Safety assessment of edible red seaweeds Gracilaria and Gelidiella of Gulf of Mannar in terms of OCP residual contamination

Abstract Organochlorine pesticides (OCPs) in the edible red seaweeds viz. Gracilaria verrucosa and Gelidiella acerosa, collected from four sites viz. Thoothukudi (1), Earvadi (2), Seeniyappa Dhargah (3) and Rameswaram (4) of Gulf of Mannar were assessed. Total OCP residues in G. acerosa ranged from 6 ngg−1 to 508 ngg−1 and in G. verrucosa from 0.36 ng g−1 to 270.41 ng g−1. The OCP residues were maximum in G. acerosa of Rameswaram and in G. verrucosa of Seeniyappa Dhargah. The OCP residues were high in the month January, which coincided with the fruiting season of seaweeds. The major OCPs in red seaweeds recorded were HCH, endosulfan, aldrin, endrin and DDT and their mean concentration was 6.864 ngg−1, 79.107 ng g−1, 1.16 ng g−1, 0.97 ng g−1 and 13.66 ng g−1, respectively. Specific accumulation of endrin residues by G. acerosa is a distinct feature. In terms of pesticide toxicity, it is inferred that the red seaweeds collected immediately after the rainy season contained high OCP residues and shall not be safe for consumption.