title: Prediction of joint algal toxicity of nano-CeO2/nano-TiO2 and florfenicol: Independent action surpasses concentration addition.
abstract: Co-exposure of aquatic organisms to engineered nanoparticles (ENPs) and antibiotics is likely to take place in the environment. However, the impacts of co-exposure on aquatic organisms are virtually unknown and understanding the joint toxicity of ENPs and antibiotics is a topic of importance. The independent action (IA) model and the concentration addition (CA) model are two of the most common approaches to mixture toxicity assessment. In this study, the joint toxicity of two ENPs (nCeO2 and nTiO2) and one antibiotic (florfenicol, FLO) to Chlorella pyrenoidosa was determined to compare the applicability of the IA and the CA model. Concentration-response analyses were performed for single toxicants and for binary mixtures containing FLO and one of the ENPs at two suspended particle concentrations. The effect concentrations and the observed effects of the binary mixtures were compared to the predictions of the joint toxicity. The observed toxicity associated with the nCeO2 or nTiO2 exposure was enhanced by the concomitant FLO exposure. The joint toxicity of nCeO2 and FLO was significantly higher than that of nTiO2 and FLO. Predictions based on the IA and CA models tend to underestimate the overall toxicity (in terms of median effect concentration) of the binary mixtures, but IA performs better than CA, irrespective of the effect level under consideration and the types of mixtures studied. This result underpins the need to consider the effects of mixtures of ENPs and organic chemicals on aquatic organisms, and the practicability of the IA and CA methods in toxicity assessment of ENPs.
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (AEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, PR China. Electronic address: zhuang.wang@nuist.edu.cn.
authors.forename: Zhuang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (AEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, PR China.
authors.forename: Se
authors.initials: S
authors.lastname: Wang
authors.affiliation: Centre for Safety of Substances and Products, National Institute of Public Health and the Environment (RIVM), Bilthoven 3720 BA, The Netherlands; Institute of Environmental Sciences (CML), Leiden University, Leiden 2300 RA, The Netherlands.
authors.forename: Willie J G M
authors.initials: WJGM
authors.lastname: Peijnenburg
mesh_terms: D002563:Cerium / Q000633:toxicity*; D002708:Chlorella / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008954:Models, Biological; D018570:Risk Assessment / Q000379:methods; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000633:toxicity; D014025:Titanium / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D002563:Cerium; C030583:ceric oxide; C035534:florfenicol; D014025:Titanium; D013839:Thiamphenicol
keywords: Antibiotics; Concentration addition; Engineered nanoparticles; Independent action; Joint toxicity