Pet dogs transfer veterinary medicines to the environment

Worldwide, the number of pet dogs increases yearly, and as a result so does the use of veterinary medicines for flea and tick control. We investigated the potential transfer of veterinary flea products from dogs to the environment in a 'proof of principle' experiment. For this purpose, samples of hair, urine, and water after swimming were investigated. Nine dogs were recruited for this study, eight of which had been recently treated with an ectoparasiticide product. Hair and urine samples were tested for afoxalaner, fluralaner, fipronil and imidacloprid. Interestingly, contamination with ectoparasiticides was frequently demonstrated in samples from dogs untreated with these particular substances, suggesting widespread secondary transfer. In addition, hair retrieved from a bird's nest contained fipronil, fluralaner and imidacloprid, indicating a potential pathway for the exposure of juvenile birds. Three of the dogs also participated in a swimming experiment. One had been treated with oral fluralaner, whilst the remaining two had received other compounds not included in our study. However, in all three dogs, both fluralaner and imidacloprid were detected in hair samples. Fluralaner concentrations in the swimming water exceeded Dutch water quality standards, indicating a potential risk to the aquatic environment. Imidacloprid levels increased after each swimming dog, but did not breach Dutch water quality standard levels. These findings all call for improvements in the current risk assessment and management for veterinary medicines, by including companion animals and their exposure pathways into ecosystems.

Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests

Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79μg a.s./g OC. The treatment-related responses observed in the microcosms are in accordance with the results of the 28-d laboratory toxicity tests. These tests showed that the insect C. riparius and the crustacean H. azteca were approximately two orders of magnitude more sensitive than the oligochaete L. variegatus. In our laboratory tests, using field-collected sediment, the lowest 28-d EC10 (0.49μg a.s./g OC) was observed for C. riparius (endpoint survival), while for the standard OECD test with this species, using artificial sediment, a NOEC of 2.35μg a.s./g OC (endpoint emergence) is reported. In this particular case, the sediment tier-1 effect assessment using the chronic EC10 (field-collected sediment) or chronic NOEC (artificial sediment) of C. riparius and an assessment factor of 10, seems to be protective for the treatment-related responses observed in the sediment-spiked microcosms.

Guidance for the prognostic risk assessment of nanomaterials in aquatic ecosystems

Our understanding of the environmental fate and effects of engineered nanomaterials (ENMs) is in a state of fast transition. Recent scientific developments open new and powerful perspectives to define a framework for the prognostic risk assessment of ENMs in aquatic ecosystems. This requires abandoning the reductionist's approach of mechanistic analysis on particle or cellular scales and calls for engineering solutions that deal with uncertainties by applying assessment factors and probabilistic approaches. An ecological risk assessment (ERA) framework for ENMs is similar to that for other classes of substances, in that it requires clear protection goals based on ecosystem services, evidence-based concepts that link exposure to effects, and a transparent tiered effect assessment. Here, we discuss approaches to assess exposure and effects of ENMs. This includes recent developments in ENP fate modeling that greatly expanded the potential of prognostic exposure assessments. For the effect assessment, we advise a cost-effective screening based on principles of read-across as a conservative first tier. The feasibility of using species sensitivity distributions as a higher tier option is discussed. Controlled model ecosystem field experiments are proposed as a highest experimental tier, and are required for the calibration of the lower tiers. An outlook to unify information from various tiers by experimental work, fate modeling, and effect modeling as cost-effective prognostic tools for the ERA of ENMs is provided.