ISO 13641-2:2003规定了一种筛选方法，通过测定污泥、沉积物和其他低生物量浓度厌氧环境中产生的沼气（二氧化碳和甲烷），评估物质、混合物、地表水、地下水和废水、废水、污泥或其他环境样品的潜在毒性。与好氧微生物相比，厌氧细菌的生长速度要低得多。因此，厌氧法的试验周期比需氧菌法的试验周期长。将该试验的条件（例如，试验瓶中接种物和基质的量）在几天内调整至规定的试验周期。接种物可以从厌氧沉积物或大型或实验室规模的厌氧消化池中收集。 本方法适用于可溶于水或不溶于水的材料，包括挥发性化学品。 注意，对于水溶性低的化合物，需要特别小心，在这些情况下，其他方法可能更合适。 在低接种物质量浓度下进行厌氧生物降解性试验之前，通过该方法获得的信息可能有助于评估化学品和废水对厌氧生物量相对较低的栖息地（例如自然沉积物和土壤）中厌氧过程的潜在影响。

ISO 13641-2:2003 specifies a screening method for assessing the potential toxicity of substances, mixtures, surface waters, groundwaters and wastewaters, effluents, sludges, or other environmental samples by determining the production of biogas (carbon dioxide and methane) from muds, sediments and other anaerobic environments with low biomass concentration. The growth rate of anaerobic bacteria is much lower, compared with that of aerobic microorganisms. For this reason, the test periods in anaerobic methods are longer than in those with aerobic bacteria. The conditions of this test (for example amount of inoculum and substrate in the test bottles) were adopted to a defined test period over several days. The inoculum can be collected from anaerobic sediments or from large, or laboratory scale, anaerobic digesters. This method is applicable to materials, soluble or insoluble in water, including volatile chemicals. Note that special care is necessary with compounds of low water-solubility, and in these cases, other methods might be more suitable. Information obtained by this method may be helpful prior to anaerobic biodegradability testing with low inoculum mass concentrations and for estimations of the potential effects of chemicals and wastewater to anaerobic processes in habitats characterized by a relatively low anaerobic biomass, for example natural sediments and soils.