Table 1.

Volatile compounds present in halitosis [23,30,31,32,33,44,47,48].

Group of Compounds	Compound Name	Chemical Formula	Chemical Structure	Odor Threshold (ppm) [49,50,51,52]	Toxicity in Rats LD50 (mg/kg)
Volatile sulfur compounds (VSC)	Hydrogen sulfide	H2S		0.00004	15 [53]
	Methyl mercaptan	CH4S		5.1 × 10−13	61 (unspecified mammal species) [54]
	Dimethyl sulfide	C2H6S		0.00012	3300 [54,55]
	Dimethyl disulfide	C2H6S2		0.00029	190 [54]
	Dimethyl trisulfide	C2H6S3		no data	no data
	Allyl methyl sulfide	C4H8S		0.00014	no data
Aromatic compounds	Pyridine	C5H5N		0.01	360–891 [54,55]
	Picoline	C6H7N		0.0026	200–790 [54,55]
	Indole	C8H7N		0.0003	1000 [54,55]
	Skatole	C9H9N		0.0000056	3450 [54,55]
Amines	Ammonia	H3N		0.043	350 [56]
	Urea	CH4N2O		no data	567–8471 [54,55]
	Methylamine	CH5N		0.00075	100 [54,55]
	Dimethylamine	C2H7N		0.00076	698 [54,55,57]
	Trimethylamine	C3H9N		0.00002	500–535 [54,55]
	Putrescine	C4H12N		no data	463–2000 [54,55,58]
	Cadaverine	C5H14N		no data	2000 [58]
Short/medium fatty or organic acids	Acetic acid	C2H4O2		0.0004	3310 [54,55]
	Propionic acid	C3H6O2		0.00099	2600–3500 [54,55]
	Butyric acid	C4H8O2		0.001	1500–2000 [54,55]
	Valeric acid	C5H10O		0.000037	2000–4600 [59]
	Isovaleric acid	C5H10O		0.000078	2 [54]
Alcohols	Methanol	CH4O		3.05	2131–7529 [54,55]
	Ethanol	C2H6O		0.09	1440–7060 [54,55]
	Propanol	C3H8O		0.031	590–2200 [54,55]
Aliphatic compounds	Cyclopropane	C3H6		no data	no data
	Cyclobutane	C4H8		no data	no data
	Pentane	C5H12		1.29	400–>2000 [54,55]
Aldehydes and ketones	Acetaldehyde	C2H4O		0.0015	640–1930 [54,55]
	Acetone	C3H6O		0.4	5500–5800 [54,55,57]
	Acetophenone	C8H8O		0.00024	815–2650 [54,55]
	Benzophenone	C13H10O		no data	>10,000 [54,55]