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                                                                   EXHIBIT 10.11

                          REGISTRATION RIGHTS AGREEMENT


     This Registration Rights Agreement, dated as of this 12th day of December,
1988, is made and entered into by Toxi-Lab, Inc., a California corporation (the
"Company"), Security Pacific National Bank, a national banking association
("SPNB"), First Interstate Capital, Inc., a California corporation ("FICI"), and
Birch Street Partners, a California general partnership ("BSP").

     1.   Background.

     The Company has entered into various securities purchase agreements with
the parties hereto (the "Purchase Agreements") pursuant to which the Company has
issued and sold to such parties, and such parties have purchased, (i) an
aggregate of 14,000 shares of Series B Convertible Preferred Stock, par value
$.0l per share, of the Company (the "Convertible Preferred Stock"), at a price
of $100 per share, which shares of Convertible Preferred Stock are convertible
into an aggregate of 303,448 shares of the Company's common stock, par value
$.0l per share (the "Common Stock"), and (ii) a warrant to purchase an aggregate
of 165,517 shares of Common Stock at an exercise price of $1.00 per share (the
"Warrant"), as follows: SPNB--the Warrant; FICI--13,860 shares of Convertible
Preferred Stock; and BSP--140 shares of Convertible Preferred Stock. Such shares
of Convertible Preferred Stock and the Warrant in the aggregate will comprise
approximately 68% of the issued and outstanding shares of Common Stock of the
Company on a fully diluted basis. This Agreement shall become effective upon the
issuance of the Convertible Preferred Stock and the Warrant to be sold under all
of the Purchase Agreements.

     2.   Definitions.

          As used in this Agreement, the following capitalized terms shall have
the following respective meaning specified below unless the context clearly
indicates to the contrary. All other capitalized terms used herein shall have
the meanings assigned to those terms elsewhere in this Agreement.

          Exchange Act - The Securities Exchange Act of 1934, as amended, and
     the rules and regulations thereunder or any similar federal statute then in
     effect, and a reference to a particular section thereof shall be deemed to
     include a reference to the comparable section, if any, of any such similar
     federal statute.

          Holder - Any party hereto (other than the Company) and any holder of
     Registrable Securities who agrees in writing to be bound by the provisions
     of this Agreement.

          Person - Any individual, partnership, joint venture, corporation,
     trust, association, unincorporated organization or government or any
     department or agency thereof.

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          Registrable Securities - Any Common Stock acquired upon conversion of
     the Convertible Preferred Stock or upon exercise of the Warrant issued or
     issuable pursuant to a Purchase Agreement, any Common Stock which may be
     issued or distributed in respect thereof by way of stock dividend or stock
     split or other distribution, recapitalization or reclassification, and the
     Warrant or any share of Convertible Preferred Stock issued or issuable
     pursuant to a Purchase Agreement; provided such Warrant and shares of
     Convertible Preferred Stock are sold to the underwriters pursuant to an
     agreement which requires such underwriters to exercise the Warrant or to
     convert the shares of Convertible Preferred Stock and to include the Common
     Stock acquired thereby in the registered public offering. As to any
     particular Registrable Securities, once issued such securities shall cease
     to be Registrable Securities when (i) a registration statement with respect
     to the sale of such securities shall have become effective under the
     Securities Act and such securities shall have been disposed of in
     accordance with such registration statement, (ii) they shall have been
     distributed to the public pursuant to Rule 144 (or any successor provision)
     under the Securities Act, (iii) they shall have been otherwise transferred,
     new certificates for them not bearing a legend restricting further transfer
     shall have been delivered by the Company and subsequent disposition of them
     shall not require registration or qualification of them under the
     Securities Act or any state securities or blue sky law then in force, or
     (iv) they shall have ceased to be outstanding.

          Registration Expenses - Any and all expenses incident to performance
     of or compliance with this Agreement, including, without limitation, (i)
     all SEC and stock exchange or National Association of Securities Dealers,
     Inc. registration and filing fees, (ii) all fees and expenses of complying
     with securities or blue sky laws (including fees and disbursements of
     counsel for the underwriters in connection with blue sky qualifications of
     the Registrable Securities), (iii) all printing, messenger and delivery
     expenses, (iv) all fees and expenses incurred in connection with the
     listing of the Registrable Securities on any securities exchange pursuant
     to clause (viii) of Section 5, (v) the fees and disbursements of counsel
     for the Company and its independent public accountants, including the
     expenses of any "cold comfort" letters required by or incident to such
     performance and compliance and (vi) any fees and disbursements of
     underwriters customarily paid by the issuers or sellers of securities,
     including liability insurance if the Company so desires or if the
     underwriters so require, and the reasonable fees and expenses of any
     special experts (excluding counsel) retained in connection with the
     requested registration, but excluding underwriting discounts and
     commissions and transfer taxes, if any.

          Securities Act - The Securities Act of 1933, as amended, the rules and
     regulations thereunder or any similar federal statute then in effect, and a
     reference to a particular section thereof shall be deemed to include a
     reference to the comparable section, if any, of any such similar federal
     statute.

          SEC - The Securities and Exchange Commission or any other federal
     agency at the time administering the Securities Act or the Exchange Act.



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     3.   Incidental Registration.

          (a)  Right to Include Registrable Securities. If the Company at any
time after the date hereof proposes to register its Common Stock or securities
convertible into, or exchangeable for, its Common Stock under the Securities Act
(other than a registration on Form S-4 or S-8, or any successor or other forms
promulgated for similar purposes), whether or not for sale for its own account,
it will each such time give prompt written notice to all Holders of Registrable
Securities of its intention to do so and of such Holders' rights under this
Section 3. Upon the written request of any such Holder made within 15 days after
the receipt of any such notice (which request shall specify the Registrable
Securities intended to be disposed of by such Holder), the Company will use its
best efforts to effect the registration under the Securities Act of all
Registrable Securities which the Company has been so requested to register by
the Holders thereof, to the extent requisite to permit the disposition of the
Registrable Securities so to be registered; provided, that (i) if, at any time
after giving written notice of its intention to register any securities pursuant
to this Section 3(a) and prior to the effective date of the registration
statement filed in connection with such registration, the Company shall
determine for any reason not to proceed with the proposed registration of the
securities to be sold by it, the Company may, at its election, give written
notice of such determination to each Holder of Registrable Securities and,
thereupon, shall be relieved of its obligation to register any Registrable
Securities in connection with such registration (but not from its obligation to
pay the Registration Expenses in connection therewith), and (ii) if such
registration involves an underwritten offering, all Holders of Registrable
Securities requesting to be included in the Company's registration must sell
their Registrable Securities to the underwriters selected by the Company on the
same terms and conditions as apply to the Company, with such differences,
including any with respect to indemnification and liability insurance, as may be
customary or appropriate in combined primary and secondary offerings. If a
registration requested pursuant to this Section 3(a) involves an underwritten
public offering, any Holder of Registrable Securities requesting to be included
in such registration may elect, in writing prior to the effective date of the
registration statement filed in connection with such registration, not to
register such securities in connection with such registration.

          (b)  Expenses. The Company will pay all Registration Expenses in
connection with each registration of Registrable Securities requested pursuant
to this Section 3. All other expenses of any registration pursuant to this
Section 3 including, without limitation, all underwriting discounts and
commissions and transfer taxes, shall be paid pro rata by the Company and all
other Persons (including the Holders) participating in such registration on the
basis of the relative number of shares of Common Stock of the Company and each
such Person included in such registration.

          (c)  Priority in Incidental Registrations. If a registration pursuant
to this Section 3 involves an underwritten offering and the managing underwriter
advises the Company in writing that, in its opinion, the number of securities
requested to be included in such registration exceeds the number which can be
sold in such offering, so as to be likely to have an adverse effect on such
offering as contemplated by the Company (including the price at which the
Company proposes to sell such securities), then the Company will include in such
registration 



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(i) first, 100% of the securities the Company proposes to sell, (ii) second, to
the extent of the number of Registrable Securities requested to be included in
such registration which, in the opinion of such managing underwriter, can be
sold without having the adverse effect referred to above, the number of
Registrable Securities which the Holders have requested to be included in such
registration, such amount to be allocated pro rata among all requesting Holders
on the basis of the relative number of shares of Registrable Securities then
held by each such Holder (provided that any shares thereby allocated to any such
Holder that exceed such Holder's request will be reallocated among the remaining
requesting Holders in like manner). For purposes of this provision, the term
Holders shall include all members of management of the Company and the term
Registrable securities shall include all shares of Common stock held by or
subject to options granted to such persons, to the extent necessary to reflect
all rights of registration to which such persons may be entitled with respect to
such shares prior to a public offering after the date hereof of shares of Common
Stock pursuant to an effective registration statement under the Securities Act.

     4.   Registration on Request.

          (a)  Request by Holders. At any time or from time to time after the
earlier of (i) 90 days after any of the Common Stock of the Company has been
registered after the date hereof under the Securities Act (other than a
registration on Form S-4 or S-8, or any successor or other forms promulgated for
similar purposes) or (ii) December 12, 1993, upon the written request of any
Holder or Holders of a majority of the shares of Registrable Securities
requesting that the Company effect the registration under the Securities Act of
all or part of such Holder's or Holders' Registrable Securities (constituting in
the aggregate at least 200,000 shares or such lesser number of Registrable
Securities then outstanding) or, in the case or the Company-Paid Demand (as
hereinafter defined) upon the written request of any Holder or Holders of
two-thirds of the shares of Registrable Securities (constituting in the
aggregate at least 200,000 shares or such lesser number of Registrable
Securities then outstanding) and specifying the intended method of disposition
thereof, the Company will promptly give written notice of such requested
registration (which request shall specify the intended method of disposition of
such Registrable Securities) to all other Holders of Registrable Securities, and
thereupon will, as expeditiously as possible, use its best efforts to effect the
registration under the Securities Act of:

               (i)  the Registrable Securities which the Company has been so
          requested to register by such Holder or Holders; and

               (ii) all other Registrable Securities which the Company has been
          requested to register by any other Holder thereof by written request
          given to the Company within 15 days after the giving of such written
          notice by the Company,

all to the extent necessary to permit the disposition (in accordance with the
intended method thereof as aforesaid) of the Registrable Securities so to be
registered; provided, that the Company shall not be obligated to file a
registration statement relating to any registration request under this Section
4(a), (A) (other than a registration statement on Form S-3 or any successor or
similar short-form registration statement) within a period of nine months after
the effective date of any



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other registration statement relating to any registration request under this
Section 4(a) which was not effected on Form S-3 (or any successor or similar
short-form registration statement) or relating to any registration effected
under Section 3 hereof or (B) if with respect thereto, the managing underwriter,
the SEC, the Securities Act or the rules and regulations thereunder, or the form
on which the registration statement is to be filed, would require the conduct of
an audit other than the regular audit conducted by the Company at the end of it
fiscal year, in which case the filing may be delayed until the completion of
such regular audit (unless the Holders agree to pay the expenses of the Company
in connection with such an audit other than the regular audit).

     (b)  Registration Statement Form. If any registration requested pursuant to
this Section 4 which is proposed by the Company to be effected by the filing of
a registration statement on Form S-3 (or any successor or similar short-form
registration statement) shall be in connection with an underwritten public
offering, and if the managing underwriter shall advise the Company in writing
that, in its opinion, the use of another form of registration statement is of
material importance to the success of such proposed offering, then such
registration shall be effected on such other form.

     (c)  Expenses. The Company shall pay all Registration Expenses in
connection with the first registration of Registrable Securities pursuant to
this Section 4 (the "Company-Paid Demand"). All other expenses of the first
registration pursuant to this section 4 including, without limitation, the
underwriting discounts and commissions and transfer taxes, shall be paid pro
rata by the Company and all other Persons (including the Holders) participating
in such registration on the basis of the relative number of shares of Common
Stock of the Company and each such Person included in such registration. All
expenses (including Registration Expenses) for any subsequent registrations of
Registrable Securities pursuant to this Section 4 shall be paid pro rata by the
Company and all other Persons (including the Holders) participating in such
registration on the basis of the relative number of shares of Common Stock of
the Company and each such Person included in such registration.

     (d)  Effective Registration Statement. A registration requested pursuant to
this Section 4 will not be deemed to have been effective unless it has become
effective; provided, that if, within 180 days after it has become effective, the
offering of Registrable Securities pursuant to such registration is interfered
with by any stop order, injunction or other order or requirement of the SEC or
other governmental agency or court, such registration will be deemed not to have
been effected.

     (e)  Selection of Underwriters. If a requested registration pursuant to
this Section 4 involves an underwritten offering, the Company shall have the
right to select the investment banker or bankers and managers to administer the
offering; provided, however, that such investment banker or bankers and managers
shall be satisfactory to Holders of a majority of the shares of Registrable
Securities and which the Company has been requested to register.

     (f)  Priority in Requested Registrations. If a requested registration
pursuant to this Section 4 involves an underwritten offering and the managing
underwriter advises the Company in writing that, in its opinion, the number of
securities requested to be included in such 



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registration (including securities of the Company which are not Registrable
Securities) exceeds the number which can be sold in such offering, the Company
will include in such registration only the Registrable Securities requested to
be included in such registration. In the event that the number of Registrable
Securities requested to be included in such registration exceeds the number
which, in the opinion of such managing underwriter, can be sold, the number of
such Registrable Securities to be included in such registration shall be
allocated pro rata among all requesting Holders on the basis of the relative
number of shares of Registrable Securities then held by each such Holder
(provided that any shares thereby allocated to any such Holder that exceed such
Holder's request shall be reallocated among the remaining requesting Holders in
like manner). In the event that the number of Registrable Securities requested
to be included in such registration is less than the number which, in the
opinion of the managing underwriter, can be sold without having an adverse
effect on such offering, the Company may include in such registration the
securities the Company proposes to sell up to the number of securities that, in
the opinion of the underwriter, can be sold.

     (g)  Additional Rights. If the Company at any time grants to any other
holders of Common Stock any rights to request the Company to effect the
registration under the Securities Act of any such shares of Common Stock on
terms more favorable to such holders than the terms set forth in this Section 4,
the terms of this Section 4 shall be deemed amended or supplemented to the
extent necessary to provide the Holders such more favorable rights and benefits.

     5.   Registration Procedures. If and whenever the Company is required to
use its best efforts to effect or cause the registration of any Registrable
securities under the Securities Act as provided in this Agreement, the Company
will, as expeditiously as possible:

          (a)  prepare and, in any event within 120 days after the end of the
period within which a request for registration may be given to the Company, file
with the SEC a registration statement with respect to such Registrable
Securities and use its best efforts to cause such registration statement to
become effective; provided, however, that the company may discontinue any
registration of its securities which is being effected pursuant to Section 3
hereof at any time prior to the effective date of the registration statement
relating thereto;

          (b)  prepare and file with the SEC such amendments and supplements to
such registration statement and the prospectus used in connection therewith as
may be necessary to keep such registration statement effective for a period of
at least 10 days, but not in excess of 180 days and to comply with the
provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement during such period in
accordance with the intended methods of disposition by the seller or sellers
thereof set forth in such registration statement; provided, that before filing a
registration statement or prospectus, or any amendments or supplements thereto,
the Company will furnish to one counsel selected by the Holders of a majority of
the Registrable Securities covered by such registration statement to represent
all Holders of Registrable Securities covered by such registration statement,
copies of all documents proposed to be filed, which documents will be subject to
the review of such counsel;



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          (c)  furnish to each seller of such Registrable Securities such number
of copies of such registration statement and of each amendment and supplement
thereto (in each case including all exhibits), such number of copies of the
prospectus included in such registration statement (including each form of
prospectus and summary prospectus), in conformity with the requirements of the
Securities Act, and such other documents as such seller may reasonably request
in order to facilitate the disposition of the Registrable Securities by such
seller;

          (d)  use its best efforts to register or qualify such Registrable
Securities covered by such registration statement under such other securities or
blue sky laws of such jurisdictions as each seller shall reasonably request, and
do any and all other acts and things which may be reasonably necessary or
advisable to enable such seller to consummate the disposition in such
jurisdictions of the Registrable Securities owned by such seller, except that
the Company shall not for any such purpose be required to qualify generally to
do business as a foreign corporation in any jurisdiction where, but for the
requirements of this clause (d), it would not be obligated to be so qualified,
to subject itself to taxation in any such jurisdiction, or to consent to general
service of process in any such jurisdiction;

          (e)  use its best efforts to cause such registrable securities covered
by such registration statement to be registered with or approved by such other
governmental agencies or authorities as may be necessary to enable the seller or
sellers thereof to consummate the disposition of such Registrable Securities;

          (f)  notify each seller of any such Registrable Securities covered by
such registration statement, at any time when a prospectus relating thereto is
required to be delivered under the Securities Act within the appropriate period
mentioned in clause (b) of this Section 5, of the Company's becoming aware that
the prospectus included in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading in the light of the circumstances then existing, and at the
request of any such seller, prepare and furnish to such seller a reasonable
number of copies of an amended or supplemented prospectus as may be necessary so
that, as thereafter delivered to the purchasers of such Registrable Securities,
such prospectus shall not include an untrue statement of a material fact or omit
to state a material fact required to be stated therein or necessary to make the
statements herein not misleading in the light of the circumstances then
existing;

          (g)  otherwise use its best efforts to comply with all applicable
rules and regulations of the SEC, and make available to its security holders, as
soon as reasonably practicable (but not more than eighteen months) after the
effective date of the registration statement, an earnings statement which shall
satisfy the provisions of section 11(a) of the Securities Act and the rules and
regulations promulgated thereunder;

          (h)  use its best efforts to list such Registrable Securities on any
securities exchange on which the Common Stock is then listed, if such
Registrable Securities are not already so listed and if such listing is then
permitted under the rules of such exchange, and to 



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Provide a transfer agent and registrar for such Registrable Securities covered
by such registration statement not later than the effective date of such
registration statement;

          (i)  enter into such customary agreements (including an underwriting
agreement in customary form) and take such other actions as sellers of a
majority of shares of such Registrable securities or the underwriters, if any,
reasonably request in order to expedite or facilitate the disposition of such
Registrable Securities;

          (j)  obtain a "cold comfort" letter or letters from the Company's
independent public accountants in customary form covering matters of the type
customarily covered by "cold comfort" letters as the seller or sellers of a
majority of shares of such Registrable Securities shall reasonably request
(provided that Registrable Securities constitute at least 25% of the securities
covered by such registration statement); and

          (k)  make available for inspection by any seller of such Registrable
Securities covered by such registration statement, by any underwriter
participating in any disposition to be effected pursuant to such registration
statement and by any attorney, accountant or other agent retained by any such
seller or any such underwriter, all pertinent financial and other records,
pertinent corporate documents and properties of the Company, and cause all of
the Company's officers, directors and employees to supply all information
reasonably requested by any such seller, underwriter, attorney, accountant or
agent in connection with such registration statement.

          The Company may require each seller of registrable Securities as to
     which any registration is being effected to furnish the Company with such
     information regarding such seller and pertinent to the disclosure
     requirements relating to the registration and the distribution of such
     securities as the Company may from time to time reasonably request in
     writing.

          Each Holder of Registrable Securities agrees that, upon receipt of any
     notice from the Company of the happening of any event of the kind described
     in clause (f) of this Section 5, such Holder will forthwith discontinue
     disposition of Registrable Securities pursuant to the registration
     statement covering such Registrable Securities until such Holder's receipt
     of the copies of the supplemented or amended prospectus contemplated by
     clause (f) of this Section 5, and, if so directed by the Company such
     Holder will deliver to the Company (at the Company's expense) all copies,
     other than permanent file copies then in such Holder's possession, of the
     prospectus covering such Registrable Securities current at the time of
     receipt of such notice. In the event the Company shall give any such
     notice, the period mentioned in clause (b) of this Section 5 shall be
     extended by the number of days during the period from and including the
     date of the giving of such notice pursuant to clause (f) of this Section 5
     and including the date when such seller of Registrable Securities covered
     by such registration statement shall have received the copies of the
     supplemented or amended prospectus contemplated by clause (f) of this
     Section 5.

6.   Indemnification.



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          (a)  Indemnification by the Company. In the event of any registration
of any securities of the Company under the Securities Act pursuant to Section 3
or 4 hereof, the Company will, and it hereby does, indemnify and hold harmless,
to the extent permitted by law, the seller of any Registrable Securities covered
by such registration statement, each affiliate of such seller and their
respective directors and officers or general and limited partners, legal counsel
and auditors (and the directors, officers, affiliates and controlling Persons
thereof), each other Person who participates as an underwriter in the offering
or sale of such securities and each other Person, if any, who controls such
seller or any such underwriter within the meaning of the Securities Act
(collectively, the "Indemnified Parties"), against any and all losses, claims,
damages or liabilities, joint or several, and expenses to which such seller, any
such director or officer or general or limited partner or affiliate or any such
underwriter or controlling Person may become subject under the Securities Act,
common law or otherwise, insofar as such losses, claims, damages or liabilities
(or actions or proceedings in respect thereof, whether or not such Indemnified
Party is a party thereto) arise out of or are based upon (a) any untrue
statement or alleged untrue statement of any material fact contained in any
registration statement under which such securities were registered under the
Securities Act, any form of, final or summary prospectus contained therein, or
any amendment or supplement thereto, or (b) any omission or alleged omission to
state therein a material fact required to be stated therein or necessary to make
the statements therein not misleading in the light of the circumstances then
existing, and the Company will reimburse such Indemnified Party for any legal or
any other expenses reasonably incurred by it in connection with investigating or
defending any such loss, claim, liability, action or proceeding; provided, that
the Company shall not be liable to any Indemnified Party in any such case to the
extent that any such loss, claim, damage, liability (or action or proceeding in
respect thereof) or expense arises out of or is based upon any untrue statement
or alleged untrue statement or omission or alleged omission made in such
registration statement or amendment or supplement thereto or in any such form
of, final or summary prospectus in reliance upon and in conformity with written
information furnished to the Company through an instrument duly executed by such
seller specifically stating that it is for use in the preparation thereof; and
provided, further, that the Company will not be liable to any Person who
participates as an underwriter in the offering or sale of Registrable Securities
or any of the Person, if any, who controls such underwriter within the meaning
of the Securities Act, under the indemnity agreement in this Section 6(a) with
respect to any form of prospectus or the final prospectus or the final
prospectus as amended or supplemented, as the case may be, to the extent that
any such loss, claim, damage or liability of such underwriter or controlling
Person results from the fact that such underwriter sold Registrable Securities
to a person to whom there was not sent or given, at or prior to the written
confirmation of such sale, a copy of the final prospectus (including any
documents incorporated by reference therein) or of the final prospectus as then
amended or supplemented (including any documents incorporated by reference
herein), whichever is most recent, if the Company has previously furnished
copies thereof to such underwriter. Such indemnity shall remain in full force
and effect regardless of any investigation made by or on behalf of such seller
or any Indemnified Party and shall survive the transfer of such securities by
such seller.

          (b)  Indemnification by the Sellers. The Company may require, as a
condition to including any Registrable Securities in any registration statement
filed in accordance with



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Section 5 hereof, that the Company shall have received an undertaking reasonably
satisfactory to it from the prospective seller of such Registrable Securities or
any underwriter to indemnify and hold harmless (in the same manner and to the
same extent as set forth in subdivision (a) of this Section 6) the Company and
all other prospective sellers with respect to any statement or alleged statement
in or omission or alleged omission from such registration statement, any form
of, final or summary prospectus contained therein, or any amendment or
supplement, if such statement or alleged statement or omission or alleged
omission was made in reliance upon and in conformity with written information
furnished to the Company through an instrument duly executed by such seller or
underwriter specifically stating that it is for use in the preparation of such
registration statement, form of, final or summary prospectus or amendment or
supplement, or a document incorporated by reference into any of the foregoing.
Such indemnity shall remain in full force and effect regardless of any
investigation made by or on behalf of the Company or any of the prospective
sellers, or any of their respective affiliates, directors, officers or
controlling Persons and shall survive the transfer of such securities by such
seller.

          (c)  Notices of claims, Etc. Promptly after receipt by an indemnified
party hereunder of written notice of the commencement of any action or
proceeding with respect to which a claim for indemnification may be made
pursuant to this Section 6, such indemnified party will, if a claim in respect
thereof is to be made against an indemnifying party, give written notice to the
latter of the commencement of such action; provided, that the failure of the
indemnified party to give notice as provided herein shall not relieve the
indemnifying party of its obligations under the preceding clauses of this
Section 6, except to the extent that the indemnifying party is actually
prejudiced by such failure to give notice. In case any such action is brought
against an indemnified party, unless in such indemnified party's reasonable
judgment a conflict of interest between such indemnified and indemnifying
parties may exist in respect of such claim, the indemnifying party will be
entitled to participate in and to assume the defense thereof, jointly with any
other indemnifying party similarly notified to the extent that it may wish, with
counsel reasonably satisfactory to such indemnified party, and after notice from
the indemnifying party to such indemnified party of its election so to assume
the defense thereof, the indemnifying party will not be liable to such
indemnified party for any legal or other expenses subsequently incurred by the
latter in connection with the defense thereof other than reasonable costs of
investigation. No indemnifying party will consent to entry of any judgment or
enter into any settlement which does not include as an unconditional term
thereof, the giving by the claimant or plaintiff to such indemnified party of a
release from all liability in respect to such claim or litigation.

          (d)  0ther Indemnification. Indemnification similar to that specified
in the preceding clauses of this Section 6 (with appropriate modifications)
shall be given by the Company and each seller of Registrable Securities with
respect to any required registration or other qualification of securities under
any federal or state law or regulation or governmental authority other than the
Securities Act.

          (e)  Non-Exclusivity. The obligations of the parties under this
Section 6 shall be in addition to any liability which any party may otherwise
have to any other party.



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     7.   Miscellaneous.

          (a)  Amendments and Waivers. This Agreement may be amended and the
Company may take any action herein prohibited, or omit to perform any act herein
required to be performed by it, only if the Company shall have obtained the
written consent to such amendment, action or omission to act, of the Holders of
two-thirds of the Registrable Securities then outstanding. Each Holder of any
Registrable Securities at the time or thereafter outstanding shall be bound by
any consent authorized by this Section 7(a), whether or not such Registrable
Securities shall have been marked to indicate such consent.

          (b)  Successors, Assigns and Transferees. This Agreement shall be
binding upon and shall inure to the benefit of the parties hereto and their
respective successors and assigns. In addition, and whether or not any express
assignment shall have been made, the provisions of this Agreement which are for
the benefit of the parties hereto other than the Company shall also be for the
benefit of and enforceable by any subsequent Holder of any Registrable
Securities, subject to the provisions contained herein.

          (c)  Notices. All notices and other communications provided for
hereunder shall be in writing and shall be sent by first class mail, telex,
telecopier or hand delivery:

               (i)  if to the Company, to:

                    Toxi-Lab, Inc.
                    2 Goodyear
                    Irvine, California 92718
                    Attn: Secretary

                    With a copy to:

                    Latham & Watkins
                    650 Town Center Drive
                    Twentieth Floor
                    Costa Mesa, California 92626
                    Attn: Jeffrey T. Pero, Esq.

               (ii) if to SPNB, to:

                    Security Pacific National Bank
                    4000 MacArthur Blvd.
                    Newport Beach, California 92660
                    Attn: Christopher A. Peterson


                    With a copy to:



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                   Cooley, Godward, Castro,
                   Huddleson & Tatum
                   Suite 1400
                   4675 MacArthur Court
                   Newport Beach, California 92660
                   Attn: Paul Jones, Esq.


             (iii) if to FICI or BSP, to:

                   First Interstate Venture Capital
                   Corporation
                   5000 Birch Street
                   Suite 10100
                   Newport Beach, California 92660
                   Attn: John M. Morris

All such notices and communications shall be deemed to have been given or made
(1) when delivered by hand, (2) five business days after being deposited in the
mail, postage prepaid, (3) when telexed answer-back received or (4) when
telecopied, receipt acknowledged.

          (d)  Descriptive Headings. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning of terms contained herein.

          (e)  Severability. In the event that any one or more of the
provisions, paragraphs, words, clauses, phrases or sentences contained herein,
or the application thereof in any circumstances, is held invalid, illegal or
unenforceable in any respect for any reason, the validity, legality and
enforceability of any such provision, paragraph, word, clause, phrase or
sentence in every other respect and of the remaining provisions, paragraphs,
words, clauses, phrases or sentences hereof shall not be in any way impaired, it
being intended that all rights, powers and privileges of the parties hereto
shall be enforceable to the fullest extent permitted by law.

          (f)  Counterparts. This Agreement may be executed in two or more
counterparts, and by different parties on separate counterparts, each of which
shall be deemed an original, but all such counterparts shall together constitute
one and the same instrument, and it shall not be necessary in making proof of
this Agreement to produce or account for more than one such counterpart.

          (g)  Governing Law. This Agreement shall be governed by and construed
and enforced in accordance with the laws of the State of California applicable
to contracts made and to be performed therein. The parties to this Agreement
hereby agree to submit to the jurisdiction 



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of the courts of the State of California in any action or proceeding arising out
of or relating to this Agreement.

          (h)  Voting by Holders of Registrable Securities. To the extent that
any provision of this Agreement calls for a vote or accounting of the Holders of
Registrable Securities to be taken, such vote or accounting shall assume that
each such Holder has exercised or converted its Registrable securities into
Common Stock.



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                                 SIGNATURE PAGE


        IN WITNESS WHEREOF, each of the undersigned has executed this Agreement
or caused this Agreement to be executed on its behalf as of the date first
written above.

                                        TOXI-LAB, INC.


                                        By:
                                            ------------------------------------
                                        Its:
                                            ------------------------------------



                                        SECURITY PACIFIC NATIONAL BANK


                                        By:
                                            ------------------------------------
                                        Its:
                                            ------------------------------------



                                        FIRST INTERSTATE CAPITAL, INC.


                                        By:
                                            ------------------------------------
                                        Its:
                                            ------------------------------------



                                        BIRCH STREET PARTNERS


                                        By:
                                            ------------------------------------
                                        Its:
                                            ------------------------------------



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