R2:2013's requirements relating to shredding are set forth in Provision 5. The Standard prohibits the shredding of Focus Materials (mercury, batteries, and circuit boards containing mercury or batteries, as well as other FMs listed in the Definitions section of the Standard). There are exceptions to this blanket prohibition that are designed to allow for innovative, safe, and environmentally preferable shredding technologies. However, few if any shredders currently in operation are designed to fully meet the requirements of these exceptions.
Failure to remove mercury-containing items can lead to the release of mercury upon shredding - a serious risk to worker health and the environment, both at the shredding facility and at facilities downstream where shredded materials are processed. If a mercury-containing item is too difficult to remove (i.e. because it may break), then the entire unit containing the mercury should not be shredded.
Batteries must not be shredded because they pose a risk of fire and/or worker health issues. Lithium primary, lithium ion, lithium polymer, and nickel metal hydride can all cause fires or produce excessive heat if damaged or activated. Nickel Cadmium, silver oxide and a few others can also be an issue from a worker health standpoint.
Many responsible electronics recyclers that engage in shredding, manually disassemble to remove Focus Materials prior to shredding even though it presents a cost in terms of labor, storage of these materials, and sending them to properly vetted downstream vendors. Additionally, ventilation systems with air filtration will pull dust and other contaminants away if/when shredding circuit boards.
Shredding of end-of-life electronic equipment is a common practice and a cost-effective means of reducing volume and separating materials. However, cost must never be the overriding consideration. Health, safety, and the environment are of paramount importance as well.