This Amendment No. 6 (this “Final Amendment”) amends and supplements the combined Tender Offer Statement and Rule 13e-3 Transaction Statement under cover of Schedule TO (as heretofore amended, the “Schedule TO”), which relates to an offer by QCH Acquisition Ltd., an exempted company limited by shares incorporated in Bermuda (“Purchaser”), a wholly-owned subsidiary of Quanta Capital Holdings Ltd., an exempted company limited by shares incorporated in Bermuda as a holding company (“Quanta”), to purchase any and all of Quanta’s 10.25% Series A Preferred Shares (the “Preferred Shares”). The Schedule TO was originally filed on June 1, 2007, and was amended on June 4, 2007, June 28, 2007, July 12, 2007, July 20, 2007 and August 8, 2007. The Schedule TO relates to an offer by Purchaser to purchase the Preferred Shares at $22.50 per share, net to the seller in cash (subject to applicable withholding taxes), and upon the terms and subject to the conditions set forth under the Offer to Purchase and Proxy Statement (as amended and supplemented, the “Offer to Purchase”), a copy of which is attached to Schedule TO as Exhibit (a)(1), as supplemented by Exhibit (a)(10), and in the related Letter of Transmittal (as amended and supplemented, the “Letter of Transmittal”), a copy of which is attached to Schedule TO as Exhibit (a)(11). Except as specifically provided herein, this Final Amendment does not amend any of the information previously reported on the Schedule TO. Capitalized terms used, but not otherwise defined in this Final Amendment shall have the meaning given in the Offer to Purchase.

Item 6. Purposes of the Transaction and Plans or Proposal; Item 8. Interest in Securities of the Subject Company; Item 11. Additional Information.

Items 6, 8 and 11 of the Schedule TO are hereby amended and supplemented by adding the following:

At 12:00 Midnight, New York City time, on August 10, 2007, the tender offer expired as scheduled and was not extended. Based on information provided by The Bank of New York, the depositary for the tender offer, as of the expiration of the tender offer, a total of 3,024,891 Preferred Shares had been validly tendered or guaranteed for tender and not withdrawn pursuant to the tender offer, representing more than 96% of the issued Preferred Shares.

On August 10, 2007, Quanta also held special general meeting of the holders of the Preferred Shares for the approval of an amendment to the Certificate of Designation of the Preferred Shares to remove a provision that would permit holders of Preferred Shares to elect two members to Quanta’s board of directors. At the special general meeting holders of the Preferred Shares approved the amendment by votes cast, in person or by proxy, representing 2,459,402 Preferred Shares, which represents a majority of the votes cast at the meeting.

On August 13, 2007, Quanta issued a press release announcing the final results of the tender offer and the approval of the amendment to the Certificate of Designation of the Preferred Shares. The full text of the press release is attached hereto as Exhibit (a)(17) and is incorporated herein by reference.

Following the purchase of the Preferred Shares tendered and guaranteed for tender pursuant to the tender offer, Purchaser will beneficially own more than 90% of the issued Preferred Shares, and subject to the approval by its board of directors, Quanta intends to file a Form 15 with the SEC, terminating the registration of Preferred Shares under Section 12(g) of the Exchange Act, and Purchaser plans to purchase the remaining issued Preferred Shares. Under Bermuda law, if Purchaser acquires 90% or more of the Preferred Shares in the tender offer within four months after commencing the tender offer, then Purchaser may require any nontendering holders to sell their Preferred Shares to Purchaser on the same terms as in the tender offer if Purchaser gives notice to those holders within two months after the closing of the tender offer.

Item 12. Exhibits.