Priority Chemicals for Toward Zero Exposure

CEPN has identified the 1st, 2nd, and 3rd Round of Priority Chemicals — process chemicals to be prioritized for elimination of substitution in electronics manufacturing and serve as an MRSL. The first three rounds of Priority Chemicals are focused on solvents used as process chemicals in electronics manufacturing.

Selection Process: CEPN’s selection process for these Priority Chemicals included nominating a starting list of chemicals using CEPN member companies’ Manufacturing Restricted Substances Lists (MRSL) as well as other publicly available MRSLs, aggregated and anonymized data collected using CEPN’s Process Chemical Data Collection (PCDC) Tool and soliciting nominations from a broad cross section of stakeholders.

The nominated chemicals were then researched and screened against 1) CEPN’s High Hazard Criteria; 2) use in the electronics industry as solvents in manufacturing processes; and 3) a high-level review of potential availability of safer alternatives. More details on the selection process are provided in CEPN’s Procedure on the Selection of Priority Chemicals.

1st Round Priority Chemicals

TZE Scope: Solvents in Cleaning Products

For the Toward Zero Exposure program, elimination is defined as concentrations in mixtures below GHS cutoff reporting values according to Table 1.5.1 of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), Eleventh revised edition (2025). For all 1st Round Priority Chemicals this is <0.1%, except for methanol which is <1%.

2nd Round Priority Chemicals

TZE Scope: Solvents in Cleaning Products

For the Toward Zero Exposure program, elimination is defined as concentrations in mixtures below GHS cutoff reporting values according to Table 1.5.1 of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), Eleventh revised edition (2025). For all 2nd Round Priority Chemicals this is <0.1%, except 1,1,2,2-tetracholoroethane which is <1%.

3rd Round Priority Chemicals

For the Toward Zero Exposure program, elimination is defined as concentrations in mixtures below GHS cutoff reporting values according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), Eleventh revised edition (2025). The general cutoff value is 1.0% (Table 1.5.1 of GHS 2005), with lower values for specific hazard categories: respiratory/skin sensitizers, mutagens, carcinogens, and reproductive toxins. Details for the three Priority Chemical rounds are provided in the table footnotes. ​

More information on the selection and research conducted for the three Rounds of Priority Chemicals can be found in the First Round Priority Chemical Selection Report, December 2019; the Second Round Priority Chemical Selection Report, June 2023, and the Third Round Priority Chemical Selection Report, April 2026.