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Introduction
The assessment of the effects and risks of chemicals for the terrestrial environment is a complex matter. This complexity comes, among others, from factors such as the need for sharing of the available landscape among urban/industrial activities, agricultural production in the form of agro-systems, and supporting terrestrial ecosystems. In addition, terrestrial systems are not associated with a single compartment, but with the interface between soil and the atmosphere.
General adverse effects on the soil organisms include effects on soil functions and on organisms (invertebrates, micro-organisms) important for proper soil function and nutrient cycle conservation. There is a common understanding that the ecological risk assessment aims not at individuals but at the protection of populations. In general, the continuance of populations of non-target organisms should be ensured. Structural and functional endpoints should be regarded of equal importance.
Soil organisms are species that dwell primarily in the soil and soil litter. Soil organisms are exposed to active constituents from contact and oral uptake routes of exposure in the surrounding soil compartment. A ‘healthy’ soil supports a range of ecosystem functions or services (such as nutrient cycling) that are essential for supporting the growth of crops as well as the organisms that depend on those crops. Soil communities of invertebrates and microorganisms are the most diverse part inhabiting agricultural landscapes.
The general protection goal is to protect biodiversity and ecosystems. EFSA (2017) has proposed specific protection goals for soil organisms being key drivers for relevant ecosystem services in agricultural landscapes such as nutrient cycling, soil structure, pest control and biodiversity. Considering the time-scales and biological processes related to the dispersal of the majority of soil organisms, risk assessment are made at in- and off-field scale considering field boundary levels.
For outdoor situations, the following applications are considered to have negligible soil exposure:
- when precautions are taken to prevent contact with the soil (eg when pots/containers are placed on plastic sheets)
- when crop is not cultured in soil, but on other substrates
- wound healing with pastes
- use under glass
- use on timber or felled trees
- use of baitboxes against rodents with their subsequent removal.
Soil sterilants and similar products are, in most cases, designed to have broad-spectrum activity against the soil microflora, and so will evidently show strong activity when tested according to the subscheme. The environmental risk posed by such products should be judged on other criteria, particularly on the basis of persistence, mobility, and effects on other non-target organisms.