Heavy Metal Toxicity - PowerPoint PPT Presentation

Loading...

PPT – Heavy Metal Toxicity PowerPoint presentation | free to download - id: 68a36a-MGY2M



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Heavy Metal Toxicity

Description:

Heavy Metal Toxicity H.R.Sarreshtahdar, MD Occupational Medicine Specialist Arsenic Mercury Lead – PowerPoint PPT presentation

Number of Views:114
Avg rating:3.0/5.0
Slides: 45
Provided by: drnase
Learn more at: http://cme.bpums.ac.ir
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Heavy Metal Toxicity


1
Heavy Metal Toxicity
  • H.R.Sarreshtahdar, MD
  • Occupational Medicine Specialist

Arsenic
Mercury
Lead
2
HEAVY METALS
  • The term heavy metal refers to any metallic
    chemical element that has a relatively high
    density and is toxic or poisonous at low
    concentrations.

3
HEAVY METALS
  • Are natural components of the Earth's crust
  • To a small extent they enter our bodies via food,
    drinking water and air
  • As trace elements, some heavy metals (e.g.
    copper,
  • selenium, zinc) are essential to maintain the
    metabolism
  • of the human body however, at higher
    concentrations
  • they can lead to poisoning
  • Heavy metal poisoning could result, for instance,
    from drinking-water contamination (e.g. lead
    pipes), high ambient air concentrations near
    emission sources, or intake via the food chain

4
Mercury - Hg
  • Mercury is the only common metal which is liquid
    at ordinary temperatures. It rarely occurs free
    in nature and is found mainly in cinnabar ore
    (HgS) in Spain and Italy.
  • It alloys easily with many metals, such as gold,
    silver, and tin - these alloys are called
    amalgams. Its ease in amalgamating with gold is
    used in the recovery of gold from its ores.

5
Health effects of mercury
  • Disruption of the nervous system
  • Damage to brain functions
  • DNA damage and chromosomal damage
  • Allergic reactions, resulting in skin rashes,
  • Tiredness and headaches
  • Negative reproductive effects, such as sperm
    damage, birth defects and miscarriages

6
Environmental effects of mercury
  • Fish are organisms that absorb great amounts of
    methyl mercury from surface waters every day
    (mercury can accumulate in fish and in the food
    chains)
  • The effects that mercury has on animals are
    kidneys damage, stomach disruption, damage to
    intestines, reproductive failure and DNA
    alteration

7
(No Transcript)
8
What is Cadmium?
  • A metal most often encountered in earths crust
    combined with chlorine (cadmium chloride), oxygen
    (cadmium oxide), or sulfur (cadmium sulfide)
  • Exists as small particles in air, result of
    smelting, soldering or other high temp.
    industrial processes
  • By-product of smelting of zinc, lead, copper ores
  • Used mainly in metal plating, producing
  • pigments, batteries, plastics and as a
  • neutron absorbent in nuclear reactors

Cadmium is used in batteries
9
Cadmium and Smelters/Mine Sites
  • Cadmium is a by-product of smelters
  • Has been a concern at the Summitville mine site
    in Colorado

Photo of Smelter
10
Exposure Sources - Tobacco
  • Tobacco smoke (a one pack a day smoker absorbs
    roughly 5 to 10 times the amount absorbed from
    the average daily diet)

Tobacco smoke is an important source of cadmium
exposure
11
Exposure Sources By Mouth
  • Foods (only a small amount is absorbed)
  • Itai Itai disease (cadmium contamination diet
    low in calcium vitamin D)

12
Cadmium CdHEALTH EFFECTS
  • Human uptake of cadmium takes place mainly
    through food
  • Foodstuffs that are rich in cadmium can greatly
    increase the cadmium concentration in human
    bodies (liver, mushrooms, shellfish, mussels,
    cocoa powder and dried seaweed)

13
Why Is Cadmium a Health Hazard?
  • Affects lungs kidneys
  • 2o effects on skeletal system
  • Binds to sulfhydryl groups, displacing other
    metals from metalloenzymes, disrupting those
    enzymes
  • Competes with calcium for binding sites on
    regulatory proteins

14
Respiratory Effects
  • Acute inhalation may mimic metal fume fever
  • Fever, chills decreases in FVC and FEV1
  • Initial symptoms flu-like symptoms
  • Later chest pain, cough, dyspnea
  • Bronchospasm and hemoptysis may occur
  • Chronic inhalation MAY result in impairment of
    pulmonary function with reduction in ventilatory
    capacity

15
Renal Effects
  • May cause tubular and glomerular damage with
    resultant proteinuria
  • May follow chronic inhalation or ingestion
  • Latency period of 10 yrs
  • Nephropathy is progressive irreversible

16
Renal Effects
  • Chronic exposure progressive renal tubular
    dysfunction
  • Toxic effects are dose related
  • Critical renal concentration
  • Decreased GFR
  • Chronic renal failure
  • Kidney stones more common

17
Skeletal Effects
  • Bone lesions occur late in severe chronic
    poisoning
  • Pseudofractures
  • Other effects of osteomalacia and osteoporosis
  • Appear to be secondary to increased urinary
    calcium and phosphorus losses

18
Signs and Symptoms - Acute
  • Food poisoning (ingestion)
  • Bronchitis (inhalation)
  • Interstitial pneumonitis (inhalation)
  • Pulmonary edema (inhalation)
  • A condition that mimics metal fume fever

Children who eat dirt (pica behavior) are at risk
19
Signs Symptoms - Chronic
  • Chronic exposure may result in renal dysfunction
    and bone disease
  • Mild anemia, anosmia yellow discoloration of
    the teeth may occur

Chronic exposure may effect the sense of smell
20
HEALTH EFFECTS
  • Diarrhoea, stomach pains and severe vomiting
  • Bone fracture
  • Reproductive failure and possibly even
    infertility
  • Damage to the central nervous system
  • Damage to the immune system
  • Psychological disorders
  • Possibly DNA damage or cancer development

21
Chromium - Cr
  • Chromium(III) is an essential nutrient for humans
    and shortages may cause heart conditions,
    disruptions of metabolisms and diabetes
  • But the uptake of too much chromium(III) can
    cause health effects as well, for instance skin
    rashes

22
Chromium - Cr
  • Chromium(VI) is a danger to human health, mainly
    for people who work in the steel and textile
    industry
  • People who smoke tobacco also have a higher
    chance of exposure to chromium
  • Hexavalent Chromium Chromium (VI) is a species
    of chromium that is forbidden to use in
    electrical electronic industry.

23
HEALTH EFFECTS
  • When it is a compound in leather products, it can
    cause allergic reactions, such as skin rash
  • After breathing it in, chromium(VI) can cause
    nose irritations and nosebleeds
  • Upset stomachs and ulcers
  • Respiratory problems
  • Weakened immune system
  • Kidney and liver damage
  • Alteration of genetic material
  • Lung cancer
  • Death

24
Environmental effects of chromium
  • Chromium(III) is an essential element for
    organisms that can disrupt the sugar metabolism
    and cause heart conditions, when the daily dose
    is too low
  • Chromium(VI) is mainly toxic to organisms - it
    can alter genetic materials and cause cancer

25
Lead - Pb
  • Foods such as fruit, vegetables, meats, grains,
    seafood, soft drinks and wine may contain
    significant amounts of lead
  • Cigarette smoke also contains small amounts of
    lead

26
Lead sources
  • application of lead in gasoline
  • fuel combustion
  • industrial processes
  • solid waste combustion

27
Lead Paint
  • The use of lead in residential paint was banned
    in 1977
  • Lead-containing pigments still are used for
    outdoor paint products because of their bright
    colors and weather resistant properties
  • Tetraethyl and tetramethyl lead are still used as
    additives in gasoline in several countries

28
ToxicoKinetics and ToxicoDynamics
  • Absorption
  • Lungs depends on size particle
  • GI
  • Adults 20-30
  • Children as much as 50 of dietary lead
  • Inadequate intake of iron, calcium, and total
    calories are associated with higher lead levels
  • Skin
  • Inorganic lead is not absorbed
  • Organic lead is well absorbed
  • Lead is carried bound to the RBC

29
PharmacoKinetics and PharmacoDynamics
  • Distributed extensively throughout tissues bone,
    teeth, liver, lung, kidney, brain, and spleen
  • Body lead storage bones- can constitute a source
    of remobilization and continued toxicity after
    the exposure has ceased
  • Lead crosses the BBB and concentrates in the gray
    matter
  • Lead crosses the placenta
  • Excretion
  • Kidneys. The excretion increases with increasing
    body stores (30?g-200 ?g/day)
  • Feces

30
Signs and Symptoms of Lead Toxicity
  • Fatigue
  • Irritability
  • Lethargy
  • Paresthesis
  • Myalgias
  • Abdominal pain
  • Tremor
  • Headache
  • Vomiting
  • Weight loss
  • Constipation
  • Loss of libido
  • Motor neuropathy
  • Encephalopathy
  • Cerebral edema
  • Seizures
  • Coma
  • Severe abdominal cramping
  • Epiphyseal lead lines in children (growth arrest)
  • Renal failure

31
Range of Lead-induced Health Effects in Adults
and Children
Blood lead levels Adults Children
10 ?g/dL Hypertension may occur Crosses placenta Impairment IQ, growth Partial inhibition of heme synthesis
20 ?g/dL Inhibition of heme synthesis Increased erythrocyte protoporphyrin Beginning impairment of nerve conduction velocity
30 ?g/dL Systolic hypertension Impaired hearing(?) Impaired vitamin D metabolism
40 ?g/dL Infertility in males Renal effects Neuropathy Fatigue, headache, abd pain Hemoglobin synthesis inhibition
50 ?g/dL Anemia, GI sx, headache, tremor Colicky abd pain, neuropathy
100 ?g/dL Lethargy, seizures, encephalopathy Encephalopathy, anemia, nephropathy, seizures
32
Health effects of lead
  • Disruption of the biosynthesis of haemoglobin and
    anemia
  • A rise in blood pressure
  • Kidney damage
  • Miscarriages
  • Disruption of nervous systems
  • Brain damage
  • Declined fertility of men through sperm damage
  • Diminished learning abilities of children
  • Behavioural disruptions of children, such as
    aggression, impulsive behaviour and hyperactivity

33
Health effects of lead
  • Lead can enter a foetus through the placenta of
    the mother
  • Because of this it can cause serious damage to
    the nervous system and the brains of unborn
    children
  • That is why women in pregnancy can not work with
    lead.

34
  • The average lead level of American children is 2
    ?g/dl
  • 8.9 of American children have lead poisoning
  • Lead intoxication is more prevalent in minority
    groups and among those living in the northeast

35
Diagnosis
  • Evaluation of clinical symptoms and signs
  • CBC
  • Serum iron levels, TIBC, ferritin
  • Abdominal radiographs (for recent ingestion of
    lead-containing material)
  • Whole blood lead level
  • X-ray fluorescence (XRF)- to asses body burden

36
Arsenic
37
Introduction
  • Commercial products
  • Wood preservatives
  • Pesticides
  • Herbicides
  • Fungicides
  • Food
  • Seafood and fish
  • Others
  • Antiparasitic drugs

38
Toxicokinetics
  • T1/2 of inorganic arsenic in the blood is 10 hrs
    and of organic arsenic is around 30 hours
  • 2-4 weeks after the exposure ceases, most of the
    remaining arsenic in the body is found in
    keratin-rich tissues (nails, hair, skin)

39
Toxicokinetics
  • Inorganic arsenic is converted to organic arsenic
    (biomethylation to monomethyl arsonic- MMA or
    DMA) in the liver. This may represent a process
    of detoxification
  • Renally excreted (30-50 of inorganic arsenic is
    excreted in about 3 days). Both forms are
    excreted depend on the acuteness of the exposure
    and dose

40
Manifestations of acute arsenic poisoning
Bodily system affected Symptoms or signs Time of onset
Systemic Thirst Hypovolemia, Hypotension Minutes Minutes to hours
Gastrointestinal Garlic or metallic taste Burning mucosa Nausea and vomiting Diarrhea Abdominal pain Hematemesis Hematochezia, melena Rice-water stools Immediate Immediate Minutes Minutes to hours Minutes to hours Minutes to hours Hours Hours
Hematopoietic system Hemolysis Hematuria Lymphopenia Pancytopenia Minutes to hours Minutes to hours Several weeks Several weeks
Pulmonary (primarily in inhalational exposures) Cough Dyspnea Chest Pain Pulmonary edema Immediate Minutes to hours Minutes to hours Minutes to hours
Liver Jaundice Fatty degeneration Central necrosis Days Days Days
Kidneys Proteinuria Hematuria Acute renal failure Hours to days Hours to days Hours to days
41
PALMAR KERATOSIS
42
Biological Monitoring
  • Urinary arsenic measurement
  • Spot sample (mcg/L)
  • Timed urine collection (mcg/24 hours)
  • Normal values
  • Spot urine 10 mcg/L (10-150 mcg/L)
  • 24 hours urine collectionlt25 mcg/24 hours
  • Whole blood lt1mcg/L (usually is elevated in
    acute intoxication)

43
Chromium
  • Common oxidation states Cr3 Cr6, in aerobic
    conditions Cr exists primarily as the chromate
    ion highly soluble, toxic, can dimerize to
    dichromate
  • Anerobic (reducing) conditions Cr exists the 3
    ion not very toxic or soluble under basic
    neutral or even acidic conditions

44
Cr Contamination of Water
  • Used for electroplating, corrosion resistance
    tanning
  • Second most abundant inorganic contaminant of
    groundwater under hazardous waste sites
  • MCL in US 100 ppb
  • Removal most heavy metals increase the pH but
    Cr6 soluble at any pH but Cr3 low solubility so
    Cr6 usually reduced to 3
About PowerShow.com