Table 1.

Potential terrestrial exposure pathways associated with different processes/practices.

process/practice	possible exposure route/risk
landfill/municipal solid waste disposal disposal of waste medication	— direct ingestion of medication/leachate by scavengers — indirect ingestion by insectivores (e.g. birds/bats) consuming insects feeding on waste/leachate — contamination of local freshwater resources and land by leachate containing drugs
animal waste disposal disposal of ‘medicated’ animal carcasses	— carcass may contain medication administered before death—ingestion by scavengers (or carnivores) — indirect ingestion by insectivores (e.g. birds/bats) consuming insects feeding on medicated carcasses — sustained release bolus (long duration medication—as tablets) may be present within carcass digestive tract
liquid waste processing STP treatment of ‘medicated’ effluent	— STPs ‘attract’ certain species, e.g. insectivores or aquatic birds at trickling filters or tertiary treatment/polishing lagoons (respectively) — direct ingestion of wastewater and/or long-term dermal exposure in lagoons (aquatic birds and mammals) — indirect ingestion by insectivores (e.g. birds/bats) consuming invertebrates feeding on effluent (e.g. at trickling filters) or emerging from lagoons — potential bioaccumulation and food chain/trophic transfer within lagoon ecosystems
applying manure, slurry or STP biosolids/effluent to land re-use of ‘medicated’ waste in agriculture	— potential for persistence and/or bioaccumulation of certain compounds in soil and soil invertebrates — food chain/trophic transfer in agricultural ecosystems — direct ingestion by birds/mammals — indirect ingestion by insectivores (e.g. birds/bats) consuming soil/aerial invertebrates
livestock/poultry production ‘medicated’ faeces deposition	— livestock/poultry receiving medication generate contaminated faeces and urine — direct ingestion by soil and aerial invertebrates — indirect ingestion by insectivores (birds/mammals, etc.) — contact with residues in hair, wool, feathers and other material used as nesting or ingestion of this material — direct ingestion by coprophagous vertebrates — risk of high exposure if sustained release bolus (long duration medication—as tablets) in use — intensive outdoor operations (e.g. feedlot CAFOs) may pose a particularly elevated risk