Document ID: EPA-HQ-OPP-2008-0171-0009
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-04-02T04:00Z

ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

                                                                        
                                    PREVENTION, PESTICIDES AND 

                                                                        
                                             TOXIC SUBSTANCES

					

March 25, 2008

MEMORANDUM  

                                                                        

	

SUBJECT:	Revised Environmental Fate Assessment of TBT for RED

Case No.:  2620		DP Barcode:  D350671

FROM:		James Breithaupt, Agronomist

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510P)

TO:			Jill Bloom, Chemical Review Manager

Reregistration Branch 2

Special Review and Reregistration Division (7508P)

Diane Isbell, Team Leader

Regulatory Management Branch I

Antimicrobials Division (7510P)

 

THRU:	Richard C. Petrie, Team Leader, Team Three

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510P)

Norman Cook, Branch Chief

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510P)

Chemical Name		PC Code	CAS#		Common Name

bis(tri-n-butyltin) oxide	083001	56-35-9	Tributyl tin oxide, TBTO

tributyltin benzoate		083106	4342-36-3	TBTB

tributyltin maleate		083118	4027-18-3	TBTM

(Data for TBTB and TBTM are limited, but the TBTO fate data were used to
support the TBTM.  No fate data were available for TBTB.

  

Environmental Fate Science Chapter and Fate Assessment for the active
ingredients in Case # 2620 are submitted for Reregistration.

ENVIRONMENTAL FATE SCIENCE CHAPTER

EXECUTIVE SUMMARY

	Tributyl tin oxide is an anti-fouling and antimicrobial preservative. 
Based on the available labels and information from the registrants, it
is used for wood treatment, cooling towers, material preservatives (e.g.
interior grout, coatings), veterinary establishments and farm animal
premises, and textiles.  There are also uses in sonar domes and
oceanographic instruments.   TBTB also is used as a materials
preservative, and TBTM is used in sponges, rubber, carpet backing,
polyurethane foam, and other related materials.    

 	The only outstanding environmental fate data requirement is leaching
from treated wood.

	The chemical structures of tributyltin oxide, tributyltin maleate, and
tributyltin benzoate are as follows in Figure 1, 2, and 3, respectively.

 

Figure 1.  Structure of TBT Oxide

Figure 2.  Tributyltin maleate

 

Figure 3.  Tributyltin benzoate

Fate Characteristics of TBTO, TBTM, and TBTB

TBT oxide has limited solubility in water (0.09 mg/L), a high log P (log
Kow, 3.84), and a vapor pressure of 7.8 x 10-6 mm Hg.  The Henry’s law
constant is 6.8 x 10-5 atm m3 mol-1.   Based on these values, TBT is
normally associated with sediment in the presence of water, has high
bioconcentration potential (low water solubility and high log P), and is
not expected to volatilize from water (vapor pressure and Henry’s
Law).  Degradation occurs primarily by microbial metabolism and in
aerobic conditions.

TBT maleate (monomer) has limited solubility in water (4.mg/L), a high
log P (log Kow, 3.79), and a vapor pressure of 1.7 x 10-7 mm Hg.  The
Henry’s law constant is 1.4 x 10-7 atm m3 mol-1.   Based on these
values, TBT is normally associated with sediment in the presence of
water and has high bioconcentration potential, and is not expected to
volatilize from water (vapor pressure and Henry’s Law).  Degradation
occurs primarily by microbial metabolism and in aerobic conditions.

TBT benzoate has limited solubility in water (2.6 x 10-1 mg/L), a high
log P (log Kow, 4.69), and a vapor pressure of 1.3 x 10-6 mm Hg.  The
Henry’s law constant is 2.8 x 10-6 atm m3 mol-1.   Based on these
values, TBT is normally associated with sediment in the presence of
water, has high bioconcentration potential, and is not expected to
volatilize from water.  Degradation occurs primarily by microbial
metabolism and in aerobic conditions.

Chemical reactions degrade TBTO to TBT ion, which degrades very slowly. 
Tributyltin oxide degrades by hydrolysis (freshwater and saltwater) to
TBT ion which forms dibutyl tin (parent minus a butyl group, DBT (MRID
41557801).  Like hydrolysis, the TBT ion is essentially stable to
photodegradation in water at pH 5, 7, and 9 and in saltwater even though
a photosensitizer was used to enhance photodegradation (MRID 41557802). 
TBTO data was used to support TBT maleate, but no fate data were
submitted for TBTB.

 

Degradates

The primary breakdown product from chemical reactions and flooded
conditions is dibutyl tin, but in non-flooded topsoil, the primary
degradate is CO2.  Chemical reactions degrade TBTO to TBT ion, which
degrades very slowly.  Tributyltin oxide degrades by hydrolysis
(freshwater and saltwater) to TBT ion which forms dibutyl tin (parent
minus a butyl group, DBT).  TBT ion is essentially stable, but there is
an apparent equilibrium between TBT ion and DBT, with about 15-18
(freshwater) and 16-23 (saltwater) times more than TBT than DBT.  These
are average ratios of TBT ion and DBT.  No other degradates were formed
(MRID 41557801).  Like hydrolysis, the TBT ion is essentially stable to
photodegradation in water at pH 5, 7, and 9 and in saltwater even though
a photosensitizer was used to enhance photodegradation.  TBT was 15-18
times greater than DBT in freshwater, and 10-11 times greater in
saltwater, with no other degradates present (MRID 41557802).  The
smaller TBT/DBT ratios in photodegradation were consistent with the
hydrolysis results.  TBTO data was used to support TBT maleate, but no
fate data were submitted for TBTB.

Metabolism

Degradation in aerobic conditions is faster than in anaerobic
conditions, and requires microbial activity.  All aquatic metabolism
studies were conducted using saltwater, not freshwater.  In filtered and
irradiated seawater, TBT ion was stable.  In non-filtered seawater
(aerobic aquatic metabolism), TBT degraded with a dark control adjusted
half-life of 6.5 days with degradation in both lighted and dark
conditions.  In an anaerobic aquatic metabolism study (saltwater and
nitrogen atmosphere), TBT was stable in sterilized water.  The half-life
of TBT in aerobic aquatic metabolism (saltwater, oxygen atmosphere) was
4.5 days.  DBT reached about 50 % of parent concentration and
hydroxylbutyl tin reached about 15 %.  In an aerobic aquatic metabolism
study (saltwater), the dark control adjusted half-life of TBT was 4.3
days with degradation in both dark control and irradiated samples.  DBT
was the only significant degradate.   In the same study volume, the
aerobic and anaerobic half-lives were 5-6 (sediment, saltwater, and
oxygen atmosphere) and 24 (sediment, saltwater, and nitrogen atmosphere)
days, respectively.  Degradation is faster in salt water than fresh
water (MRID 41024501).   In water:sediment systems from Puget Sound
(seawater, MRIDs 43831801, 43984201), TBT oxide was essentially stable
(half-life of 506 days) and virtually all present in sediment.  Water
residues did not exceed 3 % of applied.  These results are consistent
with the tight sorption to soil.  Sediment bound residues increased in
the studies.  

In non-flooded soil (aerobic soil, the top layer of soil), the half-life
of TBT oxide was 127 days.  Complete mineralization to CO2 and
non-extractable residues was observed.  There were no significant
non-volatile metabolites.   These results are consistent with the
straight chains of carbon in TBT that are systematically converted to
CO2 (MRID 43737401)  

Persistence in the Environment

TBT ion is generally persistent in the environment and sorbed tightly to
soil and suspended/ bottom sediment.  Water exposures are expected to be
small relative to sediment residues.

Leaching

Sorption to soil and sediment is a significant route of dissipation in
the environment.  The Kads values ranged from 7 to 157 ml/g with Koc
values of 650 to 16,600 (MRID 43979701).  Kads values relate sorption to
whole soil, while the Koc represents sorption to the organic carbon
content of the soil.  Sorption is related to organic carbon content
which is consistent with the structure and chemical content of TBT. 
However, desorption back into the water phase ranged from 17 to 70 %
which is inconsistent with the metabolism studies.  The desorption in
the batch equilibrium studies was likely due to the fact that the soil
and water were being shaken, which removed the compound.  In metabolism
studies, the soil:water systems are not shaken.

Bridging

Bridging for the different TBT containing compounds was conducted using
data from TBTO.  TBTO data were used for TBTM, but no fate data were
cited for TBTB.  However, the fate of these compounds is expected to be
similar and therefore no fate data for TBTB are required.   

Bioconcentration

Bioconcentration in fish is an important route of dissipation in the
environment.   In MRIDs 41668901 and 41811501, the bioconcentration
factors ranged from 13-100 for fillet (edible), 30-1800 for viscera
(non-edible), and 21-2210 for whole bluegill sunfish.  The reported
depuration rates varied between the studies, with 50 % depuration
occurring by 17-18 days for fillet, 10-14 days for viscera, and 13-15
days (whole body) (MRID 41668901).  In MRID 41811501, the percent
depuration by 21 days was 61 (fillet), 75 (viscera), and 66 (whole
body).  The results of these studies are consistent with desorption in
batch equilibrium studies.  In sheepshead minnows (MRID 92172011),
bioconcentration factors of 1810, 2120, and 4580 were observed for
fillet, head, and viscera, respectively.  The percent depuration in 28
days was 74, 80, and 64, respectively.  Within 7 days, 52 % depuration
occurred. 

The octanol/water partition coefficient Kow is very high and TBT shows a
remarkable tendency to bioaccumulate. The bioaccumulation in various
tissues can be from 200-fold to 6000-fold. This is attained by exposure
to 1.25 ppb at the most and 0.15 ppb at the least.

 

 

With such high Kds as noted above, it has been estimated that TBT levels
in the sediments need to be only 120 ng/g to give an interstitial water
value of 10 ng/L, which is enough to give rise to chronic effects in
salt water species. In actuality, it is both the desorbed TBT and the
sediment bound TBT that contribute to the bioaccumulation and
bioavailability in saltwater organisms.

According to the World Health Organization, the bioconcentration factors
in various aquatic species are as high as 60,000X with most being less
than 6,000X.  The depuration half-life in mollusks for organic tin was
40 days and 25 days for total tin.  The excretion rates in sheepshead
minnow by 20 days were 74 % in muscle and 80 % in internal organs.  The
literature data are consistent with the guideline study data.  

Aquatic Monitoring

Long-term near coastal monitoring was required in support of the
antifouling paint uses of TBTO and several other TBT derivatives no
longer registered by EPA.  While the monitoring program was plagued by
poor recoveries, sample contamination, and other difficulties, the
Agency was able to utilize some of the information that was collected. 
Monitoring data were summarized in the June 2001 EFED risk assessment
(Rexrode and Spatz, 5/11/01) and in MRID 45487301.  Annual monitoring
results and difficulties in the monitoring program were also reported to
Congress. Based on the monitoring, residues in sediment were greater
than in water which is consistent with the results of the metabolism
studies and leaching studies in soil.  Most sediment samples contained
less than 10 ng/l in pore water, which is the level of concern for
chronic effects.  However, some samples ranged as high as 109 ng/l.  DBT
and monobutyl tin (MBT) were present in most samples.  No monitoring has
been conducted which targets the non-antifouling uses of TBT. 

Bioconcentration in Aquatic Organisms

Bioconcentration and bioaccumulation were observed in a variety of
aquatic organisms, including birds, bivalves, sea otters and sea lions,
clams and mussels, tuna, harbor porpoises, and sharks.  Most of the
measured concentrations were found at parts-per-billion levels, but some
reached the parts-per-million level.  The liver of the different animals
contained the highest levels of total butyltins, but much of it was
converted to DBT.  Blubber generally contained more TBT than DBT.  Many
of the animals studied were either dead, stranded, or caught in harbors,
indicating that these exposures may represent high-end concentrations. 
However, some animals were taken from areas with lower exposure and had
lower concentrations.  

Strand and Jacobsen (2005) studied the accumulation potential of
tributyltin and triphenyl tin in two species of seaweed, four species of
invertebrates, four species of fish, five species of birds, and two
species of mammals.  They reported butyltin concentrations of 60-259
ng/g (parts-per-billion, ppb) wet weight as tin in flounder, 12-202 ng/g
in elder duck, and 134-2283 ng/g in harbor porpoises in Danish coastal
waters.   Triphenyl tin (including degradates) were found in most of the
samples with the highest concentrations in flounder (9.8-74 ng/g), cod
(23-28 ng/g), and great backed gulls (19-24 ng/g).  

Strand et al. (2005) studied butyltin concentrations in the liver of 35
harbor porpoises which were found or caught along the Danish North Sea
and the Inner Dutch waters, in addition to three porpoises from West
Greenland.  In harbor porpoises, butyltin concentrations in the livers
were 68-4605 mg/kg (parts-per-million, ppm), and these tended to
increase with age.  Butyltin concentrations in stranded porpoises were
higher than caught ones. 

Diez et al (2002) studied tributyltin and phenyltin in harbor sediments
from the Western Mediterranean Sea.  Butyltins in commercial harbors
that were attributed to large vessels averaged 5 ug/g (ppm).  In waters
used for recreational boating and fishing, the average level of tributyl
tin was 1.0 ug/g.  Phenyltin derivatives (monophenyl tins) averaged
45-945 ng/g (ppb) in sediment.  

Strand and Asmund (2003) studied the accumulation and effects of TBT and
degradates in marine mollusks from West Greenland.  The highest TBT
concentration (254 ng/g) was found in the bivalve Mytilus edulis from
Nuuk harbor, but significant TBT was also found in bivalves from the
other harbors.  Low levels of TBT were found outside the harbors. 
Imposex (masculinazation) of neogastropods (e.g. Buccinum) was observed
in the harbors, but not outside the harbors.  

Jacobsen and Asmund (January 2000) studied butyltin concentrations in
the bivalve Mytilus edulis (Blue mussel) and in marine sediments near
Nuuk in Greenland.  TBT was detected in the bivalves at approximately 1
ug/kg (wet weight, ppb) as tin.  In sediments, TBT concentrations ranged
from 1 ug/kg to 172 ug/kg (dry weight).

Chandrinou et al. (February 2007) studied organotin levels in five
bivalve species.  These included Mytilus galloprivinciallis
(Mediterranean mussels), Venus gallina (stripped venus), Modiola
barbatus L. (bearded horse mussels), Pecten jacobeus (scallops), and
Callista chione (hard clans) in seven areas of the Aegean Sea near
Greece between August 2001 and January 2003.  The geometric means of the
different butyltins were 17.1 ng/g (ppb) of TBT, 18.8 ng/g
(dibutyltin),7.8 ng/g (MBT), and 13.0 ng/g for triphenyltin.  The lowest
concentrations were observed in Mediterranean mussels due to growth in
water column in fish farms.  The highest concentrations were observed in
free-ranging species collected from fishing grounds.  

Madhusree et al. (September 1997) studied the concentrations of butyltin
compounds in harbor porpoise (Phocoena phocoena) collected from Turkish
coastal waters of the Black Sea.  Total butyltin compounds in the liver
were in the range of 89-219 ng/g (ppb) wet weight.  DBT residues were
higher than TBT, suggesting that TBT degrades to TBT in the liver.  

 Kannan et al. (1998) studied butyltin residues in southern sea otters
(Enhydra lutris nereis) found dead along California coastal waters.  The
body organs included the liver, kidney, and brain.  Hepatic
concentration of total butyltin compounds (TBT, DBT, and MBT) ranged
from 40 to 9200 ng/g (ppb).  When the 9200 ng/g concentration was
removed as an outlier, the mean liver concentrations were 1090 + 1560
ng/g.  Total butyltin concentrations in kidney and brain were in the
ranges of 4-430 (mean of 160 + 140 ng/g) and 2.7-140 (mean of 61 + 56
ng/g).  Female sea otters contained approximately twice the levels of
male otters.  Most butyltin residues were TBT, indicating recent
exposure.  Sea otters are bottom feeders and eat invertebrates such as
mollusks and gastropods, which accumulate butyltins from bottom
sediment.

Kim et al. (1996) studied the characteristics of butyltin accumulation
and its biomagnification in steller sea lion (Eumetopias jubatus) from
1976-1985 in Alaska and 1994-1995 in Hokkaido, Japan.  Liver
concentrations in sea lions from Alaska (19 ng/g, ppb) was much lower
than those from western and eastern Hokkadio (150 and 220 ng/g).  DBT
residues were higher than TBT.  The biomagnification factors of total
butyltins in stellar sea lions (mean of 0.6) indicate that this specie
is unlikely to biomagnify butyltins due to rapid degradation and
excretion. 

 

  Kannan et al (July 1996) studied the butyltin concentrations in
bottlenose dolphins (Tursiops truncates), bluefin tuna (Thunnus
thynnus), and blue shark (Prionace glauca) collected from Italian coast
of the Mediterranean Sea in 1992-1993.  Concentrations of total butyltin
in the liver of dolphins (1200-2200 ng/g, ppb) were an order higher than
in blubber (48-320 ng/g).  TBT was present more in the blubber, while
DBT was higher in the liver.  Butyltin concentrations in bluefin tuna
were lower than in dolphins, with TBT highest in the muscle and DBT in
the liver.  Concentrations of butyltins in blue sharks were lower than
those in dolphin and tuna, with the kidney having the highest
concentrations.  TBT was the predominant form of butyltin derivatives in
the tissues of shark.  

 

Data Gaps:  See Table below.

Environmental Fate Data Requirements for TBTO, TBTM, and TBTB Technical

OPP Guideline	

Data Requirement	

MRID No.	

Data Requirement Status

161-1	

Hydrolysis	41557801	Satisfied

161-2	

Photodegradation in Water	41557802	Satisfied

161-3	Photodegradation on Soil	00074584

00074585

00125042	Not required

162-1	Aerobic Soil Metabolism	43747401	Satisfied

162-2	Anaerobic Soil Metabolism	No data	Not required1

162-3	

Anaerobic Aquatic Metabolism	41024501

43831801	Satisfied

162-4	

Aerobic Aquatic Metabolism	41024501

43984201	Satisfied

163-1	

Adsorption/Desorption	43979701	Satisfied

OECD

305

	

Bioaccumulation in Fish	41668901

41811501

92172011	Satisfied

840.1100	

Monitoring/Aquatic Field Dissipation Study	45487301, May 2001 EFED
review	Satisfied

No guideline	Leaching from treated wood	No data	Required

1 May be satisfied by the anaerobic aquatic metabolism studies (MRIDs
41024501, 43831801)

BIBLIOGRAPHY

161-1       Hydrolysis (835.2110) 

41557801	Pisigan, R.; Liu, L.; Zavala, P. (1989) Hydrolysis of
Bis(Tributyl- tin) Oxide in Water: Lab Project Number: 3903019.
Unpublished study prepared by Environmental Science & Engineering, Inc.
54 p. 

161-2       Photodegradation-water (835.23210)

41557802	Liu, S.; Zavala, P.; Gensheimer, G. (1990) Photodegradation of
Bis- (Tributyltin) Oxide in Water: Lab Project Number: 3903021. Un-
published study prepared by Environmental Science & Engineering, Inc. 69
p. 

162-1       Aerobic soil metabolism (835.3300)

43737401	Schocken, M. (1995) Tributyltin Oxide--Determination of Soil
Metabolism Under Aerobic Conditions at 25 (degrees) C: Final Report: Lab
Project Number: 95-1-5658: 12442.0193.6155.760. Unpublished study
prepared by Springborn Labs, Inc. 69 p. 

162-3       Anaerobic aquatic metab. (835.3400)

41024501	Lee, R. (1988) Degradation of ?carbon 14|-Bis(Tri-n-Butyltin)
Oxide in Coastal Waters and Sediments Under Aerobic and Anaerobic
Conditions. Unpublished study prepared by Skidway Institute of
Oceanography. 24 p. 

43831801	Schocken, M. (1995) Tributyltin Oxide--Determination of
Anaerobic Aquatic Metabolism at 25 (degrees) C: Final Report: Lab
Project Number: 95-5-5879: 12442-0193-6158-755. Unpublished study
prepared by Springborn Labs, Inc. 78 p. 

162-4       Aerobic aquatic metab. (835.3100)

41024501	Lee, R. (1988) Degradation of ?carbon 14|-Bis(Tri-n-Butyltin)
Oxide in Coastal Waters and Sediments Under Aerobic and Anaerobic
Conditions. Unpublished study prepared by Skidway Institute of
Oceanography. 24 p. 

43984201	Schocken, M. (1995) Tributyltin Oxide--Determination of Aerobic
Aquatic Metabolism at 25 (degrees) C: Final Report: Lab Project Number:
94-9-5462: 12442-0193-6157-750. Unpublished study prepared by Springborn
Labs, Inc. 72 p. 

163-1       Leach/adsorp/desorption (835.1220)

43979701	Mao, J. (1995) Tributyltin Oxide--Determination of the
Adsorption and Desorption Properties: Final Report: Lab Project Number:
94-9-5476: 12442.0193.6154.710: 55-1807-05. Unpublished study prepared
by Springborn Labs, Inc. 82 p. 

164-2       Aquatic field dissipation (no guideline)

45487301	Simmons, R.; Kluck, M.; Bennett, J. et al. (2001) Annual Report
for the Long-Term National Monitoring Program for Tributylin and Its
Primary Degradation Intermediates: Year 8, 1999-2000: Lab Project
Number: 55-1807-07 (8A). Unpublished study prepared by Parametrix, Inc.
3412 p. 

165-4       Bioaccumulation in fish (850.1730)

41668901	Stuerman, L.; Lochhaas, C.; Young, B. (1990) Uptake, Depuration
and Bioconcentration of (carbon 14)-Bis(tri-n-butyltin) Oxide by
Bluegill Sunfish (Lepomis macrochirus): Lab Project No. 38561.
Unpublished study prepared by Analytical Bio-Chemistry Labora- tories,
Inc. 453 p. 

41811501	Gendusa, T.; Brancato, M. (1990) Steady State Tissue
Concentrations of Tributyltin and its Degradation Intermediates in
Bluegill Sunfish (Lepomis macrochirus) Following Tributyltin Uptake and
Depuration: Lab Project Number: Final Report: ES-7387. Unpublished study
prepared by Texas A & M University, Parametrix, ABC Labs. 40 p. 

92172011	Ben-Dyke, B. (1990) M&t Chemicals, Inc. Phase 3 Summary of MRID
00140824. Bioaccumulation and Chronic Toxicity of Bis(tributyltin)
Oxide: Tests with a Saltwater Fish. Prepared by EG&G, Bionomics. 6 p. 

165-5       Bioaccum-aquatic non-target (850.1850)

45487301	Simmons, R.; Kluck, M.; Bennett, J. et al. (2001) Annual Report
for the Long-Term National Monitoring Program for Tributylin and Its
Primary Degradation Intermediates: Year 8, 1999-2000: Lab Project
Number: 55-1807-07 (8A). Unpublished study prepared by Parametrix, Inc.
3412 p. 

Other data sources

Chandrinou, S., A.S. Stasinakis, N.S Thomaidis, A. Nikolaou, and J.W.
Wegener.  (February 2007).  Distribution of organotin compounds in the
bivalves of the Aegean Sea, Greece.  Environment International 33: pp.
226-232.  

Diez, S., M. Abalos, and J.M. Bayona.  February 2002.  Organotin
contamination of sediments from the Western Mediterranean enclosures
following 10 years of TBT regulation.  Water Research 30:pp. 905-918.

Jacobsen, J.A. and G. Asmund.  January 2000.  TBT in marine sediments
and blue mussels (Mytilus edulis) from central-west Greenland.  The
Science of the Total Environment 245:pp. 131-136.  

Kannan, K., S. Corsolini, S. Focardi, S. Tanabe, and R. Tatsukawa.  July
1996.  Accumulation pattern of butyltin compounds in dolphin, tuna, and
shark collected from Italian coastal waters.  Archives of Environmental
Contamination and Toxicology 31:pp. 19-23.

Kannan, K.,  K.S. Guruge, N.J. Thomas, S. Tanabe, and J.P. Giesy.  1998.
 Butyltin Residues in Southern Sea Otter (Enhydra lutes nereis) found
Dead along California Coastal Water.  Environ. Sci. Technol. 32:pp.
1169-1175.  

Kim, G.B., S. Tanabe, R. Tatsukawa, T.R. Loughlin, and K. Shimazaki. 
May 1996.  Characteristics of butyltin accumulation and its
biomagnification in Stelle Lion (Eumetopias jubatus).  Environmental
Toxicology and Chemistry 15:2043-2048.  

Madhusree, B., S. Tanabe, A.A Ozturk, R. Tatsukawa, N. Miyazaki, E.
Ozdamar, O. Aral, O. Samsun, and B. Ozturk.  September 1997. 
Contamination by butyltin compounds in harbor porpoise (Phocoena
phocoena) from the Black Sea.  Fresenius’ Journal of Analytical
Chemistry 3598:pp. 244-248.  

Rexrode, M. and D. Spatz.  May 11, 2001.  EFED Response to Request for
Update on Tributyltin (TBT) Environmental Risk Characterization

Strand, J. and G. Asmund.  May 2003.  Tributyl tin accumulation and
effects in marine mollusks from West Greenland.  Environmental Pollution
123:pp. 31-37.  

Strand, .J and J.A. Jacobsen.  November 2005.  Accumulation and trophic
transfer of organotins in a marine food web from Danish coastal waters. 
Science of the Total Environment 350: pp. 72-85).

Strand, J., M.M. Larsen, and C. Lockyer.  November 2005.  Accumulation
of organotin compounds and mercury in harbor porpoises (Phocoens
phocoens) from the Danish water and West Greenland.  Science of the
Total Environment 350:pp. 59-71.    

World Health Organization (1990)Tributyltin compounds, Environmental
Health Criteria 116.

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