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

Toxicity to terrestrial plants

Description of key information

Results from a chronic ISO 22030 study clearly indicates that registered substance causes no long-term effects on A. sativa or B. rapa in terms of seedling emergence, growth and reproduction. The 35-day NOEC was ≥ 101.7 mg/kg for B. Rapa (reproduction, growth) and the 52-day NOEC was  ≥ 101.7 (mg/Kg) for A. Sativa (reproduction, growth).   The registered substance is not expected to cause  long-term adverse effects  on terrestrial plants in terms of emergence, growth or reproduction based on these findings.    No PNEC for soil 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 soil organisms like terrestrial plants.   

Additional information

Short-term terrestrial plant toxicity studies have not been carried out with the registered substance. However,a long-term terrestrial plant toxicity study has been recently carried out using the ECHA recommended ISO 22030 chronic testing in higher plants guidelines to evaluate the emergence, growth and reproductive effects (i.e., flowering) of the registered substance, CAS 71010-76-9, on two plant species,Brassica rapaandAvena sativa (Butler, 2014). The findings from this chronic study should provide same information for the seedling emergence and growth endpoints as would a short-term plant toxicity study.  

 

The chronic test was performed as a limit test with the registered substance. The nominal soil loading level for this study was 101.7 mg/kg (dry weight). The treatments were prepared by adding the appropriate amount of registered substance to peat, which was then mixed with sand and clay to prepare the artificial soil. The treatments were mixed in sealed glass jars on a roller mill for 3 days prior to hydration. After hydration with deionized water the soils were placed in an environmental chamber at test temperature to equilibrate for an additional eleven days. A control treatment consisting of soil with no test substance was also included. The soil preparation were well-mixed and allowed to equilibrate or “age” for total of 14-days prior to the start of testing. 

 

Observations for seedling emergence and survival were performed daily. Seven days after sowing the number of plants per pot were reduced to 8 where applicable. This process was random. At fourteen days post emergence, 4 seedlings (randomly selected) per replicate per treatment and control were cut off at the soil surface and weighed (fresh weight). Additionally, the number of buds present and the number of flowers present were also documented (B. rapa, only). The remaining seedlings were held under test conditions until the tests were terminated on Day 35 forB. rapa and on Day 52 forA. sativa.

 

The emergence rate of the control plants was 98% for B. rapa and 100% for A. sativa. All plants were observed to be healthy (no etiolation and flowers appear during the first three weeks for B. rapa or at 8 weeks for A. sativa). No plants in any pot died during the test. There were no observations that any of the plants exhibit visible phytotoxic effects such as chlorosis, wilting, leaf or stem deformations greater than normal variation in growth and morphology.  

 

No statistical significant difference was observed for seedling emergence inA. sativaorB. rapabetween the treatment group and the control group. ForB. rapa, 50% emergence occurred on Day 3 and forA. sativa, 50% emergence occurred on Day 4. Overall, seedling emergence ranged from 93% to 100% in the control and treatment group. At 14 days post-emergence, seedling survival was 100% in both groups. The emergence rate of the control plants was 98% forB. rapaand 100% forA. sativa

 

At fourteen days post emergence, 4 seedlings (randomly selected) per replicate per treatment and control were cut off at the soil surface and weighed (fresh weight). The remaining seedlings were held under test conditions until the tests were terminated, Day 35 (B. rapa) and Day 52 (A. sativa).Avena sativatest termination endpoints consisted of fresh inflorescences weight, dry inflorescences weight, number of inflorescences, fresh shoot weight and dry shoot weight. Additionally, at test termination forB. rapaendpoints consisted of, fresh pods weight, dry pods weight, number of pods, fresh shoot weight and dry shoot weight. Dry mass of shoots, pods and inflorescences was obtained by placing fresh shoots and pods into a lab oven at approximately 60℃for approximately 24 hours. Furthermore, there was no difference between BBCH Growth stage evaluations.

 

After the 14 and 52 day harvest forA. sativa, none of the endpoint parameters (fresh inflourescences weight, dry inflourescences weight, number of inflourescences, fresh shoot weight and dry shoot weight) were observed to be statistically different from the control at a 5% level of significance. Equal variance t-tests was used to determine the 52 day NOEC of ≥101.7 (mg/Kg) forA. sativa.

 

After the 14 and 35 day harvest forB. rapa, none of the endpoint parameters (number of buds, fresh pods weight, dry pods weight, number of pods, fresh shoot weight and dry shoot weight) were observed to be statistically different from the control at a 5% level of significance. The equal variances t-test and the Steele’s Many-One Rank Test were used to determine the 35 day NOEC of ≥101.7 mg/kg forB. rapa. 

 

Overall, there was no statistically significant differences in emergence, growth and reproductive endpoints between the treated group compared to the control group in both plant species, either at Day 14, Day 35 or Day 52.

 

EC50 values could not be calculated since this was a limited dose study. However, 35-day or 52-day EC50 values are expected or deduced to be greater than 101.7 mg/kg inB. rapaandA. sativa, based on the no effects observed so far at this exposure concentration (i.e, 101.7 mg/kg).

 

In summary, results indicate there were no statistically significant treatment-related effects on any endpoints observed for either species when the treatment groups were compared to the control group.  Collectively, this ISO 22030 chronic plant study clearly demonstrates that the registered substance causes no long-term effects onA. sativa or B. rapa in terms ofemergence, growth and reproduction. 

 

The following information is taken into account for toxicity on terrestrial plants for the derivation of PNEC:

 Results from a chronic ISO 22030 study clearly indicates thatregistered substance causes no long-term effects onA. sativa or B. rapain terms ofseedling emergence, growth and reproduction.

35-day NOEC≥101.7 mg/kg forB. Rapa(reproduction, growth)

52-day NOEC≥101.7 (mg/Kg) forA. Sativa(reproduction, growth)

 

Besides not causing any acute or chronic toxicity to terrestrial plants likeB. rapaandA. sativa,the registered substance showed no long-term adverse effects to soil microorganisms in a 28-day OECD 216 nitrogen transformation test (Carter, 2014). Furthermore, the registered substance did not have long-term effect 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). Findings from a 28-day chronic sediment toxicity study (OECD 225) 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 benthicLumbriculus variegatusa in sediment (Sutherland, 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 soil organisms such as terrestrial plants. The lack of soil or terrestrial 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. Exposure to the registered substance in the terrestrial compartment is likely to be negligible.      

 

As no PNEC for water could be determined (no aquatic toxicity), it is not possible to derive a PNEC for soil using the EqPM (equilibrium partitioning method). The available toxicity data indicate that the registered substance is not expected to cause any adverse effects to soil or sediment organisms. While it is not possible to derive PNECs needed for quantitative risk assessment, it is possible to qualitatively conclude based on the available short- and long-term terrestrial test data that the registered substance does not pose an unacceptable risk to soil organisms like terrestrial plants.