Characterization of red tide aerosol on the Texas coast

In the fall of 2000, there was a red tide episode in the Gulf of Mexico near Corpus Christi, TX. We sampled at the Marine Science Institute in Port Aransas on 25 October 2000. Between 25–27 October 2000, we sampled at the Texas State Aquarium (TSA) near Corpus Christi Bay. Two high-volume samplers were equipped with a filter and a five-stage impactor, respectively. Because the amounts of brevetoxin (PbTx) collected in the air samples were low, we developed a LC/MS technique to analyze the PbTxs. Personal exposure was estimated with a personal filter sampler placed in the lapel of field workers. Concentrations of PbTx-2 and -3 were detected in the samples taken at the TSA; however, PbTx was not detected in the samples from the Marine Science Institute. The concentration of PbTx-2 was between 1.5 and 5.9 ng m⁻³ and much lower concentrations for PbTx-3. The ratio of PbTx-2 and -3 was 8.7±5.2. In the highest exposure period (26–27 October), PbTx-6 was also detected. No respiratory symptoms were reported at the Marine Science Institute, whereas at the TSA, symptoms including irritation in the nose and throat, and itchy skin were reported among seven field study workers. The PbTx concentrations estimated from both high-volume impactor and filter samplers were similar. The mass median aerodynamic diameters were between 7 and 9 μm (geometric standard deviation of 1.6), a relatively large size for inhaled ambient particles. Inhaled particles of this size would be predominantly deposited in the upper respiratory tract (nasal, oral, and pharyngeal area), and subsequent respiratory irritation could result from the presence of the particles themselves or from toxins associated with the particles. Information gained from these studies will aid in evaluations of the human risk associated with inhalation of red tide aerosols.