Transcript Blue Green algae: an overview

Blue Green algae:
an overview
Monique D’Amour
Safe Environments Programme
(Longueuil, Québec)
and
Michèle Giddings
Water Quality & Microbiology Division
(Ottawa, Ontario)
Health Canada
Federal-Provincial Roles and
Responsibilities for Drinking Water
Responsibilities divided among levels of government
Federal (Health Canada)
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advice
research
risk assessment/management
with provinces
drinking water quality on
Federal lands
Provincial/Territorial
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provision of safe DW
source water
protection
water treatment
monitoring & surveys
research
Federal-Provincial-Territorial
Committee on Drinking Water
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Representatives from each province,
territory, and the federal government
• 30+ year working collaboration
• Meets twice yearly
Establishes the Guidelines for Canadian
Drinking Water Quality
Health Canada’s Water Quality and Health
Bureau is the Technical Secretariat to the
Committee
Drinking Water Guideline
Development Process
Identification
Assessment
Evaluation
• costs
• benefits
• consultation
Cyanobactieria in Canada
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Identification of a problem
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Assessment was required
Cyanobacterial Toxins in Canada:
The History, Part I
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1990-1992-1993: M-LR identified in Alberta
lakes, detected in Shoal Lake, Winnipeg’s
drinking water source, and in the city’s
distribution system
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Manitoba requests an ‘Emergency Health
Advisory’ (EHA) from Health Canada in 1994
EHA of 0.5 µg/L derived for M-LR in DW
 EHAs are developed for specific situations; they do not
have the rigorous review/consultation of full guidelines
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Cyanobacterial Toxins in Canada:
The History, Part II
 M-LR
added to the priority list for
evaluation
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Canadian surveys to date indicate Microcystin-LR
is the most common hepatotoxin present in
water supplies
Blooms of Cyanobacteria in
Canada
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Blooms occur in all provinces
(Prairies, Québec etc)
Tend to occur repeatedly in same supply
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small shallow, slow-moving bodies of water common to
prairies generally affected
Bloom
Cyanobacteria: General
Description
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Cyanobacteria (blue-green algea)
May produce neurotoxins, hepatotoxins
 Skin irritants, other toxins
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Surface water supplies (Hepatotoxins/neurotoxins)
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Hepatotoxins more widespread
Microcystin -LR
Microcystin L-R: hepatotoxins
Produced by Microcystis aeruginosa
(an others blue-greens algal species)
Monocyclic heptapeptides
(L–amino acids; L=Leucine; R=arginine)
Microcystin-LR Structure
Sources of Human Exposure
Consumption of drinking water
 Recreational use of lakes and rivers
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Showers
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oral, dermal
inhalation, dermal
Algal food tablets
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oral
M-LR Effects on Animals &
Humans
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Animals
Primarily hepatotoxin
• Kidney damage
• Lung damage
• Tumour promotor
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Humans
• Stomach cramps,
vomiting, diarrhea,
fever, headache,
painful muscles &
joints
• Acute
gastroenteritis
• Liver damage
Critical Effects
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Microcystin administered by gavage to
mice at levels of 0, 40, 200 and 1000
µg/kg bw/day for 13 weeks
40 µg/kg bw : no definite effect
200 µg/kg bw : slight liver changes in some animals
1000 µg/kg bw : liver changes in all animals
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No-Observed-Adverse-Effect Level
(NOAEL) set at 40 µg/kg bw/day
M-LR Guideline Derivation
TDI = 0.040 mg/kg bw/day = 0.00004 mg/kg bw
Where
1000
– x10 for intraspecies variation
– x10 for interspecies variation
– x10 for less than lifetime study
MAC = 0.00004 mg/kg/day x 70 kg x 0.80
1.5 L/day
= 0.0015 mg/L (1.5 µg/L)
Factors Affecting Bloom Formation &
Toxin Production / Persistence
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Bloom Formation
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Inorganic nutrients
Water temperature
pH level: 6-9
Daylight
Turbidity
Turbulence
Water flow
Toxin production
• Environmental factors
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Temperature, light,
nitrogen levels,
carbon dioxide
and/or pH
• Genetic differences
• Metabolic processes
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Toxin release
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Persistence
• Stable in water
• Resistance to pH extremes
• Heat resistant
Microcystins – Water
Management
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Reservoir management
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Algal cell removal
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Nutrient deprivation practices
Coagulation, clarification, filtration, disinfection
Must not damage cells
Toxin removal
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Oxidation (ozonation); other methods such as UV,
chloramination & hydrogen peroxide not as effective
Activated carbon (wood-based products best)
Slow sand filtration-biodegradation
Flow chart: Management Water supply
ANNEX A
Cyanobacterial Toxins -- Microcystin -LR
Flow Chart
- Water Supplies for Human Consumption Visually monitor for
bloom formation
1
2
sample raw* and treated supplies for toxin
(algal identification)
NOTE: For recreational
water supplies, follow
the raw water protocol
(steps 1-4)
3
send both raw and treated samples for
Microcystin-LR analysis
Raw
Water
results
to
agencies
M-LR
>1.0 µg/L
4 (raw)
M-LR
<1.0 µg/L
11 (raw)
12 (raw)
5
perform toxin analysis of
treated water supplies
Treated
Water
9
resample
treated
supply
M-LR
>1.5 µg/L
6 (treated)
7
12 (treated)
M-LR
<1.5 µg/L
11 (treated)
notify community
and agencies
8
10
Consultation and
decision-making
April, 2002
results
to
agencies
alternative
supply or
treatment
adjustment
* A field kit could be used for screening. A validation
sample should be send to a laboratory for confirmation
of actual levels following a positive field test.
Find more information
To obtain the supporting document on M-LR
http://www.hc-sc.gc.ca/hecs-sesc/water/
pdf/microcys.pdf
To obtain information onDW
http://www.hc-sc.gc.ca/hecssesc/water/index.htm
Acknowledgements
Michèle Giddings for providing
technical supports,
advices and specific expertise on Microcystine L-R
and Drinking Water Guidelines