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           AMENDMENT TO LOAN AND SECURITY AGREEMENT AND LOAN DOCUMENTS

THIS AMENDMENT TO LOAN AND SECURITY AGREEMENT AND LOAN DOCUMENTS (this 
"Amendment"), dated as of August 29, 1997, is between NATIONAL BANK OF 
CANADA, a Canadian chartered bank ("Lender"), and CET ENVIRONMENTAL 
SERVICES, INC., a California corporation ("Borrower").

                                   RECITALS

A.  Lender and Borrower entered into a Loan and Security Agreement dated 
    May 29, 1997 (the "Loan Agreement"), providing for the Revolving Loans, 
    Equipment Loans, Term Loan and Letters of Credit in the aggregate maximum 
    available amount not to exceed $9,000,000. Defined terms used herein and 
    not defined herein shall have the meaning set forth in the Loan Agreement.

B.  The Loans are secured by the Collateral.

C.  The Borrower and Lender desire to enter into this Amendment in order to 
    increase the amount of Letters of Credit that may be issued pursuant to 
    the Loan Agreement.

                                  AGREEMENT

IN CONSIDERATION of the foregoing and other good and valuable consideration, 
the receipt and sufficiency of which are hereby acknowledged, Lender and 
Borrower agree as follows:

1.  AMENDMENT TO LOAN AGREEMENT. In order to increase to the maximum amount of 
    Letters of Credit that may be issued, subsection (i) of Section 2(c) of the 
    Loan Agreement is hereby amended by replacing the phrase "FIVE HUNDRED 
    THOUSAND DOLLARS ($500,000)" with the phrase "ONE MILLION FIVE HUNDRED
    THOUSAND DOLLARS ($1,500,000)".

2.  TERM LOAN ADVANCE. Lender may agree to advance all or a portion of the
    Term Loan to Borrower prior to Lender having a perfected first priority 
    lien on all vehicles owned by Borrower. However, Lender is not waiving 
    the requirement that Borrower provide Lender a valid, perfected first 
    priority lien on all vehicles owned by Borrower. Accordingly, if Lender
    elects to make an advance of the Term Loan, Lender hereby agrees that 
    Borrower shall have twenty (20) days following the advance of the Term 
    Loan to deliver to Lender the vehicle titles required pursuant to 
    Section 4(j) of the Loan Agreement and take all other actions required 
    in order to grant Lender a valid perfected first priority lien on all 
    vehicles owned by Borrower. If such vehicle titles have not been delivered 
    to Lender within twenty (20) days after such advance or Borrower fails to 
    take all other actions requested by Lender in order to grant Lender a valid,
    perfected first


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    priority lien on all vehicles owned by Borrower, such failure shall, at 
    the Lender's option, be an Event of Default under Section 13 of the Loan 
    Agreement.

3.  LOAN DOCUMENTS.

    a.  Lender and Borrower agree that any and all notes or other documents 
        executed in connection with the Loans (collectively, the "Loan
        Documents") are hereby amended to reflect the amendments set forth 
        herein and that no further amendments to any Loan Documents are 
        required to reflect the foregoing.

    b.  All references in any document to the Loan Agreement or any
        other Loan Document shall refer to the Loan Agreement or such Loan
        Document as amended pursuant to this Amendment.

4.  CONDITIONS PRECEDENT.  The obligations of Lender under this Amendment are 
    subject to the satisfaction of the following conditions:

    a.  Borrower shall have executed and delivered this Amendment; and

    b.  No Event of Default or Unmatured Event of Default shall have occurred 
        as of the date hereof.

5.  REPRESENTATIONS AND WARRANTIES.  Borrower hereby certifies to the Lender 
    that as of the date of this Amendment (taking into consideration the 
    transactions contemplated by this Amendment), all of Borrower's 
    representations and warranties contained in the Loan Agreement and all 
    Loan Documents are true, accurate and complete in all material respects, 
    and no Event of Default or event that with notice or the passage of time 
    or both would constitute an Event of Default has occurred under the Loan
    Agreement or any Loan Document. Without limiting the generality of the 
    foregoing, Borrower represents and warrants that the execution and delivery
    of this Amendment has been authorized by all necessary action on the part 
    of Borrower, that the person executing this Amendment on behalf of Borrower
    is duly authorized to do so and that this Amendment constitutes the legal, 
    valid, binding and enforceable obligation of Borrower.

6.  ADDITIONAL DOCUMENTS. Borrower shall execute and deliver to Lender at any 
    time and from time to time such additional amendments to the Loan Agreement 
    and the Loan Documents as the Lender may request to confirm and carry out
    the transactions contemplated hereby or to confirm, correct and clarify 
    the security for the Loan.

7.  CONTINUATION OF THE LOAN AGREEMENT, ETC. Except as specified in this 
    Amendment, the provisions of the Loan Agreement and the Loan Documents shall
    remain in full force and effect, and if there is a conflict between the 
    terms of this Amendment and those of the Loan Agreement or the Loan 
    Documents, the terms of this Amendment shall control.

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8.  MISCELLANEOUS.

    a.  This Amendment shall be governed by and construed under the laws of 
        the State of Colorado and shall be binding upon and inure to the 
        benefit of the parties hereto and their successors and permissible 
        assigns.

    b.  This Amendment may be executed in two or more counterparts, each of 
        which shall be deemed an original and all of which together shall 
        constitute one instrument.

    c.  This Amendment and all documents to be executed and delivered 
        hereunder may be delivered in the form of a facsimile copy, 
        subsequently confirmed by delivery of the originally executed 
        document.

    d.  Time is of the essence hereof with respect to the dates, terms and 
        conditions of this Amendment and the documents to be delivered 
        pursuant hereto.

    e.  This Amendment constitutes the entire agreement between Borrower and 
        the Lender concerning the subject matter of this Amendment. This 
        Amendment may not be amended or modified orally, but only by a 
        written agreement executed by Borrower and the Lender and designated 
        as an amendment or modification of the Loan Agreement as amended by 
        this Amendment.

    f.  If any provision of this Amendment shall be held invalid, illegal or 
        unenforceable, the validity, legality and enforceability of the 
        remaining provisions of this Amendment shall not be impaired thereby.

    g.  The section headings herein are for convenience only and shall not 
        affect the construction hereof.

    h.  Execution of this Amendment is not intended to and shall not 
        constitute a waiver by the Lender of any Event of Default.

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    EXECUTED as of the date first set forth above.


                                       BORROWER:

                                       CET ENVIRONMENTAL SERVICES,
                                       INC., a California corporation


                                       By: /s/ Rick C. Townsend
                                          ---------------------------
                                          Rick C. Townsend
                                          Executive Vice President



                                       LENDER:

                                       NATIONAL BANK OF CANADA, a
                                       Canadian chartered bank


                                       By: /s/ Andrew M. Conneen, Jr.
                                          ---------------------------
                                          Andrew M. Conneen, Jr.
                                          Vice President


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