Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

studied using Spirodela polyrhiza, Azolla pinnata, and Lemna gibba. Test durations ranged from
4 to 25 days and test concentrations ranged between 49.7 and 500,000 µg/L.
Waterborne Pb is highly toxic to aquatic organisms, with toxicity varying with the species
and life stage tested, duration of exposure, form of Pb tested, and water quality characteristics.
Among the species tested, aquatic invertebrates, such as amphipods and water fleas, were the
most sensitive to the effects of Pb, with adverse effects being reported as low as 0.45 µg/L.
Effects concentrations for aquatic invertebrates were found to range from 0.45 to 8000 µg/L.
Freshwater fish demonstrated adverse effects at concentrations ranging from 10 to >5400 µg/L,
depending generally upon water quality parameters. Amphibians tend to be relatively Pb tolerant
(Eisler, 2000); however, they may exhibit decreased enzyme activity (e.g., ALAD reduction) and
changes in behavior (e.g., hypoxia response behavior). Lead tends to be more toxic with longer-
term exposures.
The primary focus of this section was on effects at the individual level of organization.
This narrow focus is primarily due to a lack of information on the effects of lead on higher levels
of organization (e.g., populations, communities, and ecosystems). The impact of lead at higher
levels of biological organization should be considered in future reviews of lead toxicity.
In considering these higher levels of organization, cause-effect models and relationships that
examine the roles of life history strategy and optimal foraging theory, community processes and
associated theory, and ecosystem processes and the influences of redundancy/interactions should
be taken into account.
AX7.2.5 Effects of Lead on Natural Aquatic Ecosystems
Introduction
As discussed previously, lead exposure may adversely affect organisms at different levels
of organization, i.e., individual organisms, populations, communities, or ecosystems. Generally,
however, there is insufficient information available for single materials in controlled studies to
permit evaluation of specific impacts on higher levels of organization (beyond the individual
organism). Potential effects at the population level or higher are, of necessity, extrapolated from
individual level studies. Available population, community, or ecosystem level studies are
typically conducted at sites that have been contaminated or adversely affected by multiple
stressors (several chemicals alone or combined with physical or biological stressors). Therefore,
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