Table 1.

Effects of THz radiation on cells.

Frequency	Irradiance ($\mathrm{mW}/{\mathrm{cm}}^2$)	Exposure time	Object	Effects	Refs.
Broad spectrum centered at 10 THz	1	2, 6, 9 h	Mouse MSCs	Exposure of cells to THz radiation for 9 h caused changes in gene expression, whereas in response to shorter duration of exposure, the changes were less pronounced. The lipid inclusions that are a characteristic sign of MSC differentiation into adipocytes were clearly visible after 9 h of exposure.	Ref. 116
1) 2.52 THz;	1.2	1) 2 h;	Mouse MSCs	It was found that genes affected by prolonged irradiation are characteristic for already differentiated cells, i.e., for adipocytes, whereas genes differentially expressed after short (2 h) THz irradiation are characteristic of pluripotent stem cells.	Ref. 117
		2) 2, 12 h
2) 10 THz
1) 10 THz;	1.2	1) 2 h;	Mouse MSCs	1) The level of expression of the shock protein genes remains unchanged after 9 h of THz irradiation.	Ref. 114
		2) 9 h
2) 2.52 THz
				2) The level of the stress-responsive CRP gene that is activated in dying cells remains low in both the control and irradiated cells suggests the absent cellular stress response.
0.14 THz	10, 30, 50, 70, and 100	20 min	hDF	120 h after the irradiation, the proliferative activity of the irradiated cells did not differ from the non-irradiated control. The level of NO production by irradiated fibroblasts did not differ from the NO level of non-irradiated cells. The 0.14-THz radiation of 10- to 100-mW power did not affect the functional activity of human skin fibroblasts.	Ref. 115
0.15 THz	0.4	20 min	hDF	1) No effect on cell cycle;	Ref. 118
				2) no effect on heat shock response;
				3) increase in genome damage;
				4) no effect on clastogenic genome damage;
				5) no effect on telomere length; the THz radiation exposure in vitro caused non-thermal effects on the genome.
2.52 THz	84.8	5, 10, 20, 40, or 80 min	hDF	Cellular temperatures increased by 3°C during all THz exposures. At the used power, radiation at 2.52 THz can generate thermal effects in mammalian cells.	Ref. 112
0.14 THz	10, 30, 50, 70, and 100	20 min	hDF	After exposure to THz radiation, the proliferative activity of the irradiated cells did not differ from the control. The level of NO production by irradiated fibroblasts did not differ from the control.	Ref. 115
0.38 and 2.52 THz	0.03 to 0.9	2 and 8 h	hDF, HaCaT cells	No DNA damage was found in HaCaT and hFB cells after irradiation.	Ref. 119
0.10 to 0.15 THz	0.4	20 min	hDF	The THz irradiation resulted in the genome damage in hDFs. No changes in the expression of proteins associated with DNA damage sensing and repair were detected, indicating that THz radiation exposure may affect genome integrity through aneugenic effects.	Ref. 118