Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population

Figures & data

Table 1. Average measured total-Ti concentrations, and subsequently calculated TiO₂ concentrations, in selected, representative Dutch food products, raw (cow) milk, and food supplements. See Supplementary Material Table SM-2 for further details. Samples rich in calcium were analysed by ICP-HRMS, others by ICP-QMS. LOQ = 0.05 mg Ti/kg product.

	Number of samples (>LOQ)^a	Mean total-Ti (mg/kg product) (±SD)	Min total-Ti (mg/kg product)	Max total-Ti (mg/kg product)	Mean TiO2^b (mg/kg product)
Samples analysed by ICP-HRMS
Raw (cow) milk	6 (6)	0.31 (±0.23)	0.05	0.63	0.51
Regular dairy products (i.e. milk, yoghurt)	11 (10)	0.47 (±0.46)	<LOQ	1.46	0.79
Processed dairy products	10 (5)	0.12 (±0.17)	<LOQ	0.57	0.21
Soy milk	2 (2)	0.33 (±0.01)	0.32	0.34	0.55
Dutch cake with icing and cream	1 (1)	0.23	0.23	0.23	0.38
Coffee creamer (powdered)	1 (1)	1640	1640	1640	2739
Samples analysed by ICP-QMS
Energy drink (containing caffein)	1 (1)	0.07	0.07	0.07	0.11
Soft drink	2 (2)	0.06 (±0.00)	0.06	0.07	0.11
Sports drink	2 (2)	0.09 (±0.05)	0.05	0.12	0.14
Syrup	2 (2)	0.17 (±0.00)	0.17	0.17	0.28
Ice (water-based)	1 (1)	0.16	0.16	0.16	0.26
Wine gums	1 (1)	0.25	0.25	0.25	0.42
Salad dressing	1 (1)	0.43	0.43	0.43	0.72
Food supplement (multivitamin)	2 (2)	744 (±1009)	31	1458	1242

^aIn parenthesis the number of samples above the LOQ. For samples with a Ti concentration < LOQ, a value half LOQ (0.025 mg Ti/kg product) was used in the calculation of the mean value.

^b TiO₂ concentrations were calculated by multiplying the mean total-Ti levels with the mass difference factor of 1.67.

Table 2. Estimated long-term intake, and lifelong daily intake, of TiO₂ and TiO₂ nanoparticles from food products, food supplements and toothpaste (only children 2–6 years old) ingested by the Dutch population, assuming that the population would vary in the products consumed and thus would be exposed to an average TiO₂ concentration of products.

	TiO2			TiO2 nanoparticles (TiO2 NPs)
	Percentiles of intake^a (mg/kg bw per day)		Mean^a	Percentiles of intake^a (μg/kg bw per day)		Mean^a
Age groups	P50	P95	(mg/kg bw per day)	P50	P95	(μg/kg bw per day)
2–6 years old	0.59 (0.57–0.60)	1.29 (1.19–1.40)	0.67 (0.66–0.70)	1.90 (1.80–1.94)	4.16 (3.84–4.52)	2.16 (2.13–2.26)
7–69 years old	0.08 (0.07–0.08)	0.50 (0.47–0.54)	0.17 (0.16–0.18)	0.26 (0.23–0.26)	1.61 (1.52–1.74)	0.55 (0.52–0.58)
70+	0.03 (0.02–0.03)	0.23 (0.20–0.28)	0.06 (0.05–0.07)	0.10 (0.06–0.10)	0.74 (0.65–0.90)	0.19 (0.16–0.23)
Lifelong daily intake^b	0.11	0.52	0.19	0.36	1.67	0.62

^aNote: 2.5% lower – 97.5% upper confidence limits of intake are reported in parentheses.

^b The lifelong daily intake consists of the weighted average of the estimated long-term intake values of the different age groups, assuming no TiO₂ intake during the first year of life, the same intake in the second year of life as in the 2–6 years old age group, and an average life expectancy of 80 years, as reported for the Dutch population by the Dutch Central Bureau of Statistics (CBS) for 2012 (CBS, 2014).

Table 3. Top 10 of food items reported in the Dutch National Food Consumption Survey (DNFCS), food supplements and toothpaste (only children 2–6 years old) contributing most to the TiO₂ intake using average TiO₂ concentrations. The percentage of the contribution per item is indicated in parentheses.

Top 10	DNFCS-children (2–6 years old)	DNFCS-2007–2010 (7–69 years old)	DNFCS-older adults (70+)
1	Toothpaste (57%)	Chewing gum (14%)	Coffee creamer (13%)
2	Hard candy with sugar (4%)	Coffee creamer (11%)	Thickened milk for coffee, powdered (8%)
3	Sugar-coated chocolate confectionery (3%)	Mayonnaise normal (7%)	Chewing gum (4%)
4	Chewing gum with sugar (2%)	Sauce, garlic, mayonnaise-based (5%)	Cappuccino with caffein (3%)
5	Sugar-coated chocolates (2%)	Cappuccino (4%)	Cappuccino instant ready to drink (3%)
6	Biscuit with flavoured milk-filling (2%)	Thickened milk for coffee, powdered (3%)	Cappuccino (3%)
7	Biscuit with milk-filling (2%)	Iced cake “glacekoek” (3%)	Sauce, garlic, mayonnaise-based (2%)
8	Marsh mellow big (2%)	Cappuccino instant ready to drink (3%)	Pastries with cream (2%)
9	Biscuits with coffee glaze (2%)	Cappuccino with caffein (3%)	Sauce based on mayonnaise (2%)
10	Chewing gum sugar-free (2%)	Coffee liquid with sugar and milk (machine) (2%)	Mayonnaise (2%)

Table 4. Intake estimations of TiO₂ per age group as calculated by the present study, and by other comparable studies.

Intake to TiO2 (mg/kg bw per day)	Details	Source
Young children
0.59	2–6 years old, the Netherlands, P50 (point value), average TiO2 concentrations	Present study
1.4	2–6 years old, the Netherlands, P50, tier 4	Sprong et al., 2015
12.0–13.0	<10 years old, the Netherlands, P50, average measured TiO2 levels when assuming 5–20% of product consists of coating	Huybrechts et al., 2010
9.31 (3.89–13.8)	<10 years old, average EU, P50, average measured TiO2 levels when assuming 5–20% of product consists of coating (range found over nine countries)	Huybrechts et al., 2010
1–2	<11 years old, USA	Weir et al., 2012
2–3	<11 years old, UK	Weir et al., 2012
Older children, adults
0.08	7–69 years old, the Netherlands, P50 (point value), average TiO2 concentrations	Present study
0.7	7–69 years old, the Netherlands, P50, tier 4	Sprong et al., 2015
0.2–0.7	≥11 years old, USA	Weir et al., 2012
1	≥11 years old, UK	Weir et al., 2012
0.5–2.0 (Ti intake)  0.8–3.3 (TiO2 intake)^a	Range over six age classes, Germany, P50	Bachler et al., 2015
Older adults
0.03	70+, the Netherlands, P50 (point value), average TiO2 concentrations	Present study
0.5	70+ years old, the Netherlands, P50, tier 4	Sprong et al., 2015

^aBachler et al. calculated the Ti intake (0.5–2.0 mg/kg bw per day), not the intake of TiO₂. For comparison, we multiplied the Ti levels by 1.67 to obtain TiO₂ levels (and assuming that Ti levels originate only from added TiO₂).

CBS (Central Bureau for Statistics, the Netherlands). 2014. Levensverwachting; geslacht en leeftijd, vanaf 1950 (per jaar) [Life expectancy; gender and age, from 1950 (per year)] [Online]. Available at: http://statline.cbs.nl/StatWeb/publication/?VW=T&DM=SLNL&PA=37360NED&D1=3&D2=a&D3=0&D4=20-l&HD=130212-0832&HDR=T,G2,G1&STB=G3. Accessed on 12 July 2015

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