A mixture of isomers of: mono-(2-tetradecyl)naphthalenes; di-(2-tetradecyl)naphthalenes; tri-(2-tetradecyl)naphthalenes

Toxicity to terrestrial plants

Description of key information

Toxicity to terrestrial plants - read-across data available for structurally related alkylnaphthalene surrogate, namely, the reaction products of 1-hexadecene and naphthalene. 
NOEC > 1018 to 1069 mg/kg soil dw   in wheat, mung bean and Chinese cabbage - emergence endpoint  (OECD 208 TG)
NOEC > 1069 mg/kg soil dw  in wheat - growth endpoint   (OECD 208 TG)
EC50 > 1018 to 1050 mg/kg soil dw  in mung bean and Chinese cabbage - growth endpoint   (OECD 208 TG)

Additional information

No terrestrial plant toxicity studies have been carried out on the submission substance (EC No. 410-190-0). However, short-term terrestrial plant toxicity studies have been reported for a structurally related alkylated naphthalene surrogate, namely, the reaction products of 1-hexadecene and naphthalene (Synesstic 5) which can provide some useful read-across assessment for the submission substance, which is the corresponding reaction products of tetradecene and naphthalene.

The toxicity of the surrogate material, reaction products of 1-hexadecene and naphthalene,as measured by effects on emergence or growth to wheat, mung bean and Chinese cabbage was evaluated in a 14-day study using artificial soil.  Results indicated that the surrogate had no observed effect on emergence and growth in wheat plants [i.e., NOEC (14-day) > 1069 mg/kg soil dw]. In mung beans, no effect was observed in emergence [NOEC (14-day) > 1050 mg/kg soil dw] but there was a 14% reduction seen in growth weight (EC50 > 1050 mg/kg dw). Similarly in Chinese cabbage, no effect was seen for seed emergence [i.e., NOEC (14-day) > 1018 mg/kg] but a reduction (40%) in growth weight (EC50 > 1018 mg/kg). This effect is believed to be due to possible physical effects (oiling effect) of this poorly water soluble lipophilic test substance that forms oil film or emulsions in soil that covers or smothers the plant seed rather than a direct effect on the plant. Collectively, these findings indicate that the surrogate material is not acutely toxic and poses a low hazard to terrestrial plants.

Based on read-across, the submission substance would similarly be expected not to be acutely toxic to terrestrial plants and would be expected to pose a low hazard to terrestrial plants.

Read Across Justification

Category groups of chemicals that have similar structural features generally are expected to have similar properties as well as similar ecotoxicological characteristics that are predictable across the group in a homologous or structurally analogous series. Therefore, the use of surrogates having close structural similarities and same chemical group functionality as in the case of the alkylated naphthalenes (e.g., Synesstic 5) would be appropriate for read-across for the submission substance (aka MCP 2484, reaction products of tetradecene and naphthalene).

 

A chemical category groupis a group of chemicals whose physico-chemical and human health and/or environmental toxicological properties and/or environmental fate properties are likely to be similar or follow a regular pattern as a result of structural similarity (i.e., structural analogues). Under REACH, Annex XI allows for the chemical safety assessment of chemicals by the use of this chemical category group or analog approach; see Chapter R.6.2. of the ECHA guidance document (ECHA 2008) for discussion. Further read-across justification information including physico-chemical properties of the structural analogue is provided in IUCLID Section 13 Assessment Reports.