9. Metals of concern
• Arsenic (As)
• Manganese (Mn)
• Cyanide: same as adult
• Lead (Pb)
• Cadmium (Cd)
• Others: Cr, Fe, Co, Ni, Cu, Zn, Hg
10. Arsenic
• Potential uses: effective poison, very effective
against acute promyelocytic leukemia
• Antimetabolic and carcinogenic properties
• Inorganic forms:
trivalent (arsenite): more toxic and carcinogenic,
most industrial uses
pentavalent (arsenate)
• Organic forms:
Natural: nontoxic
Dimethylarsenic acid: pesticides, very toxic
11. Arsenic
Route of exposure
• Ingestion
• Inhalation
• Placenta
Soil pica behavior: when children ingest large amounts
of soil at a time (e.g. up to 1 teaspoon or 5,000mg)
12. Arsenic
Sources of exposure: common in the environment
• Natural
Groundwater
Food chain (nontoxic, organic form): Seafood and fish
• Anthropogenic
Arsenic containing mineral ores
Industrial processes
• Semiconductor manufacturing (gallium arsenide)
• Fossil fuels
• Wood treated with arsenic preservatives
• Smelting (copper, zinc, lead) and refining of metals and ores
• Glass manufacturing
Commercial products: Wood preservatives, pesticides, herbicides,
fungicides
Herbal remedies
14. Source Intake
*Iron def increase
GI absorption
Metabolism Elimination*
:mostly in urine
10% in bile
Water
Food
Air
Other
Inorganic arsenic
well absorbed (80–90%) from
GI tract
T1/2(blood): 10 hrs
Yes
Inorganic arsenic
Organic arsenic:
Methylate arsenic
Total
arsenic
Seafood
Organic arsenic T1/2(blood): 30 hrs
Arsenosugars
Arsenolipids
Yes Other
metabolites
Arsenobetaine No Arsenobetaine
*Humans are able to detoxify small
amounts from inorganicorganic forms
**Children are less able than adult
* Within 2-4 wks after exposure, the remaining body burden of arsenic is found in
hair, skin, and nails.
15. Arsenic: metabolism
The intermediate metabolites, methylarsonous acid (MMA3+) and dimethylarsinous
acid(DMA3+), are generated during this process, and these trivalent methylated
arsenicals are now thought to be more toxic than even the inorganic arsenic species
17. Arsenic: systemic affected
Acute: high dose, inorganic(>3-5 mg/kg) Chronic
GI: N/V, hematemesis, diarrhea,
abdominal cramping
Fatigue and malaise
Nervous system:
CNS: encephalopathy
PNS- mimic Guillain-Barré syndrome
IQ
CVS: intractable shock, arrhythmia, heart
failure
Bronchiectasis
Bone marrow suppression: pancytopenia Bone marrow suppression: aplastic anemia
Skin: Mee lines (white transverse creases
across the fingernails )
Skin: eczematoid eruptions,
hyperkeratosis, dyspigmentation, alopecia
Liver: hepatic dysfunction Hepatic dysfunction
Kidneys: proteinuria, hematuria, ARF Kidneys: Cancer
Carcinogen: bladder, lung, skin, kidney,
liver, AML
Spontaneous abortion, still birth, preterm
birth
18. Arsenic-associated Change To Epigenome
• Low to moderate dose exposure to inorganic
arsenic (iAS)
DNA methylation
miRNA abundance
Histone modification
Bailey KA, Fry RC.Curr Environ Health Rep. 2014 Jan 19;1:22-34.
19. Potential modes of action for Arsenic
carcinogenesis
Arsenic exposure
Carcinogenesis
Altered DNA
repair
Altered DNA
Methylation
Chromosomal
abnormality
Oxidative
stress
Modification
of cell
proliferation
20. Arsenic: diagnosis
• Urine collection: test of choice
*Children: timed urinary collection for 8-24 hrs
Some methods does not distinguish organic and
organic formsabstain seafood ingestion > 5 days
• Blood: not recommend (short t1/2)
• Hair and fingernail analyses: validity???
21. Arsenic: treatment
• Decontamination
• Chelation therapy:
dimercaprol (BAL)
d-penicillamine
succimer
Chronic poisoning: chelation therapy has not proven
effective in relieving symptoms
22.
23. Woolf A, Wright R, Amarasiriwardena C, Bellinger D.Environ Health Perspect. 2002 Jun;110(6):613-6.
uncertain how
the water became
contaminatedA 10-year-old male:
refer to PEH center
with elevated blood,
urine, hair [Mn]
24. PEH center evaluation
Patient
• Unremarkable PH and
examination
• Patient’s grades and
behavior were excellent
• Mother: for the past
several years teachers had
consistently noted a
difficulty with listening skills
and following directions
Home and environment
• Boston, Massachusetts,
suburb 5years
• Well was drilled to supply the
home with water
• Water: turbid, metallic taste,
and left an orange-brown
residue on clothes, dishes,
and appliances
• Parents, 16 and 10 years boy
• Only the younger boy had
abnormally high blood [Mn]
Woolf A, Wright R, Amarasiriwardena C, Bellinger D.Environ Health Perspect. 2002 Jun;110(6):613-6.
25. Normal IQ but
unexpectedly poor
verbal and visual
memory
Woolf A, Wright R, Amarasiriwardena C, Bellinger D.Environ Health Perspect. 2002 Jun;110(6):613-6.
26. Management
• Advised to discontinue all residential use of the
water from the well
• Interceded with town officials on the behalf of
the family 3 mo later: a standpipe was
dropped from the water main to the family home
• 18 mo later:
Still in an age-appropriate grade
Teachers: continued to remark on his difficulty in
remaining on task and his inattentiveness in class
Woolf A, Wright R, Amarasiriwardena C, Bellinger D.Environ Health Perspect. 2002 Jun;110(6):613-6.
27. Manganese
• Light weight and durability
• Inorganic: steel alloys, batteries, glass,
ceramics, incendiaries, fungicides, organic
compounds , etc.
• Organic: gasoline and fuel oil additive,
fungicides
• Essential in human nutrient: bone,
metabolism of AA, lipids, CHO, enzyme
29. Manganese
• Sources of exposure
Foods: whole barley, rye and wheat, nuts, and leafy
green vegetable
Beverages: tea, milk (soy> cow’s milk> human milk)
Remedy: Chinese herbal
Pollution: air, water, and soil
30. Manganese exposure
Blood brain barrier
Circulation
3-5% 100 %
• Children
• Female
• Iron deficiency
• Low protein
intake
• Genetic
modulation
Excretion:
t1/2 40 days
• High dietary
Ca2+
•High dietary
PO4
3-
*esp.Neonate
35. Biomarkers of manganese intoxication
• Biomarkers of exposure
• Biomarkers of effect
• Biomarkers of host susceptibility
No reliable biomarkers:
complete scientific understanding of the mechanism of
toxicity remains undiscovered
36. Biomarkers of Mn exposure
• Mn concentrations in body fluid:
whole blood, plasma, or serum
1) reasonable indicator of exposure on a group basis;
2) reflects recent, active exposure; and
3) appears to be a modest indicator for distinguishing
Mn-exposed workers from control subjects at the
individual level
38. Manganese: prevention
• Air pollution: < 0.05 µg/m3 (EPA)
• Water supplies: < 50 µg/L (EPA)
Recommended daily intake
• EPA: 0.14 mg/kg/day (adult)
• The institute of Medicine(Washington,DC):
Infants 3 µg/day
Adolescent males: 2.2 mg/day
39. Chronic intake of heavy metals
• Carcinogenic hazards
• Non-carcinogenic hazards
Neurologic and developmental involvement
Endocrine disruptor
Epigenetic
40. Chemical mixtures and children’s health
• Evaluating health effects of single chemical
exposures: under estimate the true effects
• Metal mixtures:
Children: developmental and neurological effects
More severe than exposure to each metal alone
Lead: increased toxicity in the presence of other
metals e.g., Mn, Cd, Mercury (Hg), As
Claus Henn B, Coull BA, Wright RO.Curr Opin Pediatr. 2014 Apr;26(2):223-9.
41. Chemical mixtures and children’s health
• Birth defects
• Reproductive outcome
• Cognitive and motor development
Claus Henn B, Coull BA, Wright RO.Curr Opin Pediatr. 2014 Apr;26(2):223-9.
42. • Chitwan Valley, Nepal
• Hospital-based birth cohort study with 100 pregnant women; 100 infants at 1 day
after birth
• Pb, As, and Zn concentrations in cord blood
• Pb, As inverse neurodevelopment of newborns
• High levels of Pb or As exposure during prenatal induce
retardation during in utero neurodevelopment
43. As, Cd and Mn with neurodevelopment in children
• 50% increase in As levels (urine) 0.4 decrease in the IQ of children
• 50% increase in Mn levels (hair)0.7 decrease in the IQ of children
• Mn exposure attention deficit disorder with hyperactivity
Rodríguez-Barranco M,et al. Sci Total Environ. 2013 Jun 1;454-455:562-77.
•2002-2012
•As(18), Mn(17), Cd (6)
•Neurodevelopmental or behavioral
As (13/18)
Mn (14 /17)
Cd(2/6)
The patient’s family bought a home in a suburb, but the proximity of the house to wetlands and
its distance from the town water main prohibited connecting the house to town water. The family
had a well drilled and they drank the well water for 5 years, despite the fact that the water was
turbid, had a metallic taste, and left an orange-brown residue on clothes, dishes, and appliances.
When the water was tested after 5 years of residential use, the manganese concentration was elevated
(1.21 ppm; U.S. Environmental Protection Agency reference, < 0.05 ppm). The family’s
10-year-old son had elevated manganese concentrations in whole blood, urine, and hair. The
blood manganese level of his brother was normal, but his hair manganese level was elevated. The
patient, the 10-year-old, was in the fifth grade and had no history of learning problems; however,
teachers had noticed his inattentiveness and lack of focus in the classroom. Our results of cognitive
testing were normal, but tests of memory revealed a markedly below-average performance:
the patient’s general memory index was at the 13th percentile, his verbal memory at the 19th percentile,
his visual memory at the 14th percentile, and his learning index at the 19th percentile.
The patient’s free recall and cued recall tests were all 0.5–1.5 standard deviations (1 SD = 16th
percentile) below normal. Psychometric testing scores showed normal IQ but unexpectedly poor
verbal and visual memory. These findings are consistent with the known toxic effects of manganese,
although a causal relationship cannot necessarily be inferred.