A method is presented for calculating the dissolution rate constant of a bo
rosilicate glass fiber in the lung, as measured in vitro, from the oxide co
mposition in weight percent. It is based upon expressing the logarithm of t
he dissolution rate as a linear function of the composition, it was found t
hat the calculated dissolution rate constant agreed with the measured value
within the variation of the measured data in a set of compositions in whic
h the dissolution rate constant ranged over a factor of 100. The method was
shown to provide a reasonable estimate of dissolution over a considerably
wider range of composition than what was used to determine the parameters,
such as a set of data in which the dissolution rate constant varied over a
factor of 100,000. The dissolution rate constant may be used to estimate wh
ether disease would ensue following animal inhalation or intraperitoneal st
udies.