[en] Four different classes of environmental concern are quantitatively and qualitatively assessed for environmental hazards; antibiotics (n = 226), antineoplastics (n = 81), cardiovascular (n = 272), and sex hormones (n 92). These along with an ECOSAR scan of all pharmaceuticals (n = 2848) were then classified according to the OECD aquatic toxicity classification system. The predicted species susceptibility is: daphnid > fish > algae, and the predicted rank order of relative toxicity: sex hormones > cardiovascular antibiotics > antineoplastics (Table 1). Generally, a relatively large proportion (1/3) of all pharmaceuticals are potentially very toxic to aquatic organisms (Table 2). The qualitative risk assessment ranking relative to probability and potential severity for human and environmental health effects is: antibiotics > sex hormones > cardiovascular > antineoplastics. (Q)SARs and pharmacodynamic information should be used to prioritize and steer experimental risk assessments of pharmaceuticals, and potentially, also be used in new drug discovery optimizing efficacy and in minimising environmental hazards of new products. Nuclear receptors are relatively well conserved in evolution. Currently, antibacterial resistance represents the most significant human health hazard, and potentially the largest non-target organism hazard is sex hormones acting as endocrine modulators in wildlife. Data for the individual compounds are accessible via http://www.uoguelph.ca/~hsander/

[en] Urbanization is an inevitable process in human civilization. When populations expand, socio-economic and political dynamics typically shift from agricultural predominance to one of industry and services. Accordingly, agrarian societies transform from diffuse rural communities to dense urban centers. By 2050, the world’s population is projected to reach 9.1 billion, with the urban population growing from 50 to 70%. Inevitably, this ever-expanding urban frontier encroaches along the human-ecological interface, creating a challenge for conservation and biodiversity. For the past 30 years, agricultural cropland area in the USA has remained fairly constant, despite significant population growth over the same time period. Thus, agricultural production in America has more than kept pace with rapid population growth and global export demand without increasing the farmland footprint at the expense of wildlife habitat. This is primarily due to considerable advances made in pesticide development, safety, and regulation, coupled with soil conservation and genetically modified crops. Still, the potential contribution of agriculture to ecosystem impairment remains contentious, particularly with regard to current use of pesticides. Recently, significant focus has been placed on the state of bird populations in the USA. Many species are considered imperiled, and this is often attributed in the popular media to pesticide use. However, focusing solely on the agricultural/chemical story as a significant driver of species viability and ecological risk within the broader biodiversity and conservation narrative lacks context and perspective. Moreover, the hypothesis that pesticides are indirectly affecting bird population status via reductions in food resources should be considered with caution and within the context of other likely causes. This work explores the dynamics between historical land use, human-controlled activity, and bird population trends from a holistic perspective within the USA. The aim is to provide context, developed from a relative comparison of potential contributing factors, in order to help inform discussion and foster dialogue between industry, academia, government, non-governmental organizations, and the public.

[en] Highlights: • Estimation of avian dermal LD50s is critical for assessing chemical risk to birds. • Current models generate high dermal exposure estimates. • These models also generate low dermal LD50 estimates. • Empirical dermal absorption data were used for an alternative approach. Understanding dermal exposure is important for higher-tier avian ecological risk assessments. However, dermal exposure and toxicity are often unknown for avifauna. The US EPA's Terrestrial Investigation Model (TIM) uses a method to estimate avian dermal LD50 values (and ultimately dermal exposure) that frequently results in unusually high dermal exposure and low dermal LD50 estimates. This is primarily a result of using organophosphate and carbamate toxicity data to develop the oral-dermal relationship. An estimated dermal LD50 is necessary to generate a dermal route equivalency factor that normalizes potency relative to oral toxicity within the dermal pathway dose equation. In this study, atrazine dermal absorption experiments were conducted with mallard, northern bobwhite, and rat skin. These data were used to derive an avian-mammal dermal route equivalency factor for atrazine and introduce a new approach for estimating dermal LD50 values and ultimately predicting exposure via the TIM dermal pathway. Compared to the default TIM method, this new approach yielded TIM output with lower mean total dose, lower dermal fraction of total dose, greater oral fraction of total dose, and reduced model predicted mortality for atrazine. In addition, the new approach was compared with other methods for estimating avian dermal LD50 values such as those proposed for use with mammalian data and physico-chemical properties and a triazine-specific oral-dermal equation using mammalian LD50 data. The three alternative approaches resulted in output similar to one another and different from the default TIM methods. These results indicate that a dermal route equivalency factor derived from empirical data provides a higher avian dermal LD50 estimate that is consistent with other methods. In addition, the use of this dermal route equivalency factor results in greatly reduced modeled atrazine risk to birds than previously reported in US EPA risk assessments using TIM.

[en] Embryonic growth of the yellow-spotted salamander (Ambystoma maculatum) is enhanced by the presence of the green alga Oophila amblystomatis, in the egg capsule. To further assess potential impacts of herbicides on this relationship, A. maculatum egg masses were exposed to atrazine (0–338 μg/L) until hatching (up to 66 days). Exposure to atrazine reduced PSII yield of the symbiotic algae in a concentration-dependent manner, but did not significantly affect visible algal growth or any metrics associated with salamander development. Algal cells were also cultured in the laboratory for toxicity testing. In the 96-h growth inhibition test (0–680 μg/L), ECx values were generally greater than those reported for standard algal test species. Complete recovery of growth rates occurred within 96-h of transferring cells to untreated media. Overall, development of A. maculatum embryos was not affected by exposure to atrazine at concentrations and durations exceeding those found in the environment. - Highlights: • The yellow-spotted salamander produces eggs that are colonized by a symbiotic green alga. • We tested the sensitivity of this system to the herbicide atrazine. • Embryo development was not significantly affected by exposure at up to 300 μg/L. • The alga was isolated and 96-h growth tests were performed in the laboratory. • EC50s for Oophila sp. were >100 μg/L. - Development of Ambystoma maculatum embryos in egg masses was not impacted by exposure to atrazine at concentrations and durations exceeding those commonly found in the environment.

[en] The impact of a mixture of oxytetracycline, chlortetracycline, tetracycline and doxycycline on Myriophyllum sibiricum and Lemna gibba was investigated using fifteen 12,000-L microcosms (k = 5, n = 3). Significant concentration-response relationships were only found for M. sibiricum, where dry mass was 69, 47, 30, and 7% of controls at respective treatment concentrations of 0.080, 0.218, 0.668, and 2.289 μmol/L. Somatic endpoints were strongly and negatively correlated with percent light transmission, except plant length, which was positively correlated. Treated microcosms experienced a reduction in the percent of surface irradiance penetrating the water column as high as 99.8% at a depth of 70 cm, relative to controls. Position relative to the water column was likely responsible for the differential effects observed between floating (L. gibba) and submerged (M. sibiricum) species of macrophytes. A hazard quotient assessment of the lowest EC₁₀ value indicated significant risk, exceeding the critical HQ value, but not the lowest EC₂₅ value. - Mixtures of tetracycline antibiotics pose a risk to submerged but not floating aquatic plants

[en] Tylosin is a macrolide antibiotic commonly used for therapeutic treatment and prophylaxis in livestock. As part of a larger ecotoxicological study, the potential phytotoxic effects of tylosin on the rooted macrophyte Myriophyllum spicatum and the floating macrophyte Lemna gibba were assessed under semi-field conditions using 15 12000-L microcosms. Concentrations of 0, 10, 30, 300 μg/L (n = 3), and 600, 1000, and 3000 μg/L (n = 1) were evaluated as part of separate ANOVA and regression analyses over an exposure period of 35 days. Fate of tylosin was monitored over time in the highest three treatments, where dissipation followed pseudo-first order kinetics with associated half-lives ranging from 9 to 10 days. For both M. spicatum and L. gibba, tylosin was found to cause no biologically significant changes to any endpoint assessed compared to controls at a Type I error rate of 0.1. However, subsequent power analyses revealed that there was generally insufficient power to declare that there were no significant differences at a Type II error rate of 0.2. Conclusions concerning biologically significant impacts were therefore further assessed based on other statistical criteria including comparisons of percent differences between replicated treatments and controls, minimum significant and minimum detectable differences, and coefficients of variation. Based on these criteria, at an ecological effect size of >20% change, tylosin was concluded to elicit no biologically or ecologically significant toxicity to M. spicatum or L. gibba. A hazard quotient assessment indicated that tylosin poses little risk to either species of macrophyte, with an HQ value calculated to be nearly three orders of magnitude below 1 (0.002). - Tylosin is not expected to have ecologically significant effects on Ontario freshwater macrophytes

[en] Potential effects of pesticides on stream algae occur alongside complex environmental influences; in situ studies examining these effects together are few, and have not typically controlled for collinearity of variables. We monitored the dynamics of periphyton, phytoplankton, and environmental factors including atrazine, and other water chemistry variables at 6 agricultural streams in the Midwest US from spring to summer of 2011 and 2012, and used variation partitioning of community models to determine the community inertia that is explained uniquely and/or jointly by atrazine and other environmental factors or groups of factors. Periphyton and phytoplankton assemblages were significantly structured by year, day of year, and site, and exhibited dynamic synchrony both between site–years and between periphyton and phytoplankton in the same site–year. The majority of inertia in the models (55.4% for periphyton, 68.4% for phytoplankton) was unexplained. The explained inertia in the models was predominantly shared (confounded) between variables and variable groups (13.3, 30.9%); the magnitude of inertia that was explained uniquely by variable groups (15.1, 18.3%) was of the order hydroclimate > chemistry > geography > atrazine for periphyton, and chemistry > hydroclimate > geography > atrazine for phytoplankton. The variables most influential to the assemblage structure included flow and velocity variables, and time since pulses above certain thresholds of nitrate + nitrite, total phosphorus, total suspended solids, and atrazine. Time since a ≥ 30 μg/L atrazine pulse uniquely explained more inertia than time since pulses ≥ 10 μg/L or daily or historic atrazine concentrations; this result is consistent with studies concluding that the effects of atrazine on algae typically only occur at ≥ 30 μg/L and are recovered from. - Highlights: • We monitored algal communities at 6 Midwest streams receiving atrazine in 2011 and 2012. • Partitioning of CCA models of algal community by environment assessed the influence of specific variables. • Overall, water chemistry and hydroclimate variables were most influential to community. • Time since ≥ 30 μg/L atrazine pulse was more influential than other atrazine variables. • Results are consistent with transitory community effects only at concentrations above 30 μg/L