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                                                                     Exhibit 4.2


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                                 ALLWASTE, INC.
                                        
                                        
                                      AND
                                        
                                        
                             PHILIP SERVICES CORP.
                                        
                                        
                                       TO
                                        
                                        
                    TEXAS COMMERCE TRUST COMPANY OF NEW YORK
                                   as Trustee
                                        
                                        
                             _____________________
                                        
                                        
                                        
                          FIRST SUPPLEMENTAL INDENTURE
                                        
                           Dated as of July 30, 1997
                                        
                                        
                                        
                             _____________________
                                        
                                        
                                        
                                        
         Supplementing and Amending Indenture Dated as of June 1, 1989



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     THIS FIRST SUPPLEMENTAL INDENTURE, dated as of July 30, 1997 (this
"Supplemental Indenture"), is by and among Allwaste, Inc., a corporation duly
organized and existing under the laws of the State of Delaware (herein called
"Allwaste"), having its principal executive office at 5151 San Felipe Road,
Suite 1600, Houston, Texas 77056, Philip Services Corp., a corporation duly
organized and existing under the laws of the Province of Ontario, Canada (herein
called "Philip"), having its principal executive office at 100 King Street, 
P.O. Box 2440, LCD1, Hamilton, Ontario, Canada L8N 4J6, and Texas Commerce Trust
Company of New York, a trust company organized under the laws of the State of
New York, as Trustee (herein called the "Trustee").


                        RECITALS OF ALLWASTE AND PHILIP

     Allwaste has executed and delivered to the Trustee its Indenture, dated as
of June 1, 1989 (herein called the "Indenture"), to provide for the issuance
from time to time of up to $30 million principal amount of 7 1/4% Convertible
Subordinated Debentures due 2014 (the "Debentures"), as provided in the
Indenture.

     Pursuant to the Indenture, Allwaste has issued such Debentures,
approximately $28.9 million of which are currently outstanding. No other
securities have been issued pursuant to the Indenture.

     Effective as of July 30, 1997 (the "Merger Date"), Philip/Atlas Merger
Corp., a Delaware corporation and a wholly owned subsidiary of Taro Aggregates
Ltd., an Ontario corporation and wholly owned subsidiary of Philip ("Taro"), was
merged with and into Allwaste pursuant to the provisions of the General
Corporation Law of the State of Delaware (the "Merger"), as a result of which
Allwaste became a wholly owned subsidiary of Taro.

     Each share of common stock of Allwaste which was issued and outstanding
immediately prior to the Merger was, by virtue of the Merger and without any
action on the part of the holder thereof, converted into 0.611 common shares, no
par value, the Philip ("Philip Shares").

     In connection with the Merger, Allwaste and Philip, pursuant to appropriate
resolutions of their respective Boards of Directors, have duly determined to
make, execute and deliver to the Trustee this Supplemental Indenture in order to
reflect the results of the Merger as required by the Indenture and to provide
for Philip to become a co-obligor with respect to certain obligations of
Allwaste arising under the Indenture and the Debentures.

     Pursuant to Sections 12.01 and 14.06 of the Indenture, Allwaste, as the
survivor to the Merger, is required to execute and deliver to the Trustee an
indenture supplemental to the Indenture in connection with the Merger.

     Section 11.01 of the Indenture provides that, without the consent of any
holders, Allwaste and the Trustee may enter into a supplemental indenture to
make provision with respect
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to (i) evidencing the succession of another corporation to Allwaste and an
adjustment in the conversion price pursuant to Section 14.06 of the Indenture
and (ii) to cure any ambiguity, or amend such other provisions in regard to
matters or questions arising under the Indenture, provided such action does not
adversely affect the interests of the holders of the Debentures, and Allwaste
has determined that this Supplemental Indenture may therefore be entered into
without the consent of any holder in accordance with Section 11.01 of the
Indenture.

              Allwaste and Philip have duly authorized the execution and
delivery of this Supplemental Indenture and all things necessary have been done
to make this Supplemental Indenture a valid agreement of Allwaste and Philip, in
accordance with its terms.

               NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

               For and in consideration of the premises, it is mutually agreed,
for the equal and proportionate benefit of the respective holders from time to
time of the Debentures or of any series thereof, as follows:

                                  ARTICLE ONE

                                  DEFINITIONS

Section 1.01. Definitions.

               Capitalized terms used but not defined in this Supplemental
Indenture have the respective meanings assigned to them in the Indenture.

                                  ARTICLE TWO

                           CONCERNING THE DEBENTURES

Section 2.01. Conversion Privilege.

               The holder of each Debenture outstanding on the date hereof shall
have the right from and after the date hereof, during the period such Debenture
shall be convertible as specified in Section 14.01 of the Indenture, to convert
such Debenture only into the number of Philip Shares, and cash in lieu of
fractional Philip Shares, which such holder would been entitled to receive upon
the consummation of the Merger if had held the number of shares of Common Stock
of the Company issuable upon conversion of such Debenture immediately prior to
the Merger, subject to adjustment as provided in Section 2.02 below.

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Section 2.02.  Conversion Price.

               The price at which Philip Shares shall be delivered upon 
conversion of Debentures (herein called the "conversion price") shall be the 
price specified in relation to the Debentures pursuant to Section 14.01 of the 
Indenture, as adjusted in accordance with Article Fourteen of the Indenture 
prior to the Merger. As of the date of this Supplemental Indenture, the 
conversion price is $19.5376 per Philip Share. For events subsequent to the 
effective date of this Supplemental Indenture, the conversion price shall be 
adjusted in a manner as nearly equivalent as may be practical to the 
adjustments provided for in Article Fourteen of the Indenture.

Section  2.03. Philip as a Co-Obligor.

               Allwaste, Philip and the Trustee hereby agree that as of the 
effective date of this Supplemental Indenture, Philip shall become a co-obligor 
with Allwaste under the Indenture, as modified by this Supplemental Indenture, 
and the Debentures, and shall be jointly and severally liable with Allwaste for 
the due and punctual payment of the principal of and premium, if any, and 
interest on the Debentures, as fully and effectively as Philip had originally 
been an obligor under such Debentures; provided, however, that Philip is not 
assuming, or becoming a co-obligor for, the performance of any other covenant 
or condition of the Indenture to be performed or observed by Allwaste, or any 
other obligation or liability of Allwaste under the Indenture, the Debentures 
or any other securities other than such payments and, provided further, that 
the obligations of Philip under the Indenture, as supplemented by this 
Supplemental Indenture, and the Debentures for the payment of principal of 
(including any sinking fund payment) and premium, if any, and interest on each 
and all of the Debentures is hereby expressly subordinated, to the extent and 
in the manner set forth in Article Three of the Indenture, to prior payment 
and/or cancellation (as shall be appropriate) in full of all Senior 
Indebtedness, as if the reference to the "Company" in such Article Three and in 
the definition of Senior Indebtedness, and in other applicable definitions, as 
necessary, were to Philip. 

                                 ARTICLE THREE

                             CONCERNING THE TRUSTEE

Section 3.01.  Terms and Conditions.

               The Trustee accepts this Supplemental Indenture and agrees to 
perform the duties of the Trustee upon the terms and conditions herein and in 
the Indenture set forth.

Section 3.02.  No Responsibility.

               The Trustee shall not be responsible in any manner whatsoever 
for or in respect of (i) the validity or sufficiency of this Supplemental 
Indenture, the authorization or permissibility of this Supplemental Indenture, 
the authorization or permissibility of this Supplemental Indenture pursuant to 
the terms of the Indenture or the due execution thereof by Allwaste or Philip 
or (ii)the recitals herein contained, all such recitals being made by Allwaste 
and




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Philip. The Trustee shall not be responsible in any manner to determine the 
correctness of provisions contained in this Supplemental Indenture relating 
either to the kind or amount of securities receivable by holders of Debentures 
upon the conversion of their Debentures after the Merger or to any adjustment 
provided herein.

                                  ARTICLE FOUR
                                        
                    EFFECT OF EXECUTION AND DELIVERY HEREOF

          From and after the execution and delivery of this Supplemental
Indenture, (i) the Indenture shall be deemed to be amended and modified as
provided herein, (ii) this Supplemental Indenture shall form a part of the
Indenture, (iii) except as modified and amended by this Supplemental Indenture,
the Indenture shall continue in full force and effect, (iv) the Debentures shall
continue to be governed by the Indenture, as modified and amended by this
Supplemental Indenture and (v) every holder of Debentures heretofore and
hereafter authenticated and delivered under the Indenture shall be bound by this
Supplemental Indenture.

                                  ARTICLE FIVE
                                        
                            MISCELLANEOUS PROVISIONS

Section 5.01. Headings Descriptive.

          The headings of the several Articles and Sections of this Supplemental
Indenture are inserted for convenience only and shall not in any way affect the
meaning or construction of any provision of this Supplemental Indenture.

Section 5.02. Rights and Obligations of the Trustee.

          All of the provisions of the Indenture with respect to the rights,
privileges, immunities, powers and duties of the Trustee shall be applicable in
respect of this Supplemental Indenture as fully and with the same effect as if
set forth herein in full.

Section 5.03. Successors and Assigns.

          This Supplemental Indenture shall be binding upon and inure to the
benefit of and be enforceable by the respective successors and assigns of the
parties hereto and the holders of any Debentures then outstanding.

Section 5.04. Counterparts.

          This Supplemental Indenture may be executed in several counterparts,
each of which shall be an original and all of which shall constitute but one and
the same instrument.

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Section 5.05. Governing Law.

          THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.



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          IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed, and their respective corporate seals to be
hereunto affixed and attested, all as of the day and year first above written.


                                       ALLWASTE, INC.


Attest:                                By:___________________________________
                                          Name:
                                          Title:

By:_________________________________
   Name:
   Title:


                                       PHILIP SERVICES CORP.


                                       By: /s/ Marvin Boughton
                                           -----------------------------------
                                           Name:  Marvin Boughton
                                           Title: Chief Financial Officer


                                       By: /s/ Colin Soule
                                           -----------------------------------
                                           Name:  Colin Soule
                                           Title: Executive Vice-President


                                       TEXAS COMMERCE TRUST COMPANY OF NEW YORK


Attest:                                By:____________________________________
                                          Name:  Terry L. Stewart
                                          Title: Vice President

By:_________________________________
   Name:
   Title: Vice President




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STATE OF TEXAS                 Section
HARRIS COUNTY                  Section

          On the ________ day of July, 1997, before me personally came
___________________________, to me known, who, being by me duly sworn, did 
depose and say that he is ______________________________ of Allwaste, Inc., one 
of the corporations described in and which executed the foregoing instrument; 
that he knows the seal of said corporation; that the seal affixed to said 
instrument is such corporate seal; that it was so affixed by authority of the 
Board of Directors of said corporation; and that he signed his name thereto by 
like authority.


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PROVINCE OF ONTARIO            Section
CITY OF HAMILTON               Section

          On the 25th day of July, 1997, before me personally came Colin Soule
and Marvin Boughton, to me known, who, being by me duly sworn, did depose and
say that they are Executive V.P. and CFO respectively of Philip Services Corp.,
one of the corporations described in and which executed the foregoing
instrument; that they know the seal of said corporation; that the seal affixed
to said instrument is such corporate seal; that it was so affixed by authority
of the Board of Directors of said corporation; and that they signed their names
thereto by like authority.

                                             /s/ Anna Ventresca
                                             ----------------------------------
                                                 Anna Ventresca

STATE OF ___________________  Section
COUNTY OF __________________  Section


          On the ________ day of _______________, 1997, before me personally
came ___________________________, to me known, who, being by me duly sworn, did
depose and say that he is ______________________________ of Texas Commerce Trust
Company of New York, one of the organizations described in and which executed
the foregoing instrument; that he knows the seal of said trust company; that the
seal affixed to said instrument is such corporate seal; that it was so affixed
by authority of the Board of Directors of said trust company; and that he signed
his name thereto by like authority.


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