Many baby diapers contain chlorine dioxide. Should parents be worried about it?

A baby wearing a diaper.
Experts break down the difference between TCF and ECF diapers. (Getty Images) (Getty Images)

The Honest Company has built up a reputation for providing parents with eco-conscious alternatives to common products that contain potentially toxic chemicals. The company's diapers are a hit with parents thanks to their plant-based materials and adorable designs, but Honest just announced that it's tweaking what goes into its diapers — and some consumers aren't impressed.

The company recently shared on its website that it's switching from totally chlorine free (TCF) to elemental chlorine free (ECF) fluff pulp in its diapers. (Fluff pulp, in case you're not familiar with it, is the material in the diaper's absorbent core.)

"This is an update in the way the fluff pulp is made, but the safety and quality of the diaper you know and love remain the same," Honest wrote online. The statement also noted that "numerous studies have made us confident in ECF fluff pulp processing" and that the update allows the company to source fluff pulp from North America instead of Scandinavia to reduce Honest's carbon footprint.

The company said that the change would impact all Honest Clean Conscious Diapers starting on Nov. 6, but the exact timing of when consumers will see a difference will vary by diaper size and print through the start of 2024.

Fans of the diapers are speaking out on social media about the change, and they're not exactly thrilled. "I LOVE Honest, so this is terribly disappointing," one wrote on a Reddit thread. "Now it's equivalent to Costco diapers lol," another said.

The Honest Company did not respond to Yahoo Life's request for comment by the article deadline.

Why is the change so controversial? Here's what parents need to know.

First, what is totally chlorine free and elemental chlorine free fluff pulp?

Again, pulp is the absorbent part of the diaper. "Pulp usually comes from wood and, when it's processed, it looks brown," Dr. Danelle Fisher, a pediatrician and chair of pediatrics at Providence Saint John's Health Center in Santa Monica, Calif., tells Yahoo Life. "Nobody wants their kid to be in a brown diaper, and white will show pee and poop. It also just looks better."

Typically, the pulp is bleached with chlorine to make it white, Fisher explains. "But elemental chlorine, which is a popular choice, is a little harsh and not as good for the environment or baby," she says.

"The difference between TCF and ECF is that ECF uses chlorine dioxide to bleach the fluff pulp," Jamie Alan, an associate professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life.

What's the controversy behind this?

Many diaper companies in the U.S. use ECF fluff pulp, Fisher points out. However, using TCF fluff pulp is a badge of honor for some brands, and it's one that is increasingly showing up less. Currently, only a select few brands like Coterie and Joonya use TCF pulp in their diapers. However, these diapers tend to be more expensive than their ECF counterparts.

Honest's switch to ECF fluff pulp is off-putting to parents who are concerned about this, as some have written online. The company also doesn't seem to be lowering its prices to reflect the change.

How worried about this should parents be?

The main concern around ECF fluff pulp is the dioxins in the chlorine used to bleach the pulp, Alan says. "It is the dioxins that are the potentially dangerous compounds that we are worried about."

"TCF is considered less toxic," Fisher adds.

But experts say this isn't something that parents should be stressed about. "I would not be that concerned," Alan says. "There have been several studies that show there is no difference in contaminants when comparing the two methods." She also points out that the TCF method isn't perfect. "It has issues with fiber strength and it uses more energy," she says.

Fisher agrees that this isn't worth losing sleep over. "There are a lot of chemicals in life that you and your child are exposed to," she says. "The main decision for parents around diapering should be if you're going to use cloth or disposable, or a combination of both."

Diapers also impact children differently, Fisher says. "It's really about the diaper and child," she says. "Is it going to protect your child's skin and not cause them to get rashes? That's what's most important."

If you're concerned about using ECF diapers, there are still options that use the TCF method, Fisher points out. But Alan also says parents should be just fine to use ECF diapers, if that's what they prefer. "I would feel comfortable putting my child in diapers that use ECF — in fact, I did just that and I'm a toxicologist," Alan says. "To me, the risk is very minimal. However, I completely understand the concern parents may have. There are still diapers using TCF fluff that are commercially available, and cloth diapers are another viable option for some."

Editor's note: Jessica Alba, co-founder of the Honest Company, is a member of Yahoo's board of directors.