This compound group has not yet been assigned a structural definition.

The various forms of crystalline silica are: α-quartz, β-quartz, α-tridymite, β-tridymite, α-cristobalite, β-cristobalite, keatite, coesite, stishovite, and moganite. NIOSH (2002)....Keatite, coesite, stishovite, and moganite are rarely found in nature. The most commonly occurring polymorphs are quartz, cristobalite and tridymite, which are found in rocks and soil. 

NIOSH Hazard Review: Health Effects of Occupational Exposure to Respirable Crystalline Silica (DHHS (NIOSH) Publication No. 2002–129). Cincinnati, OH, 145 pp.

From https://www.ncbi.nlm.nih.gov/books/NBK304370/#

This compound group is defined by the SMILES string 'C1CCC2C(C1)C(=O)OC2=O'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group is defined by the SMILES string 'C=[N+]=[N-]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group is defined by the SMILES string '[CH3]C1=[CH]C(=[CH]C(=C1[OH])[N+](=O)[O-])[N+](=O)[O-]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group is defined by the SMARTS string 'C(=[SD1])([ND1])[SD1]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

Populated from Swedish EPA

http://webapps.kemi.se/flodesanalyser/

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group is defined by the SMILES string 'C(CN)N'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group was populated by searching ChemIDplus for all compounds whose name contained "formaldehyde". Additionally, it contains the compounds in its subgroups. 

This compound group was populated with chemicals in Pharos with both "urea" and "formaldehyde" in the name.

This compound group is defined by the SMILES string 'C1=COC=C1'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

The SMILES string "COCC1CO1" captures all glycidyl ethers but is not specific enough as the only filter. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group is defined by the SMILES string 'COCCOC'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

The chemicals in this list are taken from many sources, including:

• The Swedish Chemicals Agency (KEMI) Report 7-15 Occurrence and use of highly fluorinated substances and alternatives. https://www.kemi.se/en/global/rapporter/2015/report-7-15-occurrence-and-use-of-highly-fluorinated-substances-and-alternatives.pdf
• Global Database of Per- and Polyfluoroalkyl Substances (PFASs) at http://www.oecd.org/chemicalsafety/portal-perfluorinated-chemicals/

This compound group is populated from its subgroups, which include methylhydrazines, dimethyl hydrazines, and phenylhydrazines https://www.cdc.gov/niosh/topics/cancer/npotocca.html

This compound group was populated from the 2016 GADSL list at http://www.gadsl.org/

This compound group has not yet been assigned a structural definition.

This compound group was populated from the 2016 GADSL list at http://www.gadsl.org/

This compound group is defined by the SMILES string '[NH4] subtracting [NH4].C'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

The following three SMARTS strings would be expected to capture all chloramines but there are unknown errors when searching PubChem

[ND1][ClD1] plus

[ClD1][ND2][ClD1] plus

[ClD1][ND3]([ClD1])[ClD1]

For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group was manually populated with inorganic cyanide compounds. It is based on an entry in Korea's GHS.

This compound group has not yet been assigned a structural definition.

This compound group is defined by the SMILES string '[ZnD0]' subtracting '[ZnD0].C' . For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group is populated by taking the more general compound group and subtracting the chemicals found in the relevent Annex.

This compound group is populated by taking the more general compound group and subtracting the chemicals found in the relevent Annex.

This compound group has not yet been assigned a structural definition.

One approach would be to use the SMILES string 'C[Pb]' and remove substances containing 'c[Pb]' (lowercase specifies aromatic). There are technical challenges since PubChem doesn't seem to provide an option to distinguish between aromatic and aliphatic carbons. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

Substructure searches in PubChem cannot easily distinguish between aliphatic and aromatic carbons. If it could, the compound group would be defined by the SMILES string 'C[Hg]' and subsequently filtered to remove substances containing 'c[Hg]' (lowercase specifies aromatic). For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group is populated by taking the more general compound group and subtracting the chemicals found in the relevent Annex.

This compound group is defined by the SMILES string 'CC(=C)C(=O)OC'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group has not yet been assigned a structural definition.

This compound group is populated by taking the more general compound group and subtracting the chemicals found in the relevent Annex.

This compound group is composed of four chemicals so no substructure search is needed to populate it