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Phase N Review Reregistration case #4086

PC We No. : 077601 \

Cate Out of EFGWB: JuN \ 1 1993 TO: Bruce Sidwell pzmdllct Manager #53 Reg-tion Division (H?505c)

FIW3M: Akiva D. Abramvitch, Ph.D., Section Head miromental Review Section #3

THIBJ: Henry M. Jaw, Chief mire- Fate and

Attached, please find the EFGWB review of: %./File #: 077601 I Common Name: Dioxide I I Chemical Name: 1 Type pmduct: Fumicide I Pmduct Name: 'The Fruit Doctortt I Ccanpany Name: Snuwden mtemrises, Inc.; Fresno. California Purpose: ReYiew of Reresistration data (Phase IVI for Sulfur ~ioxide (Funqicide for fruits)

Action Code: 602 #: 93-0685 ~otal~eviw+ Time: 1.0 days

EXWB GuidelineplRI~Slmrmzy Table: The review in this package conqins: - P II I

+ UNITED STATES ENVIRONMENTAL PROTECTION AGE~CY WASHINGTON, D.C. 20460 I I I

II I

OFFICE OF PREVENTION, PESTICIDES AND I TOXIC SUBSTANCES

SUEJECI?: Sulfur Dioxide ("The Fruit Doctortt) Reregistration Case #4086 DP BARCDDE D190758; EZWB #93-0685

FExB: Silvia C. Termes, Chemist Review Section #3 E51vhmtal Fate and Ground ~~talFate and Effects

~rea~etz, ~cting Chief /' Science Analysis and Coordination Staff Environmental Fate an5 Effeds Division (K1507C) Bruce Sidwell prcduct Manager #53 Accelerated Reregistration Branch, Sf7RD (H7508W)

THRU: ?kiwi D. Abmmovitch, Ph.D., Section Chief Review Section #3 k Eknriromtal Fate and Ground Water Branch Envhmtal Fate ard Effects Division (M507C) Henry M. Jacoby, Chief Environmental Fate and Ground Water Bran& Environmental F'ate and Effects Division (H7507C)

'Lhe chemical t~Sulfur~ioxidel~ is used as an indoor fumiqant (9-,I cold storage mftrucks. vans, boxcars and other transport vehicles) . The fruit camcdity for which this chemical product is used is CJ&ES (post-harvest). It suppresses the grey mold disease caused by Bothtis cinerea. The only environmental fate data requirement for stamDioxidet1 an indmr fumigant (food1 is Hvdmlvsis (161-1). However, the of sulfur dioxide in aqueous media is well docmented in the literature. The Branch believes that there is sufficient chemical literature to generate an environmental fate and trampa? assessment of stsulfurDioxiden. I

Recycled/RecyclableI Printed wlth SOyICan018 Ink on paper that contains at least 50% recycled fiber 1. UBEL VONS(I1The Fruit Doctorft) I I FYm the present label recammendations/supplmt it is LUIC~& to estimate the anacnxnt of sulfur dioxide that is required for algiven amount of fruit enclosed in a given volume of storage/transportation site. The Branch believes that the registrant should improve its label to provide better guidance on proper usage of this highly toxic I 2. cE.D.;MICAL RELATIONSHIPS BGlWEEN SULFUR DIOXIDE AND INORGANIC EWUTES I It is hprtant to realize that gSulf%r Dicmide1I and tfSulfity?lare very closely related. Sulfur dioxide (a gas at normal temperape and pressure) is very soluble in aqueous media. Solutions of viulffir Dioxide in water are acidic. The acidic nature of the solution is attrhtted to the hypothetical species ~lSulftnousAcid1f. ~g~~~ Acidt1 has never been isolated but its anions ttSulfitew(SOS2-) and lfpdrogen Sulfitefl so^^-: also known as ~vbisulfite~l)exist anJ are pryt in solution. Rrlfite salts do exist and are well known. I

I 3. "THE m-IxXmRS1 I This "Sulfur Dioxidew product is sold in cylinders containing a,I mixture of liquified sulfur dioxide and gaseous sulfur dioxide wrder presw.

4. OTtW USES OF SULZWt DIOXIDE I I Sulfur Dioxide is used as a blead-hg agent. Liquified Sulfur DioxideI is used as a solvent (non-aqueous) in many chemical reactions (Ref& to Non-aaueous Solvent !%stems, T.C. Waddhgbn, ed., Academic Pmy, New York, 1965). Sulfur Dioxide is also used as a refrigerant. Sulfur dioxide (as a by-prcduct of smelting opeations ard roasting of ores) is used in the manufacture of sulfuric . It is used in the manufacturing of sulfite salts and dithionites. 1

5. THE c3EmSmY OF SUL;FVR DIOXIDE (Science Chapter) See attachement. 1 THE C2EXtSIliY OF SULFUR DIOXIDE

Two very important and distinct aspects of the chemistry of sulfur dioxide must be taken into consideration. One is its reactivilty in the gaseous state; the other is its reactivity in aqueous media.

UMer no& temperature and pressure (boiling pint -10 C at ordinary pressure), sulfur dioxide (SO2) is a colorless, toxic gas with a choking odor. The of sulfur in sulfur dioxide is +IV. It oxidizes to (SO3) when reacted with dio~enin the presence of a catalytic agent.

The presence of sulfur dioxide gas in the atmosphere ccnnes from natxual and anthropogenic sources. Natural processes include geothemal activity (mostly volcanic activity) . I-Iowever,anthropogenic souroes (mostly fram industrial pmcesses and ram's dmestic activities) cause serious environmental pmblens. The most notorious of these problems jq "acid rain8',which affect the urban population as well as contributing to the pollution of water bodies. I Gaseous SO2 is readily soluble in water (3927 cm3 of SO2 dissolbe in 100 g of water at 20 C). The dissolution of SO2 in water resul"; in an acidic solution known as 18sulfurousacid8'. 8sSulfurousacid" haslnever been isolated, but spectroscopic studies suggest the presence of hydrated SO, nolecules (9 nH20) , sulfite (HSaj-) and sulfite 1 (~0~~7 anions and hydromum (~~0'). The predominance of these species depends on concentration, pH and temperature. 1 I Sulfite salts have been isolated, some of them in crystalline foh. Exoept for the sulfites of the alkali (; ) and , most of the sulfite salts are rather insoluble in water. I I solutions containing sulfite and hydrogen sulfite anions behave as Werate reducing agents. Depending on the conditions of the reaction, the sulfite anion is oxidized to or . However, in the presepce of strong reducing agents (for example, a sodium amalgam) sulfites can be reduced. Therefore, the subsequent chemistry of sulfites/hYdrogen\ sulfites in aqueous media is determined by the pH and the corditions (ofthe media. I Emriromtal Fate Assessment 1 The major concerns about this chemical (when used for pesticidal pnrrposes)I are related to accidental spills into water bodies and/or releasedlof pressurized gas into the amsphere. Ihe extent of any potential damage would depend on the munt of gas released in relation to the size \ofthe environmental canpartment (water body: clase/open spice). It has byn reported that mygreen plants could suffer severe stress at cancytrations of sulfur dioxide as low as 1-2 ppn. Sulfur dioxide dissolved in aqueous media can be toxic to aquatic life, I I \ Refer- I I Bttcn, F.A. and Willcirson, G. Advaned Inomanic Chemistry, I Fifth Edition, 1988, John Wiley New York. ard Sons, I Greenmod, N.N. ard ~w,A. Chwistly of the Elements, 1984, Pergamn Press, Oxford, UX. I