Assessment of mercury contamination and human exposure associated with coastal disposal of waste from a cinnabar mining operation, Palawan, Philippines |
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Authors: | T M Williams J M Weeks AN Apostol Jr C R Miranda |
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Institution: | (1) British Geological Survey, Keyworth, Notts, UK Fax: +44-115-9363200, GB;(2) Institute of Terrestrial Ecology, Monks Wood, Abbots Ripton, Cambs, UK, GB;(3) Mines and Geosciences Bureau, Quezon City, Metro Manila, Philippines, PH |
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Abstract: | An integrated geochemical and toxicological assessment of environmental mercury contamination and attendant human exposure
in Honda Bay, Palawan was undertaken in 1995 following a nationally reported pollution scare centered on a coastal jetty,
Sitio Honda Bay, constructed using approximately 1 million tons of tailings and beneficiation waste from a cinnabar mine.
Mercury (Hg) data for marine and fluvial sediments, fish tissues and human hair indicate that the toxicological hazard is
considerably lower than initially reported by state environment and health officials. Typical Hg concentrations in surficial
Honda Bay sediments were found to lie within the global background range (<60 μg/kg). Downcore profiles provide no evidence
of enhanced Hg fluxes coincident with the onset of mining and/or coastal tailings disposal. The mean and median Hg concentrations
recorded in tissues of six species of Honda Bay fish are compliant with thresholds established by the US Environmental Protection
Agency (US-EPA) for marketable stocks. Earlier reports of 'Minamata range' Hg concentrations in fish and shellfish from Honda
Bay remain unsubstantiated. Geochemical analyses of samples of the Sitio Honda Bay substrate have confirmed the prevalence
of solid-phase Hg concentrations to ca. 340 mg/kg. The speciation of Hg is, however, dominated by secondary oxides of low
bioavailability. The mean Hg concentration in hair from Sitio Honda Bay residents (4.41 mg/kg) was found to be statistically
analogous to that for a neighbouring coastal community unimpacted by the coastal disposal of mine waste. A negligible residential
exposure factor is thus inferred for the former. Relatively high hair Hg burdens prevail throughout the coastal Honda Bay
population, consistent with significant methyl Hg ingestion through daily fish consumption. The data presented provide no
environmental or toxicological justification for immediate remedial action.
Received: 14 May 1998/Accepted: 1 September 1998 |
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Keywords: | Mercury Mining Contamination Philippines |
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