How prevalent drunken flying is is difficult to tell. A search for the word intoxicated in the NTSB database, from 2000 to the present, returns 44 accidents of which 35 were fatal. A number of these involved cocaine, marijuana and various kinds of medications like painkillers and antidepressants rather than, or sometimes in addition to, alcohol. Whereas a high level of ethanol in tissues, after making allowance for products of putrefaction, provides a generally accepted postmortem test of intoxication, the influences of recreational and medical drugs are more uncertain. The NTSB, in its zeal to connect drugs to accidents, has contrived to forge causal links even when drug residues appear only at very low levels during forensic testing. The victim is then said to have been impaired by "withdrawal symptoms."