Contamination of bivalves by lipophilic toxins is responsible for human poisoning with manifestations that can be severe. In Portugal, the most common toxins are those of the okadaic acid group (OA), associated with Diarrhetic Shellfish Poisoning. Given the danger of these poisonings, several species of bivalves with commercial interest are analyzed weekly at the National Reference Laboratory of Marine Biotoxins of the Portuguese Institute of the Sea and the Atmosphere (IPMA) to assess the occurrence of lipophilic toxins. According to IPMA data, the fishing and capture of shellfish (Donax trunculus) in the Sotavento Algarve region can be interdicted for about 4 months a year, with a higher incidence in the summer months. The impact of this ban is high in economic and social terms, considering the great dependence on this resource in the Algarve Sotavento region.

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In the summer period, there is an increase in the local population in the Algarve Sotavento region. During this time, the use of sunscreens by vacationers is recurrent in order to protect the skin against UV rays. This consumption will lead to the introduction of a high concentration of organic compounds (with UV filter action) in coastal waters. Thus, in the summer months, there are new (and more) contaminants in the coastal waters of the Eastern Algarve, namely active ingredients of sunscreens, such as oxybenzone, which toxicity is scientifically recognized for aquatic organisms.