[env-trinity] Memo to NCRWQCB about Klamath Algae

Thu Sep 8 11:23:07 PDT 2005

M E M O R A N D U M

TO:              Matt St. John 

                     North Coast Regional Water Quality Control Board

5550 Skylane Blvd., Suite A

Santa Rosa, California 95403

VIA:            David M. Siegel, Ph.D., Chief

                     Integrated Risk Assessment Branch

FROM:        Karlyn Black Kaley, Ph.D., D.A.B.T., Staff Toxicologist

                     Applied Risk Assessment Unit

DATE:        September 1, 2005

SUBJECT: COMMENTS ON THE CYANOBACTERIAL/MICROCYSTIN TOXIN SUMMER 2005
WATER SAMPLING RESULTS FOR THE COPCO/IRONGATE RESERVOIR.

         As you have requested we have briefly reviewed the water
sampling data found in the following first three documents. We have
referenced the later two documents as part of our review as well.   

1)      memo dated August 18, 2005 re: Copco Lake Toxic Cyanobacteria
Results to Karuk Tribe/NCWQCB from Jacob Kann, Ph.D.; 

2)      memo dated August 19, 2005 re: Copco/Irongate Reservoir Toxic
Cyanobacteria Results: followup to Karuk Tribe/SWRCB/NCWQCB from Jacob
Kann, Ph.D.; 

3)      memo dated August 30, 2005 re: Copco/Irongate Reservoir Toxic
Cyanobacteria Results: 7/26-27 to Karuk Tribe/SWRCB/NCWQCB from Jacob
Kann, Ph.D.; 

4)      1999 World Health Organization, Toxic Cyanobacteria in Water: A
guide to their public health consequences, monitoring and management,
Ed. I. Chorus and J. Bartrum (html version found at:
http://www.who.int/water_sanitation_health/resourcesquality/toxicyanbact
/en/); and, 

5)      World Health Organization Guidelines for Drinking Water Quality,
3rd Edition (html version found at:
http://www.who.int/water_sanitation_health/dwq/gdwq3/en/index.html).  

         Given the time frame of less than two weeks for review, it was
not possible for us to conduct a comprehensive risk analysis or
assessment of the potential microcystin toxin exposure situation you
have presented.  However, based on the data you have presented, we can
offer with confidence the following public health statement and
supporting observations:

         The Microcystis aeruginosa cyanobacteria levels and resulting
microcystin toxin concentrations detected in water samples collected
from both shoreline and open water locations in the Copco and Irongate
Reservoirs in California pose a significant potential threat of adverse
health affects in human and animals exposed through direct ingestion of
contaminated water as well as incidental ingestion during recreational
water activities and bathing.  

Adverse Health Effects  

         Health effects that might be expected to be observed-following
exposure to the microcystin toxin levels detected in the water samples
reviewed-could range from mild non-life threatening skin conditions to
permanent organ impairment and death, depending on exposure.  More
specifically, depending on exposure concentration, duration and
individual sensitivity, symptoms could include mild to severe eye and
ear irritation, allergic skin rash, mouth ulcers, fever, cold/flu like
symptoms, vomiting, diarrhea, pneumonia, liver damage, kidney damage,
complete liver failure, increased incidence of liver cancer and death.
Children and animals are at greatest risk of serious life threatening
affects because of their smaller body size and higher water ingestion
rates.  

World Health Organization Risk Levels

         The World Health Organization (WHO) has established a Tolerable
Daily Intake (TDI) as well as Guideline Values (GV's) for microcystin
toxin in water.  These are useful in evaluating potential risk of
adverse health impacts from exposure via drinking water as well as
recreational water activities.  The TDI applies primarily to drinking
water, while the GV's have been developed to specifically address the
probability of adverse effects occurring in individuals exposed to
contaminated water during specific water use scenarios.  GV's have been
developed for drinking water consumption as well as recreational water
exposure.  

         According to WHO, a TDI is the amount of a potentially harmful
substance that can be consumed daily, via ingestion, over a lifetime,
with negligible risk of adverse health effects.  TDI's are based on
scientific data and controlled laboratory studies of observed adverse
health impacts.  The TDI for microcystin in this case was based on
observed acute effects on the liver.  The primary study used to develop
the TDI is a 13-week oral ingestion mouse study.  Because of lack of
data, no long term chronic effects or carcinogenicity potential was used
in the development of this TDI.  Although TDI's do not account for
multiple routes of exposure or cumulative risk due to exposure to
multiple toxins, they are highly valuable in assessing the potential
risk of adverse health effects from a single toxin.  The WHO TDI for
microcystin toxin is 0.04 mg/kg body weight.  

         WHO guideline values represent a scientific consensus, based on
broad international participation, of the health risk to humans
associated with exposure to microbes and chemicals found in water.  For
recreational water exposure GV's are defined at three primary
concentration levels: mild or low, moderate and high probability of risk
for adverse health impacts if exposed at a given toxin concentration.
GV's are calculated values.  They are derived using the TDI for a given
chemical along with a persons' average body weight and the estimated
amount of contaminated water that may be ingested on a daily basis
during a given activity.  GV's do not take into account health risks
that may be attributed to other routes of exposure, such as aerosol
inhalation or skin contact.  The WHO GV for moderate risk of adverse
health effects from recreational exposure to microcystin in water is 20
mg/liter (or a density of approximately 100,000 cyanobacteria cells per
milliliter (ml) of water).  The WHO GV for high risk is the presence of
active algal scums, which can increase cell densities a 1000 to
1,000,000 fold.

         The maximum Microcystis aeruginosa cyanobacteria density
detected in the water samples reviewed was 11,402,943 cells/ml in the
CRSH shoreline site sample.  This sample had a laboratory detected
microcystin toxin concentration of 667 mg/liter.  Open water locations
varied from 151,004 to 916,548 cells/ml.  We understand that it is
possible that higher concentrations of microcystin toxin than those
detected in these samples may exist in other areas of these reservoirs.
The presence of active scum may suggest a higher risk of adverse health
effects for humans and animals exposed along shorelines.  However, using
only the data provided, if we take the maximum detected microcystin
value of 667 mg/liter and compare it to the WHO GV for moderate risk of
adverse health impacts for exposure to microcystin toxin in water, we
can confirm your conclusion that microcystin toxin levels in this sample
are 33 times that identified by WHO as posing a moderate risk of adverse
health impact for recreational waters.  WHO recommends taking some kind
of mitigating action to reduce or eliminate human exposure when
microcystin toxin concentrations are found at or above a moderate risk
GV level of 20 mg/liter.     

Recreational Incidental Ingestion Levels

         Using the maximum detected toxin value reported above, the WHO
values mentioned previously, and a number of general assumptions, we
also calculated potential human exposure based on incidental ingestion
of contaminated water during recreational water activities and bathing
(i.e. swimming). 

         Adult Incidental Ingestion: For a 60 kilogram (kg) adult,
incidentally ingesting 100 mls of contaminated water in any given day,
the amount of microcystin toxin consumed would be 1.11 mg/kg body
weight.  This amount is 28 times greater than the accepted WHO Tolerable
Daily Intake value of 0.04 mg/kg body weight.  This calculation is based
on a single one-hour "swimming event" per day.  More swimming events or
activities of longer duration could result in greater exposure.   

         Child Incidental Ingestion: With respect to children that may
be exposed to microcystin at these levels there is an even greater
potential health concern.  For a 15 kilogram (kg) child (roughly 3 years
of age), incidentally ingesting an estimated 250 mls of contaminated
water in any one "swimming event" on any given day, the amount of
microcystin toxin consumed would be 11.1 mg/kg body weight.  This amount
of microcystin toxin is 278 times greater than the accepted WHO
Tolerable Daily Intake value of 0.04 mg/kg body weight.  As with adults,
more swimming events or activities of longer duration could result in
greater exposure.

Exposure Routes During Recreational Activities

         There are three main routes of exposure from recreational
bathing and participation in water sports in waters contaminated with
cyanobacteria and subsequent microcystin toxins.  These include: 1)
direct contact with exposed skin including the highly sensitive ear,
eye, nose and throat membranes, 2) accidental or intentionally
swallowing (oral ingestion), and 3) inhalation of contaminated water
aerosols.  Given the data presented and the risk values available, we
can practically address only the potential risk associated with
ingestion exposure in this limited review.  Clearly the greatest risk of
adverse affects to humans and animals would be associated with direct
deliberate ingestion of contaminated water as a source of drinking
water.  However, incidental ingestion could also present a significant
risk, especially for small children, in recreational settings.  Ways to
minimize or prevent all routes of exposures to contaminated reservoir
water include prohibiting use of the water body as a source of drinking
water and reducing contact with contaminated water by limiting and/or
prohibiting recreational access.

         Thank you for the opportunity to comment on the data set
provided.  If you have any questions please feel free to call me at
(916) 323-2808. 

cc:     George V. Alexeeff, Ph.D., D.A.B.T.

         Deputy Director for Scientific Affairs

         Office of Environmental Health Hazard Assessment

         Barbara Washburn, Ph.D.

         Office of Environmental Health Hazard Assessment

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