ASTM D6400 Compostability Standard: U.S. Buyer's Guide

ASTM D6400 is the United States standard for plastics designed to be aerobically composted in municipal or industrial facilities. Published by ASTM International, it is the U.S. equivalent of Europe’s EN 13432 and is the explicit reference standard for the Biodegradable Products Institute (BPI) certification mark, California’s SB 54 plastic-ban legislation, and most U.S. state plastic-ban regulations.

What ASTM D6400 requires

To meet ASTM D6400, packaging must satisfy four criteria under industrial composting conditions:

1. Biodegradation: ≥90% conversion of organic carbon to CO₂ within 180 days
2. Disintegration: ≥90% of material passes through a 2mm sieve after 84 days
3. Eco-toxicity: No negative impact on plant growth in resulting compost (OECD 208 plant emergence test)
4. Heavy metals and material composition: Below specified thresholds; no banned substances

BPI certification (the U.S. equivalent of TÜV’s Seedling)

The Biodegradable Products Institute (BPI) is the primary certifying body for ASTM D6400 in the U.S. and Canada. BPI certification involves third-party laboratory testing and ongoing surveillance audits. BPI-certified products carry the BPI logo, which is the most recognised compostability mark in the U.S. foodservice market.

Note: BPI does not perform the testing itself. Testing is conducted by accredited labs (Eden Research Lab, Organic Waste Systems, others). BPI reviews the lab data, issues the certification, and licenses the use of its mark.

Where ASTM D6400 is required

California SB 54

California’s plastic-ban legislation requires compostable packaging to meet ASTM D6400 (or equivalent). All single-use plastic packaging sold in California must be recyclable or compostable by 2032; compostable products must carry the BPI mark or equivalent certification.

State plastic-ban legislation

Multiple states reference ASTM D6400 in plastic-ban or compostability legislation:

• California (SB 54, 2022)
• New York (Polystyrene Foam Container Ban, 2022)
• Washington (HB 1799, 2022)
• Oregon (Plastic Pollution Producer Responsibility Act, 2022)
• Connecticut, Maine, Vermont, Maryland, New Jersey (various dates)

Municipal composting programmes

Major U.S. cities operating organics-collection programmes (San Francisco, Seattle, Portland, Boulder, Boston, Philadelphia) require BPI certification or ASTM D6400 evidence for packaging accepted in their commercial composting streams.

Commercial composters

Most commercial composting facilities accept only BPI-certified packaging such as compostable bagasse plates and molded fiber trays. Operating without BPI certification means packaging cannot enter commercial composting streams in practice, even if chemically compostable.

What to verify with suppliers

1. Request the BPI certificate, not just the logo: The BPI logo is widely misused. The actual certificate is the proof.
2. Verify SKU scope: Confirm the specific SKUs you’re buying are within the certified scope.
3. Check expiry: BPI certificates have validity periods; confirm current status.
4. Cross-reference BPI’s database: BPI maintains a publicly searchable database of certified products at bpiworld.org.
5. Confirm material composition has not changed: Reformulations void existing certifications.

ASTM D6400 vs EN 13432

The two standards are technically aligned. Both require ~90% biodegradation under industrial composting conditions. Both prohibit toxic compost residue. The differences:

• Biodegradation timeframe: ASTM D6400 allows 180 days; EN 13432 requires 90% within 6 months at a slightly higher test temperature
• Disintegration test: ASTM measures at 84 days; EN 13432 at 12 weeks (84 days)
• Heavy metal limits: Differ slightly between the two standards; ASTM’s are aligned to U.S. EPA standards, EN 13432’s to EU CEN guidance
• Certifying bodies: BPI in the U.S. and Canada; TÜV Austria, DIN CERTCO, Vinçotte in Europe

For multi-market suppliers, holding both BPI (ASTM D6400) and TÜV Austria OK Compost (EN 13432) certifications is standard.

Common pitfalls

• “Biodegradable” without ASTM D6400: Federal Trade Commission Green Guides classify “biodegradable” as misleading without specific testing evidence. ASTM D6400 is the recognised proof.
• “Home compostable” claims: ASTM D6400 covers industrial composting only. ASTM D6868 covers home composting, with significantly stricter requirements.
• Hybrid products: A bagasse bowl with a PET lid has bagasse meeting ASTM D6400; the PET lid does not. Marketing the entire product as compostable is non-compliant.

Ecofy’s ASTM D6400 position

Ecofy’s molded fiber bagasse ASTM D6400 certified bowls and bagasse clamshell containers meet ASTM D6400 and are BPI-certified. PET lids on takeaway bowls are not compostable; they are recyclable through standard PET streams. We mark this distinction explicitly on product spec sheets and recommend customers do the same in retail labelling and customer-facing communications.