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                                              EXHIBIT 4.3



                               FIRST AMENDMENT TO
                         THE REVOLVING CREDIT AGREEMENT
                         ------------------------------


        FIRST AMENDMENT to the Amended and Restated Revolving Credit Agreement
dated as of August 1, 1994 (as amended, the "Credit Agreement"), by and among 
CLEAN HARBORS, INC., a Massachusetts corporation (the "Parent"), its
Subsidiaries listed on Schedule 1 hereto (the "Subsidiaries", the Parent and
such Subsidiaries herein collectively referred to as the "Borrowers"), each of
which Borrowers (unless otherwise listed on  Schedule 1 hereto) having its
principal place of business at 1200 Crown Colony Drive, Quincy, Massachusetts
02269, CLEAN HARBORS OF BALTIMORE, INC., a Pennsylvania corporation with its
principal place of business at 1200 Russell Street, Baltimore, Maryland (the
"Guarantor"), and THE FIRST NATIONAL BANK OF BOSTON ("FNBB"), a national
banking association having its principal place of business at 100 Federal
Street, Boston, Massachusetts 02110, SHAWMUT BANK, N.A. ("Shawmut"), a national
banking association having its principal place of business at One Federal
Street, Boston, Massachusetts 02111, and  USTRUST  ("USTrust"), a Massachusetts
trust company having its principal place of business at 40 Court Street,
Boston, Massachusetts 02108 (herein collectively referred to as the "Banks"),
and FNBB, as agent for the Banks (the "Agent").

        WHEREAS, the Parent has notified the Agent of an Event of Default with
respect to 8.3 of the Credit Agreement for the fiscal quarter ending December
31, 1994 and the probable occurrence of a Default with respect to  [SECTION] 
8.4 of the Credit  Agreement in the first quarter of 1995 (the "Covenant
Default");

        NOW THEREFORE, for good and valuable consideration the receipt and
sufficiency of which is hereby acknowledged, the parties agree to amend the
Credit Agreement as follows:


        1.   Subsections (a) and (b) in definition of "Borrowing Base"
appearing in [SECTION] 1.1 of the Credit Agreement and the words "the sum of"
appearing immediately prior thereto are deleted and the following new
subsections are substituted in their place:

             "(a) until March 31, 1995,  80% of Eligible Receivables for which
invoices have been issued and are payable; or (b) on and after March 31, 1995,
75% of Eligible Receivables for which invoices have been issued and are
payable."


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        2.   The first sentence of [SECTION] 2.1 of the Credit Agreement is
amended by deleting the semicolon and the text appearing thereafter beginning
with the words "and  provided further."

        3.   The word "monthly" appearing in [SECTION]  2.8 and the clause "not
later than 15 days after the end of each month" appearing in [SECTION]
6.4(d)(ii) of the Credit Agreement is deleted and the word "weekly" is
substituted in both places.

        4.   [SECTION] 7.3 of the Credit Agreement is amended by deleting the
amount "$10,000,000" appearing in (g) therein and substituting "$1,000,000" in
its place, and by adding the following new (h) at the end thereof:

             "(h) Investments in Northeast Casualty Risk Retention Group 
        (NCRRG) not to exceed $5,000,000 at any time in the aggregate."
       
        5.   [SECTION] 7.4 of the Credit Agreement is deleted in its entirety
and the following new section is substituted in its place:

             "[SECTION] 7.4.  MERGERS,  CONSOLIDATIONS, SALES. None of the
        Borrowers nor the Guarantor shall be a party to any merger,
        consolidation or exchange of stock, or purchase or otherwise acquire
        all or substantially all of the assets or stock of any class of, or any
        partnership or joint venture interest in, any other Person (including
        without limitation the acquisition or purchase of the Ecova Facility or
        the assets, stock or interests of and any Person owning the Ecova
        Facility) or sell, transfer, convey or lease any assets or group of
        assets (except sales of equipment in the ordinary course of business)
        or sell or assign, with or without recourse, any receivables; provided
        that Clean Harbors of Cleveland, Inc. may sell any account receivable
        contributed to it by the Parent to the Subsidiary that generated such
        receivable (the "Permitted Dispositions"). Notwithstanding the
        foregoing, if the Borrowers or the Guarantor shall sell any assets or
        any group of assets (except sales of equipment in the ordinary course
        of business), the proceeds of such sale shall be applied to the
        repayment of outstanding Loans hereunder, or, if no Loans are
        outstanding, such proceeds in an amount equal to the Maximum Drawing
        Amount of the then outstanding Letters of Credit shall be deposited
        with the Agent as cash collateral for the Reimbursement Obligations
        with respect to such Letters of Credit."

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         6.   The following new  [SECTION]  7.12 is added to the Credit
Agreement:

              "[SECTION]  7.12  ECOVA EXPENDITURES. Notwithstanding
         anything herein to the contrary, the Borrowers and the
         Guarantor will not make any expenditures (including without any
         limitation, any Investment, license arrangement, assumption of
         liabilities (contingent or otherwise), loans, cash advances,
         deposits, prepayments of disposal fees, guarantees, letters of
         credit, insurance, bonds, or financial commitments of any
         nature but excluding market-rate tipping fees incurred for
         hazardous wastes actually delivered by the Borrowers or the
         Guarantor) with respect to the hazardous waste incinerator (and
         associated equipment and real property) located in Kimball
         Nebraska (the "Ecova Facility") in excess of $5,000,000 in the
         aggregate."
         
         7.   [SECTION]  8.3 of the Credit Agreement is amended by 
deleting the table and substituting the following table in its place.

<Caption
              Fiscal Quarters Ending               Ratio
              -----------------------              -----

                                              
              Closing Date through 9/30/94       1.75: 1

              12/31/94                            1.5: 1

              3/31/95-9/30/95                     1.1: 1

              12/31/95                            1.5: 1

              3/31/96                            1.75: 1

              Thereafter                            2: 1



         8.   The text of  [SECTION]  8.4 of the Credit Agreement is deleted in
its entirety and the following is substituted in its place:

              "The Borrowers and the Guarantor will not permit (a)
        Consolidated Net Loss to be greater than ($1,750,000) for the quarter
        ending 12/31/94, or ($600,000) for the quarter ending 3/31/95, or (b)
        Consolidated Net Income to be less than $0 in any two consecutive
        quarters commencing with and including the two quarters ending
        6/30/95."

         9.   [SECTION]  12.1 of the Credit Agreement is amended by deleting
the text appearing after (m) and inserting the following text in its place:

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        "then, and in any such event, so long as the same may be continuing, 
        upon the request of the Majority Banks, the Agent shall, by
        notice in writing to the Borrowers and the Guarantor, declare all
        amounts owing with respect to this Agreement, the Notes and the other
        Loan Documents and all Reimbursement Obligations to be, and they shall
        thereupon forthwith become, immediately due and payable without
        presentment, demand, protest or other notice of any kind, all of which
        are hereby expressly waived by the Borrowers and the Guarantor;  
        provided that in the event of any Event of Default specified in
        [SECTION] 12(g) or 12(h), all such amounts shall become immediately due
        and payable automatically and without any requirement of notice from
        the Agent or any Bank.  Upon demand by the Majority Banks after the
        occurrence of any Event of Default, the Borrowers shall immediately
        provide to the Agent cash in an amount equal to the aggregate Maximum
        Drawing Amount of all Letters of Credit outstanding, to be held by the
        Agent as collateral security for the Obligations."


        10.  The Borrowers and Guarantor hereby represent and warrant that to
their knowledge the Covenant Default is the only Default or Event of Default
under the Credit Agreement or any other agreement or indenture binding on them
or any one of them.

        11.  All capitalized terms not defined herein shall have the meanings
ascribed to such terms in the Credit Agreement.  Except as specifically amended
hereby, the provisions of the Credit Agreement, the other Loan Documents and
all documents, instruments and agreements related thereto are hereby ratified
and confirmed in all respects and shall remain in full force and effect.

        12.  THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS AND SHALL TAKE EFFECT AS A
SEALED INSTRUMENT IN ACCORDANCE WITH SUCH LAWS.

        13.  This Amendment may be executed in any number of counterparts and
by different parties hereto on separate counterparts, each of which when so
executed and delivered shall be an original, but all of which counterparts
taken together shall be deemed to constitute one and the same instrument. 
Complete sets of counterparts shall be lodged with the Agent.

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        IN WITNESS WHEREOF, the parties have executed this Amendment this ___
day of January, 1995; to be effective as of December 31, 1994 upon the receipt
by the Agent of the following:

        (a) An amendment fee in the amount of $50,000, to be shared by the
        Banks according to their Commitment Percentages; and

        (b) Executed financing statements listed on Schedule A hereto.
                                                    --------


                                 THE BORROWERS:
                                 --------------
                                 
                                 CLEAN HARBORS, INC.


                                     
                                 By:         /s/ JAMES A. PITTS
                                     ---------------------------------------
                                 Title: 
                                        ------------------------------------
                                     

                                 CLEAN HARBORS
                                 ENVIRONMENTAL SERVICES, INC.



                                 By:         /s/ JAMES A. PITTS
                                     ---------------------------------------
                                 Title: 
                                        ------------------------------------




                                     CLEAN HARBORS OF NATICK, INC.




                                 By:         /s/ JAMES A. PITTS
                                     ---------------------------------------
                                 Title: 
                                        ------------------------------------



                                     CLEAN HARBORS OF BRAINTREE, INC.



                                 By:         /s/ JAMES A. PITTS
                                     ---------------------------------------
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                               Title: 
                                      --------------------------------------

                               CLEAN HARBORS KINGSTON
                                FACILITY CORPORATION



                               By:          /s/ JAMES A. PITTS
                                      --------------------------------------
                               Title: 
                                      --------------------------------------

                               CLEAN HARBORS OF CHICAGO, INC.



                               By:          /s/ JAMES A. PITTS
                                      --------------------------------------
                               Title: 
                                      --------------------------------------



                                                
                               CLEAN HARBORS OF CLEVELAND, INC.



                               By:          /s/ JAMES A. PITTS
                                      --------------------------------------
                               Title: 
                                      --------------------------------------




                               MURPHY'S WASTE OIL SERVICE, INC.



                               By:          /s/ JAMES A. PITTS
                                      --------------------------------------
                               Title: 
                                      --------------------------------------


                               CLEAN HARBORS OF
                               CONNECTICUT, INC.

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                            By: ________________________________________
                            Title: _____________________________________


                            
                            MR. FRANK, INC.


                            
                            By: ________________________________________   
                            Title: _____________________________________
                             
                            
                               
                            CLEAN HARBORS TECHNOLOGY
                            CORPORATION


                            By: ________________________________________
                            Title: _____________________________________


                            SPRING GROVE RESOURCE
                            RECOVERY, INC.


                            By: ________________________________________
                            Title: _____________________________________


                            The Guarantor:
                            -------------
                            CLEAN HARBORS OF BALTIMORE, INC.  
                            
                            



                            By: ________________________________________
                            Title: _____________________________________


                            The Banks:
                            ----------

                            THE FIRST NATIONAL BANK OF BOSTON, 
                            individually and as Agent
                            
                            
                            By: ________________________________________
                            Title: _____________________________________
                            
                            
                            
                            
                            
                            
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                              SHAWMUT BANK, N.A.


                              By: ____________________________________
                              Title: _________________________________



                              USTRUST


                              By: ____________________________________ 
                              Title: _________________________________