The Ontario Health Study (OHS) takes your privacy and protecting the confidentiality of the information you provide seriously. The OHS follows strict privacy practices that govern how your information is collected, who will be able to see your information and how that information will be used. Protecting your personal information is extremely important to the OHS and safeguards are in place to ensure your privacy.

Participation in the Ontario Health Study is completely voluntary and you are free to withdraw from the Study at any time by calling 1-866-606-0686 or by writing to

Periodic Follow Up

If you agreed to be contacted for optional follow up, we will get in touch with you periodically to ask you for updated information about your health and your environment through follow-up questionnaires. These questionnaires will collect detailed information about certain areas of interest to researchers, including, for example, your diet, your level of physical activity and your work history. We may also reach out periodically to request you update your contact information, such as email, phone or mailing address.

Why We Ask for Your Health Card Number

We asked you to provide your health card number to us so we can link the information that you provide in our questionnaire with your other administrative/medical data. For example, every time you undergo certain tests conducted by a health care professional (e.g., a mammogram), these results are stored in a separate database. This is referred to as “administrative data.” Linking your questionnaire response data with additional health-related, “administrative data”, will allow researchers the ability to broaden their research questions. This will help to answer research questions such as whether screening programs in Ontario are effective or, whether there are “hot spots” across the province where a certain disease is more common.

Simply put, data linkage means linking information about the same person from multiple sources. The accuracy of this data is critical for research. Your Health card number is unique to you and the data linkage it provides.

Very strict privacy practices are in place when information from multiple sources is linked together. Your data is de-identified before being provided to researchers. These researchers must document how they will ensure the confidentiality of the information and must receive approval from a Research Ethics Board.
If you did not provide your health card number when you registered, it can be added by logging into your account, clicking “My Profile” and then clicking “Personal Information.”

Shared Email Addresses

As an online study, our communication is achieved primarily via email, and for privacy purposes, each participant should have his/her own email address. However, accounts created using a shared email address prior to August 29, 2013 remain valid and may be accessed using the unique username associated with the account.

Protecting Your Personal Information

Occasionally, researchers who have received ethics approval for their research may wish to collect additional information from OHS participants. The Ontario Health Study will contact you directly about any such voluntary requests.

In order to protect your personal information, please choose a strong password containing a combination of uppercase and lowercase letters, numbers, and special characters; do not reveal your OHS username or password to anyone; and clear your computer’s browser history and cache, particularly if you are completing the OHS questionnaire on a shared or public computer.

Information Collected on the OHS Website

The OHS uses internet tracking tools associated with standard internet protocols and web-based systems. This system information is typically stored in log files (transaction records maintained by web servers) and the information is used for aggregate reporting. Aggregate means that information is combined across a number of users and the information of any one individual is not singled out. Aggregate reporting includes information such as total number of visitors, most visited sections, peak traffic times, etc.
Log files are used for recording information such as:

  • Service provider IP addresses
  • Browser versions
  • Referring websites
  • Search terms used
  • Average number of pages requested
  • Average duration of visit
  • Total visitor traffic

The Ontario Health Study uses aggregate information gathered from visits to the website to improve its design. This information supplies a broad picture of how people use the OHS website.

Learning More About Privacy

To learn more about the Study’s privacy practices, contact The Ontario Health Study has an independent Privacy Lead who will respond to your privacy questions or concerns.

If you have questions or concerns about your rights as a research participant, you may contact the Ethics Review Office at the University of Toronto at

For questions about the Ontario Health Study, please contact 1-866-606-0686 or