Exhibit 10.21
                          CONTINGENT WARRANT AGREEMENT


         This Contingent  Warrant  Agreement (this  "Agreement") is executed and
delivered by Exsorbet  Industries,  Inc. an Idaho Corporation for the benefit of
American Physicians Service Group, Inc., a Texas corporation ("APS").

                                    RECITALS

         WHEREAS, Exsorbet and APS are engaging in certain transactions pursuant
to which,  among other things,  certain  shareholders of Exsorbet are to execute
and deliver option  agreements to APS authorizing APS to purchase certain shares
of Exsorbet common stock (the "Option Agreements"); and

         WHEREAS,  Exsorbet has agreed that,  in the event of any default  under
any of the Option  Agreements,  Exsorbet will sell the  corresponding  number of
shares of Exsorbet common stock to APS as necessary to allow APS to purchase the
same  number of shares as would  have been the case had there not been a default
under the applicable Option Agreements; and

         WHEREAS,  certain of the  stockholders  who were to execute and deliver
Option Agreements to APS at the closing of the transactions  contemplated  above
(the  "Closing")  have not done  so,  resulting  in APS  receiving  total  share
purchase rights which are 400,000 shares less than originally bargained for, and
Exsorbet  has  agreed to execute  and  deliver  this  Agreement  to APS  whereby
Exsorbet will either cause such additional  Option Agreements to be executed and
delivered to APS or will sell the corresponding number of shares to APS.

         NOW,  THEREFORE,  in  consideration of the foregoing and other good and
valuable  consideration,   the  receipt  and  sufficiency  of  which  is  hereby
acknowledged, Exsorbet hereby agrees as follows:

         1.  Exsorbet  will use its  best  efforts  to cause  one or more of its
shareholders  to execute and  deliver,  on or before  October 30,  1996,  option
agreements (the  "Additional  Options") to APS allowing APS to purchase,  in the
aggregate,  400,000 shares of Exsorbet common stock at a purchase price of $2.75
per share. The Additional  Options shall be exercisable at any time prior to the
expiration  of sixty (60) days from the date  executed and  delivered to APS, in
substance and form  acceptable to APS and shall otherwise be in the same form as
the Option  Agreements  delivered at the Closing.  The 400,000 shares subject to
the Additional  Options shall be in addition to the shares covered by the Option
Agreements delivered at the Closing.

         2. In the event  Exsorbet  is  unsuccessful,  on or before  October 30,
1996,  in  causing  the  execution  and  delivery  to APS of all the  Additional
Options,  then  Exsorbet  will execute and deliver to APS a warrant to purchase,
for $2.75 per share, the number of shares of Exsorbet common stock as determined
by  subtracting  the number of shares  purchasable  by APS under any  Additional
Options  that were  obtained  and  delivered to APS by October 30, 1996 from the
400,000 share total.

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Such additional warrant shall be exercisable at any time prior to the expiration
of sixty  (60) days  from the date  executed  and  delivered  to APS,  and shall
otherwise be identical in form to that  certain  Common Stock  Purchase  Warrant
Certificate dated September 30, 1996, pursuant to which Exsorbet granted APS the
right to purchase up to 300,000  shares of Exsorbet  common stock (the "Original
Warrant').

         3. The 400,000 share total referred to in paragraphs 1 and 2 above, and
the corresponding  $2.75 per share purchase price,  shall be subject to the same
automatic adjustments as provided for in the Original Warrant.

         4. This  Agreement  shall be construed and enforced in accordance  with
the laws of the  State of  Texas.  Exsorbet  acknowledges  and  agrees  that its
delivery of this Agreement and its performance of its obligations  hereunder are
a material  inducement to APS agreeing to  consummate  the  transactions  at the
Closing.

         IN WITNESS WHEREOF, Exsorbet has executed and delivered this Agreement,
intending to be legally bound thereby, on September 30, 1996.

                                                     EXSORBET INDUSTRIES, INC.


                                                     By:
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