Département Chimie de l’environnement

This study presents a nontarget approach to detect discharges from pharmaceutical production in municipal wastewater treatment plant (WWTP) effluents and to estimate their relevance on the total emissions. Daily composite samples were collected for 3 months at two WWTPs in Switzerland, measured using liquid chromatography high-resolution mass spectrometry, and time series were generated for all features detected. The extent of intensity variation in the time series was used to differentiate relatively constant domestic inputs from highly fluctuating industrial emissions. We show that an intensity variation threshold of 10 correctly classifies compounds of known origin and reveals clear differences between the two WWTPs. At the WWTP receiving wastewater from a pharmaceutical manufacturing site, (i) 10 times as many potential industrial emissions were detected as compared to the WWTP receiving purely domestic wastewater; (ii) for 11 pharmaceuticals peak concentrations, >10 μg/L and up to 214 μg/L were quantified, which are clearly above typical municipal wastewater concentrations; and (iii) a pharmaceutical not authorized in Switzerland was identified. Signatures of potential industrial emissions were even traceable at the downstream Rhine monitoring station at a >4000-fold dilution. Several of them occurred repeatedly, suggesting that they were linked to regular production, not to accidents. Our results demonstrate that small wastewater volumes from a single industry not only left a clear signature in the effluents of the respective WWTP but also influenced the water quality of one of Europe’s most important river systems. Overall, these findings indicate that pharmaceutical production is a relevant emission source even in highly developed countries with a strong focus on water quality, such as Switzerland.

Biotransformation plays a crucial role in regulating the bioaccumulation potential and toxicity of organic compounds in organisms but is, in general, poorly understood for emerging contaminants. Here we have used diclofenac as a model compound to study the impact of biotransformation on the bioaccumulation potential and toxicity in two keystone aquatic invertebrates: Gammarus pulex and Hyalella azteca. In both species, diclofenac was transformed into several oxidation products and conjugates, including two novel products, i.e. diclofenac taurine conjugate (DCF-M403) and unexpected diclofenac methyl ester (DCF-M310.03). The ratios of biotransformation products to parent compound were 12-17 for DCF-M403 and 0.01-0.7 for DCF-M310.03 after 24 h exposure. Bioconcentration factors (BCFs) of diclofenac were 0.5 and 3.2 L kg ww^-1 in H. azteca and G. pulex, respectively, whereas BCFs of DCF-M310.03 was 164.5 L kg ww^-1 and 104.7 L kg ww^-1, respectively, representing a 25 to 110-fold increase. Acute toxicity of DCF-M310.03 was also higher than the parent compound in both species, which correlated well with the increased bioconcentration potential. The LC50 of diclofenac in H. azteca was 216 mg L^-1, while that of metabolite DCF-M310.03 was reduced to only 0.53 mg L^-1, representing a 430-fold increase in acute toxicity compared to diclofenac. DCF-M403 is less toxic than its parent compound towards H. azteca, which may be linked to its slightly lower hydrophobicity. Furthermore, the transformation of diclofenac to its methyl ester derivative was explored in crude invertebrate extracts spiked with an S-adenosylmethionine cofactor, revealing possible catalysis by an S-adenosylmethionine-dependent -carboxylic acid methyltransferase. Methylation of diclofenac was further detected in fish hepatocytes and human urine, indicating a broader relevance. Therefore, potentially methylated metabolites of polar contaminants should be considered for a comprehensive risk assessment in the future.

Compartment-specific degradation half-lives are essential pieces of information in the regulatory risk assessment of synthetic chemicals. However, their measurement according to regulatory testing guidelines is laborious and costly. Despite the obvious ecological and economic benefits of knowing environmental degradability as early as possible, its consideration in the early phases of rational chemical design is therefore challenging. Here, we explore the possibility to use half-lives determined in highly time- and work-efficient biotransformation experiments with activated sludge and mixtures of chemicals to predict soil half-lives from regulatory simulation studies. We experimentally determined half-lives for 52 structurally diverse agrochemical active ingredients in batch reactors with three concentrations of the same activated sludge. We then developed bi- and multivariate models for predicting half-lives in soil by regressing the experimentally determined half-lives in activated sludge against average soil half-lives of the same chemicals extracted from regulatory data. The models differed in how we accounted for sorption-related bioavailability differences in soil and activated sludge. The best-performing models exhibited good coefficients of determination (R² of around 0.8) and low average errors (

Conventional pesticides are associated with numerous human and environmental health risks. Nevertheless, an increasing number of smallholder farmers in low- and middle-income countries are using conventional pesticides. Adopting safer pest management requires farmers to obtain new information. However, little is known how farmers develop an information need, seek, and use pest management related information, and whether this process differs for organic and conventional pest management strategies. In this qualitative study, we investigated pest-related information behavior in depth, from farmers' own perspective. Using an ethnographic approach, we conducted 46 semi-structured interviews, 15 on-farm observations and 302 structured questionnaire interviews with farmers in Wakiso District, Uganda, in 2017. Our results indicated that farmers develop information needs when adopting new farming practices, or when presented with disruptive information (e.g. when new pests emerged). This prompted farmers to seek information actively, or they received passive information. Whether farmers used the new information depended on successful trial of the new pest management strategy, and on the credibility of the source. Most revealing, our results suggested important differences in information behavior between conventional and organic pest management strategies. Sources of information for conventional pesticides were well-integrated into farmers' daily lives and comprised pesticide dealers and fellow farmers. Conversely, information on organic strategies was provided through external sources (e.g. NGOs), and was not available at times when farmers developed an information need. Our results imply that farmers are most likely receptive to organic pest management information at times when they develop an information need (e.g. when encountering a new pest). To promote safer pest management, information about organic and integrated pest management should be made continuously available in farmers' lives. Furthermore, we recommend leveraging established information channels (e.g. dealers) among pesticide users to promote safer use practices.