Water samples from 20 sites were tested using a panel of immortalized human cell lines corresponding to the liver, kidney and brain to measure cytotoxicity. Results show that each control toxin induced a consistent pattern of cytotoxicity in the panel of human cell lines assayed. Known toxins were seen only during blooms. Because cell toxicity was seen in the absence of blooms, it suggests that there might be either emergent toxins or a combination of toxins present at those times. Findings suggest that other toxins with the potential to be harmful to human health may be present in the lagoon.

Results of the study, published in the journal Toxins, show that each control toxin induced a consistent pattern of cytotoxicity in the panel of human cell lines assayed. During blooms, cytotoxicity due to a single type of toxin was obvious from this pattern. In the absence of blooms, the observed cytotoxicity reflected either a mixture of toxins or it was caused by an unidentified toxin. The researchers note that microcystins are primarily a threat to human health in the lagoon during blooms, and because of the necessity of active transport, the toxin would need to be ingested or inhaled to present a threat to humans.

Among the study findings, the most northern sites of the lagoon exhibited less toxicity than sites to the south. Cytotoxic blooms were seen both in the south (Microcystis) and the north (Pyrodinium) of the lagoon. In the absence of blooms, South Fork, South Fork 2, North Fork and Middle Estuary (sites one to four) in the Southern IRL and Banana River, and North Banana River (NASA) (sites 14 and 15) in the Northern IRL appeared to have the most cytotoxicity during the time of the assessment. In contrast, Jensen, Fort Pierce Inlet, Harbor Branch Link Port Canal, Vero Beach Land/Ocean Biogeochemical Observatory, and Vero Beach Barber Bridge (sites six to 10) appeared healthier as there were few samples with cytotoxicity above 50 percent in these sites, although there was statistically significant variation in these sites.