a Agents identified by IARC as known (1), probable (2A), or possible (2B) human carcinogens or by the NTP as known or reasonably anticipated to be carcinogens (NTP K or NTP R, if the agent has not been classified as 1, 2A, or 2B by IARC).
b For definition of terms and overall evaluations, see Preamble, pp.28-29 (IARC 1993).
c Where possible, synthetic agents (S) are distinguished from naturally occurring (N) (as defined in Chapter 1). Naturally occurring agents are subclassified into constitutive, derived, acquired, or added (as defined in Chapters 1 and 2).
d The TD01 is the chronic dose in mg/kg/day causing a 1% increase in tumors in experimental animals.