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I
I. I,

for Disease 
and Prevention (CDC)
Atlanta 

August 03, 2018

The Honorable Bill Nelson
United States Senate
Washington, DC 20510

Dear Senator Nelson:

Thank you for your letter requesting a study on the potential long~tertn health risks associated
with exposure to harmful algal blooms and highlighting Florida residents? need for
timely, trustworthy information that communicates the potential risks.

I understand your concerns since HABs can produce toxins that cause illness in people,
companion animals, livestock, and wildlife. Toxins can be present in both freshwater and marine
environments. Exposure can occur in a variety of ways, including direct contact with
contaminated water by swimming, breathing in aerosols from recreational activities or wind-
blown sea spray, drinking water contaminated with toxins, or eating contaminated fish or
shellfish. Human and animal illnesses and include respiratory, neurological, and
gastrointestinal problems, and severity can vary depending on the route and duration ofexposure
and the particular HAB toxin(s) involved.

The Centers for Disease Control and Prevention (CDC) maintains the One Health Harmful Algal
Bloom System (OHHABS, a voluntary reporting system
available to state and territorial public health departments and their designated enviromnental
health or animal health partners. It collects data on individual human and animal cases of
illnesses from HAB-associated exposures, as well as environmental data about HABs. The goal
of OHHABS is to use this data to support the understanding and prevention ofHABs and HAB-
assoeiated illnesses. Surveillance of HAB-?rssociated cases ofhuman and animal illnesses will
help provide additional information on the number of cases occurring each year; where illnesses
are occurring across the United States, including Florida; and in humans and animals
from exposure to HABs. These data will also help to better de?ne the effect of HABs on
humans, animals, and the environment. We are actively working with the Florida Department of
Health to enable reporting to OHHABS.

In addition, at the Florida Department ofHealth?s request, National Center for
Environmental Health (NCEH) can provide technical assistance and consultation to develop a
public health response to HAD events. The department can make this request by calling
(800) 232-4636 or submitting a request at 

While much is known about the immediate effects of harmful algal blooms, more research is
needed to study the long-term health effects. The National Institutes of Health, National Institute
ofEnviromnental Health Sciences (NIEHS) is investigating the potential long-term health effects

Page 2 The Honorable Bill Nelson

of HABs. is speci?cally looking at exposure to neurotoxins among children and the
elderly. You can find more information on their study at


In your letter, you also stressed Floridians? need for reliable resources on HABs. website
on HABs (mvuncde.gov/habs/indexhtm l) provides information on associated illnesses and
due to exposure to the different toxins, including cyanotexins and brevetoxins, in
freshwater or marine enviromnents. Interested parties can sign up for updates to this webpagc.

Our website also provides the general public and health departments, including the Florida
Department of Health, with downloadable, printable materials that warn people to stay out of
waters with ongoing blue-green algae blooms. We also have fact sheets, posters, a reference card
to share with veterinarians and physicians, and a partner toolkit for public health professionals.
You can find all of these resources at CDC publicizes
the availability of these resources through our partnership distribution list and through social
media. Most recently, on July 6, we posted HAB information on Facebook at

and on July 15, on Twitter at 1018626268047335429.

Thank you, again, for your letter and your work on behalf of the people of Florida. If you have
any questions or would like to discuss this matter in more detail, please contact Mr. Eric
Wortman in the CDC Washington Of?ce at (202) 245-0600 or EWortman@cdc.gov.

Sincerely,

rem/a6 M4 

Robert Redfield, 

Director, CDC, and

Administrator, Agency for Toxic Substances
and Disease Registry