According to the abhidharma systems of Vasubandhu and Asanga, phenomena can be divided into those that are tainted (zag-bcas, Skt. sasrava, contaminated) and those that are untainted (zag-med, Skt. anasrava, uncontaminated). In general terms, tainted phenomena constitute what is known as "samsara," the uncontrollably recurring situations of rebirth under the influence of impulses (karma) and disturbing emotions and attitudes, and which entail suffering. Untainted phenomena are either free from these situations or lead to such freedom.
Vasubandhu's Presentation According to the Vaibhashika System
In A Treasure House of Special Topics of Knowledge (Chos mngon-pa'i mdzod, Skt. Abhidharmakosha), Vasubandhu defines tainted phenomena as those that cause tainted phenomena to extend further. The tainted phenomena that are caused to extend further are the root and auxiliary disturbing emotions and attitudes, either in our own mental continuum or in the mental continuums of others.
The tainted phenomena that serve as the causes or conditions for disturbing emotions and attitudes to extend further are all nonstatic (impermanent) phenomena, other than true pathway minds. True pathway minds (true paths), the fourth noble truth, are non-conceptual cognitions of the four noble truths and of the selflessness of the person cognizing them. All nonstatic phenomena other than true pathway minds cause disturbing emotions and attitudes to extend further by being either their focal objects or by being the primary consciousness and accompanying mental factors that are congruent with them.
All true pathway minds and all static phenomena, such as true stoppings (true cessations), the third noble truth, are untainted.
Asanga's Presentation According to the Chittamatra System
In An Anthology of Special Topics of Knowledge (Chos mngon-pa kun-las btus-pa, Skt. Abhidharmasamuccaya), Asanga defines tainted phenomena as those that are related to any of the six gateways for being tainted. Thus, Asanga specifies six categories of tainted phenomena:
(1) Phenomena having the identity-nature of being a taint (zag-pa'i bdag-nyid) – the root and auxiliary disturbing emotions and attitudes.
(2) Phenomena conjoined with taints (zag-pa-dang 'brel-ba) – the primary consciousness and other mental factors congruent with the root and auxiliary disturbing emotions and attitudes, as well as the cognitive sensors (dbang-po), such as the photosensitive cells of the eyes, that are the dominating conditions (bdag-rkyen) for them to arise.
(3) Phenomena that bind one with taints (zag-pas bcings-pa) – the constructive phenomena that throw one into a future samsaric rebirth.
(4) Phenomena that are the follow-up of taints (zag-pa'i rjes-su 'brel-ba) – the ordinary beings of the plane of ethereal forms (form realm) and plane of formless beings (formless realm), thrown into such rebirth states by the tainted karmic legacies (sa-bon, karmic seeds, karmic tendencies) built up while in the plane of sensory desires (desire realm).
(5) Phenomena harmonious with taints (zag-pa'i rjes-su mthun-pa) – objects which, when focused upon, can cause disturbing emotions or attitudes to arise.
(6) Phenomena that are the outcome of tainted causes (zag-pa'i rgyu-las byung-ba) – the ripened aggregates of a liberated being (arhat), which are the ripened result (rnam-smin-gyi 'bras-bu) of tainted causes, such as craving (sred-pa). This refers to the body, mind, and so on of an arhat during the remainder of the lifetime in which the person has attained liberation. It also refers to the aggregates of any being of lesser attainment than an arhat. When tainted aggregates (zag-bcas-kyi phung-po) are differentiated from obtaining aggregates (nyer-len-gyi phung-po), "tainted" is used with this meaning. Obtaining aggregates are those that include the causes that will obtain for the person further samsaric rebirth, whereas tainted aggregates are those that have ripened from samsaric causes. Thus, the aggregates of the above-mentioned arhats are tainted, but not obtaining ones.
Asanga defines untainted phenomena as those that are not connected with any of the six gateways for being tainted. Thus, untainted phenomena also fall into six categories. Included are true pathway minds, true stoppings, and all static phenomena such as space, and the aggregate factors conjoined with them.
The Gelug Prasangika Presentation
Gelug Prasangika explains tainted phenomena to be those that are mixed with an appearance of true findable existence. Those that are not mixed with such an appearance, such as the aggregates of someone totally absorbed nonconceptually on the voidness of true findable existence, are untainted.