If you are like me and trying to study WHMIS 2015 via PDF. You might try to take notes and find you can not copy any of the text. The document is protected against that. I find that a bit funny, as the document is provided. I only had to convert each page to an image, use tesseract to ocr each image to a pdf, and finally, merge all the pdf's to one single document.
I saved you the trouble of doing this yourself, download it here.