Table 1.

The carcinogenic potential of N-nitroso compounds across various routes of administration in several in vivo models.

N-nitroso compounds	No.	Route of administration	Animal models	Tumors	Refs.
N-nitrosodimethylamine (NMDA)	1	Oral	Mice, rats, hamsters, rabbits, guinea pigs, and fish	Benign and malignant tumors of the liver	[7,28]
	2	Inhalation	Mice, prenatal exposure in mice	Benign and malignant tumors of the liver	[7,28]
	3	Subcutaneous	Hamsters, mastomys, and newborn and suckling mice and rats	Benign and malignant tumors of the liver	[7,28]
	4	Intraperitoneal	Adult and newborn mice and in newts	Benign and malignant tumors of the liver	[7,28]
	5	Intramuscular	Rats	Benign and malignant tumors of the liver	[7,28]
	6	Oral	Frogs and fish	Benign and malignant tumors of the liver	[7,28]
	7	Oral	Lung tumors in mice	Tumors of the respiratory tract	[7,28]
	8	Inhalation	Mice and rats	Lung tumors	[7,28]
	9	Inhalation	Rats	Nasal-cavity tumors	[7,28]
	10	Subcutaneous	Adult, newborn, and suckling mice and nasal cavity tumors in adult hamsters	Lung tumors	[7,28]
	11	Intraperitoneal	Adult and newborn mice	Lung tumors	[7,28]
	12	Inhalation	Rats	Nasal-cavity tumors	[7,28]
	13	Inhalation	Mice	Lung tumors	[7,28]
	14	Oral exposure	Mice, rats, and hamsters	Blood-vessel tumors	[7,28]
	15	Subcutaneous	Hamsters and adult, newborn, and suckling mice	Blood-vessel tumors	[7,28]
	16	Intraperitoneal	Mice	Blood-vessel tumors	[7,28]
	17	Oral	Frogs	Tumors of the hematopoietic system	[7,28]
	18	Oral	Mollusks	Tumors of the digestive gland and hematopoietic system	[29]
	19	Subcutaneous	Female hamsters	Ovarian tumors	[30]
	20	Oral	Foxes	Liver tumors	[31]
	21	Intraperitoneal	Rats	Lung and liver tumors	[32]
	22	Oral	Humans	Oropharyngeal cancer	[33]
	23	Oral		Stomach	[34,35]
	24	Oral		Esophageal	[[36], [37], [38], [39], [40]]
	25	Oral		Colorectal	[41]
N-nitrosodiethylamine (NDEA)	1	Inhalation	Rats	Liver tumors	[7,28]
	2	Rectal	Rats	Liver tumors	[7,28]
	3	Intramuscular	Chickens and cats	Liver tumors	[42]
	4	Intraperitoneal	Newborn mice	Liver tumors	[43,44]
	5	Intratracheal	Hamsters of both sexes	Tumors of the lung or trachea	[[45], [46], [47]]
	6	Subcutaneous	Rabbits	Tumors of the lung or trachea	[48]
	7	Intraperitoneal	Newborn mice	Tumors of the lung or trachea	[44]
	8	Oral	Larval or juvenile fish	Pancreatic tumors	[49]
	9	Oral	Mollusks	Tumors of the digestive gland and hematopoietic system	[29]
	10	Intraperitoneal	Pregnant hamsters, prenatally exposed offspring, and second generation of offspring	Benign laryngotracheal tumors	[50]
N-nitrosomorpholine (NMOR)	1	Oral	Male hamsters, female rats, and male hamsters	Respiratory or digestive-tract tumors	[51]
	2	Intravesicular	Rats	Tumors of internal organs	[52]
	3	Oral	Female rats	Tumors of the esophagus	[7]
	4	Oral	Male mice	Hepatocellular adenoma	[7]
	5	Oral	Rats	Hepatocellular carcinoma and cholangiofibroma	[7]
	6	Intravenous	Rats	Liver cancer	[7]
	7	Oral	Syrian golden hamsters	Malignant liver tumors	[[53], [54], [55]]
	8	Oral	Hamsters	Respiratory or digestive-tract tumors	[55]
	9	Oral	Hamsters	Tumors of the respiratory tract and upper digestive tract	[55]