We rely on third parties to manufacture or supply us with all or a portion of the active product ingredient or drug substance necessary for us to manufacture various products, such as  Opdivo ,  Eliquis, Sprycel ,  Yervoy, Baraclude ,  Reyataz, Reblozyl, Inrebic, Abraxane, Pomalyst/Imnovid  and the Sustiva Franchise.  We are also expanding our use of third party manufacturers for drug product and finished goods manufacturing and we continue to shift towards using third-party manufacturers for supply of our established brands .  With respect to  Revlimid  and  Thalomid , we own and operate a manufacturing facility in Zofingen, Switzerland, in which we produce the active product ingredient for  Revlimid  and  Thalomid  and we contract with a third-party manufacturer to provide back-up active product ingredient for  Revlimid and  Thalomid . To maintain a stable supply of these products, we take a variety of actions including inventory management and maintenance of additional quantities of materials, when possible, that are designed to provide for a reasonable level of these ingredients to be held by the third-party supplier, us or both, so that our manufacturing operations are not interrupted. Certain supply arrangements extend over multiple years with committed amounts using expected near or long-term demand requirements that are subject to change. As an additional protection, in some cases, we take steps to maintain an approved back-up source where available. For example, we have the capability to manufacture  Opdivo  internally and also have arrangements with third-party manufacturers to meet demand. In connection with acquisitions, divestitures, licensing and collaboration arrangements or distribution agreements of certain of our products, or in certain other circumstances, we have entered into agreements under which we have agreed to supply such products to third parties and intend to continue to enter into such agreements in the future. In addition to liabilities that could arise from our failure to supply such products under the agreements, these arrangements could require us to invest in facilities for the production of non-strategic products, result in additional regulatory filings and obligations or cause an interruption in the manufacturing of our own products. Our success depends in great measure upon customer confidence in the quality of our products and in the integrity of the data that support their safety and effectiveness. Product quality arises from a total commitment to quality in all parts of our operations, including research and development, purchasing, facilities planning, manufacturing and distribution. We maintain records to demonstrate the quality and integrity of technical information and production processes. Control of production processes involves established specifications and standards for ingredients, equipment and facilities, manufacturing methods and operations, packaging materials and labeling. We perform tests at various stages of production processes, on the final product and on product samples held on stability to ensure that the product meets regulatory requirements and conforms to our standards. These tests may involve chemical and physical analyses, microbiological testing or a combination of these along with other analyses. Quality control testing is provided by business unit/site and third-party laboratories. Quality assurance groups routinely monitor manufacturing procedures and systems used by us, our subsidiaries and third-party suppliers to assure quality and compliance requirements are met. Our facilities and operations are subject to extensive U.S. and foreign laws and regulations relating to environmental protection and human health and safety, including those governing discharges of pollutants into the air and water; the use, management and disposal of hazardous, radioactive and biological materials and wastes; and the cleanup of contamination. Pollution controls and permits are required for many of our operations, and these permits are subject to modification, renewal or revocation by the issuing authorities. Our environment, health and safety group monitors our operations around the world, providing us with an overview of regulatory requirements and overseeing the implementation of our standards for compliance. We also incur operating and capital costs for such matters on an ongoing basis, which were not material for 2019, 2018 and 2017. In addition, we invested in projects that reduce resource use of energy and water. Although we believe that we are in substantial compliance with applicable environmental, health and safety requirements and the permits required for our operations, we nevertheless could incur additional costs, including civil or criminal fines or penalties, clean-up costs or third-party claims for property damage or personal injury, for violations or liabilities under these laws. Many of our current and former facilities have been in operation for many years, and over time, we and other operators of those facilities have generated, used, stored or disposed of substances or wastes that are considered hazardous under Federal, state and/or foreign environmental laws, including CERCLA. As a result, the soil and groundwater at or under certain of these facilities is or may be contaminated, and we may be required to make significant expenditures to investigate, control and remediate such contamination, and in some cases to provide compensation and/or restoration for damages to natural resources. Currently, we are involved in investigation and remediation at 13 current or former facilities. We have also been identified as a PRP under applicable laws for environmental conditions at approximately 17 former waste disposal or reprocessing facilities operated by third parties at which investigation and/or remediation activities are ongoing. We may face liability under CERCLA and other Federal, state and foreign laws for the entire cost of investigation or remediation of contaminated sites, or for natural resource damages, regardless of fault or ownership at the time of the disposal or release. In addition, at certain sites we bear remediation responsibility pursuant to contractual obligations. Generally, at third-party operator sites involving multiple PRPs, liability has been or is expected to be apportioned based on the nature and amount of hazardous substances disposed of by each party at the site and the number of financially viable PRPs. For additional information about these matters, refer to “Item 8. Financial Statements and Supplementary Data—Note 19. Legal Proceedings and Contingencies.” Environmental Regulation 17