Florida has experienced multiple cyanobacteria blooms in recent years the most severe of which occurred in 2016 and 2018. Several toxins are produced by proliferating cyanobacteria, including the hepatotoxin microcystin (MC). Harmful algal blooms (HABs) caused by cyanobacteria have the potential to impact public health. However, to date there have been limited attempts to quantify exposure in human populations. This study investigated potential exposure to the cyanobacterial toxin, MC by measuring concentrations in swabs of the nasal mucosa. In addition, the relationships between nasal concentrations of MC, environmental concentrations and activity patterns were assessed. Participants (n = 125) were recruited in 2018 during a cyanobacterial bloom of Microcystis aeruginosa and completed a questionnaire which included location, type, and duration of recreational or occupational contact with impacted waterways within the last 10 days. Water samples were collected concurrently. A sterile swab was used to collect a sample from the nasal mucosa. Concentrations of MC were measured by ELISA. Of the 121 participants who provided nasal swabs, 115 (95.0 %) had concentrations of MC above the limit of detection with a mean concentration of 0.61 + 0.75 ppb. There were significant differences (p < 0.01) in mean MC concentration between individuals with direct contact with impacted waters (0.77 + 0.88 ppb) compared to those with no recent contact (0.37 + 0.49 ppb). Higher concentrations were observed among occupationally exposed individuals. Nasal concentrations of MC varied significantly over time and location of exposure to the bloom, concordant with concentrations in water samples. The results suggest that inhalation of aerosols may be an important pathway for exposure to MC. Nasal MC concentrations were generally highest during periods when concentrations in the surrounding waters peaked. Further research is needed to characterize the public health implications of exposure to cyanobacterial blooms.

近年来，佛罗里达州经历了多次蓝细菌开花，其中最严重的一次发生在2016年和2018年。蓝细菌的繁殖产生了多种毒素，包括肝毒素微囊藻毒素（MC）。蓝细菌引起的有害藻华（HAB）有可能影响公共健康。但是，迄今为止，定量量化人群暴露的尝试有限。这项研究通过测量鼻粘膜拭子中的浓度，研究了潜在暴露于蓝藻毒素MC的可能性。另外，评估了鼻腔MC浓度，环境浓度和活动模式之间的关系。铜绿微囊藻的蓝细菌绽放期间于2018年招募了参与者（n = 125）并完成了一份调查表，其中包括最近10天内与受影响水道的娱乐或职业接触的位置，类型和持续时间。同时收集水样品。使用无菌拭子从鼻粘膜收集样品。通过ELISA测量MC的浓度。在提供鼻拭子的121位参与者中，有115位（95.0％）的MC浓度超出了检出限，平均浓度为0.61 + 0.75 ppb。直接接触受影响水域的个体之间的平均MC浓度（0.77 + 0.88 ppb）与最近没有接触的个体之间的平均MC浓度（0.37 + 0.49 ppb）有显着差异（p <0.01）。在职业接触者中观察到较高的浓度。鼻中MC的浓度随着时间和暴露于水华的位置而显着变化，这与水样中的浓度一致。结果表明，吸入气溶胶可能是暴露于MC的重要途径。在周围水体浓度达到峰值期间，鼻MC浓度通常最高。需要进一步的研究来表征暴露于蓝藻水华的公共健康影响。