Hazardous Chemicals Associated with Plastics and Plastic Waste: Environmental Occurrence and Toxicity of TCDD, DEHP, BPA, and Acrylonitrile

Hazardous compounds including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), bis(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), and acrylonitrile (ACN) are ubiquitous in environmental matrices such as soil and water. This review synthesizes their environmental occurrence and multi-organ toxicity. Its objective was to integrate occurrence and toxicity data for TCDD, DEHP, BPA, and ACN into a single account and to identify early-hazard biomarkers and regulatory gaps. A structured documentary search covering mainly 2000 to 2024 was performed in Google Scholar, ScienceDirect, Scopus, Web of Science, and PubMed, prioritizing in vivo and in vitro experimental studies and complemented by governmental and institutional reports. The analysis shows that all four compounds act through convergent mechanisms centered on oxidative stress and mitochondrial dysfunction, via compound-specific signalling pathways, and that adverse effects arise across cytotoxic, neurotoxic, cardiotoxic, reproductive, and immune endpoints at environmentally relevant concentrations, with some reproductive effects extending across generations. HSP47 and HSP70 emerge as early biomarkers of cellular stress. Although regulation has measurably reduced some exposures, chronic low-dose risk remains underestimated, supporting harmonized limits, premarket screening of substitutes, and source control.