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Barry H. Rosen, Ph.D. - Florida Gulf Coast University. Fort Myers, FL, US

Barry H. Rosen, Ph.D.

Expert in cyanobacteria, harmful algal blooms and blue-green algae | Florida Gulf Coast University


Barry Rosen studies the nature of freshwater harmful algal blooms and their dynamics.



Barry H. Rosen, Ph.D. Publication



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FGCU professor studies health effects of algal blooms



Barry Rosen is a world-class scholar and professor in The Water School at Florida Gulf Coast University. Having studied cyanobacteria for over 40 years, Rosen is charged with creating a statewide and national program to understand freshwater harmful algal blooms (HAB), their impacts and potential solutions for mitigation. Prior to joining the university, he worked for several federal and state agencies, including the U.S. Geological Survey, U.S. Fish and Wildlife Service, the Natural Resources Conservation Service, the Environmental Protection Agency, and the South Florida Water Management District.

Areas of Expertise (11)

blue-green algae

Cyanobacterial genetics



Fish kills



Harmful Algal Blooms (HABs)


Algal Physiology


Accomplishments (3)

Joan Hodges Queneau Palladium Medal (professional)

2000 Established by the National Audubon Society in 1977, the Joan Hodges Queneau Medal recognizes an individual who encourages cooperation between engineering professionals and environmentalists to create innovative solutions to environmental problems. This award is administered by the American Association of Engineering Societies.

Aquatic Resource Management Award (professional)

1999 Given by the Florida Lake Management Society to a professional government employee who has worked to restore, protect and/or advance our understanding of Florida's aquatic resources.

Environmental Science and Engineering Fellow (professional)

1990 Appointed by the American Association Advancement of Science, Rosen was placed in the Environmental Protection Agency's (EPA) Office of Wetlands, Oceans, & Watersheds in Washington, D.C. While there, Rosen worked on the Clean Water Act, section 301(h- municipalities with sewage treatment plants that discharged into marine waters). He served as liaison between the EPA and other federal and state agencies on technical and policy aspects of the regulations.

Education (7)

University of Nebraska: Biological Sciences, Postdoctoral Research Associate 1986

Rosen worked with the Aquatic Species Program, which was part of the Biofuels Program, Department of Energy, administered through the Solar Energy Research Institute. He was part of a team of scientists working on lipid production from living organisms, which serve as biofuels. The goal of the program was to produce biofuels from microalgae grown in saline waters of the desert southwest.

Tel Aviv University/Weizmann Institute: Postdoctoral Research Associate, Biology 1985

The European Molecular Biology Organization sponsored Rosen's research in Israel, working with internationally acclaimed experts in symbiosis and lectins at the University of Tel Aviv and the Weizmann Institute in Rehovot. The main focus of the research was on understanding how symbiotic relationships between plants and cyanobacteria are initiated and maintained.

Virginia Commonwealth University: Postdoctoral Research Associate, Biology 1984

Rosen's research was supported by Bio-Technical Resources, Inc., a biotechnology company developing hybridization technology that allowed different strains of organisms to be fused to form a new strain.

The Ohio State University: Postdoctoral Research Associate, Electron Microscopist 1983

Rosen managed the transmission electron microscope facility in the Department of Botany at Ohio State University, supported by a grant from the National Science Foundation.

Bowling Green State University: Ph.D., Biology 1982

St. Cloud State University: M.A., Biology 1978

University of Connecticut: B.S., Botany 1976

Affiliations (1)

  • North American Lake Management Society : Member

Selected Media Appearances (31)

A large fish kill and a dead manatee in a Cape Coral canal sparks examination

Fox 4  tv


Dr. Barry Rosen tests an algae sample found in the Ceitus and Kuhn Canals in Cape Coral.

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Southwest Florida faces threat of red tide as Nicole approaches

NBC2  tv


Dr. Barry Rosen discusses water levels in Lake Okeechobee as Tropical Storm Nicole approaches Florida.

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Researchers watching for potential algae surges as part of Hurricane Ian aftermath

NBC2  tv


Dr. Barry Rosen explains if Southwest Florida could see a blue-green algae surge after Hurricane Ian.

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Researchers studying what people could be breathing in from blue-green algae in SWFL

NBC2  tv


Dr. Barry Rosen discusses a research project that looks at the health effects of blue-green algae

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Red drift algae stinks up Fort Myers beaches

NBC2  tv


Dr. Barry Rosen explains why red drift algae is natural and not to remove it from the shoreline.

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North Fort Myers canal still filled with algae following treatment

NBC2  tv


Dr. Barry Rosen tests a sample of blue-green algae found in North Fort Myers.

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North Fort Myers canal still filled with algae following treatment

NBC2  tv


Dr. Barry Rosen explains how blue-green algae disperse with the help of wind and rain.

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Harmful algae bloom in North Fort Myers canal concerns scientists

NBC2  tv


Dr. Barry Rosen tests a blue-green algae sample for cyanobacteria.

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Students spend first day of school in FGCU’s new Water School

NBC2  tv


Dr. Barry Rosen teaches one of the first classes in The Water School building.

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Black algae washes up along the shores of the Caloosahatchee River

NBC2  tv


Dr. Barry Rosen identifies a type of red algae called Polysiphonia.

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Why are we seeing so much blue-green algae lately?

CBS12 West Palm Beach  tv


Dr. Barry Rosen discusses the increase in blue-green algae around Lake Worth Beach, Florida.

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South Florida becomes epicenter of new algae study

NBC2  tv


Drs. Barry Rosen and Michael Parsons are working on a new study to understand how much algae exposure is bad for humans.

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FGCU brain power on display as algae specialist leads nation in identifying blooms, toxins

The News-Press  print


Dr. Barry Rosen's blue-green algae work with communities across the United States is featured in this profile story.

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Fixing the Lake O algae problem could lie well below the surface

NBC2  tv


Drs. Barry Rosen, Tom Missimer and Serge Thomas look at blue-green algae issues on Lake O.

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FGCU professor studies health effects of algal blooms

NBC2  tv


Dr. Barry Rosen introduces a device he created to conduct controlled experiments related to blue-green algae toxin.

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FGCU professor studies health effects of algal blooms

NBC2  tv


Dr. Barry Rosen creates a controlled chamber for blue-green algae.

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Pioneering algae research blooms at Florida Gulf Coast University's Water School

The News-Press  online


Dr. Rosen's new controlled chamber simulates environmental conditions that spread blue-green algae toxin.

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Boaters find yellow-green algae in the Caloosahatchee Estuary

NBC2  tv


Dr. Barry Rosen test a sample of non-toxic yellow-green algae.

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Algal bloom in Cape Coral Highlander Canal still causing problems despite city efforts

NBC2  tv


Dr. Barry Rosen tests samples from a blue-green algae bloom found in a Cape Coral canal.

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Red drift algae washes ashore on Fort Myers Beach

ABC7  tv


Dr. Barry Rosen discusses drift algae and if it is harmful.

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How might blue-green algae affect human health? This multifaceted study aims to find out

The News-Press  print


Dr. Barry Rosen partners with fellow Florida Gulf Coast University professor Mike Parsons and Florida Atlantic University professor Adam Schaefer.

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Traces of toxic algae found in Caloosahatchee River

NBC2  online


Dr. Barry Rosen identifies toxic algae in the Caloosahatchee River.

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Red tide organism detected in Cape Coral canal

NBC2  tv


Dr. Barry Rosen discusses non-toxic red tide called "Akashiwo Sanguinea."

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FOX 4 News Literacy Project: Lee County students learn importance of media literacy

Fox4  tv


Dr. Barry Rosen works with students from Lee County Schools to help them tell a story about blue-green algae.

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FGCU to break ground on new water school building

NBC2  tv


Dr. Barry Rosen talks about the launch of The Water School at Florida Gulf Coast University.

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What's that green gunk floating in Cape Coral canals?

NBC2  tv


Dr. Barry Rosen looks at algae under the microscope.

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Sargassum seaweed, invader of Florida and Caribbean beaches, may be the 'new norm'

USA Today  print


Dr. Barry Rosen talks about the way sargassum is fed via nutrients.

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Do algae warning signs around Lake Okeechobee signal more than health risks?

The News-Press  print


Dr. Barry Rosen talks about the connection between warm weather and algae blooms.

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Caloosahatchee River spared lake releases as Army Corps holds water in lake, sends some south

The News-Press  print


Dr. Barry Rosen talks about water releases into the Caloosahatchee River.

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Small traces of blue-green algae detected in Cape Coral canals

NBC2  tv


Dr. Barry Rosen talks about blue-green algae in Cape Coral, Florida.

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Hurricane Dorian could impact Lake Okeechobee, according to expert

Fox 4  tv


Dr. Barry Rosen talks about the potential impact a hurricane could have on water quality.

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Selected Event Appearances (4)


North American Lake Management Society-Florida Chapter  Virtual


Freshwater Phytoplankton Identification Workshop

10th U.S. HABs Symposium  Perdido Beach, Alabama


Cyanobacteria Ecological Strategies: Initiation, development and termination of a bloom

Florida Sea Grant, Harmful Algal Blooms State of the Science Symposium  St. Petersburg, Florida


Animal and human health at risk from algal toxins in our water: neurotoxins, hepatotoxins and climate change

Tribal Lands and Environment Forum  Washington, D.C.


Selected Research Grants (5)

Harmful Algal Bloom Innovative Technology Project: Chemical-Free Harmful Algal Bloom Control

Florida Department of Environmental Protection $355,850


This project uses novel nanobubble injection technology for the chemical-free control of freshwater harmful algae blooms (HABs).

Measurement of cyanotoxin aerosolization to understand the potential impact on human health

Florida Department of Health $128,458


This research is designed to rigorously quantify the release of cyanotoxins (microcystins, anatoxin, cylindrospermopsin, saxitoxins and BMAA) from cyanobacterial blooms.

Phytoplankton Evaluation of Lake Trafford

South Florida Water Management District - Big Cypress Basin $37,922


This project analyzes the cyanobacterial community in Lake Trafford and the community and toxin production changes induced by nutrients such as nitrogen and phosphorus.

Early detection and rapid response to harmful algal blooms using hydrogen peroxide and cyanotoxin genes

Florida Department of Environmental Protection $320,000


This project is focused on early detection of the cyanotoxin genes, which will help guide treatment when toxin producing cyanobacteria are present.

Cyanobacterial blooms impact on human health and potential mitigation strategies

Florida Department of Health $60,000


This project is designed to support the Centers for Disease Control and Prevention and its study of the health impacts from cyanobacteria.

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Selected Articles (8)

Legacy Phosphorus in Lake Okeechobee (Florida, USA) Sediments: A Review and New Perspective


Missimer, Thomas & Thomas, Serge & Rosen, Barry

2020 Lake Okeechobee is one of the largest freshwater lakes in the United States. As a eutrophic lake, it has frequent algal blooms composed predominantly of the cyanobacterium genus Micro-cystis. Many of the algal blooms are associated with the resuspension of a thixotropic benthic mud containing legacy nutrients. Since Lake Okeechobee has an area of 1732 km2 (40–50 km radius) and a mean depth of only 2.7 m, there is sufficient fetch and shallow water depth to allow frequent wind, wave, and current generated events, which cause sediment resuspension. Three types of mud exist in the lake including an immobile dark-colored, consolidated mud, a brownish-colored mud, which is poorly consolidated and mobile, and a dark-colored thixotropic, highly mobile mud that is a mixture of organic matter and clay-sized minerals. Altogether, these muds contain an estimated 4.6 × 106 kg of total phosphorus and commensurate high amounts of labile nitrogen. The thixotropic mud covers most of the lakebed and contains the suitable nutrient ratios to trigger algal blooms. A bioassay analysis of the thixotropic mud compared to the consolidated mud showed that it pro-duced up to 50% more nutrient mass compared to the consolidated mud. The thixotropic mud does not consolidate, thus remains mobile. The mobility is maintained by the dynamics of the algal blooms and bacterial decay of extracellular secretions (transparent exopolymer particles) that bind sediment, transfer it to the bottom, and undergo bacterial digestion causing gas emissions, thus maintaining the organic/sediment matrix in suspension. Despite major efforts to control external nutrient loading into the lake, the high frequency of algal blooms will continue until the muds bearing legacy nutrients are removed from the lake.

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Cyanotoxin occurrence in large rivers of the United States

Inland Waters

Jennifer L. Graham, Neil M. Dubrovsky, Guy M. Foster, Lindsey R. King, Keith A. Loftin, Barry H. Rosen & Erin A. Stelzer

2020 Cyanotoxins occur in rivers worldwide but are understudied in lotic ecosystems relative to lakes and reservoirs. We sampled 11 large river sites located throughout the United States during June–September 2017 to determine the occurrence of cyanobacteria with known cyanotoxin-producing strains, cyanotoxin synthetase genes, and cyanotoxins. Chlorophyll a concentrations ranged from oligotrophic to eutrophic (0.5–64.4 µg L−1). Cyanobacteria were present in the algal communities of all rivers (82% of samples, n = 50) but rarely dominated the phytoplankton (0–52% of total abundance; mean = 8.8%). Pseudanabaena and Planktothrix occurred most often, and many (64%) of the cyanobacterial genera identified (n = 25) have known cyanotoxin-producing strains. Cyanotoxin synthetase genes occurred in all but one river. The mcyE and sxtA genes were most common, present in 73% of rivers and 44% and 40% of samples, respectively. The cyrA gene was less common (22% of samples) but occurred in 64% of rivers. The anaC gene was detected in one river (4% of samples). Anatoxin-a and microcystins were detected at low levels (0.10–0.38 µg L−1) in 2 midcontinent rivers. Cylindrospermopsins and saxitoxins were not detected. Cyanobacteria, cyanotoxin synthetase genes, and cyanotoxins were present at low concentrations throughout this subset of US rivers. Eutrophic rivers located in the midcontinent region of the United States had the highest algal biomass, abundance of cyanotoxin synthetase genes, and cyanotoxin occurrence.

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Understanding the effect of salinity tolerance on cyanobacteria associated with a harmful algal bloom in Lake Okeechobee, Florida

USGS Scientific Investigations Report 2018-5092

Barry H. Rosen, Keith A. Loftin, Jennifer L. Graham, Katherine N. Stahlhut, James M. Riley, Brett D. Johnston and Sarena Senegal

2018 In an effort to simulate the survival of cyanobacteria as they are transported from Lake Okeechobee to the estuarine habitats that receive waters from the lake, a bioassay encompassing a range of salinities was performed. An overall decline in cyanobacteria health in salinity treatments greater than 18 practical salinity units (psu) was indicated by loss of cell membrane integrity based on SYTOX® Green staining, but this loss varied by the kind of cyanobacteria present. Microcystis aeruginosa was tolerant of salinities up to 18 psu; however, higher salinities caused leaking of microcystin from the cells. Dolichospermum circinale, another common bloomformer in this system, did not tolerate salinities greater than 7.5 psu. Stimulation of mucilage production was observed and is likely a mechanism used by both species to protect organism viability. At 7.5 psu, microcystin increased relative to chlorophyll-a, providing some evidence of biosynthesis when M. aeruginosa is exposed to this salinity. This study indicates that as freshwater cyanobacteria are transported to brackish and marine waters, there will be a loss of membrane integrity which will lead to the release of cellular microcystin into the surrounding waterbody. Additional research would be needed to determine the exact effect of salinity on this relationship.

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Nitrogen limitation, toxin synthesis potential, and toxicity of cyanobacterial populations in Lake Okeechobee and the St. Lucie River Estuary, Florida, during the 2016 state of emergency event


Benjamin J. Kramer,Timothy W. Davis,Kevin A. Meyer,Barry H. Rosen,Jennifer A. Goleski,Gregory J. Dick,Genesok Oh,Christopher J. Gobler

2018 Lake Okeechobee, FL, USA, has been subjected to intensifying cyanobacterial blooms that can spread to the adjacent St. Lucie River and Estuary via natural and anthropogenically-induced flooding events. In July 2016, a large, toxic cyanobacterial bloom occurred in Lake Okeechobee and throughout the St. Lucie River and Estuary, leading Florida to declare a state of emergency. This study reports on measurements and nutrient amendment experiments performed in this freshwater-estuarine ecosystem (salinity 0–25 PSU) during and after the bloom. In July, all sites along the bloom exhibited dissolved inorganic nitrogen-to-phosphorus ratios < 6, while Microcystis dominated (> 95%) phytoplankton inventories from the lake to the central part of the estuary. Chlorophyll a and microcystin concentrations peaked (100 and 34 μg L-1, respectively) within Lake Okeechobee and decreased eastwards. Metagenomic analyses indicated that genes associated with the production of microcystin (mcyE) and the algal neurotoxin saxitoxin (sxtA) originated from Microcystis and multiple diazotrophic genera, respectively. There were highly significant correlations between levels of total nitrogen, microcystin, and microcystin synthesis gene abundance across all surveyed sites (p < 0.001), suggesting high levels of nitrogen supported the production of microcystin during this event. Consistent with this, experiments performed with low salinity water from the St. Lucie River during the event indicated that algal biomass was nitrogen-limited. In the fall, densities of Microcystis and concentrations of microcystin were significantly lower, green algae co-dominated with cyanobacteria, and multiple algal groups displayed nitrogen-limitation. These results indicate that monitoring and regulatory strategies in Lake Okeechobee and the St. Lucie River and Estuary should consider managing loads of nitrogen to control future algal and microcystin-producing cyanobacterial blooms.

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Optical characterization of two cyanobacteria genera, Aphanizomenon and Microcystis, with hyperspectral microscopy

Journal of Applied Remote Sensing

Paine, E.C., Slonecker, E.T., Simon, N.S., Rosen, B.H., Resmini, R.G., and Allen, D.W.

2018 Cyanobacterial blooms are a nuisance and a potential hazard in freshwater systems worldwide. Remote sensing has been used to detect cyanobacterial blooms, but few studies have distinguished among genera of cyanobacteria. Because some genera are more likely to be toxic than others, this is a useful distinction. Hyperspectral imaging reflectance microscopy was used to examine cyanobacteria from Upper Klamath Lake, Oregon, at high spatial and spectral resolution to determine if two species found commonly in the lake, Aphanizomenon flos-aquae and Microcystis aeruginosa, can be separated spectrally. Of the analytical methods applied, a spectral shape algorithm applied to the derivative was found to be most successful in classifying these species in microscope scenes. Further work is required to determine if the spectral characterization of cyanobacterial genera can be scaled up to remote sensing applications.

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Cyanobacteria of the 2016 Lake Okeechobee and Okeechobee Waterway harmful algal bloom

USGS Open-File Report 2017-1054

Barry H. Rosen, Timothy W. Davis, Christopher J. Gobler, Benjamin J. Kramer and Keith A. Loftin

2017 The Lake Okeechobee and the Okeechobee Waterway (Lake Okeechobee, the St. Lucie Canal and River, and the Caloosahatchee River) experienced an extensive harmful algal bloom within Lake Okeechobee, the St. Lucie Canal and River and the Caloosahatchee River in 2016. In addition to the very visible bloom of the cyanobacterium Microcystis aeruginosa, several other cyanobacteria were present. These other species were less conspicuous; however, they have the potential to produce a variety of cyanotoxins, including anatoxins, cylindrospermopsins, and saxitoxins, in addition to the microcystins commonly associated with Microcystis. Some of these species were found before, during, and 2 weeks after the large Microcystis bloom and could provide a better understanding of bloom dynamics and succession. This report provides photographic documentation and taxonomic assessment of the cyanobacteria present from Lake Okeechobee and the Caloosahatchee River and St. Lucie Canal, with samples collected June 1st from the Caloosahatchee River and Lake Okeechobee and in July from the St. Lucie Canal. The majority of the images were of live organisms, allowing their natural complement of pigmentation to be captured. The report provides a digital image-based taxonomic record of the Lake Okeechobee and the Okeechobee Waterway microscopic flora. It is anticipated that these images will facilitate current and future studies on this system, such as understanding the timing of cyanobacteria blooms and their potential toxin production.

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Field and laboratory guide to freshwater cyanobacteria harmful algal blooms for Native American and Alaska Native communities

USGS Open-File Report 2015-1164

Barry H. Rosen and Ann St. Amand

2015 Cyanobacteria can produce toxins and form harmful algal blooms. The Native American and Alaska Native communities that are dependent on subsistence fishing have an increased risk of exposure to these cyanotoxins. It is important to recognize the presence of an algal bloom in a waterbody and to distinguish a potentially toxic harmful algal bloom from a non-toxic bloom. This guide provides field images that show cyanobacteria blooms, some of which can be toxin producers, as well as other non-toxic algae blooms and floating plants that might be confused with algae. After recognition of a potential toxin-producing cyanobacterial bloom in the field, the type(s) of cyanobacteria present needs to be identified. Species identification, which requires microscopic examination, may help distinguish a toxin-producer from a non-toxin producer. This guide also provides microscopic images of the common cyanobacteria that are known to produce toxins, as well as images of algae that form blooms but do not produce toxins.

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Is exposure to cyanobacteria an environmental risk factor for amyotrophic lateral sclerosis and other neurodegenerative diseases?

Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration

Walter G. Bradley, Amy R. Borenstein, Lorene M. Nelson, Geoffrey A. Codd, Barry H. Rosen, Elijah W. Stommel & Paul Alan Cox

2013 There is a broad scientific consensus that amyotrophic lateral sclerosis (ALS) is caused by gene-environment interactions. Mutations in genes underlying familial ALS (fALS) have been discovered in only 5–10% of the total population of ALS patients. Relatively little attention has been paid to environmental and lifestyle factors that may trigger the cascade of motor neuron death leading to the syndrome of ALS, although exposure to chemicals including lead and pesticides, and to agricultural environments, smoking, certain sports, and trauma have all been identified with an increased risk of ALS. There is a need for research to quantify the relative roles of each of the identified risk factors for ALS. Recent evidence has strengthened the theory that chronic environmental exposure to the neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) produced by cyanobacteria may be an environmental risk factor for ALS. Here we describe methods that may be used to assess exposure to cyanobacteria, and hence potentially to BMAA, namely an epidemiologic questionnaire and direct and indirect methods for estimating the cyanobacterial load in ecosystems. Rigorous epidemiologic studies could determine the risks associated with exposure to cyanobacteria, and if combined with genetic analysis of ALS cases and controls could reveal etiologically important gene-environment interactions in genetically vulnerable individuals.

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