Aluminum antimony nickel silicon titanium vanadium oxide

Toxicity to terrestrial plants

Description of key information

NOEC = 60000 mg/kg dw , probably caused by physical properties of the test item (RA Zeolite cuboidal, surface modified)

Additional information

No data for toxicity to terrestrial plants are available for the target substance Aluminium silicate and titanium oxide matrix doted with vanadium, nickel, and antimony. Therefore, data from the analogue approach source substance Zeolite, cuboidal, crystalline, synthetic, non-fibrous were applied to cover the endpoint toxicity to terrestrial plants for the target substance.

Data for toxicity to terrestrial plants with Zeolite, cuboidal, crystalline, synthetic, non-fibrous have been reported for five different plant species. Rhaphanus sativus was the most sensitive dicotyledone species, therefore, tests with this species were chosen as key studies. In addition, studies with Raphanus sativus are available with Zeolite, cuboidal, crystalline, synthetic, non-fibrous (not surface modified and surface modified) and with a structural analogue Zeolite with a monoclinic crystal structure as test substance.

One of the key studies, conducted with Raphanus sativus and Zeolite, cuboidal, crystalline, synthetic, non-fibrous (surface modified with Ca²⁺), determined a LC50 value of > 240000 mg/kg dw soil for seedling emergence, EC50 values of > 240000 mg/kg soil dw for plant height, shoot fresh weight and phytotoxicity and a NOEC of 60000 mg/kg soil dw after 21 days exposure (Friedrich 2003, RL2). The study was carried out according to OECD 208.

A further study according to OECD 208 investigated the effect of a structural analogue Zeolite with monoclinic crystall structure (Wessalith 4000) to Raphanus sativus (Paulus 2001, RL2). After 23 days, a LC50 value for seedling emergence of 5000 mg/kg soil dw, an EC50 value for growth of 4000 mg/kg soil dw and a NOEC of 1500 mg/kg soil dw were derived.

The same test design was applied for testing the effects of a further Zeolite, cuboidal, crystalline, synthetic, non-fibrous (Vegobond AX, not surface modified) on Avena sativa. According to OECD guideline 208 and after a test duration of 23 days, a LC50 value of 9000 mg/kg soil dw was derived for seedling emergence. For growth a EC50 value of 9000 mg/kg soil dw and a NOEC of 5000 mg/kg soil dw were obtained (Paulus 2001, RL2).

Several supporting studies (not included in this dossier), all conducted with Zeolite, cuboidal, crystalline, synthetic, non-fibrous (not surface modified) according to OECD 208, showed comparable data.

Thus the results from testing of the structural analogue Zeolite (Wessalith 4000) without surface modification showed a NOEC value for growth of 1500 mg/kg dw soil for the most sensitive plant species Raphanus sativus (Paulus 2001, RL2). Zeolite, cuboidal, crystalline, synthetic, non-fibrous, whose surface was modified with Ca²⁺turned out to be considerably less toxic with a NOEC of 60000 mg/kg dw for plant height (Friedrich, 2003), corresponding to a lower toxicity by a factor of 120 compared to the not modified form.

In line with similar observations in aquatic toxicity tests, it is obvious from these test results that the toxicity caused by the not modified form is due to the depletion of essential trace elements in the test system while the environmentally most relevant surface modified form mostly induces lower effects. For this reason, this study with the surfcae modified form should be taken into account for the CSA.

Furthermore Zeolite, cuboidal, crystalline, synthetic, non-fibrous seemed to take influence on the distribution of water within the soil, thus exerting rather physical than chemical property of the substance. If the initial germination (until the unfurling of the cotyledon) did occur completely, the effect on growth seemed to be a function of time only (Paulus 2001, RL2).

 

With regard to the fact, that the catalytic sites of the Aluminium silicate and titanium oxide matrix doted with vanadium, nickel, and antimony are blocked and inhibited, it is to be expected, that comparable to the surface modified Zeolite Aluminium silicate and titanium oxide matrix doted with vanadium, nickel, and antimony will cause only low toxicity to terrestrial plants. Therefore, the NOEC of 60000 mg/kg dw will also be applied for Aluminium silicate and titanium oxide matrix doted with vanadium, nickel, and antimony.

Additional data for toxicity to terrestrial plants with further analogue approach source substances are not available.

The respective references for the source substance data can be found in the data matrix of the justification for the analogue approach, which can be found either in the CSR or as attachment in Iuclid section 13.