Table 1. Examples of published studies that inform the potential public health impacts of HABs.

Table 1. Examples of published studies that inform the potential public health impacts of HABs.

Study Citation	Study methods	Summary of Public Health-related findings
Marine HABs
Backer LC, Fleming LE, Rowan A, Cheng Y-S, Benson J, Pierce RH, Zaias J, Bean J, Bossart GD, Johnson D, Quimbo R, Baden DG. Recreational Exposure to Aerosolized Brevetoxins During Florida Red Tide Events. Harmful Algae. 2003;2:19-28.	Conducted pulmonary function tests (PFT), nasal swabs, and surveys before and after beach visits.	Lower respiratory symptoms (e.g., wheezing) were reported by 8% of unexposed (N=36), 11% of moderately exposed (N=53), and 28% of the highly exposed (N=40) groups. Found inflammatory response in 33% of those experiencing moderate or high exposure. There were no clinically significant changes in PFT results.
Backer LC, Kirkpatrick B, Fleming LE, Cheng YS, Pierce R, Bean JA, Clark R, Johnson D, Wanner A, Tamer R, Baden D. Occupational Exposure to Aerosolized Brevetoxins during Florida Red Tide Events: Impacts on a Healthy Worker Population. Environmental Health Perspectives. 2005;113-5:644-649.	Longitudinal study of full-time lifeguards on Florida beaches.	Found slight increase in some respiratory symptoms during exposure days.
Kirkpatrick B, Pierce R, Cheng YS, Henry MS, Blum P, Osborn S, Nierenberg K, Pederson BA, Fleming LE, Reich A, Naar J, Kirkpatrick G, Backer LC, Baden D. 2010 Inland transport of aerosolized Florida red tide toxins. Harmful Algae 9:186-189.	Examined air samples collected at various distances from the shore during red tide blooms.	Demonstrated movement of airborne brevetoxins inland for as much as 3 miles.
Kirkpatrick B, Fleming LE, Bean JA, Nierenberg K, Backer LC, Cheng YS, Pierce R, Reich A, Naar J, Wanner A, Abraham WM, Zhou Yue, Hollenbeck J, Baden DG. 2010. Aerosolized Red Tide Toxins (Brevetoxins) and Asthma: Continued health effects after 1 hour beach exposure. 2011. Harmful Algae 10:138-143.	Longitudinal study of respiratory effects from red tides on people with asthma. Collected biomonitoring, health, and environmental data.	Showed lasting effects from inhaled brevetoxins on people with asthma
Cyanobacterial HABs
Falconer IR, Beresford AM, Runnegar MTC. Evidence of liver damage by toxin from a bloom of the blue-green alga, Microcystis aeruginosa. Med. J. Aust. 1983;1:511–514.	Used hospital records of liver function test results when the water supply was free of blooms and when there was a documented cyanobacterial bloom.	Found higher levels of liver enzymes during a time when the water supply was contaminated with a cyanobacterial bloom
Phillip R. Health risks associated with recreational exposure to blue-green algae (cyanobacteria) when dinghy sailing. Health Hyg. 1992;13:110–114.	Collected health symptom data from people sailing in small boats.	Reported health symptoms for dinghy sailors similar whether or not they were exposed to cyanobacterial blooms.
Carmichael WW, Falconer IR. Diseases related to freshwater bluegreen algal toxins, and control measures. In: Falconer, I.R. (Ed.), Algal Toxins in Seafood and Drinking Water. Academic Press, London, 1993. pp. 187–209.	Summarized health effects from exposure to cyanobacterial toxins	Summary of possible health effects.
Gilroy DJ, Kauffman KW, Hall, RA, Huang X, Chu FS. Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements. Environ. Health Perspect. 2000;5:435–439.	Examined blue-green dietary supplements from a bloom contaminated with Microcystis species.	Found that blue-green dietary supplements were contaminated with microcystins when the harvest was contaminated with Microcystis species.
De Magalhaes VF, Soares RM, Azevedo SMFO. Microcystin contamination in fish from the Jacareqagua Lagoon (Rio de Janeiro, Brazil): ecological implication and human health risk. Toxicon 2001;29:1077–1085.	Examined fish harvested during cyanobacterial blooms.	Fish harvested from lakes with ongoing cyanobacterial blooms were contaminated with microcystins.
Carmichael,WW, Azeved MFO, An JS, Molica RJR, Jochmisen EM, Lau S, Rinehart KL, Shaw GR, Eagelsham GK. Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins. Environ. Health Perspect. 2001;109, 663–668.	Outbreak investigation of people with fatal liver disease following dialysis in clinics in Brazil.	Dialysis water was contaminated with microcytsins.
Stewart I, Webb PM, Schluter J, Fleming LE, Burns JW Jr, Ganta M, Backer LC, Shaw GR. Acute effects of recreational exposure to freshwater cyanobacteria-a prospective epidemiologic study. pp. 473-474. In: Steidinger KA, Landsberg JH, Tomas CR, and GA Vargo (Eds.). 2004. Harmful Algae 2002. Florida Fish and Wildlife Conservation Commission, Florida Institute of Oceanography, and Intergovernmental Oceanographic Commission of UNESCO.	Epidemiology study including symptom surveys and environmental data collection.	Symptom reporting was low; however, cyanobacterial toxins were generally present at low levels, if at all.
Xie L, Xie P, Guo L, Li L, Miyabara, Y, Park H-D. Organ distribution and bioaccumulation of microcystins in freshwater fish at different trophic levels from the eutrophic Lake Chaohu, China. Environ. Toxicol 2005;20:293–300.	Examined the distribution of microcystins in fish and mussel tissue.	Found detectable levels of microcystins in bile and bloom of wild fish.
Kann J. Microcystin Bioaccumulation in Klamath River Fish and Freshwater Mussel Tissue: Preliminary 2007 Results. Technical Memorandum. Aquatic Ecosystem Sciences, LLC, Ashland, Oregon. 2008. 48 pp.	Examined distribution of microcystins in fish and mussels	Found microcystin bioaccumulation in fish and mussel tissues during blooms.
Backer LC, McNeel SV, Barber T, Kirkpatrick B, Williams C, Irvin M, Zhou Y, Johnson TB, Nierenberg K, Aubel M, LePrell R, Chapman A, Foss A, Corum S, Hill VR, Kieszak SM, Cheng Y-S. Recreational Exposure to Microcystins During Algal Blooms in Two California Lakes. Toxicon 2010, 55:909-921.	Observational study that collected symptom data, nasal swabs from people recreating on a lake with a bloom and those recreating on a lake without a bloom. Collected environmental data.	Low microcystin concentrations were found in water samples and personal air samples from people using the blooming lake, but not from people using the non-blooming lake. Detected low levels of microcystins on nasal swabs in people using the blooming lake.
Stewart I, Carmichael 22, Backer LC, Fleming LE, Shaw GR. Recreational Exposure to Cyanobacteria. In: Nriagu JO (ed) Encyclopedia of Environmental Health. Elsevier, The Netherlands, 2011:776-788	Overview of public health impacts from environmental exposures to cyanobacteria in recreational waters.	Report includes reference to CDC’s surveillance activities.
Hilborn ED, Roberts VA, Backer L, DeConno E, Egan JS, Hyde JB, Nicholas DC, Weigert EJ, Billing LM, DiOrio Mary, Morh, MK, Hardy J, Wade TJ, Yoder JS, Hlavsa MC. Algal bloom-associated disease outbreaks among users of freshwater lakes—United States, 2009-2010. MMWR, 2014,63(1):11-15.	Reported results from the One Health Harmful Algal Bloom System from 2009-2010	States reported 11 freshwater HAB-associated illness outbreaks, including 61 illnesses and two hospitalizations.
Backer LC, Manassaram-Baptiste D, LePrell R, Bolton B. 2015. Cyanobacteria and Algae Booms and Public Health: Data from the Harmful Algal Bloom-related Illness Surveillance System (HABISS). Toxins, 7, 1048-1064. doi:10.3390/toxins7041048	Summarized data collected via the Harmful Algal Bloom-related Illness Surveillance System (HABISS)	11 states contributed reports for 4534 bloom events, including 458 cases of suspected and confirmed human illnesses and 175 animal morbidity and mortality events from 2007-2011.
Lavery A, Backer LC, Daniel J. Evaluation of electronic claims data for monitoring exposure to harmful algal blooms in the United States. Journal of Environmental Health. 2021;83(9):8-14.	Examined the utility of using EHR in combination with bloom data to assess a possibly association.	Although HAB-related diagnostic codes were used infrequently, they were most often recorded during bloom seasons in warmer months.
Seaweed HABs
Resiere D, Mehdaoui H, Florentin J, Gueye P, Lebrun T, Blateau A et al. Sargassum seaweed health menace in the Caribbean: clinical characteristics of a population exposed to hydrogen sulfide during the 2018 massive stranding. Clinical Toxicology. 2020;59(3):215-223. https://doi.org/10.1080/15563650.2020.1789162	Data analysis using 154 patient records, H2S concentration estimates based on measurements temporal and geographic distribution of sargassum seaweed stranding in Martinique. The toxicologic syndrome associated with sargassum seaweed exposure (hospital visits) is close to the toxidrome associated with H2 exposure (0-10 ppm). Included neurologic, digestive, and respiratory symptoms.	Public health impacts from sargassum strandings likely associated with by-product gases released as the bloom material rots on the beaches.