Cross-contamination of feed with low concentrations of antimicrobials can occur at production, transport and/or farm level. Concerns are rising about possible effects of this contaminated feed on resistance selection in the intestinal microbiota. Therefore, an experiment with pigs was set up, in which intestinal and fecal concentrations of chlortetracycline (CTC), doxycycline (DOX) and sulfadiazine-trimethoprim (SDZ-TRIM) were determined after administration of feed containing a 3 % carry-over level of these antimicrobials. The poor oral bioavailability of tetracyclines resulted in rather high concentrations in cecal and colonic content and feces at steady-state conditions. A mean concentration of 10 mg/kg CTC and 4 mg/kg DOX in the feces was reached, which is higher than concentrations that were shown to cause resistance selection. On the other hand, lower mean levels of SDZ (0.7 mg/kg) and TRIM (< limit of detection of 0.016 mg/kg) were found in the feces, corresponding with the high oral bioavailability of SDZ and TRIM in pigs. The relation between the oral bioavailability and intestinal concentrations of the tested antimicrobials, may be of help in assessing the risks of cross-contaminated feed. However, future research is needed to confirm our results and to evaluate the effects of these detected concentrations on resistance selection in the intestinal microbiota of pigs.

The European Union’s goal to reduce pesticide risk, exemplified by restrictions on insecticides like neonicotinoids, necessitates a shift from single-substance risk assessment to a holistic evaluation of pest control strategies. To address this, a novel decision-support grid was developed that integrates 13 environmental, biodiversity, and human health risk indicators for multiple active substances across an entire crop season into a single Final Scenario Score (FSS), ranging from 0 to 1 (where 1 is the risk of the reference scenario). This framework was applied to three case studies in Belgium—sugar beet, apple, and pear cultivation—where neonicotinoid-based reference scenarios were compared with chemical and/or organic alternatives under low (best-case) and high (worst-case) pest pressure conditions. The results highlight the complexity of finding viable alternatives, with an FSS below 0.75 as the justification threshold. In sugar beet, only the best-case chemical alternative (FSS = 0.71) met the threshold, while worst-case chemical alternatives failed due to increased risk. For apple and pear, organic alternatives consistently showed low-risk scores (FSS 0.27–0.61) but faced important efficacy gaps against key insect. Chemical alternatives in orchards were justifiable in low-pressure scenarios (FSS 0.64–0.73) but failed under high pest pressure (FSS 0.91–0.93). This novel decision-support grid proves to be a valuable tool for guiding sustainable pest control strategies for regulators and field advisors.

The potential withdrawal of glyphosate necessitates a comprehensive evaluation of alternative weed control strategies that balances human health safety with environmental concerns. This study applied a decision-support grid to compare the impacts of glyphosate-based reference strategies against chemical and non-chemical alternatives across four Belgian case studies: pome fruit orchards, grassland renewal, arable weed patches, and railways. The assessment integrated twelve risk indicators including human, environmental and biodiversity risk, and life cycle assessment for global warming potential (GWP) into a Final Scenario Score (FSS). The results indicated that only one alternative strategy, the chemical alternative in local weed patch control, achieved the FSS threshold (<0.75) required to justify substitution (FSS = 0.70). Chemical alternatives in other case studies frequently shifted burdens; for instance, bio-herbicides in railways increased risks to residents and aquatic organisms compared to the reference. Conversely, mechanical and thermal alternatives eliminated chemical toxicity but resulted in GWP increases up to 32 times higher than glyphosate-based practices. These findings demonstrate that chemical substitutes often maintain toxicity risks while non-chemical strategies trade them for increased climate impacts. Consequently, a ban on glyphosate is currently unsupported by the environmental performance of available alternatives in these temperate high-intensity systems. Sustainable progress requires a transition period where optimized conventional strategies remain available within integrated weed management, while innovations in electrification and precision technology are accelerated to resolve current trade-offs.