Microplastics and pharmaceuticals are considered ubiquitous and emergent pollutants of high concern but the knowledge on their effects on primary producers is still limited, especially those caused by mixtures. Thus, the goal of the present study was to investigate if the presence of microplastics (1–5 μm diameter) influences the toxicity of the pharmaceuticals procainamide and doxycycline to the marine microalga Tetraselmis chuii. Bioassays (96 h) to investigate the toxicity of those substances individually and in mixtures (i.e. microplastics-procainamide mixtures and microplastics-doxycycline mixtures) were carried out. Effect criteria were the average specific growth rate (growth rate) and chlorophyll a concentration (chlorophyll). EC₁₀, EC₂₀ and EC₅₀ were determined. Microplastics alone had no significant effects on growth rate up to 41.5 mg/l, whereas chlorophyll was significantly reduced at 0.9 and 2.1 mg/l of microplastics, but not at higher concentrations. The 96 h EC₅₀ (growth rate and chlorophyll, respectively) determined for the other bioassays were: 104 and 143 mg/l for procainamide alone; 125 and 31 mg/l for procainamide in the presence of microplastics; 22 and 14 mg/l for doxycycline alone; 11 and 7 mg/l for doxycycline in the presence of microplastics. Significant differences (p < 0.001) between the toxicity curves of each pharmaceutical alone and in mixture with microplastics were found for procainamide (chlorophyll), and doxycycline (both parameters). Thus, both pharmaceuticals were toxic to T. chuii in the low ppm range, and microplastics-pharmaceutical mixtures were more toxic than the pharmaceuticals alone. Very high decreases of doxycycline concentrations in test media were found, indicating degradation of the antibiotic. Thus, although the biological results are expressed in relation to doxycycline concentration, the effects were likely caused by a mixture of the parental compound and its degradation products. The concentrations of microplastics and pharmaceuticals tested (low ppm range) are higher than those expected to be found in waters of the most part of marine ecosystems (ppt or ppb ranges). However, considering the widespread contamination by microplastics and pharmaceuticals, the concentrations already found in waters, sediments and/or organism of heavily polluted areas, the long-term exposure (over generations) of wild populations to such substances in polluted ecosystems and the possibilities of bioaccumulation and toxicological interactions, these findings are of concern and further research on microplastics-pharmaceuticals toxicological interactions is needed.

微塑料和药物被认为是普遍存在的污染物，受到高度关注，但有关其对主要生产者的影响的知识仍然有限，尤其是那些由混合物引起的污染物。因此，本研究的目的是研究微塑料（直径1-5μm）的存在是否会影响普鲁卡因酰胺和强力霉素对海洋微藻Tetraselmis chuii的毒性。进行了生物测定（96小时），以研究这些物质的单独和混合物（即，微塑料-普鲁卡因酰胺混合物和微塑料-多西环素混合物）的毒性。影响标准是平均比生长速率（生长速率）和叶绿素a浓度（叶绿素）。欧共体₁₀，确定了EC ₂₀和EC ₅₀。单独使用微塑料时，对高达41.5 mg / l的生长速率没有明显影响，而在0.9和2.1 mg / l的微塑料中，叶绿素显着降低，但在较高浓度下则不显着。96小时EC ₅₀其他生物测定法测定的（分别为生长速率和叶绿素）为：普鲁卡因酰胺单独为104和143 mg / l；在微塑料存在下普鲁卡因酰胺的剂量分别为125和31 mg / l；单用强力霉素的剂量为22和14 mg / l；微塑料存在下强力霉素的剂量为11和7 m​​g / l。对于普鲁卡因酰胺（叶绿素​​）和强力霉素（两个参数），每种药物单独的毒性曲线与与微塑料混合的毒性曲线之间都存在显着差异（p <0.001）。因此，这两种药物对T. chuii都是有毒的在低ppm范围内，微塑料与药物的混合物比单独使用的药物更具毒性。发现测试培养基中强力霉素的浓度降低非常高，表明抗生素已降解。因此，尽管生物学结果表示为与强力霉素浓度有关，但其作用可能是由母体化合物及其降解产物的混合物引起的。测试的微塑料和药品的浓度（低ppm范围）高于大多数海洋生态系统水域（ppt或ppb范围）中所期望的浓度。但是，考虑到微塑料和药品的广泛污染，已经在重度污染地区的水，沉积物和/或生物中发现了这种污染物的浓度，