Thiram

Toxicity to birds

Description of key information

Secondary poisoning is not expected

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for birds:

500 mg/kg food

Additional information

Two key studies have investigated the toxicity of tetramethylthiuram disulfide (CAS No. 137-26-8) to one bird species. Four supporting studies have investigated the toxicity of the product Biosolid T to two further bird species, under GLP conditions.

 

The available long-term, key toxicity study (1995) was performed according to the OECD Guideline No. 206 under GLP conditions. In this study Colinus virginianus (age: 25 wk, male and female) was exposed via tetramethylthiuram disulfide (CAS No. 137-26-8) spiked diet for 23 weeks. Following treatment groups were tested: 0, 100, 500 and 2500 mg a.i./kg diet (nominal). Furthermore, recovery was tested in an additional treatment group. Here birds were exposed to the highest test concentration for only 10 weeks, following a post exposure period of further 13 weeks. Analysis of tetramethylthiuram disulfide (CAS No. 137-26-8) in the diet revealed sufficient homogeneity in the diet, stability during storage and test conditions and the applied dosages were verified. No treatment-related mortality was observed for all treatment groups, resulting in a NOEC (23 wk) of ≥ 2500 mg a.i./kg diet (nominal). Furthermore, the NOEC (23 wk) for signs of toxicity, reproduction, and body weight was 500 mg a.i./kg diet (nominal).

Birds that received thiram technical at 2500 ppm for the first ten weeks of the study, and were then transferred to basal diet, demonstrated that the effects of exposure to thiram were reversible, and that no impact on reproductive success occurred.

 

In the available short-term, key toxicity study (2010) according to EPA OPPTS 850.2100 (GLP), one dose of tetramethylthiuram disulfide (CAS No. 137-26-8) in corn oil was orally intubated directly into the crop or proventriculus of each bird (18 – 20 wk old male and female, Colinus virginianus). Following doses were administered: solvent control, 156, 259, 432, 720 and 1200mg a.i./kg body weight (nominal). After 14 days post exposure period significant effects on survival of birds was observed, resulting in a LD50 (14 d) of 930 mg a.i./kg bw (nominal). Further signs of toxicity were observed in the treatment groups, resulting in a NOEC (14 d) of 156 mg a.i./kg bw.

 

In the available four supporting short-term guideline studies (GLP) the formulation Biossild T was administered either via gauge or via spiked diet to birds. Results from these studies showed absence of treatment-related mortality in different bird species, resulting in LC50 (5 d) and LD50 (14 d) values of at least > 1781 mg a.i./kg diet and > 2000 mg a.i./kg bw (acute oral), respectively. Full recovery from sub-lethal clinical symptoms (if present) was observed during the post-exposure observation period of 3 days in dietary tests.