Skip to main content

Table 2 In vitro studies of the toxicology of underground railway particulate matter

From: Health effects of particulate matter air pollution in underground railway systems – a critical review of the evidence

Author

Publication Year

Underground

[Airborne PM] (μg/m3 unless stated)

Underground PM Composition

Comparator PM

Model

Exposure Conc/Time

Findings

Seaton [38]

2005

London, UK

PM2.5 = 270–480; PNC = 14,000-29,000/cm3

PM2.5: Fe = 64–71%; Cr = 0.1–0.2%; Mn = 0.5–1%; Cu = 0.1–0.9%; quartz = 1–2%

Urban PM10; TiO2; welding fume

A549

PM2.5 1–100 μg/ml, 8–24 h

Underground PM2.5 caused concentration-dependent increase in IL-8 release, LDH release, plasmid damage.

Karlsson [40]

2005

Stockholm, Sweden

Not stated

PM10: Fe = 39% (mainly Fe3O4); Si = 6%; Al = 3%; Ca = 1%; Cu < 1%; Ba< 1%; Mn < 1%

Urban street PM10

A549

PM10 9–70 μg/ml (5–40 μg/cm2), 4 h

Underground PM10 more genotoxic and oxidative-stress inducing than urban PM10.

Karlsson [41]

2006

Stockholm, Sweden

Not stated

Not stated (may be same as [40])

Wood boiler PM; tyre wear PM10/PM2.5; urban PM10

A549; monocyte-derived macrophages

PM10 70 μg/ml (40 μg/cm2), 4 h

Underground PM10 induced more DNA damage in A549 cells than other PM tested. In macrophages, urban PM10 was most potent inducer of inflammatory mediator release.

Karlsson [42]

2008

Stockholm, Sweden

Not stated

Wood boiler PM; tyre wear PM10, urban PM10; diesel PM; Fe3O4; Fe2O3; CuO; Cu-Zn

A549

PM10 35–70 μg/ml (20–40 μg/cm2), 2–8 h

For mitochondrial depolarisation by PM10, DEP > underground = wood>street>tyre. Underground PM10 most potent ROS generator, and increased FPG sites and DNA damage more than Fe3O4, Fe2O3, CuO, Cu-Zn.

Lindbom [55]

2006

Stockholm, Sweden

PM10 = 469; PM2.5 = 258

Predominantly Fe, with some Si, Ca, Ba, Cu

Roadwear PM10; street PM10; DEP

Monocyte-derived macrophages; RPMI 2650 nasal epithelial cells; BEAS-2B

PM10 10–500 μg/ml, 18 h

Underground PM10 was less potent in eliciting IL-6, IL-8, TNFα release from macrophages, but most potent in eliciting their release from BEAS-2B.

Lindbom [56]

2007

Stockholm, Sweden

Roadwear PM10, street PM10

RAW 264.7 macrophages

PM10 1–100 μg/ml, 18 h

For inflammatory mediator release by PM10, street>underground>roadwear. For arachidonic acid release and measures of oxidative stress (DTT, TBARS), underground>street>roadwear.

Bachoual [57]

2007

Metro and RER, Paris, France

PM10 Metro = 67; RER = 3609

PM10 Metro: Fe = 41.8%; Mn < 1%; Ca = 1.25%; Cu = 1.2%; S = 2.2%; Si = 1.45%; PM10 RER: Fe = 61%; Mn = 7%; Ca = 0.2%; Cu = 0.45%; S = 1.95%; Si = 1.8%

Carbon black; TiO2; DEP

RAW 264.7 macrophages; C57BL/6 mice

PM10 RAW 264.7: 0.05–50 μg/ml (0.01–10 μg/cm2), 3–24 h; Mice: 0.22–4.48 mg/kg (5–100 μg/mouse), 8/24 h

RAW 264.7: underground PM10 sets elicited most MIP2 and TNFα release. DFX reduced TNFα release by RER but not Metro PM10. Mice: RER PM10 but not CB or DEP induced release of TNFα and MIP2, and HO-1 expression.

Jung [58]

2012

Seoul, South Korea

PM10 = 34; PM2.5 = 4.5

Not stated

None

CHO-K1; BEAS-2B

1.6–100 μg/ml organic extract of PM10

Underground PM10 induced significant cell death in CHO-K1, but not BEAS-2B cells. DNA micronucleus formation and strand breakage by underground PM10 inhibited by ROS scavengers.

Loxham [60]

2015

Mainline underground station, Europe

PM10–2.5 = 180; PM2.5 = 71; PM0.18 = 44

PM10–2.5: Fe = 32.1%, Cu = 1.68%; Mg = 1.63%; Ca = 1.52%; PM2.5: Fe = 28.4%; Cu = 1.41%; Mg = 2.12%; Ca = 1.52%; PM0.18: Fe = 32.9%; Cu = 1.71%; Mg = 2.56%; Ca = 2.20% (see also [8])

None

16HBE14o-; PBEC

PM10–2.5, PM2.5, PM0.18 6.25–50 μg/ml (0.6–12.5 μg/cm2), 24 h

PM crosses PBEC mucous barrier to cause concentration-dependent release of IL-8 increasing with smaller PM size. ROS generation and HO-1 induction observed, both inhibited by DFX and NAC.

Spagnolo [62]

2015

Not stated

PM10–2.5 = 26; PM2.5–1 = 13; PM1–0.5 = 3.7 μg/m3; PM0.5–0.25 = 14 μg/m3

(All ng/m3) PM10–2.5: Fe = 545, Ca = 1568, Ba = 122, Cr = 15, Cu = 14; PM2.5–1: Fe = 212, Ca = 256, Ba = 96, Cr = 3, Cu = 12; PM1–0.5: Fe = 71, Ca = 58 Ba = 99, Cr = 2 Cu = 4; PM0.5–0.25: Fe = 31; Ca = 30; Ba = 99; Cr = ND; Cu = 3

Commercial/intermediate station area PM; outdoor PM

NCI-H727

70 μg/ml, 3/6/24 h

Cytotoxicity: platform PM > intermediate area PM, but smallest fractions of outdoor PM most cytotoxic. ROS generation: larger PM sizes>smaller PM sizes. Correlations between transition metals and ROS generation.

Moreno [66]

2017

Barcelona (six stations), Spain

PM2.5 = 33–87 (102 during maintenance activity)

(All ng/m3) PM2.5: Fe = 8000-34,000, Ca = 500–1300 Cu = 33–331, Mn = 107–301

M120(CB), NIST1648a

Cell-free depletion of ascorbate and GSH

PM2.5, cell-free

Antioxidant depletion not associated with PM mass. Antioxidant depletion positively associated with Cu, As, Mn, Zn, Ba, ascorbate depletion negatively associated with Fe

Janssen [67]

2014

Mainline underground station, Europe

PM10 = 409; PM2.5 = 143

Not stated (see [8] for characterisation of separate samples from same location)

PM10 and PM2.5: urban background; continuous traffic; stop-go traffic; farm

Cell-free depletion of ascorbate, DTT, ESR

PM10 and PM2.5, cell-free

Underground PM had greatest oxidative potential of all PM types studied.

Gali [69]

2017

Hong Kong

PM10–2.5 = 10 ± 5; PM2.5 = 48 ± 13

Data as graph only, Fe ≈ 0.2% (similar to other PM sets in study)

PM10–2.5 and PM2.5: above ground railway journey; bus journey; ambient site

RAW 264.7 macrophages

10–100 μg PM suspension, 4/24 h

Underground PM10–2.5 had greatest negative effect on cell viability. Little difference across PM2.5 sets. Mass/mass: underground PM10–2.5 was best generator of ROS. Mass/volume: above ground PM was more potent. No association with Fe.