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## Facts about Cyanobacteria (Blue-green Algae) and Cyanobacterial Harmful Algal Blooms (CyanoHABs)

Cyanobacteria (blue-green algae) Cyanobacteria are bacteria that grow in water and are photosynthetic (use sunlight to create food and support life). Cyanobacteria live in terrestrial, fresh, brackish, or marine water. They usually are too small to be seen, but sometimes can form visible colonies. Cyanobacteria have been found among the oldest fossils on earth and are one of the largest groups of bacteria. Cyanobacteria have been linked to human and animal illnesses around the world, including North and South America, Africa, Australia, Europe, Scandinavia, and China. Cyanobacterial blooms and how they form Cyanobacterial blooms occur when algae that are normally present grow exuberantly. Within a few days, a bloom can cause clear water to become cloudy. The blooms usually fl oat to the surface and can be many inches thick, especially near the shoreline. Cyanobacterial blooms can form in warm, slow-moving waters that are rich in nutrients such as fertilizer runof f or septic tank overfl ows. Blooms can occur at any time, but most often occur in late summer or early fall. They can occur in marine, estuarine, and fresh waters, but the blooms of greatest concern are the ones that occur in fresh water, such as drinking water reservoirs or recreational waters. What a cyanobacterial bloom looks like Some cyanobacterial blooms can look like foam, scum, or mats on the surface of fresh water lakes and ponds. The blooms can be blue, bright green, brown, or red and may look like paint fl oating on the water. Some blooms may not affect the appearance of the water. As algae in a cyanobacterial bloom die, the water may smell bad.2 Cyanobacterial harmful algal blooms (CyanoHABs) CyanoHABs are algae blooms that threaten people, animals, or the environment. They are dangerous for many reasons:

• Dense CyanoHABs can block sunlight and

use up all the oxygen in the water, killing other plants and animals.

• Some cyanobacteria that can form

CyanoHABs produce toxins that are among the most powerful natural poisons known. These toxins have no known antidotes.

• CyanoHABs can make people, their pets,

and other animals sick. Often, the fi rst sign that an HAB exists is a sick dog that has been swimming in an algae-fi lled pond.

• Children are at higher risk than adults for

illness from CyanoHABs because they weigh less and can get a relatively larger dose of toxin.

Other effects of fresh-water CyanoHABs

• CyanoHABs can make drinking water smell

and taste bad.

• They can make recreational areas unpleasant.

Species of cyanobacteria that form CyanoHABs in fresh water

• Microcystis aeruginosa

• Anabaena circinalis

• Anabaena fl os-aquae

• Aphanizomenon fl os-aquae

• Cylindrospermopsis raciborskii Cyanotoxins Cyanotoxins are a diverse group of chemical substances that are categorized by their specifi c toxic effects as follows:

• Neurotoxins affect the nervous system.

° Anatoxin-a

° Anatoxin-a(s)

° Saxitoxin

° Neosaxitoxin

• Hepatotoxins affect the liver.

° Microcystins

° Nodularins

° Cylindrospermopsin

• Tumor promoters are chemicals that can

increase tumor growth.

° Microcystins

• Lipopolysaccharides are chemicals that can

affect the gastrointestinal system.
See the table below for a list of cyanotoxins and their specifi c toxic mechanisms, their effects, the symptoms they cause, and treatments for poisoning.

How you could be exposed to CyanoHABs and cyanotoxins

• Drinking water that comes from a lake or

reservoir with a CyanoHAB.

• Drinking untreated water.

• Engaging in recreational activities in waters

with CyanoHABs.

• Inhaling aerosols from water-related

activities such as jet-skiing or boating.

• Inhaling aerosols when watering lawns,

irrigating golf-courses, etc. with pond water.

• Using cyanobacteria-based dietary

supplements that are contaminated with microcystins.

• Receiving dialysis (this has been

documented only in Brazil).3 Types of illnesses people and animals can get from exposure to CyanoHABs

• Getting it on the skin may give people a

rash, hives, or skin blisters (especially on the lips and under swimsuits).

• Inhaling water dropletsfrom irrigation

or water-related recreational activities can cause runny eyes and nose, a sore throat, asthma-like symptoms, or allergic reactions.

• Swallowing water that has cyanobacterial toxins in it can cause

° Acute, severe gastroenteritis (including

diarrhea and vomiting).

° Liver toxicity (i.e., increased serum

levels of liver enzymes). Symptoms of liver poisoning may takes hours or days to show up in people or animals. Symptoms include abdominal pain, diarrhea, and vomiting.

° Kidney toxicity.

° Neurotoxicity. These symptoms can

appear within 15 to 20 minutes after exposure. In dogs, the neurotoxins can cause salivation and other neurologic symptoms, including weakness, staggering, diffi culty breathing, convulsions, and death. People may have numb lips, tingling fi ngers and toes, or they may feel dizzy.

Testing for cyanobacterial toxins

• Most of the toxins require specialized

testing that can take weeks.

• Some kits are available to test for

microcystins on site. How to protect yourself, your family, and your pets from exposure to CyanoHABs

• Donʼt swim, water ski, or boat in areas where

the water is discolored or where you see foam, scum, or mats of algae on the water.

• If you do swim in water that might have a

CyanoHAB, rinse off with fresh water as soon as possible.

• Donʼt let pets or livestock swim in or drink

from areas where the water is discolored or where you see foam, scum, or mats of algae on the water.

• If pets (especially dogs) swim in scummy

water, rinse them off immediately—do not let them lick the algae (and toxins) off their fur.

• Donʼt irrigate lawns or golf courses with

pond water that looks scummy or smells bad.

• Report any “musty” smell or taste in your

drinking water to your local water utility.

• Respect any water-body closures announced

by local public health authorities.

How to treat people or animals that have been exposed to cyanobacterial toxins

• Get medical treatment right away if you

think you, your pet, or your livestock might have been poisoned by cyanobacterial toxins.

• Remove people from exposure and give

them supportive treatment.4 How to help reduce the occurrence of CyanoHABs

• Reduce nutrient loading of local ponds and

lakes by using only the recommended amounts of fertilizers and pesticides on your yard.

• Properly maintain your household septic

system.

• Maintain a buffer of natural vegetation

around ponds and lakes to fi lter incoming water.

How to get more information about cyanobacteria:

Federal **Centers for Disease Control and Prevention (CDC)**  Harmful Algal Blooms (HABs) site http://www.cdc.gov/habs This site defi nes HABs; describes CDCʼs HABs-related activities; and provides links to data, publications, and other HABs resources.
Cyanobacteria site http://www.cdc.gov/hab/cyanobacteria/ This site defi nes cyanobacteria; describes CDCʼs cyanobacteria-related activities; and provides links to data, publications, and other cyanobacteria resources.
**Environmental Protection Agency (EPA)** Drinking Water Contaminant Candidate List Site http://www.epa.gov/safewater/ccl/cclfs.html This site provides information about EPAʼs list of contaminants that are not regulated, occur in public water systems, and may require regulation under the Safe Drinking Water Act. Algae that can be harmful are on this list.

International **State of Queensland Australia** HAB site http://www.nrm.qld.gov.au/water/blue_green/ index.html This site describes the stateʼs plans and procedures for agency responding to HABs.
**World Health Organization** Water Site http://www.who.int/topics/water/en/ This site provides links to drinking and recreational water quality, including the impacts of cyanobacteria and cyanobacterial toxins.

States **North Carolina Department of Health and Human Services**  Occupational and Environmental Epidemiology program, HABs Site http://www.epi.state.nc.us/epi/hab/ This site gives an overview of North Carolinaʼs HAB program and provides links to the stateʼs HAB-related surveillance, research, and education activities.5 

### Cyanobacterial toxins, effects, signs and symptoms of poisoning, and therapy

Toxin Acute Effect Signs and Symptoms Therapy

Anatoxin-a Neurotoxicity Humans: not documented. Animals: progression of muscle fasciculations, decreased movement, abdominal breathing, cyanosis, convulsions, death. Birds: opisthotonos (“s”-shaped neck). Supportive care. Respiratory support may allow time for detoxifi cation and respiratory recovery.

Anatoxin-a (s) Neurotoxicity Humans: not documented. Pigs: hypersalivation, mucoid nasal discharge, tremors, fasciculations, ataxia, diarrhea, recumbency. Ducks: regurgitation, paresis, opisthotonos, clonic seizures. Mice: lacrimation, hypersalivation, urination, defecation, death from respiratory arrest. Rats: red-pigmented ears. Supportive care.

Cylindrospermopsin Hepatotoxicity, renal toxicity, chromosome breakage, aneuploidy Humans: enlarged liver, malaise, anorexia, vomiting, headache. Mice: huddling, anorexia, slight diarrhea, gasping respiration. Supportive care.

Microcystins Hepatotoxicity Humans: elevated gamma-glutamyl transpeptidase. Humans, mice: elevated alanine aminotransferase. Rats: embryo lethality, teratogenicity. Mammals: weakness, reluctance to move, anorexia, pallor of extremities and mucous membranes, mental derangement, survivors may be photosensitized. Humans: powdered charcoal, supportive

care. Animals: cholestyramine.

Nodularin Hepatotoxicity Humans: Skin and eye irritation from skin contact. Experimental systems: inhibition of protein phosphatases, tumor-promoter. Supportive care.

Saxitoxin, neosaxitoxin Neurotoxicity Humans: paresthesia and numbness of lips and mouth within 1⁄2 to 3 hours after exposure, extending to face, neck, extremities; motor weakness; incoordin-ation; respiratory and muscular paralysis. Animals: incoordination, death by respiratory failure. Activated charcoal, artifi cial respiration. Supportive care.6 References: Carmichael WW, Beasley V, Bunner DL, Eloff JN, Falconer IR, Gorham PR, et al. Naming of cyclic heptapeptide toxins of cyanobacteria (blue-green algae). Toxicon. 1988;26:971-3. Carmichael, WW, Falconer IR. Diseases related to freshwater blue-green algal toxins, and control measures. P. 187-209. In: Falconer I R (ed.). Algal Toxins in Seafood and Drinking Water. London: Academic Press. 1993: pp187-209. Dahlem AM, Hassan AS, Swanson SP, Carmichael WW, Beasley VR. A model system for studying the bioavailability of intestinally administered microcystin-LR, a hepatotoxic peptide from the cyanobacterium Microcystis aeruginosa . Pharmacol. Toxicol. 1989;64:177-81. Falconer, IR, Beresford AM, Runnegar MT. 1983. Evidence of liver damage by toxin from a bloom of blue-green algae, Microcystis aeruginosa . Med J Aust. 1983;1: 511-4. Hawkins PR, Chandrasena NR, Jones GJ, Humpage AR, Falconer IR. Isolation and toxicity of Cylindrospermopsis raciborskiifrom an ornamental lake. Toxicon. 1997;35:341-346. Humpage A R, Hardy SJ, Moore EJ, Froscio SM, Falconer IR. Microcystins (cyanobacterial toxins) in drinking water enhance the growth of aberrant crypt foci in the mouse colon. J Toxicol Environ Health, Part A. 2000;61:155-65. Kirpenko YA, Sirenko LA, KirpenkoNI. Some aspects concerning remote after-effects of blue-green algal toxin impact on warm-blooded animals. In: Carmichael WW (ed.). The Water Environment, Algal Toxins and Health. New York: Plenum, 1981: pp257-69. Soong F S, Maynard E, Kirke K, Luke C. Illness associated with blue-green algae. Med J Aust. 1992;156:67. Turner PC, Gammie AJ, Hollinrake K, Codd GA (1990). Pneumonia associated with contact with cyanobacteria. Br Med J. 1990;300:1440-1.