ASTM D5988-18 (2025) PDF

Full title and description

Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in Soil — ASTM D5988‑18, reapproved/confirmed in 2025. The method measures the degree and rate at which plastics (including formulation additives and residual materials after composting) are biodegraded in aerobic soil by monitoring evolved carbon dioxide or oxygen consumption over time under controlled laboratory conditions.

Abstract

ASTM D5988‑18 specifies a laboratory test to determine the aerobic biodegradability of plastic materials in contact with soil (or a soil/compost mixture) by measuring net gaseous carbon generation (CO2 evolution) or oxygen uptake as a function of time and comparing results to a defined reference material. The method is intended to estimate the degree and rate of mineralization by soil microorganisms and to provide numerical results that support biodegradability claims only within the tested duration.

General information

• Status: Active (D5988‑18, reapproved/confirmed 2025).
• Publication date: Original designation 2018; reapproval/confirmation published in 2025 (listed as ASTM D5988‑18(2025)).
• Publisher: ASTM International.
• ICS / categories: 13.030.10 — Solid wastes / biodegradability testing.
• Edition / version: D5988‑18 (designation appears as D5988‑18R25 for the 2025 reapproval).
• Number of pages: 7 pages (full method text).

Scope

This test method covers laboratory determination of the degree and rate of aerobic biodegradation of plastic materials (including additives and residual materials after composting) in contact with soil or a soil/mature‑compost mixture. It is designed to express biodegradability relative to a reference material and is applicable to materials that are not inhibitory to soil bacteria and fungi. The standard uses SI units and is stated equivalent to ISO 17556. Results are numerical and must not be extrapolated beyond the test duration.

Key topics and requirements

• Measurement principle: net CO2 evolution (or oxygen consumption) as a function of time to quantify mineralization to CO2.
• Test matrix: natural fertile soil or a laboratory mixture of soils; a soil/mature‑compost mixture is acceptable for residual materials after composting.
• Controls and reference: blank (soil) controls and a well‑defined positive reference material (e.g., cellulose or other accepted reference) are required for validity.
• Test conditions: controlled moisture content, adequate aeration, controlled temperature (laboratory conditions; method specifies appropriate ranges and incubation practice to maintain biological activity).
• Dosage & sample form: test specimens may be films, fragments, powders, or formed articles; carbon content (or ThOD) must be known for theoretical CO2/oxygen calculations.
• Duration & end point: continue incubation until no net CO2 production is observed over consecutive measurements (method includes criteria for test termination and validity, e.g., reference reaching an expected degradation level within months).
• Reporting: percentage of theoretical carbon mineralized for test and reference samples at test completion; do not use results for unqualified “biodegradable” claims beyond test conditions.

Typical use and users

Used by environmental testing laboratories, polymer and additive manufacturers, product certification bodies, composting researchers, regulatory agencies, and R&D groups developing biodegradable plastics or assessing environmental persistence of plastic residues. Typical uses include material screening, claim substantiation, comparative biodegradation studies, and end‑of‑life assessment following composting.

Related standards

Commonly referenced or complementary standards include ISO 17556 (equivalent test for biodegradability in soil), ASTM D5338 (aerobic biodegradation under controlled composting conditions), ISO 14855 (biodegradability by measuring CO2 in controlled composting), and standards for compostability and packaging (for example, ASTM D6400 and EN 13432) that address labelling and performance criteria for compostable plastics.

Keywords

aerobic biodegradation; plastics; soil biodegradability; CO2 evolution; mineralization; biodegradability testing; compost residuals; ASTM D5988; ISO 17556; biodegradation rate.

FAQ

Q: What is this standard?

A: ASTM D5988‑18(2025) is a laboratory test method that determines the degree and rate of aerobic biodegradation of plastic materials in soil by measuring evolved carbon dioxide (or oxygen consumption) over time to quantify mineralization.

Q: What does it cover?

A: It covers sample preparation, required controls and reference materials, test matrix selection (soil or soil/compost), incubation practice (moisture, aeration, temperature), measurement of CO2 or O2, test duration and end‑point criteria, and reporting of percent mineralization relative to theoretical carbon.

Q: Who typically uses it?

A: Environmental testing labs, polymer manufacturers and formulators, certification bodies, academic and industrial researchers, and regulators evaluating environmental fate or substantiating biodegradability claims.

Q: Is it current or superseded?

A: The designation D5988‑18 was reapproved/confirmed in 2025 and is listed as active (often referenced as D5988‑18(2025) or D5988‑18R25). Users should check for any corrigenda or subsequent revisions before test implementation.

Q: Is it part of a series?

A: It is part of the body of test methods addressing biodegradability and compostability (ASTM Committee D20 and subcommittees) and is used alongside related methods for composting and biodegradation assessment such as ASTM D5338 and standards harmonized with ISO tests (e.g., ISO 17556).

Q: What are the key keywords?

A: Aerobic biodegradation, soil, plastics, CO2 evolution, mineralization, biodegradability testing, compost residues, reference material, ASTM D5988, ISO 17556.