Whether your tots are tiny or in college, chances are a backpack is a pretty vital component in their busy lives. Toting books, folders, homework assignments, planners, art supplies and even classroom odds and ends like Kleenex or paper towels would be nearly impossible without a good backpack.

And what child isn’t excited about either getting a backpack that has their favorite character, helps express them in some way, or is prime for decorating with buttons, patches and ink? You may even use one in your daily commute to work or on weekend trips. Suffice to say, it’s a pretty necessary—and handy—carry-all to have around.

But backpacks can also cause back, shoulder and neck pain, as well as poor posture, circulation problems and other injuries, if they’re not used properly. September is Backpack Safety Month, so be sure to take this opportunity to check the use of backpacks in your home and keep your family healthy. Here are some basic tips to use.

• Make sure the backpack’s weight is evenly distributed across the bearer’s body. The straps should also be even with one another. This also means that the backpack should not be worn over one shoulder, but over both shoulders.
• Kids should not carry more than 10 to 15% of their body weight within their backpacks. If their nightly book load exceeds this, you may want to help carry books home from school, or talk to a teacher about keeping a spare book at home, if available, to avoid having to carry it in the backpack each night.
• Tighten backpack straps so that they are two inches above the waist and close to the body.
• Backpacks should be lightweight to begin with. Avoid heavy leather backpacks and go for canvas ones instead. They should also have two wide shoulder straps to keep the pack from digging into the shoulders, as well as a padded back to protect your child from being poked by objects within the backpack. Waist belts and multiple compartments can also help balance the weight of the backpack.
• And be sure to check all backpacks to be sure that they don’t contain PVC. You can use this guide when you purchase school supplies to make sure none of them contain PVC. Some key things to look for are products made out of vinyl, or that contain the letter “V” beneath their recycling symbols.