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    WORLD HEALTH ORGANIZATION              FOOD AND AGRICULTURE ORGANIZATION
    ORGANISATION MONDIALE DE LA SANTE      ORGANISATION POUR L'ALIMENTATION
                                           ET L'AGRICULTURE

                                           VBC/PDS/DS/85.65
                                           ORIGINAL: ENGLISH


    DATA SHEET ON PESTICIDES No.  65

    BIS(TRIBUTYLTIN)OXIDE


    CLASSIFICATION

    Primary use:   Fungicide

    Secondary use: Molluscicide, Algicide, Bactericide



         It must be noted that the issue of a Data Sheet for a
    particular pesticide does not imply endorsement of the pesticide by
    WHO or FAO for any particular use, or exclude its use for other
    purposes not stated. While the information provided is believed to
    be accurate according to data available at the time when the sheet
    was compiled, neither WHO nor FAO are responsible for any errors or
    omissions, or any consequences therefrom.

    The issue of this document does    Ce document ne constitue pas une
    not constitute formal              publication. Il ne doit faire
    publication. It should not be      l'objet d'aucun compte rendu ou
    reviewed, abstracted or quoted     résumé ni d'aucune citation sans
    without the agreement of the       l'autorisation de l'Organisation
    Food and Agriculture               des Nations Unies pour
    Organization of the United         l'Alimentation et l'Agriculture
    Nations or of the World Health     ou de l'Organisation Mondiale de
    Organization.                      la Santé.


    1.   GENERAL INFORMATION

    1.1  COMMON NAME: No officially recognized common name

    1.1.1 Identity:

          IUPAC: Bis(tributyltin)oxide

          CAS No. 1: Distannoxane, hexabutyl-

          CAS Reg. No.: 56-35-9

          Molecular formula: C24H54OSn2

          Molecular weight: 596.1 

          Structural formula:
          
          Structural formula

    1.1.2 Synonyms: Biamet TBTOR; BTOR; ButinoxR; C-Sn-9R; ENT 24,979; 
          hexabutylditin; LS 3394; tributyltin oxide; TBTO; 
          Bis(tributyloxide) of tin; Bis(tributylstannyl)oxide; 
          Oxybis-(tributyltin) 

    1.2  SYNOPSIS: Bis(tributyltin)oxide is a broad spectrum, non-systemic 
         and cumulative organometal pesticide; a metabolic inhibitor with 
         good contact and limited stomach action; and, a very persistent 
         poison.  It is a primary irritant and highly toxic to mammals, 
         other non-target animals and to plants. It is used primarily as an 
         antifouling agent and preservative. 

    1.3  SELECTED PROPERTIES

    1.3.1 Physical characteristics - Bis(tributyltin)oxide is a colourless 
          to light yellow liquid.  It boils at 180°C at 2 mmHg; freezing 
          point -45°C. Its viscosity at 25°C is 4.8 x 10-6 m2/s; density 
          (d204), 1.14; refractive index n20D, 1.4870. It is 
          non-corrosive to most metals.

    1.3.2 Solubility - In water, 100 mg/l at 25°C; in sea water, 60 mg/l; 
          miscible with most organic solvents. 

    1.3.3 Stability - It is stable in storage in dark, closed containers, 
          usually forms tributyltin carbonate on exposure to air. 

    1.3.4 Vapour pressure - Negligible at 20°C.

    1.4  AGRICULTURE, HORTICULTURE, FORESTRY AND INDUSTRY

    1.4.1 Common formulation - Bis(tributyltin)oxide is readily emulsified 
          with many anionic, cationic and non-polar surfactants at various 
          concentrations. 

    1.4.2 Pests controlled - The compound is used against moulds, yeasts 
          and algae. 

    1.4.3 Use pattern - It is primarily used as an antifouling agent in 
          paints, industrial water systems and on inner surfaces of 
          cardboard and cellophane containers for tomatoes, and as a wood 
          preservative. 

    1.4.4 Unintended effects - It is phytotoxic and unsuitable for use on 
          or near growing crops or cultivated soil. 

    1.5  PUBLIC HEALTH USE - Bis(tributyltin)oxide has been effectively 
         used in hospitals and other public buildings, and in industrial 

         plants to control mould and bacterial growth in damp areas not 
         associated with food preparation or storage; to prevent odours in 
         garbage pails and equipment; and to control athletes foot in 
         shower areas and locker rooms.  It has also been used in 
         manufacturing processes (e.g., leather goods, textiles, wood, and 
         plastics) and to mothproof stored garments. 

    1.6  HOUSEHOLD USE - No recommended uses.

    2.   TOXICOLOGY AND RISKS

    2.1  TOXICOLOGY - MAMMALS

    2.1.1 Absorption route - Bis(tributyltin)oxide (TBTO) is absorbed 
          through the intact skin; only to a limited extent from the 
          digestive tract and through inhalation of spray mist. 

    2.1.2 Mode of action - The exact mode of action of TBTO is not well 
          understood.  It is a metabolic inhibitor, as are most trialkyl-
          tin compounds, inhibiting oxidative phosphorylation and causing 
          mitochondrial swelling.  Death is usually caused by respiratory 
          or cardiac failure, or coma. 

    2.1.3 Excretion products - The absorption and metabolism of TBTO has 
          not been well studied.  It appears that only a small fraction of 
          the ingested compound is absorbed.  Metabolism of trialkyl-tin 
          compounds to mono- or dialkyl compounds is a rare occurrence, and 
          breakdown to inorganic tin has not been demonstrated in mammalian 
          systems.  Mice fed 14-C labelled TBTO in drinking-water excreted 
          most of the radioactivity in the faeces and very little in urine.  
          Evidence suggests that the faecal radioactivity represented a 
          large component of unabsorbed TBTO and bile circulated TBTO.  
          Initially elimination was rapid, the half-life being from one to 
          two days; after two weeks time the elimination became much slower 
          and the half-life increased to three to four weeks. 

    2.1.4 Toxicity, single dose

          Oral LD50:

          Rat     194 mg/kg bw; technical material in aqueous suspension

          Rat      87 mg/kg bw; technical material in aqueous suspension

          Mouse    55 mg/kg bw; technical material in aqueous suspension

          Rabbit   50 mg/kg bw; technical material in aqueous suspension


          Dermal LD50:

          Rat   11 700 mg/kg bw; technical material in aqueous suspension

          Rabbit   900 mg/kg bw; technical material in aqueous suspension


          Intravenous LD50:

          Mouse      6 mg/kg bw; technical material in aqueous suspension

          Intraperitoneal LD50:

          Mouse     16 mg/kg bw; technical material in aqueous suspension

          Rat (F)  7.2 mg/kg bw; technical material in aqueous suspension

    2.1.5 Toxicity, repeated doses

          Oral: See Cumulation of compound.

          Inhalation: No information available.

          Dermal: Five daily applications of paper disks containing 8 ppm 
          of TBTO to the shaved backs of rabbits produced no evidence of 
          toxicity or dermal irritation. 

          Primary irritation: In rabbits, 0.46, 0.61, 4.6 or 6.1 mg/kg bw 
          of TBTO was administered to the eye in a 0.3 ml volume.  A dose-
          related response was produced with several mortalities occurring 
          at the highest dose. Within one to three minutes conjunctival 
          inflammation, severe lacrimation, miosis and belpharospasms were 
          seen in all animals.  The severity of the signs increased with 
          time, including extensive tissue necrosis. Within two to five 
          days, in the highest dosage group, irreversible eye deterioration 
          occurred (ulcerations of the eyelid and cornea, and complete 
          suppression of the pupil reflex).  Autopsies of the dead animals 
          revealed brain and abdominal organ hyperaemia, necrotic corneas, 
          oedematous sclera and hyperplasia of the reticuloendothelial 
          cells of the spleen. 

          Cumulation of compound: Mice given TBTO in their drinking-water 
          at concentration levels of 0.51, 3.75 or 18.5 ppm for periods of 
          up to 30 days showed evidence of concentration dependent tissue 
          accumulation of the compound.  Rapid body clearance occurred upon 
          cessation of treatment; no mortalities and no signs of toxicity.  
          Adipose tissue demonstrated the highest cumulative activity. 

    2.1.6 Dietary studies

          Short-term: Groups of 10 rats, male and female, were fed TBTO in 
          their diets at concentration levels of 0, 32, 100 or 320 ppm for 
          30 days.  At 100 ppm growth was suppressed though food 
          consumption was normal.  At 320 ppm both bodyweights and food 
          consumption were reduced.  Approximately 60% of the animals on 
          the highest diet died.  There were no gross pathological changes 
          observed in the dead animals except depletion of fat depots.  
          Prior to death the animals displayed typical signs of acute 
          poisoning including progressive respiratory failure. 

          Long-term: No information available.

    2.1.7 Supplementary studies of toxicity

          Carcinogenicity: Tributyltin fluoride (TBTF) did not exhibit 
          carcinogenic activity in a six-month dermal application test.  
          Four groups of 50 Swiss white mice were tested; a vehicle 
          control, a positive control and two treatment groups initially 
          receiving 10% and 30% TBTF preparations in propylene glycol three 
          days a week.  The highest dosed group developed severe skin 
          lesions after only three weeks of treatment; the dosage was 
          reduced to 5% for the remainder of the test period.  There were 
          no signs of abnormal behaviour nor systemic poisoning in either 
          group.  There were no neoplastic lesions nor gross pathological 
          changes related to TBTF treatment. 

          Mutagenicity: TBTO demonstrated mutagenic potential in several 
          pre-screening tests including a Drosophila melanogaster test and 
          mammalian cell culture tests. 

          Teratogenicity: No information available.

          Neurotoxicity: No information available.

          Reproduction: No information available.

    2.1.8 Modification of toxicity - No information available.

    2.2  TOXICOLOGY - MAN

    2.2.1 Absorption - TBTO may be absorbed percutaneously, by ingestion 
          and by inhalation, of spray mist or dust. 

    2.2.2 Dangerous doses

          Single: No information available.

          Repeated: No information available.

    2.2.3 Observations on occupationally exposed workers - Women using a 
          latex spray paint containing a TBTO additive experienced 
          immediate toxic effects: profuse lacrimation, eye inflammation, 
          eye and nasal mucosa irritation. After 14 days of spray painting 
          the signs and symptoms became more severe but subsided on 
          weekends and disappeared completely when the additive was 
          discontinued. 

          Seventy per cent. of the workers in a rubber factory using TBTO 
          in the vulcanizing process experienced upper respiratory tract 
          and eye irritations.  Approximately 20% also experienced lower 
          chest symptoms (irritation, tightness, and pain) though none of 
          those tested showed any adverse changes in pulmonary function 
          test parameters (FVC and FEV-1).  Approximately 20% complained of 
          skin irritation and loss of appetite.  In another rubber device 
          manufacturing unit, the rubber dust from polishing activity found 
          to be a significant source of TBTO, caused mild symptoms of 
          poisoning. 

    2.2.4 Observations on exposure of the general public - No information 
          available.  If recommended use practices are followed the general 
          population are not likely to be exposed to hazardous amounts of 
          TBTO. 

    2.2.5 Observations on volunteers - Dermal applications of undiluted 
          TBTO to the back of the hands of five volunteers produced 
          follicular inflammation and pustulations.  Healing was usually 
          complete in seven days. 

    2.2.6 Reported mishaps - No information available.

    2.3  TOXICITY TO NON-MAMMALIAN SPECIES

         TBTO is toxic to all animal types: vertebrates and 
         non-vertebrates.

    3.   FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF 
         COMPOUND

    3.1  RECOMMENDED RESTRICTIONS OF AVAILABILITY

         (For definition of categories, see the Introduction to Data 
         Sheets) 

         Liquid formulations over 10%, Category 3.

         Other liquid formulations, Category 4.

    3.2  TRANSPORTATION AND STORAGE

         Formulations in categories 3 and 4 - Should be transported or 
         stored in clearly labelled rigid and leakproof containers and away 
         from containers of food and drink.  Storage should be under lock 
         and key and secure from access by children and other unauthorized 
         persons. 

    3.3  HANDLING

         Formulations in categories 3 and 4 - Full protective clothing (see 
         part 4) should be provided for all handling of the compound.  
         Adequate washing facilities should be available at all times
         during handling and should be close to the site of handling.
         Eating, drinking and smoking should be prohibited during handling
         and before washing after handling. 

    3.4  DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS

         Containers must either be burned or crushed and buried below 
         topsoil.  Care must be taken to avoid subsequent contamination of 
         watersources.  Decontamination of containers in order to use them 
         for other purposes should not be permitted. 

    3.5  SELECTION AND TRAINING AND MEDICAL SUPERVISION OF WORKERS

         Pre-employment and periodic medical examinations are necessary and 
         should include the skin, blood, eyes and central nervous system, 
         and pulmonary, liver and kidney function tests.  Comprehensive 
         medical and work records should be maintained.  Workers with 
         active hepatic or renal diseases should be excluded from contact.  
         Special account should be taken of worker's ability to comprehend 
         and follow instructions. Training in techniques to avoid contact 
         is essential. 

    3.6  ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT

         Not applicable: It is phytotoxic and unsuitable for use on growing 
         crops, forest lands or on cultivated soil. 

    3.7  LABELLING

         All formulations - "DANGER - POISON" (skull and cross-bones 
         insignia). Bis(tributyltin)oxide is a metabolic poison of very 
         high toxicity.  Contact with the skin, swallowing or inhalation of 
         spray may be fatal.  Wear protective gloves, clean protective 
         clothing, and a respirator of the organic-vapour type when 
         handling concentrated material.  Bathe immediately after work.  
         Ensure that containers are stored under lock and key.  Empty 
         containers must be disposed of in such a way as to prevent all 
         possibility of accidental contact with them.  Keep the material 
         out of reach of children and well away from foodstuffs, animal 
         feed and their containers. 

         In case of contact, immediately remove contaminated clothing and 
         wash the skin thoroughly with soap and water; flush with water for 
         15 minutes.  If poisoning occurs, call a physician. 

    3.8  RESIDUES IN FOOD

         Maximum residue levels - The Joint FAO/WHO Meeting on Pesticide 
         Residues has recommended maximum residue levels. 

    4.   PREVENTION OF POISONING IN MAN AND EMERGENCY AID

    4.1  PRECAUTIONS IN USE

    4.1.1 General - Bis(tributyltin)oxide is a metabolic poison of very 
          high toxicity.  It penetrates the intact skin and is also 
          absorbed from the gastrointestinal tract and by inhalation to a 
          limited extent.  Concentrated material should be handled only by 
          trained personnel wearing protective clothing. 

    4.1.2 Manufacture and formulation - TLV - (A.C.G.I.H.) 0.1 mg/m3.  
          Formulation should not be attempted without advice from the 
          manufacturer.  Although volatality is low, vapour and dusts 
          should be controlled preferably by mechanical means.  Wear safety 
          glasses, polyvinyl gloves and a direct connection gas mask. 

    4.1.3 Mixers and applicators - When opening the container and when 
          mixing, protective impermeable boots, clean overalls, safety 
          glasses, gloves and respirator should be worn.  Mixing, if not 
          mechanical, should always be carried out with a paddle of 
          appropriate length.  The applicator should avoid working in spray 
          mist and avoid contact with the mouth.  Particular care is needed 
          when equipment is being washed after use.  All protective 
          clothing should be washed immediately after use, including the 
          inside of the gloves.  Splashes must be washed immeditely from 
          the skin or eyes with large quantities of water.  Before eating, 
          drinking or smoking, hands and other exposed skin should be 
          washed. 

    4.1.4 Other associated workers (including flagmen in aerial operations) 
          - Persons exposed to the compound and associated with its 
          applications should wear protective clothing and observe the 
          precautions described above in 4.1.3 under "Mixers and 
          applicators". 

    4.1.5 Other populations likely to be affected - With good application 
          practice subject to 4.2  below, other populations should not be 
          exposed to hazardous amounts of bis(tributyltin)oxide. 

    4.2  ENTRY OF PERSONS INTO TREATED AREAS - Unprotected persons should 
         be kept out of treated areas until the compound is dry. 

    4.3  SAFE DISPOSAL OF CONTAINERS AND SPILLAGE - Residues in containers 
         should be emptied in a diluted form into a deep pit taking care to 
         avoid contamination of ground waters.  The empty container may be 
         decontaminated by rinsing two or three times with water and 
         scrubbing the sides.  An additional rinse should be carried out 
         with 5% sodim hydroxide solution which should remain in a 
         container overnight. Impermeable gauntlets should be worn during 
         this work and a soakage pit should be provided for the rinsings. 
         Decontamination of containers in order to use them for other 
         purposes should not be permitted.  Spillage of 
         bis(tributyltin)oxide and its formulations should be removed by 
         washing with 5% sodium hydroxide solution and then rinsing with 
         large quantities of water. 

    4.4  EMERGENCY AID

    4.4.1 Early symptoms of poisoning - Early symptoms of poisoning may 
          include tears; irritation and inflammation of the skin, eyes, and 
          mucous membranes, headaches, dizziness, vision disturbances; sore 
          throat and coughing; nausea, vomiting, abdominal pains and 
          diarrhoea.  Tributyl compounds may cause acute and non-painful 
          burns to the skin upon contact. 

    4.4.2 Treatment before a person is seen by a physician, if these 
          syptoms appear following exposure - The person should stop work 
          immediately, remove contaminated clothing and wash the affected 
          skin with water and soap, if available, flush the area with large 
          quantities of water, and call a physician immediately.  If 
          swallowed, call a physician and transport to nearest hospital 
          immediately.  Often the milder symptoms will rapidly cease upon 
          removal from the source of contamination. 

    5.   FOR MEDICAL AND LABORATORY PERSONNEL

    5.1  MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING

    5.1.1 General information - Bis(tributyltin)oxide is a metabolic poison 
          of very high toxicity.  It is absorbed from the gastrointestinal 
          tract, by inhalation and through the intact skin.  The mode of 
          action is probably by inhibition of oxidative phosphorylation.  
          Trialkyltin compounds show a predilection for the central nervous 
          system where they may cause interstitial oedema of the white 
          matter, a potentially fatal condition. 

    5.1.2 Symptoms and signs - These include profuse lacrimation, 
          headaches, dizziness, photophobia and progressive weakness; 
          convulsions and flaccid paralysis in severe cases; irritation and 
          inflammation of the skin and mucous membranes upon contact; sore 
          throat and coughing upon inhalation; nausea, vomiting, abdominal 
          pain and diarrhoea after ingestion. Occasionally EEG changes have 
          been observed.  Weight loss and loss of appetite are common in 
          chronic poisonings. 

    5.1.3 Laboratory - The presence of tributyltin may be detected in all 
          body tissues after exposure, and in urine, faeces and vomit.  In 
          forensic studies, brain levels of tin are specifically diagnostic 
          of organotin poisoning. 

    5.1.4 Treatment - If the pesticide has been ingested, unless the 
          patient is vomiting, rapid gastric lavage should be performed 
          with water, followed by activated charcoal and a mild laxative.  
          For skin contact the skin should be washed with soap and water.  
          If the compound has entered the eyes they should be washed with 
          isotonic saline or water.  There is no specific antidote for 
          organotin poisoning.  In extreme cases, if the patient is 
          unconscious or is in respiratory distress, oxygen may be 
          required.  Provide patient support as required, including: 
          suction of secretions, maintenance of airways, intravenous fluids 
          pro re nata and bladder catheterization. Symptomatology and 
          autopsy findings indicate that oedema of the white matter of the 
          brain is usually the cause of fatality.  In severe cases of 
          poisoning intracranial and spinal pressures should be monitored; 
          surgical decompression of the brain may be the only useful 
          treatment if these pressures are elevated. 

    5.1.5 Prognosis - If the acute toxic effect is survived the chances of 
          complete recovery are very good provided brain damage has not 
          occurred. 

    5.1.6 References of previously reported cases - There have been no 
          published reports of bis(tributyltin)oxide poisoning. Useful 
          references involving other organotin compounds are: 

          Alajauamine, T. et al. (1958) Rev. Neurol., 98 85
          Lyle, W. H. (1958) Br. J.Ind. Med., 15, 193
          Prull, G. & Rompel, K. (1970) Electroencephologr. Clin.
          Neurophysiol., 29, 215 

    5.2  SURVEILLANCE TESTS

          Medical surveillance should be provided where occupational 
          exposure is likely.  A comprehensive medical and work record 
          should be maintained for each worker.  A periodic comprehensive 
          medical examination should include pulmonary efficiency, serum 
          enzymes (SGOT and SGPT) and other tests of hepatic function, eye 
          examination (acuity, colour vision, pupillary reaction, glaucoma, 
          etc.), an ECG, a neurological examination with specific attention 
          to intracranial and spinal pressures, urinalysis and a medical 
          history. 

    5.3  LABORATORY METHODS

    5.3.1 Detection and assay of compound

          Clark, R. E. D. (1936) Analyst (London), 61, 242
          Clark, R. E. D. (1937) Analyst (London), 62, 661
          Kumpulainen, J. & Koivistoinen, P. (1977) Residue Rev., 66, 1
          Sherman, L. R. & Carlson, T. L. (1980) J. Anal. Toxicol., 4(1), 
          31 
          Sherman, L. R. & Hiep Hoang (1981) Anal. Proc. (London), 18(5), 
          196 

    5.3.2 Other tests in case of poisoning - No information.