Cigarette butts (CBs), one of the most common litter items found on beaches, represent a still unexplored environmental hazard. This study aimed at a multidisciplinary characterization of their ...toxicological risks on marine organisms integrating chemical analyses of released compounds with a wide panel of biological responses, such as ecotoxicological bioassays on species of different trophic positions, molecular responses in an ex vivo model (Precision-Cut Tissue Slices, PCTS of mussels digestive glands), bioavailability and cellular biomarkers in mussels exposed to CBs in laboratory experiments. Trace metals, aliphatic and polycyclic aromatic hydrocarbons, nicotine and cotinine were released in artificial seawater after 24 h which determined a significant inhibition of bacterial bioluminescence, oyster embryo development and growth in different algal species. Modulation of peroxisomal proliferation and antioxidant gene expression was observed in mussels PCTS, while the in vivo exposure determined accumulation of chemicals and significant alterations of immune system, antioxidant and neurotoxic responses, peroxisomal proliferation and genotoxic damage. Using a quantitative Weight of Evidence model, the risks of CBs to the marine environment were summarized, highlighting the importance of integrating chemical analyses, batteries of ecotoxicological bioassays, molecular and cellular biomarkers to assess the impact of these hazardous materials on marine environment.
Sharks are generally taken in multispecies fisheries worldwide so in many cases it is logistically infeasible and cost prohibitive to assess the impact on all species caught. Risks of fishing impacts ...to the sustainability of shark species were assessed using a weight of evidence risk-based framework. Whiskery (Furgaleus macki), gummy (Mustelus antarcticus), dusky (Carcharhinus obscurus), and sandbar (C. plumbeus) sharks provide a good case study as they are the main (~80% of the catch) shark species taken in Western Australia (WA) and represent the range of life history strategies of other shark species typically caught. Based on the available lines of evidence for stock status (spatial and temporal time series of catch, effort, catch rates, size composition and population modelling), the 2015–16 risk level for the four species was scored as medium―i.e. it is unlikely (5–20% chance) that there is a high level of stock depletion. The status of each of the four species was scored as ‘acceptable’ with risk control measures in place, indicating that no additional restrictions are required.
The main commercial shark species of Western Australia have a moderate sustainability riskTheir status is acceptable so no further management restrictions are required. Display omitted
•A large proportion of shark populations is considered to be in high risk mostly due to overfishing.•The information required for traditional fisheries stock assessments is not available for the vast majority of species.•We assessed the main commercial shark species in Western Australia using a risk-based weight-of-evidence approach (WoEA).•The current risk level for the four species is medium, i.e. it is unlikely that there is a high level of stock depletion.•Our study exemplifies the use of WoEA for the assessment of shark stocks.
Lidocaine has not been associated with cancer in humans despite 8 decades of therapeutic use. Its metabolite, 2,6-xylidine, is a rat carcinogen, believed to induce genotoxicity via N-hydroxylation ...and DNA adduct formation, a non-threshold mechanism of action. To better understand this dichotomy, we review literature pertaining to metabolic activation and genotoxicity of 2,6-xylidine, identifying that it appears resistant to N-hydroxylation and instead metabolises almost exclusively to DMAP (an aminophenol). At high exposures (sufficient to saturate phase 2 metabolism), this may undergo metabolic threshold-dependent activation to a quinone-imine with potential to redox cycle producing ROS, inducing cytotoxicity and genotoxicity. A new rat study found no evidence of genotoxicity in vivo based on micronuclei in bone marrow, comets in nasal tissue or female liver, despite high level exposure to 2,6-xylidine (including metabolites). In male liver, weak dose-related comet increases, within the historical control range, were associated with metabolic overload and acute systemic toxicity. Benchmark dose analysis confirmed a non-linear dose response. The weight of evidence indicates 2,6-xylidine is a non-direct acting (metabolic threshold-dependent) genotoxin, and is not genotoxic in vivo in rats in the absence of acute systemic toxic effects, which occur at levels 35 × beyond lidocaine-related exposure in humans.
•Lidocaine metabolite 2,6-xylidine primarily metabolises via an amino-phenol pathway.•Published studies show variable genotoxicity consistent with cytotoxic/ROS-related effects.•A new rat study was negative for bone marrow MN, nasal tissue and female liver comets.•At MTD there was a metabolic overload threshold with low rise in male liver comets.•2,6-xylidine is not genotoxic in vivo in the absence of acute systemic toxicity.
Alcohol ethoxylates (AE) are high production volume (HPV) chemicals globally used in detergent and personal care products and are truly a work-horse for the household and personal care industries. ...Commercial AE generally consist of a mixture of several homologues of varying carbon chain length and degree of ethoxylation. Homologues that are not ethoxylated are also known as aliphatic alcohols or simply fatty alcohols (FA). This group of homologues represents a special interest in the context of environmental risk, as these are also abundant and ubiquitous naturally occurring compounds (e.g. animal fats and in human feces). Hence, in a risk assessment one needs to distinguish between the natural (background) concentrations and the added contribution from anthropogenic activities. We conducted a weight-of-evidence risk assessment in three streams, documenting the exposure and predicted risk, and compared these to the habitat and in situ biota. We found that the parameters (e.g., habitat quality and total perturbations hereunder total suspended solids (TSS) and other abiotic and biotic stressors) contributed to the abundance of biota rather than the predicted risk from AE and FA. Moreover, the documented natural de novo synthesis and rapid degradation of FA highlight the need to carefully consider the procedures for environmental risk assessment of naturally occurring compounds such as FA, e.g. in line with the added risk concept known from metal risk assessment.
Textile mill effluents (TMEs) are wastewater discharges from textile mills that are involved in wet processes such as scouring, neutralizing, desizing, mercerizing, carbonizing, fulling, bleaching, ...dyeing, printing and other wet finishing activities. TMEs are complex mixtures containing a wide variety of chemicals which have a range of pH, temperature, colour and oxygen demand characteristics. Most wet processing mills in Canada discharge to municipal wastewater collection systems where those effluents receive some form of wastewater treatment. This paper reports the results of a tiered assessment approach that was used to determine the impacts on the aquatic environment of whole effluents discharged by wet processing textile mills in Canada. A conservative assessment indicated that no substantial threat to the aquatic environment was associated with TMEs receiving secondary or tertiary treatment, on- site or at a municipal wastewater treatment plant, prior to discharge to receiving waters. In the case of TMEs receiving only primary treatment or no treatment prior to discharge, a weight-of-evidence risk assessment supported the conclusion that those effluents could produce significant environmental harm in aquatic environments.
Abstract The ability to conduct weight-of-evidence assessments to inform the evaluation of potential environmental neurotoxicants is limited by lack of comparability of study methods, data analysis, ...and reporting. There is a need to establish consensus guidelines for conducting, analyzing, and reporting neurodevelopmental environmental epidemiologic studies, while recognizing that consistency is likewise needed for epidemiology studies examining other health outcomes. This paper proposes a set of considerations to be used by the scientific community at-large as a tool for systematically evaluating the quality of proposed and/or published studies in terms of their value for weight-of-evidence assessments. Particular emphasis is placed on evaluating factors influencing the risk of incorrect conclusions at the level of study findings. The proposed considerations are the first step in what must be a larger consensus-based process and can serve to catalyze such a discussion. Achieving consensus in these types of endeavors is difficult; however, opportunities exist for further interdisciplinary discussion, collaboration, and research that will help realize this goal. Broad acceptance and application of such an approach can facilitate the expanded use of environmental epidemiology studies of potential neurodevelopmental toxicants in the protection of public health, and specifically children's health.
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