Environmental Fate of Bisphenol
The vast majority of BPA produced, greater than 99.9%,
is consumed at manufacturing sites to make products
such as polycarbonate plastic or epoxy resins (Staples
et al, 1998). Bisphenol A dust (particulates) is controlled
by workplace practices and engineering design and is
not a significant contributor to environmental exposures.
The relatively small amount of vapor released to the
atmosphere is rapidly degraded by sunlight. Low levels
may be released to the environment in the effluent water
from biological wastewater treatment plants.
The distribution of BPA in the environment can be predicted
by its physical properties (Staples et al, 1998). Bisphenol
A is a solid with low volatility at ambient temperature
conditions, water solubility of 120-300 milligrams per
liter and a greater solubility at alkaline pH values.
Based on these properties, a simple equilibrium model
predicts that about 50% of BPA in the environment has
the potential to bind to sediments or soils with the
rest remaining in the water column.
Bisphenol A has been shown to be readily biodegradable,
meaning that it breaks down rapidly in the environment.
A study using guidelines of the Organization
for Economic Cooperation and Development demonstrated
that bisphenol A meets its criteria for classification
as "readily biodegradable."
Biodegradation plays a major role in the removal of
BPA from the environment. Recent studies demonstrate
that BPA degrades rapidly in surface waters and sediments
taken from a wide variety of geographies (including
those with no known exposure history), suggesting that
microorganisms with the capability to degrade BPA are
ubiquitous in the environment (Klecka et al, 2001).
Real world monitoring studies also confirm that BPA
is rapidly biodegraded and extensively removed in wastewater
treatment systems. For instance, 92-98% removal was
reported in the most common type of sewage treatment
system, an activated sludge plant (Staples et al, 1998).
The trace amounts of BPA remaining in treated wastewater
will continue to biodegrade in receiving waters and
downstream of treatment plants (Klecka et al, 2001).
Studies using real world surface water samples taken
from various geographies demonstrate rapid degradation
with a half-life in the range of 1 to 4 days (i.e.,
time for 50% degradation).