The carcinogenic effect of various multi-walled carbon nanotubes (MWCNTs) after intraperitoneal injection in rats

Table 2 Dose groups, substances and dosing

Substance	Carbon source	Catalyst	Generation method	Length (μm) all fibers	Length (μm) WHO fibers*	Diameter (μm) WHO fibers*	Specific fiber concentration (10⁹WHO fibers*/mg)	Fibers [length >20 μm] (% of WHO fibers*)	Dose WHO fibers* 10⁹per rat (targeted^#)	Dose WHO fibers 10⁹per rat (actual^##)	Dose (mg in 2 ml)^###	Inner angle	No. of rats
Medium control	-	-	-	-	-	-	-	-	-	-	-	-	50
MWCNT A low	Benzene	Fe	Sublimation method	2.72 ± 2.29	8.57 ± 1.51	0.085 ± 1.60	2.39	3.81	1	0.48	0.2	174.85°±5.82°	50
MWCNT A high	Benzene	Fe	Sublimation method	2.72 ± 2.29	8.57 ± 1.51	0.085 ± 1.60	2.39	3.81	5	2.39	1.0	174.85°±5.82°	50
MWCNT B low	Cyclohexane	Fe	Aerosol method	2.13 ± 2.46	9.30 ± 1.63	0.062 ± 1.71	1.60	9.35	1	0.96	0.6	148.10°±11.48°	50
MWCNT B high	Cyclohexane	Fe	Aerosol method	2.13 ± 2.46	9.30 ± 1.63	0.062 ± 1.71	1.60	9.35	5	4.80	3.0	148.10°±11.48°	50
MWCNT C low	Cyclohexane	Fe	Aerosol method	4.18 ± 2.41	10.24 ± 1.64	0.040 ± 1.57	10.91	11.77	1	0.87	0.08	144.55°±11.48°	50
MWCNT C high	Cyclohexane	Fe	Aerosol method	4.18 ± 2.41	10.24 ± 1.64	0.040 ± 1.57	10.91	11.77	5	4.36	0.4	144.55°±11.48°	50
MWCNT D low	Acetonitrile	Co	Aerosol method	2.53 ± 2.02	7.91 ± 1.40	0.037 ± 1.45	30.15	2.13	1	1.51	0.05	Not measured	50
MWCNT D high	Acetonitrile	Co	Aerosol method	2.53 ± 2.02	7.91 ± 1.40	0.037 ± 1.45	30.15	2.13	5	7.54	0.25	Not measured	50
Long amosite asbestos	-	-	-	6.22 ± 3.12	13.95 ± 2.10	0.394 ± 1.83	0.1	28.55	0.1	0.14	1.4	-	50

Fiber types, lengths and diameters (geometric mean, GMSTD), % of WHO fibers* (length greater than 20 μm) and inner angles (to evaluate the degree of circumflexion of the different CNTs, the angle at the concave side [inner angle] was measured between two straight lines, the first from the beginning of the circumflexion to the middle and the second from the middle to the end of the circumflexion).
*WHO fibers: length greater than 5 μm, diameter less than 3 μm, and a length-to-width ratio (aspect ratio) of at least 3:1.
^#Targeted fiber number dose according to WHO guideline and TRGS 905.
^##Actual fiber number dose; deviations from target values are due to inhomogeneities during successive synthesis or suspension of test items.
^###Total mass dose per rat in mg of substance including also fibers shorter than WHO fibers.

ISSN: 1743-8977