Mapping the EU Ecolabel Detergent Ingredients Database to CAS Registry Numbers: a multi-source effort and the case for an identifier-based DID list redesign

The Detergent Ingredients Database is the reference used across Europe to compute the Critical Dilution Volume of cleaning and cosmetic products under the European Union Ecolabel. Its 2023 version identifies each of 265 ingredients by a descriptive name and a database number, but carries no Chemical Abstracts Service or European Community registry number. This design makes it difficult for formulators, regulators and researchers to link the list to substance-level databases-such as the European chemicals registration dossiers, United States aquatic-toxicity resources, and public structure repositories-where environmental fate and ecotoxicity data are keyed on registry numbers. We consolidated five complementary sources of chemical attribution: An industry environmental-safety cross-reference tool, the household-ingredient risk assessments jointly published by the European detergent and chemical industries, a national surfactants suspect list, chemical-category tables, and a web-assisted search citing primary sources. Each retained substance was enriched with canonical structural identifiers. The resulting mapping attaches at least one registry number to 232 of the 265 entries (87.5%), providing 1,276 entry-substance couples that span 932 unique substances, with a structure recorded for most couples and a five-level reliability indicator on every one. Beyond the dataset, the exercise exposes recurrent difficulties: Many entries denote substances of unknown or variable composition for which no single registry number can stand; others are finer segmentations of one registered substance; and some act as catch-all categories aggregating chemicals of distinct identity. The mapping is a working tool that still requires expert and regulatory validation. We argue that rebuilding the list on a substance-registry foundation would give direct access to authoritative fate and toxicity data. A companion paper uses this mapping to recompute the list's toxicity and degradation factors.