Yes, if your job is covered by the Occupational Health and Safety Act (OHSA). Workers in most workplaces in Ontario are covered by OHSA. There are rules in OHSA about the right to refuse unsafe work. When you've talked to your supervisor (and maybe others), and you still have reason to believe that the work you have been asked to do may endanger your safety or the safety of those around you, you have the right under the Occupational Health and Safety Act to refuse to perform the work.
There are times when the supervisor might not agree with you, doesn't take what you're saying seriously or politely ignores you. If the problem isn't properly addressed and you still feel you could be injured say "NO" to the work. You have the legal right to refuse unsafe work
Tell your supervisor that you believe that the situation is not safe, and that you will not continue the work until the situation is made right. If necessary, let them know that you are exercising your right under the Occupational Health and Safety Act to refuse work.
Make sure there's no doubt that it's not a discussion or a complaint investigation, but that you're refusing to perform the work until they do something about your concerns. At this point your boss or supervisor may not agree with you, but once you have "refused to work" under the Act, you can't be ordered or forced to do the work and you can't be disciplined for refusing the unsafe work.
To find out if your job is covered by the Occupational Health and Safety Act (OHSA), see the section of the WorkSmart web site titled Is my job covered?