Lead,
Ageing and Death
By
Ewan MacAulay McDonnell, The LEAD Group Inc
[LID
9496] Updated 4th April 2011
When old people die, who ever asks the question – "Did lead
kill this person?"
As
you age you become more likely to suffer from heart disease, heart attack,
stroke, renal problems, and Alzheimer's disease or tremors but what you may
not realise is that these symptoms are connected with having lead in your
system.
With
so many people having higher blood lead levels in the past than today, it is
little wonder that we associate ageing with many of the effects of lead
poisoning, but especially:- poor memory and hearing, falls (from loss of
balance), reduced sperm count, loss of libido, strokes and heart attacks
(from raised blood pressure), tooth decay, and Alzheimer’s disease. It is
fair to say that all these effects of lead add up to a reasonable
description of what we think of as "normal" ageing and it is
certainly time that we measured blood lead levels in older people who
display these symptoms before discounting their symptoms as just "a
natural part of getting old". (14)
Lead
gathers in the body as you are exposed to it over time. There is no safe
level of lead within the body and the threshold for safe lead levels has
gradually been lowered over the decades as data has improved and further
research has been conducted. The US CDC currently lists the threshold as
< 10 µg/dL level, however more recent research is showing even levels as
low as 2.5 µg/dL have a detrimental health impact, more so than increases
from 10-20 µg/dL or 20-30 µg/dL. (16)
According
to a recent Archives of Internal Medicine article: "Blood lead and
exposure to lead throughout life has also been associated with increased
death rates in older people where "after adjustment for potential
confounders, individuals with baseline blood lead levels of 20 to 29 µg/dL
(1.0-1.4 µmol/L) [two to three times the CDC goal to be below 10 µg/dL,
but much less than the level that an Australian worker must be moved off a
lead task – 50 µg/dL] had a 46% increase in mortality (all causes), 39%
increased circulatory mortality, and 68% increased cancer mortality compared
with those with blood lead levels of less than 10 µg/dL (<0.5 µmol/L)."
(14)
In
fact a blood lead level of 2 µg/dL has been connected in an American study
by the CDC with higher rates of cardiovascular disease. A blood lead level
of 3.63 µg/dL or greater was connected with an 89% greater rate of death
from heart attack, and a 250% greater chance of stroke (15). A higher rate
of Arteriosclerosis has been found in adults with Blood lead levels of
greater than 10 µg/dL. (18)
Lead
becomes stored within your bones, which acts like a sort of Reservoir. (17)
From there, it causes a second round of negative impacts on Haem synthesis,
vitamin D metabolism, and kidney function.
Initially Lead is a neurotoxin causing similar symptoms to
Alzheimer's disease and for similar reasons and hence is associated with it
(12;
3). If you have been exposed to it as a child changes in gene
expression will create additional health problems for you later in life,
including the build up of proteins in the brain in a pattern similar to
Alzheimer's disease (4). Cumulative lead exposure is also linked to poorer
performance in learning, memory and visual-motor tasks for older subjects
and this negative impact can be exacerbated by stress (20). This may be
because early-childhood lead exposure has led to poorer-school performance
or because lead may accumulate in the myelin sheath that surrounds some
neurons in the brain, connecting it to neuro-degenerative diseases. (19) In
one recent study the mean Blood lead level for subjects was 3.5 µg/dL and
tibia lead level was 18.7 µg/dL. The higher tibia lead levels were
consistently associated with worse cognitive function in tested subjects. (21)
Another
neurological disease that may be associated with Lead is Essential Tremor
(ET). Essential Tremor is an incurable age-related disease whose symptoms
involve tremors of the hands and head. At present its cause is unknown.
Laboratory animals and humans exposed to high levels of lead have displayed
similar symptoms. Pb blood levels in ET patients have been found to be
higher than in controls. ET is a very common neurological disease in
subjects over 60, and can be as prevalent as up to 20.5% of the elderly. (17)
As
well as Lead speeding up brain ageing (1;
2), as you age your bones
demineralise, meaning they release lead back into your blood stream. (13;
8)
This
means the toxic effect of lead exposure in younger years, such as industrial
work dealing with lead substances, such as lead-based paint or fuel
containing lead will add to any lead exposure you are currently experiencing
and cause a cumulative impact on your health. (16) Adults who have been
exposed to lead in the workplace and at home throughout their lives are more
susceptible to lead-related health risks such as cardiovascular disease,
high blood pressure (hypertension), stroke, renal failure and osteoporosis.
(5;
6;
7;
9; 10)
The
implications of lead exposure early in life on menopausal women have also
been investigated; indicating that exposure to lead throughout life may
result in heightened lead levels in blood throughout menopause. Studies have
also found that Hormone Replacement Therapy (HRT) had a negative effect on
blood lead levels, where women using HRT had lower blood lead levels than
postmenopausal women who report not using HRT. (4)
There
is also a fact-sheet which comprehensively describes the effects of lead
poisoning on various groups of people, sorted into ‘children’,
‘prenatal development and reproductive health effects’ and ‘adults’.
Listed within these groups are implications of lead poisoning in categories
including nervous system, peripheral nervous system, growth and development,
cognitive development, behaviour, hearing, sight, movement and muscular,
digestive system, renal, blood and circulation, foetal, kidneys,
cardiovascular and circulation, intellectual and mental, sensory, bone,
muscle and joint and death. Also listed are the effects of lead known from
animal studies. This fact sheet can be found at www.lead.org.au/fs/fst7.html.
(11)
Sources
Cited:
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McKinney,
Merritt, "Lead Exposure Speeds Up Brain Aging"
Accessed (2011/04/04) [LID: 4836]
http://www.thisisms.com/article-print-60.html
-
Schwartz,
BS; Stewart, WF; Bolla, KI; Simon, D; Bandeen-Roche,
K; Gordon, B; Links, JM; & Todd, AC, "Past adult lead exposure
is associated with longitudinal decline in cognitive function"
NEUROLOGY 55: 1144–1150 October (2 of 2)
2000:
Accessed (2011/04/04) [LID: 4838] http://www.nmic.org/nyccelp/medical-studies/neurology%20-%20schwartz%20.pdf
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Ellen K, "Menopause And Lead: Consequences And Determinants Of Bone
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Chinese
铅,衰老和死亡
PDF version 铅,衰老和死亡
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Ageing and Death
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