“…However, as shown in Table, the amounts and sizes of particles have varied between the different studies (Howie et al 1988, Goodman 1994, Bobyn et al 1995, Dowd et al 1995, Frökjaer et al 1995, Goodman et al 1995, 1999, Kraemer et al 1995, Allen et al 1996, Aspenberg and Herbertsson 1996, Shanbhag et al 1997, Van Der Vis et al 1997, Kim et al 1998, Frökjaer et al 1999, Lalor et al 1999, Brooks et al 2000, Rahbek et al 2000, 2001, Bechtold et al 2001, Bi et al 2001b, Sundfeldt et al 2002. The time of introduction of the particles and the design of the studies also varied greatly.…”