Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Normal-Heptane has the potential to volatilize to air, based on a relatively high vapor pressure, where it is subject to atmospheric oxidation. In air, Normal-Heptane can react with photosensitized oxygen in the form of hydroxyl radicals (OH-). According to Atkinson (1985) the half-life of Normal-Heptane, normalized to a 12-hour day, is 4.47 days, based on 12-hour light / 12-hour dark periods and an OH- concentration of 5E5. Estimation with the APOWIN model (HSPA Consortium 2009) resulted in a test substance half-life, as mediated by hydroxyl radical (OH-) attack, of 18.68 hours based on a 12-hour day.

 

Normal-Heptane as other constituent chemicals of the C7-C9 aliphatic hydrocarbon solvents category are not amenable to hydrolysis because of their molecular structure.

 

Normal-Heptane exhibits ready extents and rates of biodegradation.

Data on bioaccumulation are estimated. BCF values for the category members are in the range of 11.81 to 1216 (log BCF of 1.07 to 3.08), including Normal-Heptane with a BCF and Log BCF of 552 and 2.74, respectively.

 

Category members are not expected to sorb significantly to organic matter in soil, sediment, and wastewater solids based on calculated log Koc values, with Normal-Heptane having a log Koc of 2.38.

 

Fugacity-based multimedia modelling provides basic information on the relative distribution of a chemical between selected environmental compartments (i.e. air, soil, water, sediment, suspended sediment, and biota). A widely used fugacity model is the EQC (Equilibrium Criterion) Level I model (Mackay et al. 1996). This models requires the input of basic physico-chemical parameters (i.e. molecular weight, melting point, vapor pressure, water solubility, log Kow). Available results of the Mackay Level I environmental distribution model show that members of the C7 to C9 hydrocarbon solvents category have the potential to partition primarily to air. These results can be explained by their relatively high vapor pressures.

The distribution of the substance in the environmental compartments, air, water, soil, and sediment, has further been calculated using the PETRORISK Model, version 5.2. Based on the regional scale exposure assessment, the multimedia distribution of the substance is 79% to air, 7.8% to water, 3.8% to soil and 10% to sediment. Distribution modeling results are included in the 'Multimedia distribution modeling results' tab in the PETRORISK spreadsheet attached to IUCLID Section 13.