Smoked cigarettes are the most prevalent form of litter worldwide, often finding their way into oceans and inland waterways. Cigarette smoke contains more than 4000 individual chemicals, some of them carcinogenic or otherwise toxic. We examined the cytotoxicity, genotoxicity, aryl hydrocarbon receptor (AhR), estrogen receptor (ER), and p53 response pathways of smoked cigarette leachate in vitro. Both seawater and freshwater leachates of smoked cigarettes were tested. Cytotoxicity and genotoxicity were negligible at 100 smoked cigarettes/L, while statistically significant AhR, ER, and p53 responses were observed in the extracts of both leachates, suggesting a potential risk to human health through exposure to cigarette litter in the environment. To identify responsible chemicals for the AhR response, an effect directed analysis approach was coupled with nontargeted chemical analysis based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC/TOF-MS). Eleven compounds potentially responsible for the AhR response were identified. Among them, 2-methylindole was partially responsible for the AhR response.

No abstract

This article is part of the special series "Ecological consequences of wildfires." The series documents the impacts of largescale wildfires in many areas of the globe on biodiversity and ecosystem condition in both terrestrial and aquatic ecosystems, the capacity for systems to recover and management practices needed to prevent such destruction in the future.

No abstract

To evaluate the ultraviolet (UV) advanced oxidation process (AOP) in a potable reuse facility, we characterized organic compounds in upstream reverse osmosis (RO)-treated recycled municipal wastewater samples collected before and after UV/H 2 O 2 AOP by implementing nontargeted analysis (NTA) based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Five sampling events were conducted at an advanced water purification facility. Fewer compounds were found consistently in the UV-AOP product water (UVP) than the corresponding feedwater (RO permeate (ROP)): on average, 28 compounds (by quality control criteria) in ROP vs 10 in UVP. On average, 80% of the qualified compounds were tentatively identified by mass spectral comparison with the NIST EI library, followed by a 87.5% verification success rate with standards for 24 selected compounds. Halogenated acetonitriles were most frequently found in UVP. Six compounds found in UVP were also present in tested tap water. Only one of the compounds, bromodichloromethane, has a regulatory limit in drinking water. This exploratory study concluded that, in the context of potable water reuse, NTA was useful for identifying contaminants without a priori knowledge of their occurrence and that the UV/H 2 O 2 AOP effectively removed trace organics that persisted in the ROP.