Biodegradable and compostable get used as if they were synonyms. They are not. Biodegradable describes what a material can eventually do. Compostable describes a tested result: a product that turns into usable compost, in a specific setting, within a specific time, without leaving anything harmful behind.

That difference is not just semantics. In the United States, both words are regulated marketing claims. The Federal Trade Commission sets the baseline for the whole country, and California has its own law that goes further, applies to every product sold in the state, and carries civil penalties. Under those rules, a bamboo brush or a plant fiber sponge is not automatically "compostable" just because it grew in the ground.

This post explains what each word legally means, why a brand like ours does not put "compostable" on natural products without certification, what certification actually costs, and what to look for on a label.

What "biodegradable" actually means

In plain science, biodegradable means microorganisms can break a material down into natural elements such as water, carbon dioxide, and biomass. Almost everything organic is biodegradable on a long enough timeline. Wood is biodegradable. So is cotton. So, technically, are some plastics, given enough centuries.

That is exactly why regulators restrict the word. A claim that is true on a geological timescale tells a shopper nothing useful about what happens after they throw the item away.

The federal rule

The FTC Green Guides (16 CFR 260.8) say a marketer making an unqualified biodegradable claim should have competent and reliable scientific evidence that the entire item will completely break down and return to nature within a reasonably short time after customary disposal. For anything that enters the solid waste stream, the FTC defines that window as one year. The same section states that unqualified degradable claims are deceptive for items that are customarily thrown in the trash, because landfills, incinerators, and recycling facilities do not provide the conditions for complete decomposition within one year.

In other words, a toothbrush that ends up in a landfill cannot be marketed as biodegradable, no matter what it is made of, unless the seller can prove it fully decomposes there within a year. Landfills are engineered to be dry and low in oxygen, which is the opposite of what decomposition needs.

The California rule

California goes further. Public Resources Code section 42357(b) prohibits selling a product in the state that is labeled "biodegradable," "degradable," or "decomposable," or any form of those words, or that in any way implies the product will break down, fragment, biodegrade, or decompose in a landfill or other environment. There is no testing route to earn the word. It is simply off the table for consumer products sold in California, with a narrow exception for certified agricultural mulch film.

What "compostable" actually means

Compostable is a narrower, stricter claim. It does not mean "will eventually rot." It means the product has been shown to become usable compost, in a defined environment, in a defined time, without harming the compost.

The federal rule

Under 16 CFR 260.7, a marketer calling an item compostable should have competent and reliable scientific evidence that all the materials in the item will break down into, or otherwise become part of, usable compost in a safe and timely manner. "Timely" means in roughly the same time as the materials it is composted with. If the item will not compost safely and on time in a home compost pile, the claim has to say so clearly. If it needs an industrial facility and most communities do not have one, the claim has to disclose that too.

The standards behind the word

Compostability in the United States is tested against ASTM International specifications, mainly ASTM D6400 for plastics and ASTM D6868 for paper and fiber products that contain plastic coatings or additives. ASTM D6400 has three pass or fail requirements:

Certification

Passing the test in a lab is one step. The Biodegradable Products Institute (BPI) and other third-party bodies review the lab data and license a certification mark. BPI certifies to ASTM D6400 and D6868, and its rules require the certification mark to appear on the product or packaging unless a category exemption applies. In Europe, the equivalent standard is EN 13432, and home compostability is certified separately under TÜV Austria's OK compost HOME program.

The California rule

Section 42357(a) and (g) prohibit selling any product in California labeled "compostable" or "home compostable" unless it meets the applicable ASTM standard in full, carries certification from a third-party certifier approved by CalRecycle (in force since January 1, 2024), is an allowable organic input under the USDA National Organic Program (a requirement that took effect January 1, 2026), contains no more than 100 parts per million total organic fluorine (a PFAS limit), and is labeled so consumers and composting facilities can tell it apart from non-compostable items. Partial compliance with an ASTM standard does not count. "Home compostable" additionally requires OK compost HOME certification.

Biodegradable vs compostable at a glance

Why we can't just say "compostable" about natural products

If a loofah is a dried gourd and a washcloth is woven agave fiber, why not call them compostable? The answer is that "natural" is not the legal test. Four things are.

What a compostable certification actually costs

Certification is not a form you fill out. It is a lab testing program followed by a third-party review, and both cost money and time. Here is what the published numbers look like for the main US certifier, the Biodegradable Products Institute (BPI), which certifies to ASTM D6400 and ASTM D6868 and is the certifier most often referenced for California compliance.

BPI fees (published on bpiworld.org)

Lab testing is usually the largest cost and BPI does not set it. Industry guides put full ASTM D6400 testing at several thousand dollars up to roughly $10,000 per product, depending on the material and how many tests are needed. A product with several components, colors, or coatings may need more than one round.

Time is the other cost. BPI states that disintegration testing takes a minimum of 3 months for commercial compostability and 6 months for home compostability, biodegradation testing takes a minimum of 6 months commercial and 12 months home, and the whole process can take twelve months or more. Lab queue time is outside the certifier's control.

OK compost HOME, the TÜV Austria scheme California requires for any "home compostable" claim, does not publish its fees. Pricing is set in a contract after the product is reviewed, and testing must be done at a TÜV Austria registered lab.

Why this is harder for a small business

The fees are the same whether you sell 500 units of a product or 5 million, so the cost per unit is dramatically higher for a small brand. Beyond the invoices, the administrative load falls on the same two or three people who run everything else:

• Full ingredient disclosure. The certifier needs the complete material composition of the product, including every additive, colorant, glue, and coating. A small brand that sources finished goods from a manufacturer has to obtain that documentation from its suppliers, who may treat formulations as proprietary.
• One certificate per product. Certification is tied to a specific product and formulation. A catalog of a dozen plant fiber items means a dozen testing programs, not one.
• Any material change restarts the clock. Switching suppliers, bristle blends, dyes, or packaging coatings can invalidate the certificate and require new testing.
• A year of waiting before the word can be printed. Inventory, packaging design, and listings all have to be planned around a claim that cannot be made until testing is complete.
• Ongoing paperwork. Annual license renewals, recertification every three years, and California's requirement to produce scientifically accurate compliance documentation to any member of the public within 90 days of a request.
• Cash tied up in advance. Lab and certifier invoices are due before testing begins, long before the product carrying the claim can be sold.

None of this makes certification a bad system. It exists because unverified compostable claims contaminate compost streams and mislead shoppers. It does explain why a small brand can believe its loofah will break down in a backyard pile and still, correctly, decline to print the word on the package.

What this means for Me Mother Earth products

We build our products around plant materials and plastic-free packaging, and we describe them by what they are made of rather than by what we hope happens to them after use. Here is how that plays out across the catalog.

What we do say, because we can back it up: the material each product is made from, that our packaging is plastic free, that our products are vegan and Leaping Bunny certified, and that choosing a bamboo handle or a loofah over a petroleum plastic version keeps that plastic out of the waste stream in the first place.

Four billion plastic toothbrushes are discarded worldwide every year, about one billion of them in the United States, and a polypropylene handle outlasts its owner by centuries. Replacing that handle with bamboo is the part of the problem a toothbrush can solve today, and it does not depend on what happens in a landfill.

For the full component breakdown and end-of-life steps, see The Toothbrush You Throw Away Every 3 Months and Bio-Based Toothbrush Bristles Explained.

How to read a label

• Look for a certification mark, not just the word. A legitimate compostable product in the US carries a BPI, CMA, or similar mark, usually with a product listing you can check on the certifier's site. The word alone, with no mark, is a claim without proof.
• Check which kind of composting. "Commercially compostable" or "industrially compostable" means it needs a facility running at high temperatures. It will not break down in a backyard bin. "Home compostable" is a separate certification.
• Be skeptical of "biodegradable" on anything you throw in the trash. The FTC treats that claim as deceptive for landfill-bound items unless the seller can prove full decomposition within a year, and California bans the word on products outright.
• Watch for implied claims. Green or brown coloring, leaf icons, and phrases like "returns to the earth" or "breaks down naturally" can be treated as degradability claims under both the FTC Green Guides and California law.
• Ask for documentation. In California, any member of the public can request compliance documentation from a manufacturer or supplier that makes compostability claims, and the company has 90 days to provide it.
• Prefer material transparency. A label that tells you exactly what a product is made of gives you more useful information than one that promises an outcome.

Frequently asked questions