— comparing to a maximum concentration of an identified or unidentified constituent in an extract (see ISO 10993-18);

— supporting toxicological equivalence;

— comparing to a maximum exposure dose estimate of an identified constituent (see ISO 10993-17).

NOTE Constituent is defined in 3.1.

ISO 10993-18 specifies how to convert TTC (µg/d) into a concentration (µg/ml).

TTC is not applicable to constituents with adequate toxicity data for deriving a tolerable intake (TI) value (see ISO 10993-17).

The TTC values established in this document are protective for carcinogens, systemic toxicants, and reproductive toxicants (see Clause 5). This document does not include TTC values for other biological endpoints assessed as part of the biological evaluation of a medical device, per ISO 10993-1, for example:

— cytotoxicity;

— irritation;

— sensitization;

— hemocompatibility;

— material mediated pyrogenicity;

— local effects that occur in tissues at the site of contact between a medical device and the body (e.g. the observations from implantation studies).

The TTC values in this document do not apply to potential exposure via gas pathways of medical devices. For application of TTC for constituents present/released from these devices, see the ISO 18562 series.

The TTC values presented in this document are not applicable for the safety assessment of cohort of concern (see 5.3).

ISO/TS 16782:2016 does not address supplements (e.g. blood or blood products) that are added to the medium to support growth of fastidious bacteria[3][4][5][6]. Those additives are provided after the dehydrated medium is prepared in its liquid state as a final product and fall outside of the scope of this Technical Specification. Although dMHA can be used for determination of MICs using the agar dilution method[4][6] or the gradient diffusion method, ISO/TS 16782:2016 only includes performance testing of dMHA using disc diffusion methodology as described by the Clinical and Laboratory Standards Institute (CLSI)[5] and European Committee on Antimicrobial Susceptibility Testing (EUCAST)[3].

ISO/TS 10993-20:2006 is based on several publications written by various groups of immunotoxicologists over the last few decades in which the development of immunotoxicology as a separate entity within toxicology took place.

This document does neither address the identification or quantification of degradation products nor the evaluation of the physico-chemical properties of the degraded materials, which are covered in ISO 10993-9, ISO 10993-13, ISO 10993-14 and ISO 10993-15.

Chemical characterization of materials is covered by ISO 10993-18.

The ISO 10993 series is not applicable when the material or device is not in contact with the body directly or indirectly.

The TSE-removal methods used to process animal tissues should also reduce the risk of transmitting TSE infections via non-viable tissues of human origin; this Technical Report does not address this issue. Some current information on human tissues and TSEs is presented which may be applied by analogy to other animal tissues.

ISO/TR 22442-4:2010 does not intend to imply a need for validation of methods involving specific materials identified as having a "negligible risk" of contamination with TSE agents as listed in Annex C of ISO 22442-1:2007.

It is intended to clarify final draft international standards included in the ISO 22442 series, as well as in ISO 14160.

ISO/TR 22442-4:2010 builds upon the specific discussion in ISO 22442-3 relative to TSE agents and attempts to summarize the current state of the art in the arena of TSE agent elimination. As the understanding of inactivation and elimination of TSE agents evolves, this document will be revised when possible.

This guidance is applicable to all biological evaluation of all types of medical devices including active, non-active, implantable and non-implantable medical devices.