toxicity of metals chronic health hazards prevention and surveillance l.
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Toxicity of metals - chronic health hazards, prevention and surveillance. Vesa Riihimäki Unit for toxicological risk assessment Finnish Institute of Occupational Health. TYÖTERVEYSLAITOS. Metals causing harm in the occupational setting. Aluminium Cadmium

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toxicity of metals chronic health hazards prevention and surveillance
Toxicity of metals - chronic health hazards, prevention and surveillance

Vesa Riihimäki

Unit for toxicological risk assessment

Finnish Institute of Occupational Health

TYÖTERVEYSLAITOS

metals causing harm in the occupational setting
Metals causing harm in the occupational setting
  • Aluminium
  • Cadmium
  • Chromium(VI), note: chromium(III) is essential to man
  • Cobolt, note: essential component of B12 vitamin
  • Lead
  • Manganese, note: essential trace element
  • Mercury
  • Nickel
  • Vanadium
  • Zinc, note: essential trace element

TYÖTERVEYSLAITOS

occupational exposures to metals
Metal foundry

Flame cutting and welding- stainless steels (Cr, Ni)- special steels (Mn)- cadmium plating- zinc plating- painted steel (Pb)- aluminium

Soldering- silver solder (Cd)- lead solder

Grinding and polishing (Co, Cr, Ni)

Storage batteries- lead- cadmium and nickel- manganese

Instrument repair- mercury

Furnace cleaning- vanadium

Chemicals, catalysts

Occupational exposures to metals

TYÖTERVEYSLAITOS

common concepts in metal toxicology
Common concepts in metal toxicology
  • Most metals exhibit limited absorption
  • Metabolism is usually limited to oxidation/reduction, alkylation/dealkylation or complexation
  • Many have a long residence time in the body due to binding (sequestering) or storage
  • Toxicokinetics and target organ toxicity are highly dependent on the metal species
species specific metal toxicity
Species specific metal toxicity
  • Underlying factors: solubility, uptake (systemic, cellular), tissue distribution, specific biological reactivity
  • Examples: mercury compounds- metallic mercury- mercuric salts, e.g. chloride- methylmercury- methoxymethylmercury acetate
species specific toxicity cont d
Species specific toxicity, cont'd
  • Aluminium: oxide versus sulphate
  • Chromium(VI) versus chromium(III)
  • Lead dust & salts versus alkyl lead
  • Nickel: metallic Ni, Ni oxides, Ni subsulfide, Ni carbonyl
  • Zinc: freshly generated fumes of Zn oxide versus Zn chloride
target organs for metals toxicity in humans
Aluminium

Kadmium

Chromium(VI)

Cobolt

Lead

Manganese

CNS, bone

Kidney, lung, carcinogenicity

Airways, skin, sensitisation, carcinogenicity, kidney

Lung, skin, sensitisation

CNS & PNS, blood forming organs, kidney, reproduction

CNS (signs of Parkinsonism)

Target organs for metals toxicity in humans
target organs for metals toxicity in humans cont d
Mercury- elemental vapour- mercuric salts- alkyls

Nickel

Vanadium

Zinc

- CNS, kidney- kidney, skin sensitisation- CNS, developmental toxicity

Airway carcinogenicity, skin sensitisation

Respiratory system

Respiratory system

Target organs for metals toxicity in humans, cont'd
t issue distribution and elimination of lead
Tissue distribution and elimination of lead
  • Central compartment: blood lead- half-time about 30 days- about 4% of the body burden
  • Soft tissue lead- half-time about 30-40 days- about 2% of the body burden
  • Lead in bone- half-time up to 30 years- 94% of the body burden
slide11

Dose-effect and dose-response relationship: lead

decreased erythrocyte delta-ALAD

activity

increased zinc protoporphyrin

anemia

CNS effects

decreased peripheralnerve

conductivity

Nervous paralysis, lead colics

Adapted from Elinder C-G et al., Biologisk monitoring av metaller

hos människa. Arbetsmiljöfonden, Uppsala, 1991

prevention and surveillance
Prevention and surveillance
  • Control exposure from all sources that may lead to hazardous accumulation
  • Perform biological monitoring of body burden U-Cr, U-Co, B-Pb, U-Mn (?), U-Hg, U-Ni, U-V to ensure that accumulation will not reach critical levels
  • Perform health surveillance for early effects, making note of individual susceptibility
basis for health surveillance among aluminium welders
Basis for health surveillance among aluminium welders
  • Indication of increasing body burden with time at exposure
  • Suspicion of aluminium accumulation in the target organ of toxicity (the brain)
  • Demonstration of a dose-response between aluminium in serum and urine and CNS effects (symptoms, attention & working memory impairment, EEG abnormality)
  • Effect threshold: U-Al 4-6 µmol/l, S-Al 0.25-0.35 µmol/l