Toxicological Effects of Methylmercury (2000) / Chapter Skim
Currently Skimming:
Introduction
Introduction
Pages 13-30
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 13... ...
The second report, the Study of Hazardlous Air Pollutant Emissions from Electric Utilihy Steam Generating Units. Final Report to Congress (EPA 1998)
|
From page 14... ...
Due to disagreement over the appropriate level of concern for MeHg exposure, the potentially widespread implications for human health, and the challenges associate-d with further regulating Hg emissions, Congress directed EPA in the House Appropriations Report for EPA's Fiscal 1999 funding to contract with the National Research Council (NRC) to prepare recommendations on the appropriate value for a Hg exposure reference dose (RfD)
|
From page 15... ...
Potential sources of general population exposure to Hg include inhalation of Hg vapors in ambient air, ingestion of drinking water and foodstuffs contaminated with Hg, and exposure to Hg from dental amalgams and medical treatments. Dietary intake is one of the most important sources of nonoccupational exposure to Hg, fish and other seafood products being the dominant source of Hg in the diet.
|
From page 16... ...
A spectrum of adverse health effects has been observed following MeHg exposure, with the severity depending largely on the magnitude of the dose. Fatalities and devastating neurological damage were observed in association with the extremely high exposures that occurred during the Minamata and Iraqi poisoning
|
From page 17... ...
At much lower doses that result from chronic maternal fish consumption, infants might appear normal during the first few months of life but might later display deficits in subtle neurological end points (e.g., {Q deficits, abnormal muscle tone, decrements in motor function, attention, and visuospatial performance)
|
From page 18... ...
or cardiovascular death 2- to 3-fo1~. The estimated daily dietary Hg intake ranged from -1.1 ,ug to 95.3 fig (mean, 7.6 Age.
|
From page 19... ...
In Iraq, exposure was due to the consumption of home-made bread that was made with grain treated with MeHgas a fungicide. In that outbreak, the most common symptom In adults was paresthesia; the most severely affected individuals exhibited ataxia, blurred vision, slurred speech, hearing difficulties, blindness, deafness, and death (Marsh et al.
|
From page 20... ...
pressure, heart rate, ancl heart-rate variability were also taken when the children reached 7 years of age. Researchers found that cliastolic and systolic blood pressures increased, and heartrate variability decreased as cord-blood Hg concentrations rose from to1O~g/L A prospective study carrier!
|
From page 21... ...
Specific details on the derivation of EPA's MeHg RfD can be found in the section on The Current EPA Reference Dose In Chapter S In the United States, responsibility for regulating Hg is shared by two federal agencies: the Food and Drug Administration (FDA)
|
From page 23... ...
23 Do o be o o ~ ~ ~ ~ ~ ~ ° ~ =; e =,>0,= => ~~ ~ be ·^ O O ~ LO ., .
|
From page 25... ...
The effect on public health of using one dose rather than another to set acceptable exposure levels might be substantial, leaving open the question of which value best ensures public safety. Differences in acceptable levels can affect many government programs, including state fish advisories, and regulation of such industries as commercial fishing and electric power plants (Renner 1999~.
|
From page 26... ...
in Chapter 4, issues involved in assessing MeHg exposure and dose are presented. The focus is on the selection and interpretation of dose metrics and the implications of the possible dose metrics for dose-response assessment and nutritional assessment.
|
From page 27... ...
1998. Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: Outcomes at 66 months of age in the Seychelles Child Development Study.
|
From page 28... ...
1998. Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units.
|
From page 29... ...
1987. Fetal methylmercury poisoning: Relationship between concentration in single strands of maternal hair and child effects.
|
From page 30... ...
1999. Consensus on health risks from mercury exposure eludes federal agencies.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.