Ecotoxicological and health risks associated with sediment-bound polycyclic aromatic hydrocarbons in peri-urban closed and open coastal lagoons.

Coastal urbanisation has ramifications for the sustainable development of developing nations. There are often unquantified ecological and health risks associated with urbanisation. Sixteen polycyclic aromatic hydrocarbons (PAHs) were analysed in surface sediment from three peri-urban coastal lagoons in southern Ghana. We found significant spatial variations of sediment PAHs. These variations were attributed to physiography of the lagoons and diverse anthropogenic activities surrounding them. Total PAHs ranged from 20.81 to 24,801.38 µg/kg (dry weight), underscoring a low to very high pollution level. Diagnostic ratios revealed both pyrogenic and petrogenic origins. Over 50 % of individual PAHs were of moderate ecological risk to benthic organisms, and cancer risk to humans was above the World Health Organisation's recommended safety limit (1 × 10-6). These ecological and health risks should be wake-up call for a more integrated urban planning approach to coastal urbanisation as coastal communities largely depend on natural ecosystems for food and livelihood opportunities.

Remediation of pesticide residues using ozone: A comprehensive overview.

Pesticide residues historically represent a severe threat to public health and the environment. Several species worldwide are still in danger from pesticide residues, despite efforts to mitigate the adverse health effects of these pollutants. As agricultural output has increased and scientific understanding has advanced, new methods have emerged for degrading pesticide traces. The remarkable effectiveness of ozone as a broad-spectrum disinfectant and its potential to destroy pesticide residues have led to its widespread use as a residue-free method for improving soil quality, disinfecting food, and treating water, among other benefits. Ozone is cheap to manufacture, making it an affordable option for treating harmful pesticide residues. Its capacity to degrade pesticides without negatively impacting the environment has increased its adoption as a tool for cleaning up after pesticide use. This review extensively provides an overview of ozonation for pesticide residues removal in different settings and applications. Ozone treatment of pesticide residues in the soil, water and food is effective in removing pesticides residues. We highlight recent advances in methods of removing pesticide residues. We discuss several challenges related to the ozone treatment of pesticide residues. Whether used alone or in conjunction with other processes, ozone is highly effective at removing pesticide residues from the environment. Therefore, we recommend this holistic and environmentally friendly strategy to reduce pesticide residues.

Influence of pH on the toxicity of ionisable pharmaceuticals and personal care products to freshwater invertebrates.

The majority of pharmaceuticals and personal health-care products are ionisable molecules at environmentally relevant pHs. The ionization state of these molecules in freshwater ecosystems may influence their toxicity potential to aquatic organisms. In this study we evaluated to what extent varying pH conditions may influence the toxicity of the antibiotic enrofloxacin (ENR) and the personal care product ingredient triclosan (TCS) to three freshwater invertebrates: the ephemeropteran Cloeon dipterum, the amphipod Gammarus pulex and the snail Physella acuta. Acute toxicity tests were performed by adjusting the water pH to four nominal levels: 6.5, 7.0, 7.5 and 8.0. Furthermore, we tested the efficiency of three toxicity models with different assumptions regarding the uptake and toxicity potential of ionisable chemicals with the experimental data produced in this study. The results of the toxicity tests indicate that pH fluctuations of only 1.5 units can influence EC50-48 h and EC50-96 h values by a factor of 1.4-2.7. Overall, the model that only focuses on the fraction of neutral chemical and the model that takes into account ion-trapping of the test molecules showed the best performance, although present limitations to perform risk assessments across a wide pH range (i.e., well above or below the substance pKa). Under such conditions, the model that takes into account the toxicity of the neutral and the ionized chemical form is preferred. The results of this study show that pH fluctuations can have a considerable influence on toxicity thresholds, and should therefore be taken into account for the risk assessment of ionisable pharmaceuticals and personal health-care products. Based on our results, an assessment factor of at least three should be used to account for toxicity differences between standard laboratory and field pH conditions. The models evaluated here can be used to perform refined risk assessments by taking into account the influence of temporal and spatial pH fluctuations on aquatic toxicity.