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Hazards of heavy metal contamination.Br
Med Bull. 2003;68:167-82.
The main
threats to human health from heavy metals are associated with
exposure to lead, cadmium, mercury and arsenic. These metals have
been extensively studied and their effects on human health regularly
reviewed by international bodies such as the WHO. Heavy metals have
been used by humans for thousands of years. Although several adverse
health effects of heavy metals have been known for a long time,
exposure to heavy metals continues, and is even increasing in some
parts of the world, in particular in less developed countries,
though emissions have declined in most developed countries over the
last 100 years. Cadmium compounds are currently mainly used in
re-chargeable nickel-cadmium batteries. Cadmium emissions have
increased dramatically during the 20th century, one reason being
that cadmium-containing products are rarely re-cycled, but often
dumped together with household waste. Cigarette smoking is a major
source of cadmium exposure. In non-smokers, food is the most
important source of cadmium exposure. Recent data indicate that
adverse health effects of cadmium exposure may occur at lower
exposure levels than previously anticipated, primarily in the form
of kidney damage but possibly also bone effects and fractures. Many
individuals in Europe already exceed these exposure levels and the
margin is very narrow for large groups. Therefore, measures should
be taken to reduce cadmium exposure in the general population in
order to minimize the risk of adverse health effects. The general
population is primarily exposed to mercury via food, fish being a
major source of methyl mercury exposure, and dental amalgam. The
general population does not face a significant health risk from
methyl mercury, although certain groups with high fish consumption
may attain blood levels associated with a low risk of neurological
damage to adults. Since there is a risk to the fetus in particular,
pregnant women should avoid a high intake of certain fish, such as
shark, swordfish and tuna; fish (such as pike, walleye and bass)
taken from polluted fresh waters should especially be avoided. There
has been a debate on the safety of dental amalgams and claims have
been made that mercury from amalgam may cause a variety of diseases.
However, there are no studies so far that have been able to show any
associations between amalgam fillings and ill health. The general
population is exposed to lead from air and food in roughly equal
proportions. During the last century, lead emissions to ambient air
have caused considerable pollution, mainly due to lead emissions
from petrol. Children are particularly susceptible to lead exposure
due to high gastrointestinal uptake and the permeable blood-brain
barrier. Blood levels in children should be reduced below the levels
so far considered acceptable, recent data indicating that there may
be neurotoxic effects of lead at lower levels of exposure than
previously anticipated. Although lead in petrol has dramatically
decreased over the last decades, thereby reducing environmental
exposure, phasing out any remaining uses of lead additives in motor
fuels should be encouraged. The use of lead-based paints should be
abandoned, and lead should not be used in food containers. In
particular, the public should be aware of glazed food containers,
which may leach lead into food. Exposure to arsenic is mainly via
intake of food and drinking water, food being the most important
source in most populations. Long-term exposure to arsenic in
drinking-water is mainly related to increased risks of skin cancer,
but also some other cancers, as well as other skin lesions such as
hyperkeratosis and pigmentation changes. Occupational exposure to
arsenic, primarily by inhalation, is causally associated with lung
cancer. Clear exposure-response relationships and high risks have
been observed.
Metals and women's health.Environ
Res. 2002 Mar;88(3):145-55
There is a lack
of information concerning whether environmental-related health
effects are more or less prevalent or manifested differently in
women compared to men. Previously, most research in the area of
toxicology and environmental and occupational health involved male
subjects. The present work aims at reviewing exposure and health
effects of cadmium, nickel, lead, mercury, and arsenic manifested
differently in women than in men. The gender difference in exposure
to nickel results in a much higher prevalence of nickel allergy and
hand eczema in women than in men. The internal cadmium dose is
generally higher in women than in men, due to a higher
gastro-intestinal absorption at low iron stores. This was probably
one major reason why Itai-itai disease was mainly a woman's disease.
Yet, data are sparse regarding the risk for women relative to men to
develop cadmium-induced kidney damage in populations exposed to low
levels of cadmium. Lead is accumulated mainly in bone and increased
endogenous lead exposure has been demonstrated in women during
periods of increased bone turnover, e.g., menopause. Both lead and
mercury exposure in pregnant women has to be kept low in order to
prevent neurodevelopment effects in the developing fetus and child.
Limited data indicate that women are more affected than men
following exposure to methylmercury at adult age, while males seem
to be more sensitive to exposure during early development. Regarding
arsenic, some data indicate gender differences in the
biotransformation by methylation, possibly also in susceptibility to
certain arsenic-related cancers. Obviously, gender-related
differences in exposure and health effects caused by metals are
highly neglected research areas, which need considerable focus in
the future.
Trace
elements and cancer risk: a review of the epidemiologic evidence.Cancer
Causes Control. 2007 Feb;18(1):7-27.
Worldwide,
there are more than 10 million new cancer cases each year, and
cancer is the cause of approximately 12% of all deaths. Given this,
a large number of epidemiologic studies have been undertaken to
identify potential risk factors for cancer, amongst which the
association with trace elements has received considerable attention.
Trace elements, such as selenium, zinc, arsenic, cadmium, and
nickel, are found naturally in the environment, and human exposure
derives from a variety of sources, including air, drinking water,
and food. Trace elements are of particular interest given that the
levels of exposure to them are potentially modifiable. In this
review, we focus largely on the association between each of the
trace elements noted above and risk of cancers of the lung, breast,
colorectum, prostate, urinary bladder, and stomach. Overall, the
evidence currently available appears to support an inverse
association between selenium exposure and prostate cancer risk, and
possibly also a reduction in risk with respect to lung cancer,
although additional prospective studies are needed. There is also
limited evidence for an inverse association between zinc and breast
cancer, and again, prospective studies are needed to confirm this.
Most studies have reported no association between selenium and risk
of breast, colorectal, and stomach cancer, and between zinc and
prostate cancer risk. There is compelling evidence in support of
positive associations between arsenic and risk of both lung and
bladder cancers, and between cadmium and lung cancer risk.
Occlusive
irritant dermatitis: when is "allergic" contact dermatitis not
allergic?Skinmed.
2007 Mar-Apr;6(2):97-8.
CASE 1: A
38-year-old teacher presented with a 3- to 4-week history of a
linear, erythematous, vesicular, and pruritic eruption of her left
wrist. She had been wearing a new elastic bracelet for 4 weeks
before the onset of her eruption. Although there was no history of
allergy to rubber products or jewelry, an allergic contact
dermatitis to rubber was suspected. Patch testing to rubber
chemicals and the elastic bracelet revealed no reactions at 48, 72,
and 96 hours. She stopped wearing the bracelet and used a
corticosteroid cream with rapid resolution of the problem. The
patient resumed wearing the bracelet, and there has been no
recurrence in the past 2 months. CASE 2: A 12-year-old boy presented
with a 1-month history of an itchy, scaly, erythematous 1-cm patch
over the midline of his lower lip. The patient complained of tiny
blisters initially with persistent erythema, mild scaling, and
associated pruritus. The patient plays the saxophone and he had been
practicing more intensely (3 to 4 h/d) for a musical competition.
Allergic reaction to his wood reed was suspected, but patch testing
with a moistened portion of his reed and reed shavings in a drop of
water revealed no reaction at 48 and 72 hours. Treatment with
hydrocortisone 1% cream bid for 3 days led to complete resolution of
the dermitis and pruritus. Playing the saxophone 1 h/d has not led
to any recurrence. CASE 3: A 33-year-old woman presented with
erythema, scaling, and pruritus of 1 month's duration beneath her
engagement and wedding rings, which were worn together on her left
fourth finger (Figure 3). Although she had no history of previous
sensitivity to earrings, watch clasp, blue jean rivets, or other
jewelry, allergic contact dermatitis to nickel was suspected. Patch
testing was performed to the common metal allergens nickel, cobalt,
chromium, and gold. Readings at 48 hours and 1 week revealed no
positive reactions. The patient wore her rings on the right hand for
1 week and used fluocinonide 0.5% cream twice daily for 1 week with
resolution of the dermatitis. She has subsequently begun wearing the
rings again on her left hand with care to dry her hands and rings
after washing, and there has been no recurrence of her dermatitis.
Inhalation of inorganic particles as a risk factor for idiopathic
pulmonary fibrosis-Elemental microanalysis of pulmonary lymph nodes
obtained at autopsy cases.Pathol
Res Pract. 2007 Jun 22.
Exposure to
inorganic particles may induce fibrosis in the lung. However, the
association between exposure to inorganic particles and the
pathogenesis of idiopathic pulmonary fibrosis (IPF)/usual
interstitial pneumonia (UIP) is obscure. We examined inorganic
particles in the pulmonary hilar lymph nodes affected by IPF/UIP to
investigate whether inhaled elements are involved in the etiology,
and whether there is an increasing risk of developing IPF/UIP.
Twenty-three IPF/UIP cases and 23 controls without IPF/UIP were
investigated. Pulmonary hilar lymph nodes constituted the study
material. The elemental analysis was performed using scanning
electron microscopy with an energy dispersive X-ray spectroscope,
and we analyzed particles quantitatively and qualitatively. The
results showed that the cases contained silicon and aluminum as
compared with the control in lymph nodes, and these deposits were
statistically significantly associated with an increased risk of IPF/UIP
(adjusted odds were 2.99, 95% CI: 1.29-6.85 and 57.84, 95% CI:
1.45-2306.19, respectively). In addition, higher nickel levels in
lymph nodes were associated with lung cancer. This study shows that
inorganic particles, such as Si and Al, have higher concentrations
in the hilar lymph nodes in IPF/UIP, and may play a role in one of
the risk factors in the pathogenesis of IPF/UIP.
Distribution
of trace metal concentrations in paired cancerous and non-cancerous
human stomach tissues.World
J Gastroenterol. 2007 Jan
28;13(4):612-8.
AIM: To
assess whether trace metal concentrations (which influence
metabolism as both essential and non-essential elements) are
increased or decreased in cancerous tissues and to understand the
precise role of these metals in carcinogenesis. METHODS:
Concentrations of trace metals including Cd, Ni, Cu, Zn, Fe, Mg and
Ca in both cancerous and non-cancerous stomach tissue samples were
determined by atomic absorption spectrometry (AAS). Tissue samples
were digested using microwave energy. Slotted tube atom trap was
used to improve the sensitivity of copper and cadmium in flame AAS
determinations. RESULTS: From the obtained data in this study, the
concentrations of nickel, copper and iron in the cancerous human
stomach were found to be significantly higher than those in the
non-cancerous tissues, by using t-test for the paired samples.
Furthermore, the average calcium concentrations in the cancerous
stomach tissue samples were found to be significantly lower than
those in the non-cancerous stomach tissue samples by using t-test.
Exceedingly high Zn concentrations (207-826 mg/kg) were found in two
paired stomach tissue samples from both cancerous and non-cancerous
parts. CONCLUSION: In contrast to the literature data for Cu and Fe,
the concentrations of copper, iron and nickel in cancerous tissue
samples are higher than those in the non-cancerous samples.
Furthermore, the Ca levels are lower in cancerous tissue samples
than in non-cancerous tissue samples.
Gender
differences in the disposition and toxicity of metals.Environ
Res. 2007 May;104(1): 85-95. Epub 2006
Sep 22.
There is
increasing evidence that health effects of toxic metals differ in
prevalence or are manifested differently in men and women. However,
the database is small. The present work aims at evaluating gender
differences in the health effects of cadmium, nickel, lead, mercury
and arsenic. There is a markedly higher prevalence of nickel-induced
allergy and hand eczema in women compared to men, mainly due to
differences in exposure. Cadmium retention is generally higher in
women than in men, and the severe cadmium-induced Itai-itai disease
was mainly a woman's disease. Gender differences in susceptibility
at lower exposure are uncertain, but recent data indicate that
cadmium has estrogenic effects and affect female offspring. Men
generally have higher blood lead levels than women. Lead accumulates
in bone and increased endogenous lead exposure has been demonstrated
during periods of increased bone turnover, particularly in women in
pregnancy and menopause. Lead and mercury, in the form of mercury
vapor and methylmercury, are easily transferred from the pregnant
women to the fetus. Recent data indicate that boys are more
susceptible to neurotoxic effects of lead and methylmercury
following exposure early in life, while experimental data suggest
that females are more susceptible to immunotoxic effects of lead.
Certain gender differences in the biotransformation of arsenic by
methylation have been reported, and men seem to be more affected by
arsenic-related skin effect than women. Experimental studies
indicate major gender differences in arsenic-induced cancer.
Obviously, research on gender-related differences in health effects
caused by metals needs considerable more focus in the future.
Metal ions
and carcinogenesis.EXS.
2006;(96):97-130.
Metals
are essential for the normal functioning of living organisms. Their
uses in biological systems are varied, but are frequently associated
with sites of critical protein function, such as zinc finger motifs
and electron or oxygen carriers. These functions only require
essential metals in minute amounts, hence they are termed trace
metals. Other metals are, however, less beneficial, owing to their
ability to promote a wide variety of deleterious health effects,
including cancer. Metals such as arsenic, for example, can produce a
variety of diseases ranging from keratosis of the palms and feet to
cancers in multiple target organs. The nature and type of
metal-induced pathologies appear to be dependent on the
concentration, speciation, and length of exposure. Unfortunately,
human contact with metals is an inescapable consequence of human
life, with exposures occurring from both occupational and
environmental sources. A uniform mechanism of action for all harmful
metals is unlikely, if not implausible, given the diverse chemical
properties of each metal. In this chapter we will review the
mechanisms of carcinogenesis of arsenic, cadmium, chromium, and
nickel, the four known carcinogenic metals that are best understood.
The key areas of speciation, bioavailability, and mechanisms of
action are discussed with particular reference to the role of metals
in alteration of gene expression and maintenance of genomic
integrity.
Sino-nasal
inverted papillomas and occupational etiology.G
Ital Med Lav
Ergon.
2005 Oct-Dec;27(4):422-6.
The
sino-nasal inverted papilloma is a rare benign tumour with certain
aggressive features because of frequent relapses and the high
probability of malignant degeneration. For these reasons, several
studies have been made to evaluate the efficacy of the different
courses of treatment, but only afew studies have been carried out to
establish the etiology of this tumour, which is still uncertain.
Although it is believed that viral infection, chronic inflammation
and cigarette smoking can play an important etiological role, it has
recently been suggested that occupational risk factors, such as
those involved in malignant epithelial sino-nasal cancer (SNC), can
also be involved in causing sino-nasal inverted papilloma. A group
of 70 patients was examined who have been diagnosed with inverted
papilloma from 1991 to 2003; the occupational history, collected via
the standardized questionnaire, showed that risk factors like wood
and leather dusts, chromium and nickel vapours or fumes and
formaldehyde were associated with only 5% of all cases. This
proportion is much lower than that established for SNC in several
epidemiological studies. Although occupational environmental
pollution can be a source of chronic sino-nasal mucosa irritation,
on the basis of our results we believe that a causal relationship
between exposure to occupational risk factors and inverted papilloma
is not likely, differently from the suggestions made in other
studies. Consequently, an epidemiological surveillance of inverted
papilloma as a "sentinel" tumour, as has been proposed in Italy for
SNC, is not considered necessary. Among the possible
non-occupational risk factors we observed that 75% of the male
patients were smokers and 40% of all patients suffered from chronic
sinusitis and sino-nasal polyps. Lastly, among the 70 cases of
inverted papilloma, we observed 5 with malignant degeneration.
The
carcinogenicity of metals in humans.Cancer
Causes Control. 1997 May;8(3):371-85.
Epidemiologic evidence on the relation between exposure to metals
and cancer is reviewed. Human exposure to metals is common, with
wide use in industry and long-term environmental persistence.
Historically, the heaviest metal exposures occurred in the workplace
or in environmental settings in close proximity to industrial
sources. Among the general population, exposure to a number of
metals is widespread but generally at substantially lower levels
than have been found in industry. The carcinogenicity of arsenic,
chromium, and nickel has been established. Occupational and
environmental arsenic exposure is linked to increased lung cancer
risk in humans, although experimental studies remain inconclusive.
Experimental studies clearly demonstrate the malignant potential of
hexavalent(VI) chromium compounds, with solubility being an
important determining factor. Epidemiologic studies of workers in
chromium chemical production and use link exposure to lung and nasal
cancer. Experimental and epidemiologic data show that
sparingly-soluble nickel compounds and possibly also the soluble
compounds are carcinogens linked to lung and nasal cancer in humans.
Some experimental and epidemiologic studies suggest that lead may be
a human carcinogen, but the evidence is inconclusive. Although
epidemiologic data are less extensive for beryllium and cadmium, the
findings in humans of excess cancer risk are supported by the clear
demonstration of carcinogenicity in experimental studies. Other
metals, including antimony and cobalt, may be human carcinogens, but
the experimental and epidemiologic data are limited.
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