Page 5 - Lake Roosevelt Forum 2020 Public Guide

UPPER COLUMBIA VALLEY
Human Health Risk Assessment Findings
This section summarizes findings related to the Upper Columbia Valley, public beaches, fish consumption, swimming and surface water, and air quality. It also summarizes the exposure pathways of populations evaluated and related cleanup activities that are completed or planned.
The section “Calculating Lead, Cancer, and Non-Cancer Human Health Risks” (pages 15-17) summarizes how benchmarks and results of modeling and calculations were used to support these findings.
Upper Columbia Valley Lead Exposure Risks for Children
The Upper Columbia River (UCR) Site extends approximately 150 river miles from the U.S.-Canada border to the Grand Coulee Dam. The Upper Columbia Valley (Valley) area includes approximately 100 square miles (64,000 acres) east and west of the Columbia River that extends from the U.S.-Canada border to China Bend (about 40 river miles).
In the Valley, exposure to lead in soils is a concern. This is primarily due to smelter air emissions linked to air deposition of lead that contaminated surface soil. Exposure to lead is particularly dangerous for children under six because their growing bodies absorb more lead than adults. As their brains develop rapidly, adverse effects can impair cognitive development such as IQ and self-control.
Exposure to Lead can Seriously Harm a Child’s Health
Damage to
the brain and nervous system
Learning and behavior problems
Slowed growth and development
Hearing and speech problems
Source: CDC.com
Because children under six are most at risk, blood lead level modeling focuses on determining a protective standard for them. The development of risk-based standards developed for children is also generally protective of adults.
Historically, EPA has used a target blood lead level of 10 micrograms of lead per deciliter of blood (μg/dL) as the benchmark for human health risk. More recently, however, research studies have demonstrated risks to children at concentrations below the target blood lead level of 10 μg/dL. As a result, for this investigation EPA selected a blood lead level target range of low (3 μg/dL), medium (5 μg/dL) and high (8 μg/dL) to evaluate human health risk in the Upper Columbia Valley.
EPA used the Integrated Exposure Uptake Biokinetic (IEUBK) model, which is commonly used by risk assessors to evaluate lead exposure risk, to estimate blood lead levels in children. See the “Calculating Lead, Cancer, and Non-Cancer Human Health Risks” section to learn more about how the model works.
5