Effects of the Veterinary Pharmaceutical Ivermectin on Soil Invertebrates in Laboratory Tests

Abstract

As part of the risk assessment of veterinary pharmaceuticals, the potential impact of these chemicals on soil ecosystems has to be determined according to European law. However, almost no data from standardized laboratory tests are available. Therefore, in the EU FP6 ERAPharm, the effects of the widely used veterinary pharmaceutical ivermectin, an anthelminthic, were studied in chronic laboratory tests performed according to OECD (Organisation for Economic Co-operation and Development) and ISO (International Organization for Standardization) guidelines. In detail, three soil invertebrate species--the earthworm Eisenia fetida, the springtail Folsomia candida, and the predatory mite Hypoaspis aculeifer--were tested. The nominal concentrations of ivermectin mixed into the test substrate artificial soil was verified using residue analysis, which indicated that the test substance is persistent for at least up to 28 days. As expected when considering the mode of action of this substance, survival and reproduction of collembolans were clearly affected [LC(50) = 8.4 mg/kg soil dry weight (dw); NOEC(repro) = 0.3 mg/kg soil (dw)]. Predatory mites reacted less sensitively [LC(50) > or = 31.6 mg/kg soil (dw); NOEC(repro) = 3.2 mg/kg soil (dw)]. Earthworm survival and reproduction were affected in the same order of magnitude as the predatory mites [LC(50) > or = 10 mg/kg soil (dw); NOEC(repro) = 2.5 mg/kg soil (dw)]. These results are in good agreement with the few data known from nonstandardized tests for the same or related soil invertebrate species. The results of these tests indicate that the effects of ivermectin on soil invertebrates--in particular, collembolans--cannot be excluded at field-relevant concentrations, as determined in a risk assessment according to VICH guidelines. More sophisticated higher-tier tests (e.g., in multispecies or semifield test systems) are recommended in order to assess the potential risk more accurately.

Fate and effects of ivermectin on soil invertebrates in terrestrial model ecosystems

“…In fact, for reasons not clear yet the reaction of earthworms and enchytraeids was positive. The high sensitivity of collembolans is well in line with test data gained in the laboratory (Jensen et al 2003;Römbke et al 2010). On the community level, a significant impact was detected at all sampling dates.…”

“…Data from literature confirm the low to moderate sensitivity of enchytraeids and earthworms to ivermectin, indicating effects on reproduction for both groups in the low mg/kg range (e.g. NOECs: 3.0 and 2.5 mg ivermectin/kg soil dw, respectively) (Jensen et al 2003;Römbke et al 2010).…”

“…First results gained in standard laboratory tests with predatory mites show basically the same picture: For example, a NOEC reproduction of 3.2 mg/kg soil dw was determined for the species Hypoaspis aculeifer, which is about a factor of ten higher than the NOEC for two collembolan species tested under the same conditions (Jensen et al 2003;Römbke et al 2010). In the TMEs, numbers of collembolans were reduced at almost all treatment levels to less than 50% of the numbers in the control (Fig.…”

Transport of oxytetracycline, chlortetracycline, and ivermectin in surface runoff from irrigated pasture

“…[4] A 2002 review of pharmaceutical contaminants in the environment reports that the overall excretion rates of unmetabolized chlortetracycline, oxytetracycline, and ivermectin in feces and urine in veterinary treatment are 17-75%, 20%, and 40-75%, respectively. [1] Numerous studies have been conducted on the environmental fate of avermectins with a focus on effects on dung arthropods, [5] soil invertebrates, [6][7] and aquatic ecosystems. [8] Studies looking at the mobility [9] and dissipation [10] of ivermectin in different soil types have shown that pH and cation exchange capacity of the soil can affect the ionic binding potential of ivermectin, and that the dissipation of ivermectin is slow in many soils under aerobic conditions.…”

Indução de ivermectina na hormese sobre Eisenia foetida durante a vermicompostagem de esterco bovino

“…Embora as pesquisas conduzidas por Kaneda et al (2006) apontem que as concentrações ambientalmente relevantes de ivermectina não afetam as minhocas, outros estudos demonstraram que este endectocida prejudica os aspectos reprodutivos, como a produção e a eclodibilidade dos casulos (Gunn & Sadd 1994;Rombke et al, 2009) enquanto que a mortalidade só é evidenciada em concentrações elevadas, entre 56 mg kg -1 (Wang et al, 2012) e 314 mg kg -1 (Halley et al, 1989). Recentemente, tem-se observado uma reemergência de estudos científicos em relação a um fenômeno conhecido como efeito hormético (Calabrese, 2005).…”