Customers shop for back-to-school supplies at a Target store in Colma, Calif. (David Paul Morris/Bloomberg News)

When picking out school supplies, children often clamor for their favorite cartoon characters or colors, but health advocates are urging parents to consider the safety of products before moving to the checkout line.

Some plastics that have been linked to health problems still can be found in many backpacks, lunchboxes and water bottles marketed to children.

“We are living in an age of plastics,” said Charles Moore, founder of Algalita, an organization that raises awareness about plastic pollution and its effect on marine life and ecosystems.

Products containing plastics are ubiquitous, and researchers are working to understand their health effects. A group of health advocates at a panel discussion Wednesday organized by the Washington-based Environmental Working Group discussed some toxic materials to look out for and offered tips on how to avoid them while perusing the shelves.

PVC, or polyvinyl chloride, also known as vinyl, contains chemical additives including phthalates that research has linked to asthma, learning disabilities, diabetes and other chronic health problems. Congress banned phthalates in children’s toys, yet they are widespread in school supplies such as backpacks and three-ring binders.

Public-health advocates recommend buying backpacks made of natural fibers and avoiding the shiny plastic models that often contain PVC. It’s harder to find binders that are not made of vinyl, but they suggest looking for brands that are PVC-free.

BPA, or bisphenol A, is used in plastics to make them stronger. Research has linked the chemical to reproductive problems, cancer and other health problems. The Food and Drug Administration in 2012 banned the use of BPA in baby bottles and toddler sippy cups, but it is still used in many water bottles and lunchboxes.

Advocates recommend buying stainless-steel or glass water bottles or stainless-steel lunchboxes, which are more environmentally sustainable and do not leach harmful chemicals into food or liquids.

If parents let their children participate in the selection of school supplies and talk with them about the effects of plastic pollution or the hazards associated with plastics, they will have a better chance of getting their buy-in, said Heather White, executive director of the Environmental Working Group.

Other toxins to avoid can be found in crayons. Some crayons that are imported from China have been found to be contaminated with asbestos. Advocates said it’s safer to purchase crayons that have been manufactured in the United States. In addition, hand sanitizers are good at killing germs, but the gels also contain chemicals that can disrupt thyroid function and encourage bacterial resistance to antibiotics.

To kill germs, soap and water is the best approach, according to the Food and Drug Administration.