In vitro genotoxic and mutagenic potentials of combustion particles from marine fuels with different sulfur contents

Ship emissions significantly impact both the environment and human health. To address these concerns, the International Maritime Organization has imposed restrictions on the sulfur content in marine fuels. Specifically, the fuel sulfur content (FSC) must be below 0.5% m/m globally and below 0.1% m/m in designated sulfur emission control areas. These regulations apply to a range of fuels including distillate diesel-like fuels and low-sulfur heavy fuel oils (HFOs). As a result, there has been a reduction in emissions, particularly sulfur oxides and particulate matter (PM). However, the relationship between FSC and the toxicity of ship emissions remains unclear. This study aimed to investigate how the physical and chemical properties of PM from a marine engine operating on five marine fuels with varying FSCs, influence toxicological outcomes. For this scope, the study assessed cytotoxic, genotoxic, mutagenic, and pro-inflammatory effects of the emitted particles using lung cell models. The involvement of intracellular reactive oxygen species and xenobiotic metabolism was also exanimated. The results showed that PM from the combustion of different fuels reduced cell viability and clonogenicity at the highest concentration. However, other toxicological outcomes, such as genotoxic potential, were more strongly associated with the polycyclic aromatic hydrocarbon content of the PM than with FSC. Notably, an aromatic-rich HFO with intermediate FSC induced a significant increase in gene mutation frequency and alterations of cellular processes. In conclusion, while reducing FSC is an important step in mitigating ship emissions, this study underscores the need for a comprehensive evaluation of fuel properties.