products. Rather than assess their suppliers' laboratories themselves, some manufacturers accept accreditation of these laboratories by a third party. In this case, achieving a single, third-party accreditation relieves suppliers of the burden of audits by each of their customers.

The National Aerospace and Defense Contractors Accreditation Program (NADCAP) is one example of a private assessment program established to reduce costs for an industry sector by streamlining the accreditation process. NADCAP was established by the Performance Review Institute, an affiliate of the Society of Automotive Engineers, to accredit laboratories and quality systems of suppliers to prime contractors in the aerospace and defense industry.65

Regulatory authorities rely on third-party accreditation to judge the validity of tests performed on such items as building materials and electrical equipment. For example, OSHA's NRTL program accredits laboratories as competent to test and certify products used in the workplace. Only certifications from accredited laboratories are accepted by OSHA as proving product compliance to its regulations.

Companies seeking registration of their quality assurance systems choose registrars, in part, on the basis of the registrars' accreditation. In the United States, the only nationwide system for accrediting ISO 9000 quality system registrars is operated by the Registrar Accreditation Board, under a joint venture with ANSI. For many independent laboratories and quality system registrars, third-party accreditation has become a basic requirement to attract customers.

Accreditation of a laboratory's or certifier's competence in a particular field typically involves review of the following elements, among others: technical procedures; staff qualifications; product sample handling; test equipment calibration and maintenance; quality control; independence; and financial stability. Teams of accreditors make on-site inspections of facilities and conduct interviews. A laboratory may be required to show its proficiency by measuring known test samples. To maintain accredited status, periodic reassessment, with follow-up testing and site visits, is required.66

In comparison to most of its trading partners, the United States has a decentralized system of accreditation. More than 100 public and private-sector accreditation programs are listed in Tables 3-2, 3-3, and 3-4. Accreditation programs exist at all levels of government and in many private organizations, such as trade and professional associations. Directories of laboratory accreditation programs compiled by NIST's Office of Standards Services, list 31 federal, 21 state, 11 local, and 40 private laboratory accreditation programs. These figures understate the number of state, local, and private programs, as a result of low survey response rates by these organizations during the compilation of directories.

The two largest programs in the United States both focus on testing laboratory accreditation. (Many certifiers are also testing laboratories, however, and are eligible for accreditation of their testing services.) The National Voluntary Laboratory Accreditation Program (NVLAP) is a fee-for-service program operated

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