text: The range and degree of human health effects seems to vary annually and temporally in coastal regions, depending on the red tide density as well as variation in toxicity differences among dinoflagellate strains and their subsequent consumers. The Gulf of Mexico, and in particular the west coast of Florida, is the most heavily impacted by the adverse health and environmental effects of nearly annual K. brevis blooms. This region has suffered significant economic losses in local communities that rely on tourism and recreational fishing along with bad publicity over the years. Shellfish poisonings have been known about in Florida since the 1880s, although the cause was not identified as K. brevis until 1960.
  The fishing industry loses around 18 million dollars annually due to brevetoxin exposure and the resulting fish kills. Also, around one million dollars has been spent annually on public health due to shellfish poisoning from 1987 to 1992. A major obstacle for these industries and public health is inability to contain a bloom, and it is undetectable in taste and smell, only chemically. One major concern for exposure is not just illness, but that brevetoxin can alter human DNA in lymphocytes, impacting immune function.
  The metabolism of brevetoxins in shellfish is particularly concerning, as certain derivatives have been shown to remain in the animal over extended periods of time. It has been shown that the main toxin produced by K. brevis, PbTx-2, is rapidly metabolized, resulting in the production of metabolites that endure in the animal's system for a significantly longer period of time. This stands in contrast to PbTx-3, which is typically eliminated from the shellfish in more or less its original form within a few weeks. 
  Brevetoxin concentrations in seafood and the regulation of toxic substance monitoring in the animals is concerning. In Florida, only oysters and clams are monitored for NSP. Scallops are not monitored, although scallop-related NSP does not normally occur because in most cases, the muscle which does not accumulate brevetoxin to dangerous levels is consumed. Additionally, scallops are less tolerant to brevetoxins as compared to other bivalves and die off quickly after exposure to K. brevis red tides. However, smaller bivalves such as chione clams and coquinas can accumulate extremely high levels of brevetoxins and are not monitored, which could potentially impact both human and wildlife health in negative ways. According to evidence from Poli et al., whelks are implicated in an NSP event in 1996.
  With respect to ichthyotoxicity, reports of massive fish kills have been reported in the Gulf of Mexico as far back as 1844. Originally, fish bioassay-guided fractionation was used to isolate the toxins, but accumulation in or food-web transfer by fish has not been regarded as a threat. Steidinger hypothesized that the presence of brevetoxin found in dolphin mortalities and prey mortalities in 1987-1988 were in part due to brevetoxin transfer through fish. While dangerous levels of brevetoxins have not been found in the muscles of live fish to date, the internal organs of fish are highly susceptible to dangerous levels of toxicity and should not be eaten. It is conjectured that chronic low-level exposure to brevetoxin metabolites can occur through shellfish and fish, although the effects of this have not been studied in detail and remain largely unknown.