Characterization of Human Health and Wildlife Risks from Mercury Exposure in the United States

By Environmental Protection Agency

Book Id: WPLBN0000041665
Format Type: PDF eBook
File Size: 0.8 MB
Reproduction Date: 2007

Title:	Characterization of Human Health and Wildlife Risks from Mercury Exposure in the United States
Author:	Environmental Protection Agency
Volume:
Language:	English
Subject:	Ecology, Natural resource issues, Environemtal protection
Collections:	Environmental Awareness Library Collection
Historic Publication Date:
Publisher:	United States Environmental Protection Agency


Citation APA MLA Chicago Agency, E. P. (n.d.). Characterization of Human Health and Wildlife Risks from Mercury Exposure in the United States. Retrieved from http://gutenberg.us/

Description
Excerpt: A study of Iraqi populations by Marsh et al. (1987) was chosen as the most appropriate study for determination of an RfD protective of a putative sensitive subpopulation, namely infants born to mothers exposed to methylmercury during gestation. This report described neurologic abnormalities observed in progeny of women who consumed bread prepared from methylmercury-treated seed grain while pregnant. Among the signs noted in the infants exposed during fetal development were cerebral palsy, altered muscle tone and deep tendon reflexes, as well as delayed developmental milestones (i.e., walking by 18 months and talking by 24 months). The data collected by Marsh et al. (1987) summarize clinical neurologic signs of 81 mother and child pairs. From x-ray fluorescent spectrometric analysis of selected regions of maternal scalp hair, concentrations ranging from 1 to 674 parts per million (ppm) mercury were determined, then correlated with clinical signs observed in the affected members of the motherchild pairs. Among the exposed population there were affected and unaffected individuals throughout the exposure range.

Table of Contents
TABLE OF CONTENTS Page U.S. EPA AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii SCIENTIFIC PEER REVIEWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv WORK GROUP AND U.S. EPA/ORD REVIEWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix LIST OF SYMBOLS, UNITS AND ACRONYMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x 1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 2. HUMAN HEALTH EFFECTS: HAZARD IDENTIFICATION AND DOSERESPONSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Health Hazards Associated with Mercury Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Dose-Response to Methylmercury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2.2.1 Calculation of Methylmercury RfD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2.2.2 Human Dose-Response Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.3 Uncertainty in the Human Health RfD for Methylmercury . . . . . . . . . . . . . . . . . . . . 2-15 2.3.1 Qualitative Discussion of Uncertainties in the RfD for Methylmercury Alternate Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15 2.3.2 Quantitative Analysis of Uncertainty in the Methylmercury RfD . . . . . . . . . 2-18 3. RISK CHARACTERIZATION FOR WILDLIFE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Scope of the Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.2 Exposure of Piscivorous Wildlife to Mercury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.2.1 Estimation of Current Average Exposure to Piscivorous Wildlife on a Nationwide Basis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2.2 Estimation of Mercury Deposition on a Regional Scale (40 km grid) and Comparison of These Deposition Data with Species Distribution Information 3-2 3.2.3 Estimation of Mercury Exposure on a Local Scale in Areas Near Emissions Point Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.3 Effects Assessment for Mercury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.4 Risk Assessment for Mercury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.5 Risk of Mercury from Airborne Emissions to Piscivorous Avian and Mammalian Wildlife . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.5.1 Lines of Evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.5.2 Risk Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 4. CHARACTERIZATION OF FATE OF ENVIRONMENTAL MERCURY . . . . . . . . . . . . . . 4-1 4.1 The Modeling Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.1.1 Study Design of the Modeling Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.1.2 Long-Ran