There is no official Ontario MOL-sanctioned policy or program for designated substances in general and isocyanates in particular. But there are guidelines and samples from MOL, its partner associations, e.g., IHSA and WSPS, as well as some real life examples. Take a look at the following. Hope that helps. Glenn

MOL Guidelines on Doing Pre-Start Safety Review for Designated Substances, https://www.labour.gov.on.ca/english/hs/pubs/psr/index.php
MOL Presentation on Designated Substances, scroll down to slide 24 for info on medical surveillance for isocyanates, https://orm.uottawa.ca/sites/orm.uottawa.ca/files/designated-substances-program.pdf
WSPS Guidelines on Designated Substance Assessments, http://www.wsps.ca/WSPS/media/Site/Resources/Downloads/WrkbkDesigSubst_Final.pdf’ext=.pdf
Model Designated Substances Program (from Ontario university), https://orm.uottawa.ca/sites/orm.uottawa.ca/files/designated-substances-program.pdf
IHSA Model Designated Subst. Policy for Const Sites, scroll down to page 18 (as numbered in document) https://www.ihsa.ca/PDFs/Products/Id/B045.pdf
Federal Guidelines, http://publications.gc.ca/collections/collection_2017/edsc-esdc/Em8-29-2008-eng.pdf
Federal Guidelines on Controls, https://www.canada.ca/en/employment-social-development/services/health-safety/reports/control-measures.html
Sample Safe Work Procedures, https://www.actsafe.ca/wp-content/uploads/2017/11/Safe-work-procedures-for-isocyanate-containing-products-Report-PDF.pdf
Detailed Hygiene Guidelines–from Quebec and fairly old but potentially useful–http://www.irsst.qc.ca/media/documents/PubIRSST/RG-773.pdf