Cyanobacteria and Human Cyanobacteria and Human Health in the Mississquoi BayHealth in the Mississquoi Bay

Lake Champlain, VermontLake Champlain, Vermont

Problem/Issue

• There is a lack of understanding on the potential risks to human health posed by different levels blue-green algae contamination within the Mississquoi Bay.

• There has yet to be an effective public alert system that protects human health while minimizing negative impacts on Vermont’s tourism industry.

• Andrew Notte, Jennifer Sinish, Kristen Rigney, and Adam Trescott

Goal/Purpose Statement

• To assess the level risk to human health posed by cyanobacteria contamination in the Mississquoi Bay while considering associated economic factors and public policy.

• Determine the most significant impacts on human health.

• Occur naturally in lakes and rivers• Commonly referred to as Blue-Green Algae• Species can range in color from olive-green

to red • Photoautotrophs

– Use CO2 as carbon source

– Can convert sunlight into energy

CyanobacteriaCyanobacteria

Human Activities that Encourage Bloom Growth

• Urban and agricultural runoff

• Reduction in water flow as a result of increase water usage

• Degradation through land clearing and other urban and agricultural activities

Toxic Blooms

Certain species of cyanobacteria release toxins when they decompose called cyanotoxins.

Thermal Stratification

• Cyanobacteria are able to control their buoyancy by adjusting their gas vacuoles

• This allows them to travel to the warmer photic zone at the surface• The lack of mixing leaves the cyanobacteria virtually undisturbed at

the surface where it receives full light and can flourish

Cyanobacteria in Lake Champlain

• In 1999 cyanobacteria were first documented in Lake Champlain

• Each year there are one to two dog deaths attributed to cyanobacteria

• There have been no human deaths

Summer Tourism in Vermont

• In 2001, tourism was estimated to have a $4.24 billion impact on Vermont’s economy – Summer 2001 was $1.23 billion

• Out of the total summer visitors in Vermont– 22% participated in outdoor recreation– Of that percentage, 27.5% participated in water

recreation

Chronic Exposure

• Outdoor recreation participants are more likely to visit multiple times a year

• They spend an average of 8 nights per visit

Since outdoor enthusiasts visit longer and more often, their likelihood of suffering

from chronic exposure is increased

Alert System and Tourism

Human health is more important than the impact beach closures and swimming advisories would have on Vermont’s overall economy

Peak season for algal blooms

• Algae grows most during the warm summer months

• The peak blooms often coincide with peak months for water recreation and tourism

Blooms tend to occur at times when turbulent storms are followed by mild weather.

(Chorus & Bartram, 1999)

Wind accumulation

(Chorus & Bartram, 1999)

Objectives

• Determine the most common routes of exposure.

• Evaluate current and alternative monitoring systems.

• Develop recommendations to improve efficiency in order to minimize risk and negative economic impacts.

Findings

• 60% of cyanobacteria are toxic– Most species contain a slew of toxic & non-

toxic strains

• Routes of exposure– Ingestion – most significant for recreation– Inhalation – most severe health effects– Dermal contact – least severe health effects

Findings continued

• Allowable dose is based on healthy adults

• Certain demographic groups may be at a higher risk for adverse effects

• Studies on long-term effects are limited

Findings continued

• Cyanobacteria have a cumulative effect with multiple doses (swimming 7 days in a row)

• Most common adverse health effects– Lung infection, pneumonia– Vomiting– Sore throat– Blistering around the mouth– Darrhea– Skin rash

Findings continued

• Lack of comprehensive data

• Need common management plan for Quebec and Vermont in regards to the Mississquoi Bay

• Public education is important

Conclusions

• There is a lack of a comprehensive knowledge base for timing, duration, and location of potentially hazardous blooms.

• Human health is more important than the impact beach closures and swimming advisories would have on Vermont’s overall economy.

• Outdoor enthusiasts who visit longer and more often, are more likely to suffer from chronic exposure.

Recommendations

• A need for continued monitoring

• If detailed research analysis does not exist, the following framework may be used

Table 1: Guidelines for potential risks and suggested actions for cyanobacteria contamin

Guidance Level Health risks Suggested actions

Low probability of adverse health effects20,000 cyanobacterial cells/mL Short-term effects, ie: skin

irritation, gastrointestinal illness-Post warning signs -Inform authorities

Moderate probability of advers health effects100,000 cyano cells/mL Potential for long-term illness

Short-term effects, ie: skin irritation gastrointestinal illness

-Watch for scums -Discourage swimming and further investigate hazard -Post warning signs -Inform authorities

High probability of adverse health effects Formations of visable cyanobacterial scum in areas where recreation is common

Potential for acute poisoning Potential for long-term illness Short-term effects, ie: skin irritation gastrointestinal illness

-Immediate action to control contact with scums -Prohibition of sweimming and other recreational activites -Follow up with public health investigation -Inform public and authorities

Derived from Chorus & Bartram, 1999

Acknowledgements

• Lake Champlain Basin Program

– Mike Winslow• Staff scientist on the Lake Champlain Committee

• Erica & Breck