably, methyl methacrylate, phenol, and benzoic acid have
not yet been included in indoor air quality management limits.
Overall, the evidence mentioned above indicates a possible release of substantial
quantities of toxic and carcinogenic VOCs during 3D printing processes. Some of these
VOCs were found to be close to the recommended indoor levels associated with adverse
health effects [
91
]. This review emphasizes the necessity for further investigation into the
toxicity of air pollutants in 3D printing environments, particularly regarding exposure to
mixtures of VOCs and their long-term health implications. Additionally, considering the
extensive utilization of ME printing technology in offices and households, it is necessary
to consider indoor safety and health principles in 3D printing workplaces [
92
]. Manu-
facturers of ME printers should encourage the adoption of best practices for 3D printing
operations to minimize emissions during the printing process. These practices may include
choosing materials with lower VOC emissions, ensuring proper ventilation and installing
local exhaust ventilation systems when working with 3D printers to reduce exposure to
harmful VOCs. Additionally, it is important to ensure that workers wear suitable protective
equipment to minimize human exposure.
Toxics 2025,13, 276 11 of 16
Table 2. Calculation result of cancer and non-cancer risk of exposure to selected VOCs.
Compounds Classification
Exposure
Concentration
(EC, µg/m3)
Cancer Risk (CR) Hazardous
Quotient (HQ)
benzene 1 0.51 3.97 ×10−60.0170
ethylbenzene 2B 84.26 2.11 ×10−40.0842
formaldehyde 1 1.83 2.38 ×10−50.0062
acetaldehyde 2B 0.81 1.79 ×10−60.0905
styrene 2A 26.46 0.0265
isopropyl alcohol 3 142.47 0.7123
methyl methacrylate
3 1.93 0.0028
phenol 3 0.92 0.0000
toluene 3 0.51 0.0001
o-xylene / 29.51 0.2951
p-xylene / 0.61 0.0204
acetic acid / 1.32 0.0001
butanone / 0.81 0.0002
acetone / 11.19 0.0004
benzoic acid / 1.93 0.0010
Total cancer risk 2.40 ×10−4
Total hazard quotient (HQs) 1.2567
5. Summary and Future Perspectives
In the literature, it has been found that numerous VOCs are emitted from ABS and
PLA filaments during printing, including styrene, isopropyl alcohol, and ethanol, among
others. The raw materials of filaments, additives (i.e., the dye and stabilizer), printing
operation temperature, and conditions of the indoor environment affect the composition
and concentration of emitted VOCs. We concluded that there are significant variations
in VOC emission levels across studies, even when using the same printing materials of
the same color. These variations are influenced by (1) analytical methods; (2) testing envi-
ronments such as a chamber or real indoor environment; (3) the volume of test chambers
or workplaces; and (4) the duration of printing operations. Underwriters of Laboratory
Chemical Safety and the Georgia Institute of Technology published the “Standard method
for testing and assessing particle and chemical emissions from 3D printers” [
93
]. This stan-
dardized method and standard protocols enable the collection of comparable measurement
data in various research results. However, studies on the characteristics of VOC emissions
during 3D printing using this standardized method are still limited. In addition, due to
the limited analytical techniques, the number of VOC categories emitted from 3D printing
remains largely unknown. Based on real indoor measurement studies, it is evident that
most of the emitted VOCs can be inhaled, and their concentrations could cause health
risks for workers or users exposed over the long term. The identified VOCs, i.e., benzene,
formaldehyde, and acetaldehyde, are considered carcinogenic compounds, indicating a
potential carcinogenic concern with a total cancer risk of 2.40
×
10
−4
. Exposure to styrene,
isopropyl alcohol, xylene, and other substances leads to potential non-carcinogenic health
impacts for workers. Therefore, several suggestions and recommendations are presented:
(1) apart from standardizing measurement methods and protocols, appropriate strategies
Toxics 2025,13, 276 12 of 16
and policies for controlling VOCs from printers and filament manufacturing are necessary.
(2) Proper guidance for improving and ensuring good indoor ventilation is needed to
reduce exposure levels. (3) Best practices of 3D printer operation are needed to minimize
harmful pollutants. (4) It is necessary to incorporate additional pollutant parameters into
the occupational safety regulatory framework.
Furthermore, there are still many unanswered questions regarding the characteristics
of VOC emissions from 3D printers. These include (1) identifying the types of VOCs emitted
by different types of 3D printers and printing filaments available in the current market
using high-throughput screening methods; (2) in addition to temperature, determining
how other environmental factors, such as humidity, affect VOC emissions from 3D printing;
(3) investigating secondary formation processes or emitted VOCs that interact with common
indoor gaseous or particulate pollutants like O
3
, OH, nitrate, sulfate, etc.; and (4) assessing
the overall impact of mixtures of VOCs released from 3D printers on human health and
indoor environments. Therefore, additional experimental studies are needed in the future to
obtain a comprehensive understanding of the VOC emission characteristics of 3D printers.
Supplementary Materials: The following supporting information can be downloaded at: https:
//www.mdpi.com/article/10.3390/toxics13040276/s1. Table S1. VOC emission rates (
µ
g/min)
during ME printing using different ABS filaments; Table S2. VOC emission rates (
µ
g/min) during ME
printing using different PLA filaments; Table S3. Toxicological data and worst-case VOC concentration
measured in real indoor environment; Table S4. Exposure parameters of adult workers and equations
of exposure concentration (EC), non-cancer risk (HQ), and cancer risk (CR). [
13
,
21
,
35
,
38
,
39
,
41
,
42
,
44
,
45,47–50,50,51,51–61,87,89].
Author Contributions: Data analysis, writing—original draft preparation, visualization, and editing:
Y.G.; data analysis, writing—original draft preparation, visualization, and editing: Y.P.; literature
collection, organization, and data analysis: Y.X.; literature collection, and data analysis: C.S.; literature
collection, and data analysis: L.S. All authors have read and agreed to the published version of
the manuscript.
Funding: This work is supported by the Research Start-up fund of Beijing Normal University at
Zhuhai (28714-111032101; 28707-310432103).
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement: This is a review paper where no new data were created.
Conflicts of Interest: The authors declare no conflicts of interest.
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