Decanoic acid, mixed esters with heptanoic acid, octanoic acid, pentaerythritol and valeric acid

Sediment toxicity

Description of key information

Findings from a chronic sediment OECD 225 study showed that the registered substance did not cause any long-term effects on mortality, growth (biomass) or reproduction (number of live worms) in the benthic sediment blackworm, Lumbriculus variegatus, after 28 days of exposure in sediment at 102 mg/kg (limit test).   The 28-day NOELR was ≥ 102 mg/kg soil d.w. based on no effects on mortality, growth and reproduction.  The registered substance is not expected to cause any long-term toxicity or adverse effects to organisms in the sediment or terrestrial compartments.   No PNEC for sediment could be derived for quantitative risk assessment.  However, it is possible to qualitatively conclude that the registered substance does not pose an unacceptable risk to sediment-dwelling organisms.     . 

Additional information

A recent chronic sediment study was performed to evaluate the long-term effects of the registered substance, CAS No. 71010-76-9, on the sediment-dwelling benthic oligochaete, Lumbriculus variegatus, using a static exposure system in which the test substance was spiked in the sediment phase at a nominal concentration of 102 mg/kg for 28 days (Sutherland, 2014). The spiked sediment was allowed to equilibrate or “age” for 7 days prior to its use in the experiments. Control sediment was similarly allowed to equilibrate for same amount of time. Allowing for equilibration over time is more reflective of long-term release of low levels of a substance to the environment or sediment, mimicking ”real-world” conditions and exposure scenarios. It allows a more complete equilibration, mixing, sequestering, complexing, binding, etc. with the sediment test system. Testing was carried out at a limited sediment dose of 102 mg/kg to minimize the possibility that at higher concentrations the registered substance, being an oily lubricant material, might form an oily film or emulsion layer in the sediment which could cause a “physical effect” or smothering effect on theLumbriculus variegatusworm, which may confound interpretation of test findings. 

 

After 28 days of exposure, there were no statistically significant treatment-related effects on the reproductive output (number of live worms) or growth (e.g., biomass - dry weight) when the treatment group was compared to the control (p= 0.05). As such, the 28-day NOELR for both reproduction and growth is equal to or greater than the limit loading concentration tested (102 mg/kg). The 28-day EL50 (reproduction, growth) is expected or can be deduced to be greater than 102 mg/kg since no differences were observed between the control and treated groups.

 

In conclusion, the findings from this chronic OECD 225 toxicity test indicate that the registered substance did not cause any long term effect on mortality, growth (biomass) or reproduction (i.e., number of live worms) in the benthic Lumbriculus variegatus after 28 days of exposure in sediment. In addition, no behavioral effects were observed in the blackworms when the treatment group was compared with the control group.

 

The following information is taken into account for sediment toxicity for the derivation of PNEC:

Results from a 28-day chronic sediment study clearly indicate that the registered substance is not expected to cause any long term effects on sediment organisms likeLumbriculus variegatus. The 28-day NOELR ≥ 102 mg/kg soil d.w. based on no effects on mortality, growth and reproduction. 

 

Besides not causing any long-term effects on sediment organisms, the registered substance showed no long-term adverse effects to soil microorganisms in a 28-day OECD 216 nitrogen transformation test (Carter, 2014). Futhermore, the registered substance did not have any long-term effects on terrestrial earthworm reproduction and growth in a 56-day OECD 222 test (Kelley 2014) and did not have any acute mortality to earthworms in a 14-day OECD 207 acute toxicity test (Kelley 2013). Lastly, the registered substance did not have any long-term effects on the seedling emergence, growth and reproduction of two terrestrial plants,B. rapaandA. sativain 35-day and 52-day ISO 22030 chronic plant toxicity tests, respectively (Butler, 2014). Collectively, these findings as well as the previously discussed lack of acute and chronic aquatic toxicity provide further support that the registered substance, CAS 71010-76-9), is not likely to pose a concern to sediment dwelling organisms. The lack of sediment toxicity is probably attributable to the low water solubility, high log Kow (inability to cross biomembrane) and low bioavailability of the registered substance. In addition, the registered substance is readily biodegradable, rapidly metabolized and it is not persistent or bioaccumulative.     

 

As no PNEC for water could be determined (no aquatic toxicity),it is not possible to derive a PNEC for sediment using the EqPM (equilibrium partitioning method). The available chronic toxicity data inLumbrulus variegatusindicate that the registered substance is not expected to cause any adverse effects to sediment. While it is not possible to derive PNECs needed for quantitative risk assessment, it is possible to qualitatively conclude based on the available sediment toxicity data above as well as related terrestrial test data that the registered substance does not pose an unacceptable risk in sediment-dwelling organisms.