The uptake of brevetoxin into both humans and animals occurs primarily through inhalation and ingestion. Dermal contact, such as through swimming in the red tides, is a suspected method of uptake, although direct contact with the toxin in the water is not well studied. In the case of inhalation, aerosolized toxins carried onshore in sea spray can cause respiratory irritation that can escalate, in more extreme cases, to more severe airway constriction, an effect observed at pM concentrations. More significant are the cases of ingestion, whether by direct swallowing of seawater during blooms of "K. brevis" or digestion of contaminated filter-feeding animals. After feeding upon "K. brevis", aquatic invertebrates and shellfish in particular can accumulate brevetoxins, resulting in neurotoxic shellfish poisoning (NSP). In humans, the characteristic symptoms of NSP include Paresthesia (tingling), reversal of hot-cold temperature sensation, myalgia (muscle pain), vertigo, ataxia (loss of coordination), abdominal pain, nausea, diarrhea, headache, bradycardia (slow heart rate), dilated pupils and as respiratory distress, as previously mentioned. The bioaccumulation effect has been observed for this toxin in the food web, and it has been noted that this accumulation is not restricted to times when "K. brevis" is present.