Toxicologic Assessment of the Army's Zinc Cadmium Sulfide Dispersion Tests (1997) / Chapter Skim
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Toxicity and Related Data on Selected Cadmium Compounds
Toxicity and Related Data on Selected Cadmium Compounds
Pages 39-56
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From page 39... ...
The toxicity of zinc, its interaction with cadmium, and the toxicity of copper and silver are discussed in Appendix D This chapter reviews the physical and chemical properties, toxicokinetics, and toxicity of cadmium and cadmium compounds.
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From page 40... ...
This must be taken into account whenever an attempt is made to extrapolate the quantitative and qualitative effects of a metal compound with, say, high solubility and known toxicity to a compound with unknown toxicity, such as ZnCdS that contains the same metal but is poorly or not at all soluble in water or acid. Because ZnCdS is neither water-soluble nor apparently bioavailable, the subcommittee believes that the use of toxicity data on cadmium compounds to estimate the toxicity of ZnCdS constitutes a worst-case-scenario; this approach wall lead to an overestimate of the risk associated with ZnCd S
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From page 41... ...
The ATSDR toxicological profile on cadmium shows that cadmium compounds highly soluble in viva (such as CdCI2, CdSO, and cadmium oxide, CdO) are considerably more toxic and can cause death at substantially lower concentrations than cadmium compounds poorly soluble in viva (such as CdS and cadmium carbonate, C6C03~.
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From page 42... ...
Oberdorster (1990) estimated that 90% of the remaining inhaled CdS was removed slowly from the Jung into the gastrointestinal tract by normal mechanical clearance processes.
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From page 43... ...
These data are summarized below. IN VIVO INSOLUBLE CADMIUM COMPOUNDS Many animal studies have identified toxic responses to the inhalation or ingestion of soluble cadmium compounds, but relatively few studies have examined the health effects of cadmium compounds that are poorly soluble in viva, such as CdS, CdSe, C6C03, or cadmium dyes.
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Long-term chronic occupational exposure can cause emphysema in humans. In experimental animals, inhalation of soluble cadmium compounds has been shown to produce acute lung injury (chemical pneumonitis)
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From page 45... ...
K/DN=Y-The kidney is a major target organ for cadmium toxicity after chronic, low-level exposure to forms of cadniium that can be absorbed by the body and transported to the kidney. Workers occupationally exposed to cadmium and cadmium compounds (for example, CdO dust and cadAlum Ames in factories producing nickel-cadm~um batteries)
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From page 46... ...
The effects of low-dose exposures on bone metabolism are subtle, but chronic exposures, particularly in combination with other factors, lead to calcium loss from bone. Factors contributing to the severity of cadmium toxicity to bone include renal disease, dietary deficiencies (particularly low dietary calcium)
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From page 47... ...
DEV~LOPM~NTA] Tox/c/Tr Two epidemiologic studies looked at pregnancy outcomes in occupationally exposed populations (ATSDR 1993~; the primary route of exposure was probably inhalation.
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From page 48... ...
Those studies suggest that the ambient concentrations of CdO, a compound soluble in vivo, might cause developmental toxicity in humans. However, ZnCdS is an insoluble cadmium compound, and that suggests that it is urdikely to produce developmental toxicity at the low ambient concentrations.
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From page 49... ...
Concentrations of lead, cadmium, and zinc in the testes of 41 autopsied men were evaluated (Oldeneid and others 1993~; no associations between sem~nal-plasma cadmium content and semen quality or fertility changes were noted, despite the ability of cadmium to reach human semen. Favino and others (1968)
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Overall, cadmium appears to have the capability of altering genetic material, particularly chromosomes in mammalian cells, but germ cells appear to be protected except at high acute parenteral doses (AT SDR 1993~. The subcommittee concludes that until more conclusive mutagenicity
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From page 51... ...
in 1993. {ARC concluded that cadmium and cadmium compounds are carcinogenic in humans on the basis of epidemiologic studies of occupationally exposed workers, experimental studies in animals, and genotoxic effects in a variety of types of euka~yotic cells, including human cells (lARC 1993~.
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From page 52... ...
for lung cancer increases with either length of employment or cumulative exposure to cadmium.
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Rats exposed to 10 weekly intratracheal instillations of 250 ,ug of CdS hac! a statistically significant in
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Early studies of occupational exposure suggested increased deaths from prostatic cancer, but the association weakened with continued followup and has not shown a clear dose-response trend (TARC 1993~. Japanese men who ingested cadmium-contaminated rice during World War II exper~enced higher mortality from prostatic cancer (standardized mortality ratio, 1.66)
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From page 55... ...
(IPCS 1992~. CONCLUSIONS Faced with the task of evaluating the potential toxicity of ZnCdS, a substance with largely unknown toxic potential but reasonably well-known physical and chemical properties, the subcommittee considered it to be prudent to examine the toxicity and related data on the most-tox~c element in ZnCdS, cadmium.
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From page 56... ...
· Cadmium exposures associated with increased lung-cancer risk in human and animal studies were to much higher concentrations for longer periods and involved more biologically soluble compounds than the exposures to cadrn~um Dom ZnCdS in the Army's testing program. · A quantitative risk assessment for lung cancer based on occupational exposure of humans to cadmium compounds is likely to overestimate the lung-cancer risk for ZnCdS exposures from the Army's dispersion tests.
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