**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON, DC 20460**

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

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Memorandum Feb 19, 2008

Subject: Environmental Fate and Transport Assessment of CCA-C for
Reregistration Eligibility Decision (RED) Process

From: A. Najm Shamim, PhD., Chemist

Regulatory Management Branch II

Antimicrobials Division (7510P)

To: Tim McMahon, PhD., Senior Toxicologist, and Risk Assessor

Antimicrobials Division (7510P)

Jonathan Chen, Toxicologist

Risk Assessment and Science Support Branch

Antimicrobials Division (7510P)

And

Lance Wormell, CRM for CCA-C RED

Regulatory Management Branch II

Antimicrobials Division (7510P)

Thru: Mark Hartman, Chief

Regulatory Management Branch II

Antimicrobials Division (7510P)

**[Environmental Fate and Transport Assessment of Chromated Copper
Arsenate (CCA)]{.underline}**

**[Executive Summary]{.underline}**

Copper, chromium and arsenic as oxides are the active ingredients of the
water-borne wood preservative of chromated copper arsenate (CCA). There
are a number of commercially available wood preservatives which contain
these three metals. These products are identified as CCA-A, CCA-B,
CCA-C. This assesssment is about CCA-C. The major difference between
these CCA products is the ratio of the metal oxides in the formulations.
CCA is primarily used as a pressure treatment wood preservative for
utility poles. The major exposure from the use of this wood preservative
are in three environmental compartments: soil /sediments, surface and
ground water and bioaccumulation in the aquatic and benthic organisms.

The leaching of these metals (Copper, Chromium, and arsenic) into water
from CCA is widely investigated and both the laboratory and field
studies, though contradictory in results and interpretations, generally
indicate that leaching of the metals is a function of pH, salinity
(fresh water, sea water, estuaries, natural and synthetic, sterile
buffered water), temperature, moisture content of the treated wood, wood
type, and wood texture. Results form a number of studies indicate that
most of the leaching takes place in the first few days after the
application. Most of these studies have shown that the extent and rate
of leaching is: Cu\>As\> Cr. Available studies were conducted under
different conditions and the exact concentrations of CCA solution
absorbed by wood (e.g. utility poles) are not known. Sorption constants
of these metals are high for various soils. Leaching of the metals into
soils also depends on the pH of the soil, type and texture of the soils,
organic content of the soils; however, studies on sorption into soils
from utility poles have shown that the release of metals into
soils/sediments from the base of treated wood, decks or utility poles or
from the pressure treatment facilities, do not show a high degree of
downward or ground level migration. In most cases, after migration of
the metals a few meters down into soil, these metals attain the
background level concentration of soil.

Bioaccumulation studies indicate that copper, as Cu(II), released from
CCA has a greater tendency to bioaccumulate in various aquatic and
benthic organisms than the other two metals. Chromium is released into
water and soil as Cr(III), but the concentration of Cr(III) is least of
the three metals, partly due to the fixation process in the wood
structure. Arsenic is leached into soil and water as As(V). However, few
open literature studies report short depuration rates.

In general, the metals in water exist as hydrated species (coordinated
with water), or hydroxy species or the metal is bound to inorganic
anions like FeF~6~^-3^, or bonded to organic ligands to form metal
complexes or as organometallics (contains C-Metal bonds). Fate and
transport processes, and interaction with aquatic and benthic organisms
by these chemical species will vary from one of type of organism to
another. The metals from CCA when released into water systems usually
attain background concentrations. In view of the fact that the metals
attain background level concentrations in soil and water, and the
tendency of the metals to speciate, it is hard to ascertain the source
of contamination in water and soil. Considering absence of comprehensive
ground water monitoring relative to the leaching of metals from CCA into
soils and water, it appears no significant possibility exists for ground
water contamination in areas where utility poles have been placed and
where decks have been built.

**[Appendix : Environmental Fate and Transport Assessment
Studies]{.underline}**

Copper, chromium and arsenic as oxides are the three active ingredients
of the water-borne wood preservative [chromated copper
arsenate]{.underline} (CCA). As a wood preservative it is unique in more
than one way. First, it is a mixture of inorganics metal species.
Second, its efficacy as a wood preservative improves if, and when, it
goes through the 'fixation' process during wood pressure treatment.

The physical properties and the chemistry of the three metals (arsenic,
chromium and copper) of the water-borne wood preservative CCA are very
well understood in aqueous and soil compartments. Most of the Agency's
environmental fate guideline studies (hydrolysis, photolysis, soil
aquatic metabolism, etc.) cannot be conducted on the individual, or a
mixture of these, metallic actives due to their complex interactions
with soil and water, sediments, plants, aquatic organisms and animals.

Chromium and copper are transition metals and have a tendency of
existing in variable oxidation states in water and soils. Common
oxidation states of chromium are Cr(III) and Cr(VI). Common oxidation
states for copper are Cu(I) and Cu(II) and copper is more stable as
Cu(II). Arsenic is a metalloid (shows the characteristics of both a
metal and a non-metal) and also has a tendency to exist in variable
oxidation states. Common oxidation states of arsenic are As(III) and
As(V). In addition, the pH of aqueous media or soil, nature of soil
(texture of soil, percent of organic carbon of the soil, etc.), salinity
of water, temperature of water, and soil are some of the factors that
give rise to the phenomenon of chemical speciation (formation of
different metal species) which is a common phenomenon in these
environmental compartments. Because of these variables, the metal ions
can form soluble or insoluble substance which can be cationic or anionic
species or full simple molecules or complex compounds. In general, these
metal ions exist in water and soil as:

a\. A free metal ion, which in aqueous medium is aquated (solvated or
complexed with water molecules);

b\. Simple inorganic species like oxides, hydroxides, halides,
carbonates etc.; or

c\. Complexed with organic and inorganic ligands.

[Copper:]{.underline}

The chemistry of aqua copper ions is dependent on the pH of the aqueous
medium. Up to pH 5, the only species present in water is aquated copper
ions. Starting at pH 7 and up to pH 14, at room temperature (25^o^ C ,
ionic strength of 1.0 M and incipient copper concentration of
1x10^-5^M), the prominent hydrolyzed copper species present are:
CuOH^+^, Cu(OH)~2~, Cu(OH)~3~^-^, Cu(OH)~4~^-2^ and Cu~2~(OH)~2~^+2.^ (
Baes C.F. and R.E.Mesmer 1976). The last two copper species are replaced
by the following species in the fresh and sea waters: CuHCO~3~^+^,
CuCO~3~, CuSO~4~, CuCl^+^, CuCl~2~ and Cu(CO~3~)~2~^-2^ (Long, D.T. and
E.E. Angino 1977). Cu(II) predominantly exists under aerobic conditions
and as Cu(I) under anaerobic conditions .

Literature searches have shown that in sea water, the average copper
concentration is 3μg/L (Emsley, J. 1989). The US EPA, however has
estimated that the dissolved copper concentrations in natural waters
varies from 1 to 10 μg/L (EPA Water Quality Criteria, 1984).

Copper binds strongly to hydrous iron, manganese oxides, clay minerals
and organic matter in the soils. Sorption of copper is a pH dependent
phenomenon and various chemical species of copper have different
sorption capacities. For example, CuOH^+^ is sorbed preferably to soils
than Cu^+2.^ The presence of anions can either increase or decrease the
sorption process. An experiment on the sorption of copper to Metapeak
soil showed that the presence of anions like phosphate, glycine/titrate,
nitriloacetate and humic acid increased the sorption of copper at pH ≤ 6
but no effect was seen above pH 6. Langmuir sorption constants for
copper on various media vary remarkably: The sorption constant for
copper on clay is 6, on hydrous iron oxide it is 130, while on manganese
oxide it becomes 1670 and decreases with organic matter down to 200. For
soils/sediment the sorption constant ranges from 28-34.

Copper is present in minerals like chalcopyrite (CuFeS~2~), cupric
ferrite

(α-CuFe~2~O~4~ and cuprous ferrite ( α-Cu~2~Fe~2~O~4~), most insoluble
copper substances, cuprite (Cu~2~O), malachite (Cu~2~(OH)~2~CO~3~)
(Hetrick, J. 1991). Copper occurs in sedimentary rocks like shales and
carbonates (from 4 to 50 μg-Cu/g), in ingenuous rocks like mafic and
felsik which may contain between 20 to 100 μg-Cu/g (Krauskopf 1979).
Copper concentration in soil water (pore water, which is chemically
bound to soils and sediments) is estimated to be between 10 and 60 μg/L
and between 2 and 100 μg/g for soils (Sanders 1982). Dissolved copper in
water and soils is a function of pH. It is estimated that at pH 5 and pH
7, at a constant ionic strength of 0.03M, dissolved copper
concentrations can be 7.77 μg/L and 1.52 ng/L respectively. At pH 9 the
copper concentration is about 0.749 ng/L (Lindsay, 1979). Soil/water
partitioning coefficients are estimated to be between 10 and 100,000
L/kg. This shows that since copper has a high binding affinity with
soils/sediments, copper introduced from non-natural sources is not
likely to migrate into ground water. However, copper could possibly move
over land via surface water runoff as well as through erosion of
contaminated soil particles.

[Chromium:]{.underline}

Cr(II) is unstable in water. Cr(III) goes through hydrolysis and forms
various species. The important species of Cr(III) found in aqueous
systems are: CrOH^+2^, Cr(OH)~2~^+^, Cr(OH)~4~^-^, Cr(OH)~3~(s). In
addition, polymeric species like: Cr~2~(OH)~2~ and Cr~3~(OH)~4~^+5^ are
also formed in water. All these species are present in aqueous systems
in the absence of any complexing agents. Similarly, Cr(VI) also
hydrolyzes in water and forms CrO~4~^-2^, (at pH \> 6.5), and HCrO~4~^-^
and Cr~2~O~7~^-2^ in acidic medium. In fresh water at pH 6 species
detected are: HCrO~4~^-^, Cr(OH)^+2^, Cr(OH)~2~^+^, CrO~4~^-2^, Cr^+3^
and Cr(OH)~3~(s). On the other hand, the species detected in sea water
at pH 8 are: CrO~4~^-2^, Cr(OH)^+^~2~, Cr(OH)~3~, NaCrO~4~^-^,
Cr(OH)^+2^, Cr(OH)~4~^-^, KCrO~4~^-^, HCrO~4~^-^ . Cr(III) is
kinetically stable and Cr(VI) is thermodynamically stable in aqueous
medium. Cr(VI) is more water soluble, and more mobile and can easily
move through wet soils into ground water and may become more
bioavailable. (Lebow, S. 1996). The half life of Cr(III) in water has
been estimated from being one month to 20 months and this shows
persistency of the metal (Pettine, M. and F.J. Millero, 1990)

Chromium goes through oxidation-reduction reactions when sorbed in
soils. Organic matter in soils, which has a high sorption capacity for
chromium, reduces Cr(VI) to Cr(III) spontaneously. Manganese oxides in
the soils, on the other hand, oxidize Cr(III) to Cr(VI). Chromate and
dichromate ions form soluble salts and increase the mobility of toxic
Cr(VI) in soils. Chromium as Cr(VI) reduces to Cr(III) under anoxic
conditions. In water at neutral conditions (pH 7), formation of
dichromate ions (chromium as Cr(VI)) is minimized. Cr(VI) is adsorbed
less and less by hydrous metal oxides and soils as the alkalinity of the
medium increases. The presence of anions like sulfate and phosphate
decrease the sorption phenomenon. At low pH and low concentrations of
chromium, however, adsorption of Cr(III) on iron and manganese oxides
increases.

[Arsenic:]{.underline}

The common and important arsenic ores are: tenantite, cobaltite,
arsenopyrite, niccolite and enargite. Arsenic has a great tendency to
sorb to soils and sediments. Its sorption capacity (μg total As/g soil)
with silty fine sand with little clay ranges from 1.0 to 252. For brown
clay sand it is between 1.0 to 80.0 and with fine sand the sorption
capacity varies from 1.1 to 7.9. Arsenic sorption is dependent on pH,
redox conditions, competing anions, salinity and clay content and
hydrous oxide content (aluminum or iron). Arsenic mobility in clay soils
is low to moderate. As(V) under proper conditions can reduce to As(III).
In aerobic and anaerobic sediments, arsenate is more strongly sorbed
than methylarsenic acid ( Holm, R.T. 1979; Wauchope, R.D. 1975).

As the sorption of arsenic decreases with rising pH, the mobility of
arsenic increases. Organoarsenates decrease the sorption of arsenic and
increase the arsenic mobility Organoarsenates are more mobile than
arsenic. Arsenic mobility in clay soils is low to moderate. However, in
loamy and sandy soils, mobility increases (6-10 cm/day for loamy sand).
Between pH 2 and 11, the common species of arsenic present in aqueous
medium are: H~2~AsO~4~^-^ and HAsO~4~^2-^. Beyond pH 12, it is mostly
HAsO~3~^2-^ and AsO~3~^-3^.

**[Fixation:]{.underline}**

Fixation is a chemical process which consists of a series of chemical
reactions that ensue after the wood has been pressure treated with CCA.
Fixation precedes the actual 'action' of CCA to act as a wood
preservative. It depends on a number of parameters: temperature,
humidity (moisture content of the wood), pH and drying period for the
wood after the pressure treatment has been completed. Under laboratory
conditions, increasing concentration of the wood preservative will lower
the pH of the solution mixture and will accelerate the rate of fixation
(Anderson, A.G. 1990).

The process of fixation consists of a series of chemical reactions:

First, 'an initial reaction' of absorption of the preservative to the
cellulosic and lignin components of the wood. Second, a primary
precipitation reaction which converts Cr(VI) to Cr(III) and this process
continues for the duration of fixation period. Lastly, the conversion of
copper arsenate into basic copper arsenate (Anderson, A.G. 1990).

Earlier research on the temperature effect on the fixation process on
scot pine and beech wood showed that increased fixation occurs when the
temperature was raised to 30 ^o^C and that the maximum fixation was
attained in 42 hours (Wilson, A. 1971). In another study on fixation
(Cooper, et al. 1992), it was shown that for western red cedar the
fixation process was best achieved at 70 ^o^C and 93% relative humidity
within 14.3 hours. For Douglas fir, red pine, lodge pole pine, southern
pine and jack pine the fixation at the same temperature and humidity
conditions was best achieved between 5.9 to 8.3 hours. In a study on red
pine it was shown a freshly treated wood when freezed dried and
reequilibrated with moisture, reduction of Cr(VI) to Cr(III) took place
even at low moisture contents or even at over dried conditions (Kaldas,
M. and P.A. Cooper, 1996).

Another series of studies on hemlock, grand fir, white fir, noble fir,
pacific silver fir and Douglas fir showed when the wood samples were
removed as the drying process was on, and systemically treated with CCA
by a full-cell process, the treatability and penetration of CCA into the
wood depended on the drying rate ( Lebow et al., 1996). In a related
study, it was shown that the fixation process is temperature dependent
(McNamara W., 1989).

In another study, the fixation rate of commercially available CCA on
sawdust, measured by arsenic leaching, showed that at about 20 ^o^ C,
98-99% CCA was fixated by day five. The same study also showed that as
the fixation process proceeds, the pH of the preservative rises
(Dalhgren S.E., 1972). Another study showed that rate of fixation also
depended on the type of wood (Wilson A., 1971).

The process of fixation has been traditionally looked upon as the
fixation of Cr(VI) changing into Cr(III) in the wood tissues. A recent
work on southern pine, jack pine, and red pine has indicated that copper
and arsenic components are stabilized (fixated) earlier than chromium
(Cooper et al., 1996).

[Special Leaching or Aqueous Availability:]{.underline}

The leaching of CCA metals (copper, arsenic and chromium) and subsequent
entrance of these metal ions into environmental compartments (water,
soil, plants and animals), two of these (arsenic and copper) are on the
EPA's list of Priority Pollutants, is an important process for
environmental fate and transport assessment. A very earlier work on
leaching of CCA was done on the wood used in residential houses to build
foundations and this study showed no significant leaching of CCA
components and the conclusion drawn at that time was that there was no
environmental hazard to the ground water, soil, plants or animals
(Arsenault, R.D., 1975). Later studies have not only contradicted this
observation but have elucidated the mechanisms of leaching and also
estimate the amounts of leaching of CCA metals from the treated wood.

A study conducted on the leaching of CCA from the treated wood into
saline water at different ionic strengths showed that chromium leached
the maximum amount and progressively as the ionic strength increased so
did copper leaching but at 9 and 24 percents copper salt concentrations,
leaching declined due to the formation of insoluble Cu~3~(AsO~4~)~2~ and
Cu(OH)CuAsO~4~. Arsenic leached the minimum amount under the
experimental conditions of this study (Irvine, J. and S.E. Dahlgren,
1976).

To elucidate the leaching mechanism of arsenic from CCA-treated wood, an
extensive study was carried out in the presence and absence of
electrolytes. This leaching study was conducted with a simulated
rainfall (rain intensity: 1±0.15 inch/hour). Southern pine, kiln-dried
plywood specimen (29.2 cm x 29.2 cm x 1.9 cm) were selected and treated
with 4% CCA solutions (CCA-A, B and C) in the presence and absence of
electrolytes. The mean absorption of the preservation solution was 17.12
pounds per cubic feet (pcf). Initially water runoff and soil leachate
samples were collected after 15, 30, 45 and 60 minutes of simulated
rainfall and then after 3, 9 and 27 hours of rainfall.

After the simulated rainfall, it was determined that plywood samples
showed a significant decline of arsenic on one face of the plywood from
3.23 mg/g to 1.441 mg/g and on the other face from 3.23 mg/g to 1.22
mg/g. Analysis of the soils (sand and loam) revealed that the amounts of
arsenic were not different for the soil in contact with the treated
plywood sample than the soils in contact with untreated (blank) plywood.
The amounts of arsenic in the surface water runoff was depended on the
texture of the soil and the time of exposure to the rainfall. Runoff
samples collected after one hour of simulated rainfall did not show the
presence of arsenic. The samples of CCA-C in the presence of the
electrolyte (sodium dichromate and copper sulfate) indicated the highest
arsenic absorption to the wood but also the highest leaching. The
surface water runoff collected from the loam soil had a higher
concentration of arsenic (44.5 μg/L) but in the sand the amount of
arsenic was only 7.3μg/L. The concentration of arsenic increased
dramatically for the first three hours of rainfall and then slowly
decreased thereafter. The soil leachates from the sand after the first
hour of rainfall with the CCA-B (non-electrolytic) showed the higher
concentration of arsenic (98.6 μg/L) but with CCA-C (electrolytic) the
amount was 61.3 μg/l. Loam soil leachates for CCA-B (non-electrolytic)
showed the presence of 11.9 μg/L arsenic and for CCA-C (electrolytic)
the arsenic amount was 22.2 μg/L. (Chen and Walters, 1979).

In another study, it was shown that from the southern pine wood the
metals from CCA leached much more from the high-temperature pressure
treated kiln-dried wood than the air-dried pressure treated wood.(Less
et al., 1993).

A leaching study conducted on southern pine, pressure treated with CCA-C
wood preservative, was submittted by the registrants to the Agency. The
study was carried out at three pHs: 5, 7 and 9, in 0.10M HCl and in
simulated sea water which was prepared according to the ASTM Method
D1141-90. The southern pine blocks (3.8 cm x 3.8 cm x 29 cm) were
pressure treated upto 0.80 pounds per cubic feet (pcf) for the studies
in pHs 5,7 and in 0.10 M HCl while the for simulated sea water, the
blocks were pressure treated upto 2.5 pounds per cubic feet (pcf). The
pressure treatment was carried out according to the AWPA Standards. The
study was conducted for 60 days altogether. The amounts of the metal
ions leaching was found highest with 0.10 M HCl solutions: total arsenic
leaching in 0.10M HCl on day 1 was 170 μg/cm^2^/day and it declined to
27 μg (day 30). However, when arsenic was examined in its two common
oxidation states, As(III) leached at a rate of 10μg/cm^2^/day ( day 21)
and it increased to 38 μg/cm^2^/day on day 30 while for As(V), the rate
was 10μg/cm^2^/day on day 21 and it increased to 22 μg/cm^2^/day on day
30. The rate of leaching for Cu(II) in 0.10M HCl was 149 μg/cm^2^/day on
day 1 and declined to 22 μg/cm^2^/day on day 30. The rate of leaching
for total Cr in the in presence of 0.10M HCl was 46 μg/cm^2^/day for day
5 and declined to 30 μg/cm^2^/day on day 30. When analyzed for Cr(VI),
the leaching rate in 0.10M HCl was 1.5 μg/cm^2^/day for day 21 and
reduced to 1.0 μg/cm^2^/day for day 30 (Stanley, J.S., 1994).

In a 40-day study conducted in Canada on the pressure-treated jack-pine
with CCA at various pHs of 3.5, 4.5, 5.5, 7.0 and 8.5 and also in a
solution containing dilute sulfuric acid (0.10N). The pressure treated
blocks were separated into two sets: One set was kept in open air for
one year to simulate 'weathering'. The second set of blocks were kept
in-house to simulate 'new conditions'. All blocks were of uniform
dimensions of 5 cm^2^. The preservation retention of the blocks was
close to but not exactly like CCA-C (the recommended level by AWPA
Standards is 0.40 pcf (6.4 kg/m^3^).

'Weathered' blocks leached copper significantly more at pH 3.5, 4.5 and
5.5 than the 'fresh' blocks. Release of chromium was less at pH 3.5 and
4.5. Arsenic showed a higher release rate at pH 5. Generally, the
leaching order was Cu \> As\>Cr. It is recognized that fixation of
chromium (conversion of Cr(VI) to Cr(III) ) prevents the leaching of
chromium from the wood. The pHs in this study were maintained using
citric acid/NaOH mixture solutions, and in distilled water a pH of 7 was
maintained. The borax/HCl solution resulted in pH 8.5. A similar trend
was observed when the leaching was conducted in dilute sulfuric acid
solution at pHs 2.5, 3.5 and 4.5 (preservation retention was 0.13 pcf
(1.99 kg/m^3^) (Warner, J.E. & K.R. Solomon, 1990).

A 13-day study on leaching from douglas-fir, redpine, lodgepole fir and
western red cedar, pressure treated with 2.3% CCA showed and confirmed
that the presence of citric acid/NaOH buffer increases the rate of
leaching from the wood at a high pHs like pH 7. (Cooper, P.A., 1991).

A twelve month study was conducted on leaching of CCA-C metals from
pressure treated jack pine wood with 1.8% CCA-C treatment solution and a
preservative retention of 0.40 pcf (6.4 kg/m^3^ ). In this study,the CCA
metals from these pressure treated wood blocks were leached into four
different compartments: leaching into distilled water, leaching into
natural weathering conditions, leaching into soil burial and leaching
into compost (made by vegetable matter). It was observed that leaching
into compost was higher than into other compartments: 13% leaching was
observed in the compost, in soil burial it was 1.3%, weathering sample
showed about a 1.5% leaching and leaching into distilled water was about
5%. Leaching order, however, was the same as with other studies: Cu\>
As\> Cr. (Cooper et al., 1992).

A similar 21-day leaching study with southern pine sapwood, pressure
treated with 1.03% CCA-C with preservative retention of 0.3 pcf (4.8
kg/m^3^ ) showed a leaching rate of 1 μg/cm^2^/day for Cu and As and
0.01 μg/cm^2^/day for Cr which is the same trend (copper ≈ arsenic \>
chromium) as other leaching studies have shown (Merkle, et al., 1993).

In an Australian Study, Tasmanian Parks and Wildlife Service (M.
Comfort, Scientific Rep. 93/1, 1993), conducted a leaching study on
Southern Tasmanian boardwalks (ages 1 to 14 years) which were the
pressure treated with CCA. Soil samples collected about 6 inches and a
few meters away form the boardwalks showed that the chromium (88 ppm)
and copper levels (49 ppm) in the close proximity samples were high
compared to the distant ones which were not different from the blank
samples. The blank samples showed chromium at 20 ppm and copper between
1-3 ppm. The ages of the boardwalks did appear to contribute in the high
levels of the metals.

In a European study (Italy), on CCA leaching from treated wood, rain
water was used for extraction. CCA treated wood samples from a post were
meshed through a 5 mesh, 25 springs/cm^2^ sieve. The coarse powder so
obtained was digested in 96% sulfuric acid and 3% hydrogen peroxide in a
5:1 ratio and the analyses showed the presence of As ( 1.602 mg/g), Cr(
1.345 mg/g) and Cu(0.813 mg/g). Before the extraction, rainwater which
was collected in Turin in 1994, was analyzed for the presence of anions
and cations including As, Cr and Cu and the amounts of these
respectively were: 0.068, 0.029 and 0.021(all in mg/L). This rainwater
was then used to extract the coarse powder and the leachates were
collected at different times, the last one was 78-hour leachate. The 78
hour extraction sample contained As and Cr ( 50 μg/g) and Cu( 150μg/g).
The same study also conducted the extractions at pHs 6 down to 3.
Maximum amounts of metal ions were released at pH 3. A similar trend was
observed in another study. The CCA solution used in the study was
purchased commercially and in the stock solution each metal ion was
about 1000mg/L from which running samples were prepared (Aceto, M. and
A. Fedele, 1994).

In a study in simulated sea water, it was observed that copper leached
into water from pressure treated full-sized pilings at 529 mg level and
arsenic level was measured at 60 mg and little or no chromium was
measurable (Baldwin et al., 1994).

In a freshwater study on the old lockgates and freshly constructed
lockgates of pressure treated wood with CCA the copper concentrations
(200 ppb) were high at the newly constructed lockgates, 40 meters
downstream, while the concentrations of copper were low at the old
lockgates (40 ppb). Chromium concentrations were the same (90 ppb) at
both locations while arsenic was 90 ppb level at the new lockgate and at
60 ppb level 40 meters downstream (Cooper, P.A., 1991).

In another study, the leaching of the metals from CCA was investigated
as the fixation process was in progress. It was carried out on the pole
sections (8\" x 2\' diameter) of red pine poles which were pressure
treated with CCA-C of 1.7% and 3.5% concentrations as well as with
pressure treated (1.5% CCA-C) the jack pine boards (2\" x 6\" ). The
study was conducted at 95% humidity and 60 ^o^ C. As the fixation
process proceeds, the metals from the CCA-C were extracted by 2-hour
long spray of simulated rain (rainfall: 150 mm). The concentrations of
the metal ions in the leachates progressively declined as chromium
fixation process progressed. Arsenic stabilized (fixed) faster than
copper fixation which in turn was faster than chromium fixation. For red
pine, pressure treated with 1.7% CCA-C at 95% humidity and 60 ^o^ C, the
preservation retention was 0.48 pcf (7.7 kg/m^3^ ) and 1.02 pcf (16.4
kg/m^3^ ) when the CCA-C solution was 3.5%. The retention for jack pine,
under the same humidity and temperature conditions, the preservation
retention was 0.24 (3.9 kg/m^3^ ) when the wood was pressure treated
with 2 % CCA-C solution.

For the red pine pole at both the preservation retentions of 0.48 and
1.02 pcf and 99.9% chromium fixation level, the leaching losses from the
wood were: 4 μg/cm^2^ for Cr, 9 μg/cm^2^ for Cu and 3 μg/cm^2^ for As.
For the jack pine wood, on the other hand, at 99.9% chromium fixation
level, the leaching losses of the metal ions from the wood were: 0.28
μg/cm^2^ for Cr, 0.88 μg/cm^2^ for Cu and 0.62 μg/cm^2^ for As. The
leaching losses continued to decline as the Cr(VI) fixation progressed
from 60-70% to 99.9% level (Cooper et. al, 1995).

A recent estuarine study on the southern yellow pine, pressure treated
with CCA-C, reaffirmed the results from previous studies that the
leaching of the metal ions from the wood was highest for Cu and lowest
for Cr. This study measured the laboratory leaching rates for copper,
arsenic and chromium from the freshly pressure treated southern yellow
pine as well as the actual loss of these metal ions from a weathered
CCA-C treated lumber which had been service for 14 years as a bulkhead
in Sayville, New York, south shore estuarine canal. The retention level
of the CCA-C in this weathered bulkhead was between 0.61 pcf to 1.0 pcf
(=9.6 to 16.0 kg/m^3^ ) as communicated by S. Roller Lumber Corp. This
lumber from the canal was chosen as it had experienced 4 types of
weathering:the wood surface at the water level

(air exposure), the wood surface exposed to tidal water off and on
(air/water exposure), the wood surface continuously submerged in water
(water exposure) and last, the wood surface buried deep in the sediment
below the canal. (soil exposure). The CCA-C retention level for the
weathered lumber was 0.20 pcf (=3.1 kg/m^3^ ) for surface exposed to
air, 0.30 pcf (=5.0 kg/m^3^ ) for the wood surface exposed to tidal
water off and on, 0.068 pcf (=1.1 kg/m^3^ ) for the wood surface
submerged under water and 0.60 pcf (9.9 kg/m^3\ )^ for the wood surface
buried in the sediment. The leaching losses of the metal ions from these
weathered surfaces were in the order of: subtidal (wood surface exposed
to air and water) \> tidal ( wood surface submerged in water) \> air \>
sediment. The extent of metal ions leaching was in the same order as the
laboratory leaching studies: Cu \> As \> Cr.

The laboratory leaching study by the same group showed that the freshly
pressure treated southern yellow pine (CCA-C), the leaching rates for
the metal ions were: 5.71-17.78 μg/cm^2^/day for Cu, 0.20-0.98
μg/cm^2^/day for Cr and 0.15-0.90 μg/cm^2^/day for As, for the initial
12-hour. This laboratory leaching study was conducted under saline
conditions (3,13, and 26 ppt) which generally mimic the estuary
conditions. The preservation retention level for CCA-C in the southern
yellow pine was between 0.29 pcf to 4.0 pcf (4.6-64.0 kg/m^3^ ) when
measured all over the wood. Overall, the preservation retention level,
however, was 2.5 pcf (40.7 kg/m^3^ ). The analysis of the metal ions in
the leachates, expressed as the oxide ratio yielded: 48.8:36:15.4
(CrO~3~:As~2~O~5~:CuO) which was very close to the actual ratio of
47.5:34:18.5 which is the recommended ratio by AWPA Standards. The
Agency has noted that the retention level of CCA-C under marine water,
as recommended by AWPA, should be at least 2.5 pcf (40.7 kg/m^3^ ).
However, AWPA recommends that retention level southern yellow pine wood
in some areas of the USA like north of New Jersey and north of San
Francisco can be about 1.5 pcf (24 kg/m^3^ ) ( Breslin and
Adler-Ivanbrook, 1998).

Some laboratory and field studies have shown that the leaching process
is aided by slow or drizzling rain than by heavy showers (Evans, F.G.,
1987; and Cockroft and Laidlaw, 1978).

Most of the leaching from the treated wood in the field and laboratory
tests take place in the first few days after the application of the wood
preservative. Leaching rates depend on the size of the wood, type of
wood, fixation process. I has been shown that the round posts show a
higher rate of leaching than the saw dust of the lumber. Hardwood leach
more than softwood. Pressure-treated red-pine leaches at a higher level
than do the lodgepole, Douglas fir, and the red pine (Cooper, P.A.,
1990).

No leaching study has addressed the issue of whether the metals leach as
copper, or copper arsenate, or chromium arsenate or as complexes with
inorganic or organic ligands or as derivative of wood-metal moieties or
as water soluble wood extracts. If the metals get complexed with organic
ligands and become more mobile in soils and these then will not be
adsorbed to humic substances.

Mobility in water for these metal ions from the CCA depend on many
factors which may give rise to a number of pathways: these metals can
first diffuse through the soils as complexes, simple salts, or free
ions, or percolate through the soils as insoluble substances and are
then carried to the water systems. Porous soils help the wood
preservative components to move through into water and this increases
the mobility of the metals in water. As insoluble and having been
deposited on the sediments, these metals can be of environmental concern

(bioaccumulation) for the benthic organisms.

[Migration into soils:]{.underline}

In an earlier work (DeGroot, et al., 1979) on CCA-A, CCA-B and
ACA-treated southern pine wood stakes which were installed thirty years
prior to the leaching study in acidic porch fine sandy soil in southern
Mississippi, it was shown that the amount of leaching and mobility of
the metal ions in the acidic soil is not significant. Background levels
of As, Cr and Cu in this soil core depths were measured and are shown
below:

Depth As\* Cr\* Cu\*

0-6 in. 1.3 3.8 4.0

6-12 in. 0.6 7.5 4.2

12-18 in. 1.0 6.9 6.6

\* All values were reported in ppm and at 95% confidence interval

The preservation retention level for CCA-A was 0.70 pcf (10.6 kg/m^3^ )
and for CCA-B it was 0.55 pcf ( 8.8 kg/m^3^ ).

Table 1 summarizes the amounts of the metal ions that have leached into
the soil from these stakes over a period of thirty years. The data
includes the vertical transfer (downward migration from the stake) and
vertical or lateral migration from the base of the stake of the metal
ions.

TABLE 1

+---------+---------+---------+---------+---------+---------+---------+
| Le      |         |         |         |         |         |         |
| vels^4^ |         |         |         |         |         |         |
| of As,  |         |         |         |         |         |         |
| Cr and  |         |         |         |         |         |         |
| Cu in   |         |         |         |         |         |         |
| soil    |         |         |         |         |         |         |
| core    |         |         |         |         |         |         |
| after   |         |         |         |         |         |         |
| v       |         |         |         |         |         |         |
| ertical |         |         |         |         |         |         |
| (       |         |         |         |         |         |         |
| do      |         |         |         |         |         |         |
| wnward) |         |         |         |         |         |         |
| and     |         |         |         |         |         |         |
| lateral |         |         |         |         |         |         |
| t       |         |         |         |         |         |         |
| ransfer |         |         |         |         |         |         |
| from    |         |         |         |         |         |         |
| the     |         |         |         |         |         |         |
| stakes  |         |         |         |         |         |         |
+=========+=========+=========+=========+=========+=========+=========+
| Soil    | As      | As      | Cr      | Cr      | Cu      | Cu      |
| core    |         |         |         |         |         |         |
| loca    | C       | CC      | CCA-I   | CCA-II  | CCA-I   | CCA-II  |
| tion^2^ | CA-I^1^ | A-II^1^ |         |         |         |         |
+---------+---------+---------+---------+---------+---------+---------+
| (b      | 18.9^3^ | 108.1   | 25.1    | 22.9    | 56.6    | 48.3    |
| eneath) |         |         |         |         |         |         |
|         |         |         |         |         |         |         |
| 0-6     |         |         |         |         |         |         |
+---------+---------+---------+---------+---------+---------+---------+
| 6-12    | 1.6     | 21.4    | 8.2     | 7.4     | 6.9     | 8.2     |
+---------+---------+---------+---------+---------+---------+---------+
| 12-18   | 1.2     | 1.1     | 9.2     | 6.2     | 5.7     | 6.4     |
+---------+---------+---------+---------+---------+---------+---------+
| (       | 73.2    | 183.2   | 45.9    | 24.2    | 75.8    | 47.9    |
| lateral |         |         |         |         |         |         |
| tr      |         |         |         |         |         |         |
| ansfer) |         |         |         |         |         |         |
|         |         |         |         |         |         |         |
| 0-0     |         |         |         |         |         |         |
+---------+---------+---------+---------+---------+---------+---------+
| 0-3     | 5.6     | 117.7   | 9.4     | 8.2     | 11.8    | 15.3    |
+---------+---------+---------+---------+---------+---------+---------+
| 6       | 1.3     | 7.0     | 4.7     | 6.4     | 5.6     | 4.9     |
+---------+---------+---------+---------+---------+---------+---------+
| 9       | 1.5     | 4.9     | 6.2     | 5.3     | 12.3    | 7.2     |
+---------+---------+---------+---------+---------+---------+---------+

Notes:

1\. CCA-A and CCA-B in the present terminology

2\. Distance reported in inches

3\. All values in ppm

4\. At 95% confidence interval.

The above data indicated that in acidic soil the leaching and migration
of metal ions was not very high either beneath (downward migration) the
soil or by lateral transfer (ground level migration) of the metal ions
from the stakes.

In a Nigerian study, on soil and vegetable contamination in and around a
CCA wood treatment factory, very high levels of the metal ions were
detected and these levels progressively decline significantly as one
moves away from the treatment and storage sites. High levels of the
metal ions were also detected in the vegetables and crops grown within
the premises of the factory. The concentrations of the metal ions were
measured in the top 4 cm of soil at and around the treatment/storage
facility. Table 2 summarizes the concentrations of the metal ions at
various location in and outside the factory. The study did not provide
the information of the type of soil at the factory premises and also
which type of CCA (A, B or C type) was used by the wood treatment
factory.

Table 2

  -------------------------------------------------------------------------------------
  Measured metal                                                             
  ion                                                                        
  concentrations                                                             
  in top 4 cm soil                                                           
  in a wood                                                                  
  treatment                                                                  
  factory &                                                                  
  background level                                                           
  concentrations (                                                           
  in μg/g, dry                                                               
  weight)                                                                    
  ---------------- ----------- ---------- ----------- ---------- ----------- ----------
  Sampling Site    As(conc.    As (mean)  Cr(conc.    Cr(mean)   Cu(conc.    Cu(mean)
                   range)                 range)                 range)      

  1                3456-7148   5312       2154-5810   3996       3817-7216   5424

  2                956-4678    2552       868-3740    2046       1618-5478   3460

  3                1092-3508   2211       788-3158    2005       2031-5180   3710

  4                238-921     597        197-764     498        407-1062    763

  5                8.4-21      16.1       38-78.6     59.3       67.4-103    82.9

  6                0.1-40      6          5-1500      70         2-250       30
  -------------------------------------------------------------------------------------

Notes: Sampling site \# 1: soil samples from the preparation and mixing
sites in the factory.

Sampling site #2: soil samples from the areas in the factory where
freshly treated wooden poles are stacked.

Sampling site# 3: soil samples from the areas where sludge is deposited
inside the factory.

Sampling site#4: soil samples from 12 randomly selected sites inside the
factory.

Sampling site 5: soil samples from 1 km distance from the factory site.

Sampling site 6: Background concentrations as reported in literature.

(Bowen, H.C., 1979)

In a recent study, 85 samples of contaminated soil were obtained from
under and around seven decks which were CCA pressure treated and the
ages of these decks were from 4 years to 15 years. These soil samples
were composites of the upper 5 cm soil layers and the soil type was
sandy loam. The extraction of the metal ion from the soil samples was
carried out by digesting into conc. nitric acid under a pressure of 120
psi in a microwave oven and then diluted with deionized water. The
concentration of the metal ions were determined by using ICP-AES
(inductively coupled plasma atomic emission spectrometry). In addition,
arsenic also determined with graphite furnace atomic absorption
spectrometer (GFAAS). The average amounts (in mg/kg) were: 75 for Cu, 43
for Cr and 76 for As. These amounts indicate the leaching of the CCA
components into the soil is high. This study also showed that the
amounts of the metal ions increased in the soil with the age of a deck.

The same study also indicated that soil samples taken 15 cm from the
deck perimeter showed the average amounts (mg/kg) of the metals to be:
67 for Cu, 46 for Cr and 32 for As which indicates that the soil
contamination decreases a short distance away from the deck perimeter.

Table 3 summarizes the average amounts of these metal ions along with
the amounts from control samples as well as EPA's statutory limits on
these metal ions.

Table 3

+-------------+-------------+-------------+-------------+-------------+
| Average     |             |             |             |             |
| amounts of  |             |             |             |             |
| metal ions  |             |             |             |             |
| (mg/kg) in  |             |             |             |             |
| the soil    |             |             |             |             |
| samples     |             |             |             |             |
| beneath     |             |             |             |             |
| decks and   |             |             |             |             |
| statutory   |             |             |             |             |
| limits      |             |             |             |             |
+=============+=============+=============+=============+=============+
| Location/   | Copper      | Chromium    | C           | Arsenic     |
| Statutory   |             |             | hromium(VI) |             |
| Limits      |             | ( total)    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Beneath     | 75          | 43          | nd          | 76          |
| decks       |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Control     | 17          | 20          | nd          | 4           |
| soils       |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| EPA         | 1500        | 1200        | \-          | 41          |
| 503(1993)   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| State of CT | 2500        | 3900        | 100         | 10          |
| (1996)      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

This study, did not point out which type of wood was used for the decks

(southern pine or red pine etc.) and which type of CCA was used for
pressure treatment of the lumber (Stilwell, D.E. and K.D. Gorny, 1997).

3\. [Biotic Transformations & Bioaccumulations]{.underline}:

An earlier study (Chou, et al., 1973) showed that between 3-4% of the
metal ions were taken up by the Poria Monicola Fungal Hyphae on the
pressure treated southern pine veneers with CCA which contained
potassium dichromate, copper sulfate pentahydrate and arsenic pentoxide
dihydrate in the ratio of 9:7:4.

Another comprehensive study (Irvine and Dahlgren 1976), the growth of
number of marine and non-marine fungi and bacteria were affected when
exposed to copper -chrome-arsenate put in an agar media. Table 4
summarizes the Minimum Inhibition Concentration (MIC) of the CCA
components needed to affect the growth of the these organisms.

Table 4

**[Minimum Inhibition Concentration Values for Marine & Non-Marine
Fungi]{.underline}**

  --------------------------------------------------------------------------
  Type of Fungi          CuSO~4~      Na~2~Cr~2~O~7~   As~2~O~5~    CCA %
                         (mg/L)       (mg/L)           (mg/L)       
  ---------------------- ------------ ---------------- ------------ --------
  Marine:                                                           

  Corollospora cristata  137          482              244          0.2

  Lulworthia sp.         274          482              488          0.1

  Ceriosporopsis halima  546          1,928            976          0.2

  Asteromyces cruciatus  546          2410             \>1220       0.4

  Cladosporium herbarum  \>1,370      482              \>1,220      0.2

  Dendryphiella salina   1,096        964              1,220        0.4

  Monodictys pelagica    274          482              244          0.1

  Diplodia oraemaris     274          964              122          0.1

  Zalerion maritimum     137          241              122          0.05

  Cirrenalia             68.5         482              244          0.05
  macrocephala                                                      

  Non-Marine:                                                       

  Chaetomium globosum    546          241              488          0.05
  (P117)                                                            

  Chaetomium             274          482              244          0.025
  globosum(R24)                                                     

  Leptosphaeria sp.      546          120.5            488          0.025

  Melogramma sp.         1,096        241              61           0.0125

  Botryosporium sp.      1,370        120.5            244          0.4

  Phoma sp.              546          964              976          0.1

  Fusarium sp.           546          482              976          0.025

  Doratomyces sp.        137          120.5            488          0.025

  Stachybotrys atra      274          120.5            488          0.025

  *Graphium              274          60.3             244          0.0125
  sp[.]{.underline}*                                                
  --------------------------------------------------------------------------

Note: \* means that growth of the fungi were stimulated at low
concentrations.

For most of the microorganisms the M.I.C. values for chromium ranges
from 120.5 to 964 mg/L except for *Ceriosporopsis halima* (1928 mg/L)
and *Asteromyces cruciatus*

(2410 mg/L). In case of arsenic tolerance, most of the organisms had
M.I.C. values between 244 to 976 mg/L except for *Asteromyces cruciatus*
(1220 mg/L), *Cladosporium herbarum* (1220 mg/L) and Dendryphiella
salina (1220 mg/L). The majority of the organisms showed M.I.C. values
between 274 to 546 mg/L vis-a-vis copper except for *Melogramma sp.*
(1370 mg/L) and *Dendryphiella salina* (1370 mg/L). The range of
tolerance for arsenic and chromium by these microorganisms were more
than for copper.

It has been shown that in an estuary there are different pathways by
which the CCA components leaching from the treated wood can impact the
aquatic biota.. CCA components can dissolve in water forming aquated
cations. These species can then be taken up by biota. Epibiotic
organisms. Fouling organisms that live directly on the wood have the
highest uptake of the contaminants. These metallic contaminants can be
absorbed by sediments near the wood (e.g. docks). These can then are
taken up by the benthic organisms. These could be biomagnified through
the food chain. The uptake (bioaccumulation) of these metallic
contaminants depend on the concentration of the metallic species which
in turn depend on the amount of water flow in an estuary, amount and age
of the CCA treated wood. Green algae *Ulla lactuca and Enteromorpha
intestinalis*, collected from the CCA-treated bulkheads in Southhampton,
NY showed a higher degree of bioaccumulation for all three metal ions
whereas the species collected from the nearby rocks showed a lower
degree of bioaccumulation. *Enteromorpha*, for example, collected from
the dock showed a bioaccumulation of 55 μg/g Cu, 6 μg/g of Cr and 4.7
μg/g of As; however, the same microogranism collected from the nearby
rocks showed a bioaccumulation level of 14 μg/g for Cu, 2.5 μg/g of Cr
and 1 μg/g of As. (Weis and Weis, 1992a).

In another study, (Weis, et al., 1993a) it was shown that if the
organisms are tested for bioacuumulation in a body water where the water
flow rates are different, the contaminants are bioaacuumulated at
different levels. For example, algae *Cermium sp.*, oysters

*Crassostrea virginica*, barnacles *balanus eburneus*, and mussles
*Brachydontis recurvis* were collected from a CCA-treated dock in an
open water environment and from bulkheads in a poorly flushes
residential canal adjoining Santa Rosa Sound, Pensicola Beach, Florida
as well as from the nearby rocks in open water. Open-water docks
organisms had a significantly higher level of bioaccumulation. For
example *Ceramium*, living in open water area, showed a copper
concentration of 3 μg/g , an increase of 2 μg/g from non exposed
organisms, arsenic showed an increase from 3 μg/g (non-exposed organism)
to 5.5 μg/g. The same study showed that organisms (e.g. barnacles) that
grew on rocks nearby the dock, had a 1 μg/g of copper bioaccumulation,
those on the open water dock had 3 μg/g of copper, those in the canal
(poorly flushed areas) has about 10 μg/g of Cu and those that grew on
the new wood docks (1 year old) inside the canal had a bioaccumulation
of 80 μg/g Cu. In a related study (Weis, et al., 1993 b), it was shown
that the tissues of oysters living inside a canal showed the
concentration of Cu to be 150 μg/g, an increase of 12-fold over the
controls. The same oysters did not show an increased bioaccumulation for
the other two metals. Other studies have also shown the same trend,
oysters have a tendency of bioacumulating copper more than other metals
(Schuster & Pringle, 1969).

A study on the sediments adjacent to and close by distances to
CCA-treated bulkheads, on analyses showed a higher level of the three
metal ions. Sediments adjacent to bullheads in New York and New Jersey
estuaries consist of fine-grained particles (silt and clay often less
than one percent). These sediments in these locations showed a very high
concentration of the metals between 100-2000 μg/g. Sediments which were
ten meters away from the bulkheads, consisted of higher percentages of
silt and clay (up to 60%) showed a lower concentrations of the metals.
Sediments in poorly flushed areas showed a higher concentrations of the
metals then the ones which are open water areas with regular water
flows. Again the sediments around the newly built bulkheads showed the
highest concentrations of the metals.

These sediments can possibly become a pathway of exposure to the benthic
biota as shown in another study. Fiddler crabs *U. Pugilator* showed
that the metal concentrations were double in the organisms than on the
sediments (Weis and Weis, 1992 a).

In 1979, The Agency published a document Water-Related Environmental
Fate of 129 Priority Pollutants ( EPA-440/4-79-029a) which summarized
the open literature searches the fate of these Priority Pollutants in
aqueous medium. The fate and transport of arsenic, chromium and copper
are discussed in the following paragraphs:

Arsenic:

Table 5 summarizes the bioconcentration factors for arsenic in various
taxa:

Table 5

  -----------------------------------------------------------------------
  Taxon                   Bioconc. Factor         Reference
  ----------------------- ----------------------- -----------------------
  Freshwater Plants       333                     Chapman, et al., 1968

                          6000                    Reay, 1973

  FreshWater fish         333                     Chapman, et al., 1968

  Marine Plants           333                     Chapman, et al., 1968

  Marine Invertebrates    333                     Chapman, et al., 1968

  Marine Fish             333                     Chapman, et al., 1968
  -----------------------------------------------------------------------

Note that the bioconcentration factors were reported as the ratio of the
concentration of the element in the aquatic organism (in ppm, dry
weight) to the concentration of the element in water (in ppm).

The data from the table indicate that arsenic does show a tendency to
accumulate through water and biomagnification (food). The
bioconcentration factors are not large, however, The EPA document also
reported other bioaccumulation studies:

a\. Isensee et al. (1973) conducted a microcosm study on the
bioaccumulation of cacodylic acid derived arsenical and dimethyl arsine
for 32 days. This simulated ecosystem contained algae, snails, daphnia
and fish. Fish had minimum bioaccumulation in this selected group.
Snails were next in line in bioaccumulating arsenic while the algae and
daphnia showed the highest tendency to bioaccumulate arsenic. At the end
of the study period (32 days), only 30% of arsenic was incorporated by
the biota.

b\. Green sunfish *Lepomis cyanellus* was exposed to various
concentrations of sodium arsenate and the data indicated that the
bioaccumulation of arsenic (presumbaly as As^+5^) was a function of the
sodium arsenate concentrations. The uptake of arsenic by liver, gut and
muscle was also found to depend on the temperature.

c\. A sixteen week exposure with sodium arsenate to young and adult
bluegills

*Leomis marchochirus* showed that the concentration of arsenic in the
adult bluegill was the same as in the pond but the arsenic levels in the
young bluegills were twice as high as in the adults

d\. A fish in a pond which was accidently contaminated with arsenical
was analyzed and arsenic level was 2.5 mg As/L; fish accumulated 6.6 μg
As/g in muscle, one fifth of what is in water. Lake Michigan plankton
and benthos showed a concentration factor of 6.0 and 6.6 μg/ As /g
respectively. Analysis of biota in Lake Superior showed the plankton
contained 30% less As than the Lake Michcigan Plankton.

The same EPA document reported bioaccumulation and bioconcentration
information about chromium which is summarized in the following:

Chromium:

Table 6

Bioconcentration Factors for Chromium

Taxon Bioconcentration Factor Reference

Freshwater fish 200 Chapman et al., 1968

Freshwater invertebrates 2,000 Chapman et al., 1968

Fresh water plants 4,000 Chapman et al., 1968

Marine fish 400 Chapman et al., 1968

Marine invertebrates 200 Chapaman et al., 1968

Marine plants 2,000 Chapman et al., 1968

Benthic algae 1,600 NAS\*, 1974

Phytoplankton 2,300 NAS, 1974

Zooplankton 1,900 NAS, 1974

Mollusc viscera 440 NAS, 1974

Crustacean muscle 100 NAS, 1974

Fish muscle 70 NAS, 1974

NAS \* means National Academy of Sciences.

An early study determined the chromium partitioning between water,
sediment and chironomid larvae (a benthic invertebrate). Highest
concentration of chromium was found in the sediment (7.64 μg/g),
followed by bioaccumulation of 2.96 μg/g of Cr in the chironomid

and 1.1 μg/l in water (Namminga and Wilhm, 1977).

Another study showed a biomagnification of chromium when benthic worm
(tubificid) when fed with chromium rich bacteria bioaccumulated
(extracted) the metal from the bacteria

(Patrick and Loutit, 1976).

Radiolabed Cr(III) was found to biomagnify through the food chain in an
estuarine. The food chain consisted of phytoplankton, brine shrimp,
post-larval fish and mummichog. The concentration of the radiolabeled
chromium declined in the food chain through trophic levels

(Baptist and Lewis, 1969).

Copper:

EPA's 1984 document also reported some studies on the bioaccumulation of
copper. These are summarized as follows:

Namminga and Wilhm in 1977 reported the results of study on heavy metals
conducted in an Oklahoma Stream. It was observed that chrionomid larvae
( benthic biota) accumulated copper as do the water column and the
sediment matrix where this species is found. The concentrations of
copper in water column, sediment and the larvae respectively were: 4.1
μg/L, 1.8 μg/g and 1.91μg/g.

In other studies it was established that copper was not biomagnified.
Bioconcentration in fish were lower than the concentrations in algae.

Table 7 summarizes the Bioconcentration Factors for Copper in various
trophic levels.

Table 7

Bioconcentration Factors for Copper

Taxon Bioconc. Factor Reference

Algae

*Scenedesmus guadricarda* 12 Khobot' et al. 1976

*Anabaena variabilis* 300 Khobot' et al. 1976

*Scenedemus sp.* 2400 Stokes et al. 1973

*Chlorella sp.* 2400 Stokes et al. 1973Bacteria 630-1567 Patrick &
Loutit 1976Plants, Marine and Fresh 1000 Chapman et al.
1968Invertebrates

Marine 1670 Chapman et al. 1968

Freshwater 1000 Chapman et al. 1968

Mollusc 30,000 Raymont 1979

Insects 546 Namminga, Wilhm 1977

Fish

Marine 667 Chapman et al. 1968

Freshwater 200 Chapman et al. 1968

Another study was conducted on the bioaccumulation of metals on the
benthic (sediments and microorganisms) impacted by the CCA treated wood
bullheads in a large Atlantic Coast Estuaries. Accumulation of metals
around the bulkheads and bioaccumulation in microorganisms were
investigated at distance zero to 1, 3 and 10 meters from the bulkheads.
Five sites, with different bulkhead ages, were chosen:

a\. Middle Pond in Southhampton, New York. The bulkhead was one year
old. Additionally, two reference sites, one an unbulkheaded site in the
same pond and the second a bulkhead made up of aluminum in the nearby
estuary at Bullhead bay in Southampton, N.Y.

b\. Old Fort Pond, also in Southampton. This was an eight year-old
bulkhead in a poorly flushed location. A transect from the opposite
shoreline was chosen as a reference.

c\. Bulkheads along the Debardaue Canal, at the North Inlet Research
Reserve in South Carolina. These were 2 year-old bulkheads with
intertidal situation and the Canal itself was very well-flushed. An
aluminum bulkhead in the same vicinity was chosen as a reference site.

d\. A two-year old bulkhead in Osborn Cove off the Patuexent River in
the Chesapeake Bay, Maryland. This was a poorly flushed location and the
natural shoreline was used as a reference site, 30 m across the cove.

e\. A pair of adjacent bullheads at the Drum Point in Solomon, Maryland.
One bulkhead was a CCA-treated (approximately 6-8 year old) and the
second was made up of concrete.

Generally, the impact of CCA-treated wood in an estuary depended on the
surface area exposed to leaching, the leaching rate itself, metal
speciation (type of metal species present under the conditions), rate of
uptake ( bioaccumulation) by epibiota,, tidal activity ( well or
poorly-flushed) locations, adsorption by sediment ( a function of
particle size of the soil), trophic transfer to grazers and predators.

In the following the data summary is presented:

[Middle Pond:]{.underline}

Sediments around the bulkhead were variable and made up of coarse and
fine mixture. Fine sediment fraction was more at 10 meter from the
bulkhead and find fractions generally retained the metals more tightly
than the coarse fraction of the sediment. However, the percent of the
contaminants (the metals from the leaching from the wood) was highest at
distance 0 meter from the bulkhead.

The concentration (bioaccumulation) was highest in the microrgansims at
distance 0 meter from the bulkhead and progressively decreased to 1 to 3
to 10 meters away form the bulkhead. Comparatively, the metal
contamination (bioaccumulation) of mcirorganisms at the reference site
was much lower than at the experimental site. The organisms present at
the experimental and references sites were: Marenzelleria virdis,
Leitoscoloplos sp., Neanthes spp., Clymenella torquada, a Capetillid and
the snail Ilyanassa obseleta. Of these Neanthes was the most predominant
organism.

[Old Fort Pond:]{.underline}

Chromium levels in the fine fractions of the sediment remained the same
irrespective of the distance from the bulkhead, while the copper
concentration was twice as high at zero distance from the bulkhead than
at a distance away from it. Arsenic levels progressively declined moving
away from the bulkhead. The change in the percent of total carbon in the
sediment did not show any change in the accumulation numbers.

The dominant organisms at this site (both actual and reference) were:
*Marenzelleria virdis*, *Leitoscoloplos sp.*, *Neanthes spp*.,
*Clymenella torquada*, a *Capitellid* and *Hypaniola* gray as well as
clams *Melaena lateralis*, the bubble snail *Haminoea* and *Cyathura
polita*. The data analysis for the bioaccumulation in these species was
difficult as it did not show any trend in the concentration levels of
metals at various distances from the bulkhead.

[North Inlet, Debardeau Canal]{.underline}

The highest concentrations of the metals was at the site at zero meter
distance from the bulkhead. Since this site consisted of the wood
bulkhead and the reference site was aluminum, the analysis showed that
there were no organsims at the wood bulkhead at distance of zero and one
meter from the wood bulkhead while at 3 meter distance *Notomastus* was
the main organism and other organisms were also present like *Neanthes*,
a nemertean *Lineus socialis* At the Al bulkhead also the dominant
organism was *Notomastus* and besides there were *Clymenella*, *Lineus*,
*Neanthes*, *Melaena lateralis* and *Mercenaria*.

[Osborne Cove]{.underline}

The copper accumulations did not vary much from zero meter distance to
the maximum (10 meters). However, arsenic did show some variations with
distance.

The type of organisms existing at the zero meter actual site were:
*Lanonereis culveri*, *Hargeria rapax*, *Marenzerellia virdis*, and
*Hobsonia florida*. Reference sight consisted of, in addition to the
ones mentioned, the follwoing: *Hypereteone heteropoda*,
*Leitoscoloplos* *fragili*s, *Streblospio benedecti*, *Macoma balthica*,
*M. Mitchelli*, *Lepidodactylus dyticus*, *Balanus improvsus* and
*Cyathura polita*.

[Drum Point]{.underline}

Both copper and chromium showed a declining accumulation moving away
from the bulkhead.

The organisms present on this site were predominantly: *Leitoscoloplos
fragilis*, *marenzelleria virdus*, *Leptocheirus plumulosus*, *Gemma
gemmma*. No significant difference bioacummulation differences were
observed at various locations on this site.

In summary, bioaccumulation in Middle Pond organisms were highest in the
organism living closest to the wooden bulkheads. Bioaccumulation in
tissues declined dramatically at a 3 meter distance from the bulkhead.
In some cases, it rose again by 10 meters but primarily due to the
increase in the fine sediment fraction which has a tendency to adsorb
and retain the metals.

It appears at all bulkhead sites metals are retained (accumulated) by
fine-grained sediments and a reduction ensues in the nearby biota.
Unbulkheaded and aluminum bulkheads do not show this tendency. The biota
at 10 meter out from the bulkhead at Middle Pond showed reduction
because of percent increase of fine-grained sediments while for Old Fort
Pond the same phenomenon was observed at 3 and 10 meters away from the
bulkheads because of the same reason. At all sites, the impact on biota
was highest between zero and 1 meter distance from the bulkheads. And in
all cases, copper was observed to be responsible for the reduction in
the biota around the bulkheads (Weis et al., 1998)

A recent study on bioaccumulation of CCA components in Blue Mussels
*Mytilus Edulis* was conducted and the laboratory and field expsoure
data were collected over a period of one year. The CCA-treated wood was
of the Southern Yellow Pine type. CCA-C treated wood boards (4.4 cm x
22.8 cm x 3 m) were pressure-treated at a treatment retention of 2.5 pcf
(40 kg/m^3.^ ). Two sets of blue mussels, one 4-5 cm long and the other
3.5 to 4 cm long were collected from the east jetty at the Flax Pond
inlet, Old field, New York. the laboratory sea tables were arrnged in
such a way that one set of blue mussles were upstream to water flow and
the other downstream to water flow. The mussles were sampled form each
sea table at time 0, one week and one month. Similar arrangements,
samples of blue mussles, submerges in water and were placed adjacent to
the wood. After the experiment was terminated, freeze-dried mussles were
digested in nitric/perchloric acid mixture and samples collected were
anlayzed for copper, chromium and arsenic by flame (Cu) and graphite
furnace (Cr and As) atomic absorption spectrophotometry. The laboratory
and field exposure studies showed that no significant difference in the
average dry tissue weight and length between CCA-C treated and control
treatments.

Table 8 summarizes the concentrations of Cu, Cr and As in the tissues of
blue mussel. Concentration of these metals obtained by Mussel Watch,
organized by national Status & Trends sampling stations in Long Island
Sound are also included in the table for comparison purposes.

[TABLE 8]{.underline} ^1^

  -----------------------------------------------------------------------
  Contaminant       Lab. Exposure     Field Exposure    Mussel Watch^2^
  ----------------- ----------------- ----------------- -----------------
  Cu                7.88              8.54              8.91

  Cr                0.86              0.72              1.61

  As                8.82              7.14              6.24
  -----------------------------------------------------------------------

Notes: 1. All values in μg/g

2\. Data from 1990 reports

Note that the measured metal contents of mussel tissues in both
laboratory and field exposure studies are at or lower than the average
values obtained from the national or regional monitoring studies. The
species of these elements affect their bioaccumulation in mussel
tissues.

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