Human health risk assessment of Tire and Road Wear Particles (TRWP) in air

Figures & data

Table 1. Measured characteristics of aerosolized TRWP by treatment group.

Target concentration (µg/m3)	Measured concentration (SD) (µg/m3)	NMAD (GSD) (um)	MMAD (GSD) (µm)	% Mass < 3 um
100	112.2 (29.7)	1.29 (1.60)	3.68 (1.83)	45.7
40	37.8 (19.1)	1.13 (1.56)	3.04 (1.80)	56.6
10	12.5 (10.5)	1.04 (1.46)	2.38 (1.81)	71.0

SD = Standard deviation; NMAD = Number median aerodynamic diameter; MMAD = Mass median aerodynamic diameter; GSD = Geometric standard deviation.

Table 2. Key information on calculation of NOAEC_HEC for TRWP.

NOAEC (µg/m^3)	NOAECAdj (µg/m^3)	RDDR	NOAECHEC (µg/m^3)
112	28	1.955	55

Table 3. Summary results from TRWP global air sampling campaign by Panko et al. (2013).

		Air concentration (µg/m^3)
Country	N	Mean	Maximum	95^th UCL of mean
France	27	0.243	1.34	0.565
Japan	27	0.102	0.32	0.123
United States	27	0.135	0.48	0.169
All	81	0.160	1.34	0.275

Table 4. Distribution of time (minutes) spent in microenvironments by exposure group.

Age group (yrs)	Outdoor	Transit	Indoor, residential	Indoor, institutional	Total (min)
Infant (<1)	44	43	1353	0	1440
Child (1 - 16)*	132	64	1086	158	1440
Teenager (16 to < 21)	102	90	1090	158	1440
Adult (21–65)	180	101	851	308	1440
Adult Retiree (>65)	211	87	1142	0	1440
Outdoor Worker	488	101	851	0	1440

^* Used maximum time for outdoors for all ages in this group to be conservative.

Table 5. Selected infiltration ratios for calculation of average daily TRWP exposure.

Microenvironment	Infiltration ratio
Indoor, residential (average of open and closed windows)	0.25
Indoor, institutional	0.2
Transit	0.7
Outdoors	1.0

Table 6. Daily TRWP exposure concentrations by population group and microenvironment based on 95th UCL of mean measured TRWP concentrations from sampling campaign.

Exposure scenario	Exposure duration (min)	Infiltration factor	95th UCL mean (µg/m^3)	Average daily exposure (µg/m^3)
Infant (<1)
Indoor, residential	1353	0.25	0.275	0.065
Indoor, institutional	0	0.2	0.275	0.000
Outdoor	44	1	0.275	0.008
Transit	43	0.7	0.275	0.006
TOTAL	1440			0.079
Child (1 - 16)*
Indoor, residential	1086	0.25	0.275	0.052
Indoor, institutional	158	0.2	0.275	0.006
Outdoor	132	1	0.275	0.025
Transit	64	0.7	0.275	0.009
TOTAL	1440			0.092
Teenager (16-21)
Indoor, residential	1090	0.25	0.275	0.052
Indoor, institutional	158	0.2	0.275	0.006
Outdoor	102	1	0.275	0.019
Transit	90	0.7	0.275	0.012
TOTAL	1440			0.090
Adult (21-64)
Indoor, residential	851	0.25	0.275	0.041
Indoor, institutional	308	0.2	0.275	0.012
Outdoor	180	1	0.275	0.034
Transit	101	0.7	0.275	0.014
TOTAL	1440			0.100
Retired Adult (>64)
Indoor, residential	851	0.25	0.275	0.055
Indoor, institutional	0	0.2	0.275	0.000
Outdoor	488	1	0.275	0.040
Transit	101	0.7	0.275	0.012
TOTAL	1440			0.106
Outdoor Worker
Indoor, residential	851	0.25	0.275	0.041
Indoor, institutional	0	0.2	0.275	0.000
Outdoor	488	1	0.275	0.093
Transit	101	0.7	0.275	0.014
TOTAL	1440			0.147

Table 7. MOEs by exposure scenario.

Exposure scenario	NOAELHEC (µg/m^3)	Daily exposure (µg/m^3)	MOE
Infant	54.74	0.079	695
Child	54.74	0.092	597
Teenager	54.74	0.090	611
Adult	54.74	0.100	546
Retired Adult	54.74	0.106	514
Outdoor Worker	54.74	0.147	372

Panko JM, Chu J, Kreider ML, Unice KM. 2013. Measurement of airborne concentrations of tire and road wear particles in urban and rural areas of France, Japan and the United States. Atmos Environ. 72:192–199.

 Web of Science ®Google Scholar