Osteochondral defects can degenerate into osteoarthritis and currently there are no good treatment alternatives available to most Orthopaedic surgeons. Osteochondral allografting can restore damaged joint surfaces but its clinical use is limited by poor access to high quality tissue. Vitrification of osteochondral tissue would allow the banking of this tissue but requires high concentrations of cryoprotective agents. This study was designed to ascertain dimethyl sulfoxide (DMSO) toxicity kinetics to chondrocytes in situ after exposure to DMSO at different temperatures recorded as a function of time. Porcine osteochondral dowels were exposed to 1, 3, 5, and 6M DMSO at 4, 22, and 37 degrees C for 0.5 min to 120 min. Chondrocyte recovery was determined by membrane integrity (Syto 13 and ethidium bromide) and mitochondrial (WST-1) assays. Results demonstrated that cell recovery was concentration, temperature and time dependent. At higher concentrations and temperatures, significant cell loss occurred within minutes. A rate constant calculated for chondrocyte death was dependent on temperature. 1 M DMSO appeared relatively non-toxic. This experiment established a method to examine systematically toxicity parameters for chondrocytes in situ and this data can be used to tailor vitrification protocols by limiting exposure temperature and time or lowering DMSO concentrations below toxic levels recorded.

As described by Environment and Climate Change Canada,[1] the Prohibition of Certain Toxic Substances Regulations, 2012 developed under the Canadian Environmental Protection Act, 1999 are “a multi‐substance risk management instrument used to prohibit the manufacture, use, sale, offer for sale or import of certain toxic substances and products containing these substances with a (limited) number of exemptions.” The substances currently prohibited by these regulations have been declared toxic to the environment and/or human health; are generally persistent, bioaccumulative, and/or inherently toxic as per the Act; and tend to be used in industrial applications. The Regulations are amended from time to time to add substances for which prohibition has been deemed appropriate, or to amend existing controls when necessary. Compliance with the requirements of the Regulations is mandatory and the provisions apply to every person or company in Canada, unless otherwise noted. This article summarizes the prohibitions, exemptions, and key features of the Prohibition of Certain Toxic Substances Regulations, 2012, including permitting provisions, reporting and record‐keeping, as well as considerations for compliance.