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

Information Collected by the Ontario Health Study

After you agree to take part in the Ontario Health Study, you will be asked to complete an online questionnaire. You may skip any questions that you don’t feel comfortable answering. The information collected will include:

  • Demographic information, such as your address, sex and birth date
  • Environmental and occupational information, such as the type of work you do and how long you have lived at your current residence
  • Medical history, including diagnoses of medical conditions
  • Physical data, such as your weight and waist circumference
  • Some participants may register for the Study by logging on to an OHS website address that is available through an OHS partner organization, such as a clinic, institution, or another research study. This information will be reviewed to see if the partnerships are effective and the information will be kept until the study has concluded or the information is no longer required. This information will not be shared with the partner organizations.
  • Other participants may register for the Study by logging on to an OHS website address associated with a promotional program, such as an incentive rewards program. This information will be used to track the success of the rewards program and the information will be kept until the study has concluded or the information is no longer required. This information will not be shared with anyone, including the organization we are working with to offer the reward. However, if you do choose to participate in an incentive rewards program offered in partnership with another organization, that organization may become aware of your participation in the OHS when you claim the incentive reward.

After you have completed the Ontario Health Study’s baseline questionnaire, you may be asked to visit the Ontario Health Study’s Assessment Centre. The information collected will include physical measurements, such as your height, weight and percentage of body fat. Assessment Centre staff will also collect blood and urine samples. You may skip any physical measurements or sample collections that you do not feel comfortable providing.

When measures and samples are collected at the Assessment Centre, anything that personally identifies you, such as your name, will be removed and replaced with a unique code. This unique code will let us link the measures and samples you have provided to you while allowing us to keep your identity confidential. Only a handful of staff at the Ontario Health Study have access to the electronic key that matches your unique code to your identity. For more information on how your privacy is protected when you visit the AC, please read the privacy FAQ on the Assessment Centres page.

Why We Ask for Your Health Card Number

You do not have to provide your Health card number in order to participate in the Ontario Health Study. However, we ask you to give it 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.

Annual Follow Up

If you agree to be contacted for optional follow up, we will get in touch with you once a year to ask you for updated information about your health and your environment. Additionally, there will be an annual questionnaire designed to collect detailed information about certain areas of interest to researchers, including, for example, your diet, your level of physical activity and your work history. During the consent process, you have the opportunity to opt out of ongoing follow-up.

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.

Tailored Information

When you take part in the Ontario Health Study, you will have the opportunity to receive tailored health information on your OHS personal home page. The type of information that you are sent will be determined by the information provided in your questionnaire responses. If you wish to change the way information is tailored to you, please visit the notifications section of your personal home page.

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