The possibility that parkinsonism might be caused by environmental MPTP present in soot formed from partial combustion of coal has been assessed. Soot was fractionated and the bases were examined by gas chromatography-mass spectrometry (GC-MS) for 1,2,3,6-tetrahydro-1-methyl-4-phenylpyridine (MPTP). Although this method was considered to be capable of detecting MPTP in soot at about 1 in 10(-6) its presence was not detected.