I traveled earlier this month to Philadelphia for the
flower show where this year’s theme was the national parks.
Listening to the local news, there was a lot of
concern voiced about the safety of the aging, municipal water supplies in response to the
recent headlines out of Flint, Michigan.
WHAT ARE SOME POSSIBLE SOURCES OF LEAD?
Lead based paint in older homes, older linoleum
floors, and contaminated soil (then licking paws and fur) are major sources. Lead can also
be obtained via other sources: toys, fishing tackle, drapery weights, and improperly
glazed ceramic food or water bowls (imported from Mexico or China) http://www.cfsan.fda.gov/~lrd/fdaact.html#lead.
Water contamination via lead pipes has rarely made
headlines until recently.
WHY WERE LEAD PIPES & SOLDER (to connect
copper pipes) USED PRIOR TO THE 1980’S?
Going back thousands of years, lead pipes resisted
pinhole leaks AND WERE soft enough to form shapes to deliver water
efficiently.
AS CONCERN IS VOICED FOR CHILDREN, WHY ARE PUPPIES AT
HIGHER RISK?
They are more likely to show signs due to chewing on
foreign objects, greater intestinal absorption rates, and increased toxicity to
the brain.
DEFINE “TENNESSEE LEAD POISONING.” IS BUCKSHOT A RISK
TO CAUSE LEAD TOXICITY?
Pictured below are lead pellets found on the radiograph of a dog from a pellet gun and shotgun. NO, buckshot does not elevate blood lead levels. Lead is
only absorbed out of an acid environment (GI tract, joints) leading to poisoning.
WHY THE SUDDEN NOISE ABOUT LEAD POISONING IN MUNICIPLE
WATER SUPPLIES?
As a cost cutting measure, the city of Flint, Michigan
cut off Detroit as their water supplier and switched to the Flint River as a
source. THE INAPPROPRIATE CHEMICALS UTILIZED IN THE FLINT WATER
WORKS’ FILTRATION LEACHED LEAD OUT OF THE PIPE LINING AT AN ALARMING RATE. Unfortunately, there are probably hundreds of cities,
in the USA that have a silent risk.
HOW HIGH IS THE LEAD LEVEL IN FLINT, MICHIGAN?
From what I can gather about the Flint issue, the
levels are still in the part per billion (ppb) range (5 to 1000 ppb depending
on the reference). THE EPA SAYS ANYTHING OVER 15 ppb is unacceptable.Two Flint dogs recently tested positive for lead
toxicity. It’s the state’s first lead toxicity cases involving dogs in five
years.
SO WHAT IS CONSIDERED TOXIC ENOUGH TO CAUSE LONG TERM PROBLEMS?
This is where it gets confusing, as long standing
thoughts are that no ill effects occur until levels rise to parts per million. So, to put
it in prospective, I will use the data for pets as they are important household
sentinels
<10 mcg/dl (0.1 ppm) baseline "normal"
15-20 mcg/dl (0.15-0.2 ppm) --suggest exposure to
environmental lead
but not toxicosis
20 mcg/dl (0.2 ppm) --supportive of toxicosis in birds
if accompanied by appropriate clinical signs
30-35 mcg/dl (0.3-0.35 ppm) --supportive of toxicosis
in mammals if accompanied by appropriate clinical signs
50 mcg/dl (0.5 ppm) in birds--diagnostic for toxicosis
60 mcg/dl (0.6 ppm) --diagnostic for toxicosis in
mammals (dogs, cats, people, etc.)
ppm = parts per million
So when I read of outrage in the news when a child’s
level is 6.5 mcg/dl or 0.1 ppb, I am confused if the chart above is inaccurate or if this is a crisis blown out of proportion. I believe that story needs to be investigated
from a scientific, not political, standpoint.
It is now accepted that there is NO safe level of lead
for humans, and I would presume that's also true for mammals and birds
.
EXPLAIN WHY THAT CAN BE CONFUSING TO ASSUME ALL IS
GOOD!
Blood levels are not that reliable, especially for
longer-term exposure, since lead will ACCUMULATE outside the bloodstream in
bone, nervous system, and other organs (replacing Ca++ in bones and other organs,
including the nervous system). Unfortunately, I think there's no good alternate
testing, although hair samples are being investigated.
ARE THERE COMMON SIGNS OF LEAD POISONING IN PETS?
Gastro-intestinal signs, behavioral changes, and
neurological signs with slow onset in chronic exposure.
My SOAPBOX ON THIS ISSUE!
There seems to be a strong economic and political
motivation rather than pure science to explain the risk levels of lead. Blame
is shared among many agencies to reach solutions.
DISCUSS OPTIONS FOR TREATMENT IN PETS SHOWING SIGNS.
The two chelators (BINDERS) of choice are calcium EDTA
injections and oral succimer.
PREVENTION TIPS FOR PETS
Use stainless steel bowls for pets made in the USA.
In at risk situations, consider filtered water for your pets; if not an
option then run faucet 3 to 5 minutes before using the water in systems at risk.
HOW CAN YOU TEST WATER IN WAKE CO, NC? Goals?
Lead levels below 15 ppb
Well water testing: http://www.wakegov.com/water/wells/pages/watersampling.aspx
Municipal water supplies: www.epa/gov/ccr
Betsy T. Sigmon, DVM, Diplomate ABVP, canine and
feline practice
Creature Comforts Animal Hospital
Cary, NC
