Occupational Inhalation Exposures to Nanoparticles at Six Singapore Printing Centers

Abstract

Laser printers emit high levels of nanoparticles (PM0.1) during operation. Although it is well established that toners contain multiple engineered nanomaterials (ENMs), little is known about inhalation exposures to these nanoparticles and work practices in printing centers. In this report we present a comprehensive inhalation exposure assessment of indoor microenvironments at six commercial printing centers in Singapore, the first such assessment outside of the United States, using real-time personal and stationary monitors, time-integrated instrumentation and multiple analytical methods. Extensive presence of ENMs, including titanium dioxide, iron oxide and silica, were detected in toners and in airborne particles collected from all six centers studied. We document high transient exposures to emitted nanoparticles (peaks of ~500,000 particles/cm 3 , lung deposited surface area of up to 220 m 2 /cm 3 , and PM0.1 up to 16 g/m 3 ) with complex PM0.1 chemistry that included 40-60 wt% organic carbon, 10-15 wt% elemental carbon, and 14 wt% trace elements. We also record 271.6 -474.9 pmol/mg of Environmental Protection Agency-priority polycyclic aromatic hydrocarbons. These findings highlight the potentially high occupational inhalation exposures to nanoparticles with complex compositions resulting from widespread usage of nano-enabled toners in the printing industry, as well as inadequate ENM specific exposure control measures in these settings. congeners detected in PCP, background indoor ambient air, toners, and outdoor environment (PDF).

Elevated Urinary Biomarkers of Oxidative Damage in Photocopier Operators following Acute and Chronic Exposures

“…The daily geometric mean NP concentrations in copy centers in the Northeast USA ranged from 3700 to 34,000 particles/cm 3 , with emission peaks reaching up to 1.4 million particles/cm 3 and a count median diameter centered around 30 nm [10,11]. Similar findings were reported recently in Singaporean photocopy centers [12] and in chamber studies [3]. The composition of the nanoscale fraction (PM 0.1 or particulate matter less than 0.1 µm aerodynamic diameter) generated from the photocopiers has also been documented in three comprehensive studies [4,11,12] to include approximately 6-63% organic compounds (as organic carbon), <1% elemental carbon, and 2-8% metals.…”

“…Similar findings were reported recently in Singaporean photocopy centers [12] and in chamber studies [3]. The composition of the nanoscale fraction (PM 0.1 or particulate matter less than 0.1 µm aerodynamic diameter) generated from the photocopiers has also been documented in three comprehensive studies [4,11,12] to include approximately 6-63% organic compounds (as organic carbon), <1% elemental carbon, and 2-8% metals. Polycyclic aromatic hydrocarbons (PAHs) species, including phenanthrene, fluoranthene, pyrene, chrysene, and benzo(b)fluoranthene at concentrations from 2-10 ng/m 3 have been quantified in printer-and copier-emitted NPs [4,12,13].…”

“…The composition of the nanoscale fraction (PM 0.1 or particulate matter less than 0.1 µm aerodynamic diameter) generated from the photocopiers has also been documented in three comprehensive studies [4,11,12] to include approximately 6-63% organic compounds (as organic carbon), <1% elemental carbon, and 2-8% metals. Polycyclic aromatic hydrocarbons (PAHs) species, including phenanthrene, fluoranthene, pyrene, chrysene, and benzo(b)fluoranthene at concentrations from 2-10 ng/m 3 have been quantified in printer-and copier-emitted NPs [4,12,13]. Furthermore, toner-based printing and photocopying enrich airborne aerosols with higher molecular weight and more carcinogenic PAHs by approximately 2-3 fold [12][13][14].…”

Concentrations and Size Distributions of Particle Lung-deposited Surface Area (LDSA) in an Underground Mine

“…Although the concentrations are high in comparison to ambient levels, they are comparable to several other working environments. For instance, personal exposure measurements by Setyawati et al at a printing center revealed a maximum exposure of 220 µm 2 cm -3 (Setyawati et al, 2020). The worker with highest exposure levels had an overall mean exposure of 106 µm 2 cm -3 .…”

“…Studies conducted in working environments and indoor conditions have measured LDSA e.g. to characterize LDSA exposure in printing centers (Setyawati et al, 2020) or to study influence of air cleaner devices to LDSA in offices (Küpper et al, 2019). In ambient air the LDSA concentrations typically vary from ~10-50 µm 2 cm -3 measured at clean background areas (Kuula et al, 2020), to values up to ~100-150 µm 2 cm -3 typically observed near PM sources such as roads (Cheristanidis et al, 2020;Leavey et al, 2017).…”