Polychlorinated n-alkanes (PCAs) are the main components of chlorinated paraffins (CPs) mixtures, that have been commonly grouped into short-chain (SCCPs, C10-13), medium-chain (MCCPs, C14-17), and long-chain (LCCPs, C18-30) CPs. PCAs pose a significant risk to human health as they are broadly present in indoor environments and are potentially persistent, bioaccumulative, and toxic. The lack of specific terminology and harmonization in analytical methodologies for PCA analysis complicates direct comparisons between studies. The present work summarizes the different methodologies applied for the analysis of PCAs in indoor dust, air, and organic films. The large variability between the reviewed studies points to the difficulties to assess PCA contamination in these matrices and to mitigate risks associated with indoor exposure. Based on our review of physicochemical properties of PCAs and previously reported sum of measurable S/M/LCCPs levels, the homologue groups PCAs-C10-13 are found to be mostly present in the gas phase, PCAs-C14-17 in particulate matter and organic films, and PCAs-C≥18 in settled dust. However, we emphasized that mapping PCA sources and distribution in the indoors is highly dependent on the individual homologues. To further comprehend indoor PCA distribution, we described the uses of PCA in building materials and household products to apportion important indoor sources of emissions and pathways for human exposure. The greatest risk for indoor PCAs were estimated to arise from dermal absorption and ingestion through contact with dust and CP containing products. In addition, there are several factors affecting indoor PCA levels and exposure in different regions, including legislation, presence of specific products, cleaning routines, and ventilation frequency. This review provides comprehensive analysis of available indoor PCA data, the physicochemical properties, applied analytical methods, possible interior sources, variables affecting the levels, human exposure to PCAs, as well as need for more information, thereby providing perspectives for future research studies.

Reliable quantification of polychlorinated alkanes (PCAs) remains a major challenge, hindering environmental research across diverse matrices. Each sample can contain over 500 homologue groups, collectively producing >1000 m/z ratios that require interference checks. High-resolution mass spectrometry methods vary in ionization signals and data formats and require specialized algorithms for quantification. CPxplorer streamlines data processing through the integration of three modules: (1) CPions generates target ion sets and isotopic thresholds for compound identification into the next module; (2) Skyline performs instrument-independent data integration, interference evaluation, and homologue profiling; and (3) CPquant deconvolves homologues and reports concentrations using reference standards and homologue profiles from Skyline. Evaluation of the workflow with NIST-SRM-2585 dust and ERM-CE100 fish tissue material yielded comparable results across raw data formats from different instruments. Further applications of CPxplorer across diverse matrices, including indoor dust, organic films, silicone wrist bands, and food samples, demonstrated the usefulness in biological and environmental monitoring. Compared to existing tools limited to qualitative detection, CPxplorer enables quantitative outputs, reduces processing time, and expands functionality to PCA-like substances (e.g., BCAs) and PCA degradation products (e.g., OH-PCAs). CPxplorer reduces learning barriers, empowers users to quantify PCAs across various analytical instruments, and contributes to generating comparable results in the field.

ndoor environments have shown to be a major source of human exposure of polychlorinated alkanes (PCAs), yet information on their distribution across indoor matrices and associated exposure pathways remains limited. PCAs, the main components in chlorinated paraffin mixtures, are widely used as flame retardants and plastic additives in numerous indoor consumer products and materials. This study quantified PCAs in paired indoor dust and indoor organic films (IOFs) from homes, offices, schools and gym sports halls (n = 41) in Sweden and assess their contribution to human exposure. Mean PCA concentrations in indoor dust were 7.3, 43.2, and 14.6 μg g− 1 for ∑PCAs-C10–13, ∑PCAs-C14–17, and ∑PCAs-C18–30, respectively, while corresponding concentrations in IOFs were 38.2, 312, and 123 ng m− 2. PCAs-C14–17 dominated both matrices, but IOFs showed an enrichment tendency towards longer-chain, higher-KOA PCAs, reflecting the less frequent cleaning and longer-term PCA accumulation in IOFs. IOF concentrations were particularly elevated in schools, and PCA variation across sites was influenced by differences in ventilation practices and building age. Dermal uptake was the dominant exposure pathway for children, with substantially estimated doses from IOFs, while adults show comparable dust dermal and dust ingestion exposures. PCA transformation products formed through hydroxylation, hydrolysis, and sulfation were also tentatively detected in both matrices. These findings highlight the importance of jointly assessing dust and IOFs to better characterize multipathway exposure to the diverse PCA mixture in indoor environments.