Thiram

Toxicity to terrestrial arthropods

Description of key information

NOEC (28 d, mortality, reproduction): ≥ 52.75 mg a.i./kg soil dw (nominal, OECD 232, Thiram 80 WG, spiked soil, Folsomia candida)

Additional information

Several short and long-term studies investigating the toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) towards five species of terrestrial arthropods are available.

 

In the available long-term key study (2010), performed according to the OECD Guideline No. 232 (GLP), the collembolan Folsomia candida (10-12 days old) were exposed via spiked soil to the product Thiram 80 WG for 28 d. Following concentrations were tested: control, 0.86, 1.55, 2.79, 5.02, 9.04, 16.28, 29.30 and 52.74 mg a.i./kg soil dry weight (nominal). After 28 days no effects on survival or reproduction of Folsomia candida were observed, resulting in NOEC (28 d) values of ≥ 52.75 mg a.i./kg soil dw (nominal), respectively.

 

Furthermore, following long- and short-term supporting studies are available:

Chronic oral exposure of Apis melifera to tetramethylthiuram disulfide (CAS No. 137-26-8) spiked diet (max. 120 mg/kg diet) for 10 d caused no effects on survival (NOEC (10 d) > 120 mg/kg diet).

 

A long-term supporting study (2010) according to the OECD Guideline No. 226 (GLP) and the product Thiram 80 WG, showed no effects on the mortality and reproduction of the mite Hypoaspis aculeifer resulting in a NOEC ≥ 52.75 mg a.i./kg soil dw (nominal).

 

Two further studies (2013a and b) with the mite Typhlodromus pyri and the wasp Aphidius rhopalusiphi investigated the mortality of the organisms after 7 d and 48 h exposure. The studies were extended to 14 d with the survived animals to test reproductive effects. The latter two organisms were exposed via spray application (max. 8.40 kg a.s./ha). No guideline was followed for these tests but the test procedure is in accordance with generally accepted scientific standards, GLP and described in sufficient detail. The studies resulted in LR50 (48 h) values of > 8400 g/ha (recalculated to 11.2 mg a.i./kg d.w. soil). No dose-response effects on reproduction were observed for both Typhlodromus pyri and Aphidius rhopalusiphi.

 The acute oral and acute contact toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to honey bees was investigated in additional studies. These tests were conducted according to the EPPO Guideline No. 170 Guideline for Evaluation of Side Effects of Plant Protection Products on honey bees (Apis mellifera, GLP) with the product Thiram 80 WG and according to the OECD Guidelines 213/214 (GLP) with Thiram technical. No significant lethal effects were observed up to the highest concentrations tested during oral or contact exposures, resulting in a LD50 (48 h) of > 113.91 µg a.i. per animal (nominal, oral) and of > 100 µg a.i. per animal (nominal, contact) in the tests according to the EPPO Guideline No. 170, respectively. These results are confirmed by the findings of the studies performed according to OECD 213/214, showing a LD50 (48 h) value of > 106.81 µg a.i. per animal (nominal, oral) and a LD50 (48 h) of > 100 µg a.i. per animal (nominal, contact), respectively.