The Collaborative International Dictionary of English v.0.48:

Disintegrate \Dis*in"te*grate\, v. t. [imp. & p. p.
   Disintegrated; p. pr. & vb. n. Disintegrating.] [L. dis-
   + integratus, p. p. of integrare to renew, repair, fr.
   integer entire, whole. See Integer.]
   To separate into integrant parts; to reduce to fragments or
   to powder; to break up, or cause to fall to pieces, as a
   rock, by blows of a hammer, frost, rain, and other mechanical
   or atmospheric influences.
   [1913 Webster]

         Marlites are not disintegrated by exposure to the
         atmosphere, at least in six years.       --Kirwan.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "disintegrating":
   ablative, biodegradable, coming apart, corrosive, cracking,
   crumbling, decadent, declining, decomposable, decomposing,
   decrepit, degenerate, degradable, deteriorating, dilapidated,
   disintegrable, disintegrated, disintegrative, disjunctive,
   disruptive, draining, drooping, dwindling, ebbing, effete, erosive,
   fading, failing, falling, flagging, fragmenting, going to pieces,
   infirm, languishing, marcescent, moldering, pining, poor, poorish,
   ravaged, regressive, resolvent, retrograde, retrogressive, rotten,
   rotten at, ruinous, separative, shriveling, sinking, sliding,
   slipping, slumping, solvent, subsiding, tabetic, unfirm, unsolid,
   unsound, unstable, unsturdy, unsubstantial, waning, wasting,
   wilting, withering, worn, worsening