ISO 23517:2021 pdf download – Plastics — Soil biodegradable materials for mulch films for use in agriculture and horticulture — Requirements and test methods regarding biodegradation, ecotoxicity and control of constituents.
5.2 Ultimate aerobic biodegradation 5.2.1 Test method and evaluation criteria The ultimate aerobic biodegradability shall be determined for the whole material or for each organic constituent. Test samples shall not be subjected to conditions or procedures, such as a pre-treatment by heat and or an exposure to radiation exposure, designed to accelerate biodegradation prior to testing according to ISO 17556. The material is considered to have demonstrated a satisfactory rate and level of biodegradation in soil if, when tested in accordance with ISO 17556, it achieves a minimum biodegradation percentage as specified hereunder: a) 90 % of the organic carbon shall have been converted to CO 2 by the end of the test period (relative to a reference material). Both the reference material and the test item shall be tested for the same length of time and the results compared at the same point in time; b) as an alternative, 90 % (in absolute terms) of the organic carbon shall have been converted to carbon dioxide by the end of the test period. If the level of biodegradation exceeds 90 % (relative to a reference material or in absolute terms), then the biodegradation test can be terminated. However, the test period shall be no longer than 2 years. The biodegradation test shall be performed at a temperature constant to within ±2 °C in the range between 20 °C and 28 °C, preferably 25 °C. Use, as reference material, a well-defined biodegradable polymer (microcrystalline-cellulose powder or ashless cellulose filters). If possible, the physical form and size of the reference material should be comparable to that of the test material.
5.2.2 Requirements regarding constituents Organic constituents which are present at concentrations of less than 1 % (dry mass) do not need to demonstrate biodegradability. However, the sum of such constituents shall not exceed 3 % (dry mass). For organic constituents which are present in the material at a concentration between 1 % and 15 % (by dry mass), the level of biodegradation shall be determined separately and meet the criteria specified in 5.2.1. Organic constituents at a concentration between 1 % and 15 % (by dry mass) that turned out to be readily biodegradable in a ready biodegradation test according to an OECD test guideline (OECD 301, Methods A to F [30] ; OECD 310 [31] ) are considered as biodegradable in the context of ISO 23517. As an alternative to testing the single organic constituent used between 1 % and 15 % (by dry mass), the level of biodegradation of that organic constituent can be determined using an artificial blend of the same material consisting of at least 15 % by total organic carbon (TOC) content. In case this artificial blend meets the criteria specified in 5.2.1, then the organic constituent in question is considered to be biodegradable in the context of ISO 23517 and can be used at the same or lower concentration in a material on the condition that the co-substrate is present as tested in the artificial blend.