Sub-chronic toxicity study in rats orally exposed to nanostructured silica

Table 1 Intended and actual silica exposure doses

Group	Intended total silica exposure dose (mg/kg bw/day)		Actual exposure dose
Group	Intended total silica exposure dose (mg/kg bw/day)	Total silica (mg/kg bw/day)	Added silica^a(mg/kg/bw/day)	Silica in nano-size range^b(mg/kg bw/day)
SAS low	100	222	83	33
SAS medium	1000	942	819	328
SAS high	2500	2142	2047	819
NM-202 low	100	221	82	82
NM-202 medium	500	537	405	405
NM-202 high	1000	933	810	810
Negative control	0	133	0	<21

The actual exposure doses were calculated from the (HDC) ICP-MS silicon measurements in the feed mixture (0.95 ± 0.19 mg silica/g), standard feed pellets (1.8 ± 0.9 mg silica/g), and drinking water (0.019 ± 0.003 mg silica/g). Exposure to silica originating from consumption of standard feed pellets and drinking water was based on an average feed intake of 27 g/day and an average water intake of 45 ml/day at an average body weight of 350 g [22] (for a more detailed calculation, see Additional file 1: Table S1). ^aTotal silica (mg/kg bw/day) – (dose of silica from the standard diet + drinking water in mg/kg bw/day) = dose of added silica (i.e. SAS or NM-202 in mg/kg bw/day). ^bWith a size of 5 – 200 nm.

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