Silicon dioxide and titanium dioxide particles found in human tissues

Figures & data

Figure 1. Box and whisker plots of total-Si concentration in human (post mortem) liver, spleen, kidney, jejunum, and ileum. The boxes represent the upper 25% quartile (Q3), median (Q2), and lower 25% quartile (Q1) concentrations, respectively. The whiskers indicate 1.5IQR (Q3–Q1).

Figure 2. Box and whisker plots of total-Ti concentration in human (post mortem) liver, spleen, kidney, jejunum, and ileum. The boxes represent the upper 25% quartile (Q3), median (Q2), and lower 25% quartile (Q1) concentrations, respectively. The whiskers indicate 1.5IQR (Q3–Q1).

Table 1. Summary of total-Si and -Ti concentrations in the organs.

	All organs	Liver	Spleen	Kidney	Jejunum	Ileum
n	69	15	15	15	12	12
Total-Si	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg
Non-detects^a	12	3	2	3	1	3
Minimum^b	2.7	3.2	3.0	4.4	2.7	5.2
Maximum	191	26	47	21	23	191
Median^c	7.2	5.8	9.5	7.7	6.8	7.6
Average^c	12	7.8	12	8.2	8.9	23
Std. dev.^c	23	7.7	12	6.1	6.4	53
Total-Ti	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg
Non-detects^a	8	4	2	1	1	0
Minimum^b	0.01	0.01	0.02	0.01	0.02	0.06
Maximum	2.0	0.16	0.25	0.37	2.0	1.4
Median^c	0.06	0.02	0.04	0.05	0.13	0.26
Average^c	0.17	0.03	0.06	0.08	0.34	0.43
Std. dev.^c	0.33	0.04	0.06	0.09	0.57	0.43

^a Number of samples below the LOD of 2 mg total-Si/kg and 0.0 mg total-Ti/kg.

^b Minimum measured value.

^c For calculation of median, average and std. dev. non-detects were set at half of the LOD value.

Figure 3. TiO₂ particles in human (post mortem) tissue. Time scan of the spICP-MS analyses of a human tissue sample.

Figure 4. Box and whisker plots of the SiO₂ particle concentration in human (post mortem) organs. The boxes represent the upper 25% quartile (Q3), median (Q2), and lower 25% quartile (Q1) concentrations respectively. The whiskers indicate 1.5IQR (Q3–Q1).

Figure 5. Number-based particle size distribution for SiO₂ particles found in tissues of human organs. Particles can consist of primary particles, aggregates or agglomerates.

Table 2. Summary of particle SiO₂ and TiO₂ concentrations in the organs.

	All organs	Liver	Spleen	Kidney	Jejunum	Ileum
n	69	15	15	15	12	12
Particle SiO2	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg	mg Si/kg
Non-detects^a	14	3	3	2	3	3
Minimum^b	0.2	0.3	0.4	0.3	0.2	0.3
Maximum	25	2.2	6.5	4.1	2.2	25
Median^c	0.6	0.4	1.0	0.4	0.7	0.6
Average^c	1.2	0.6	1.3	0.9	0.7	2.6
Std. dev.^c	3.1	0.6	1.6	1.1	0.7	7.1
Particle TiO2	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg	mg Ti/kg
Non-detects^a	0	0	0	0	0	0
Minimum^b	0.01	0.01	0.01	0.01	0.01	0.01
Maximum	1.8	0.05	0.13	0.21	1.8	1.2
Median^c	0.03	0.02	0.02	0.03	0.08	0.25
Average^c	0.14	0.02	0.03	0.05	0.31	0.34
Std. dev.^c	0.30	0.01	0.03	0.06	0.55	0.37

^a Number of samples below the detection limit of 0.2 mg Si/kg and 0.01 mg Ti/kg.

^b Minimum measured value.

^c For calculation of median, average and std. dev. non-detects were set at half of the LOD value.

Figure 6. Box and whisker plots of the TiO₂ particle concentration in human (post mortem) organs. The boxes represent the upper 25% quartile (Q3), median (Q2), and lower 25% quartile (Q1) concentrations respectively. The whiskers indicate 1.5IQR (Q3–Q1).

Figure 7. Number-based particle size distribution for TiO₂ particles found in tissues of human organs. Particles can consist of primary particles, aggregates or agglomerates.

Figure 8. SEM characterization of detected particles detected in a dried liver sample. In addition to the elements indicated in the picture, oxygen was also measured but not shown in the picture. The SEM image on the left shows TiO₂ and SiO₂ particles as well as aluminum silicate and iron particles. The images on the right show a TiO₂ particle (top) and a SiO₂ particle (bottom).

Table 3. Literature data of total-Si and -Ti concentrations in human liver and spleen.

	Liver (mg/kg)	Spleen (mg/kg)	Comments/reference
Total-Si	8 ± 8	12 ± 12	This study, ICP-MSMS, n = 15
	2 to 50	2 to 50	WHO, colorimetric method (WHO 1974)
	12	17	Austin et al., colorimetric method (Austin, Rinehart, and Ball 1972)
	33.6 ± 13.8	–	Carlisle et al., atomic absorption spectrometry (Carlisle and Mertz 1986)
	1.4 ± 0.5	3.3 ± 0.8	Evans et al., ICP-AES (n = 10, female) (Evans et al. 1996)
Total-Ti	0.03 ± 0.04	0.06 ± 0.06	This study, ICP-HRMS, n = 15
	0.04 ± 0.02	0.08 ± 0.11	Previous study, ICP-HRMS, n = 15 (Heringa et al. 2018)
	1.3	0.2 to 1.4	NRC, X-ray fluorescence analyses (National Research Council 2005)
	1.7 ± 3.4	1.9 ± 2.4	Yukawa et al., neutron activation analysis, n = 15 (liver) and n = 6 (spleen) (Yukawa et al. 1980)

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