Global patterns of pesticide residues in seaweeds: A systematic review

Seaweeds, crucial for coastal ecosystems and of growing socioeconomic importance, have been threatened by pesticide contamination in their environments. This systematic review identifies, critically evaluates, and synthesizes recent global literature (2015-2024) on pesticide residues detected in seaweeds to delineate contamination patterns. Following PRISMA guidelines, studies were selected from the CAPES Journal Portal database, focusing on in situ seaweed samples with reported pesticide contamination. Of the 85 studies identified in the search, 12 met the inclusion criteria, addressing multiple seaweed groups. This resulted in 20 descriptions, primarily focusing on Chlorophyta (40 %), Rhodophyta (35 %), and Phaeophyceae (25 %). Organochlorine pesticides (OCPs), such as HCH (12 %), aldrin, DDT, and endosulfan (each at 11 %), were frequently detected, indicating a legacy of persistent contamination. Pesticide concentrations varied significantly by geographical location, with a notable number of studies originating from India (58 %). Variations were also observed by seaweed species and pesticide types, with QuEChERS extraction (58 %) and GC-MS (83 %) being the commonly used analytical methods. This review highlights the widespread presence of pesticides in marine algae, emphasizing the need for standardized analytical protocols, broader geographic and taxonomic research, and studies linking residues of those xenobiotics to their ecological impacts for robust risk assessment and mitigation.