Syngenta Crop Protection. Inc. LegalGroup 2 RighterParkway Wilmington, DE t 9803 Heather C. Winett Tel. (302) 476-2112 Fax (302)476-2012 heather.winett@syngenta.com


### September 25,2001
Kathleen Franklin U.S.Environmental Protection 

### Agency Ariel 

### Rios Building -5 104 1200Pennsylvania Avenue, N. W. Washington, DC 20460
Re: RequestedDe-Listing ofParaqua fDichlorideJi.omSARA 

### Title111,Section 302; ZenecaAg ProductsInc. 

### v. 

### U. 5.EPA
Dear Ms. Franklin: Set forth 

### below is the supplement following up on 

### the 

### inf mation sent August 30, 2001 to demonstrate that Paraquat dichloride, though classified 

### as restricteduse pesticide, would notbe a danger to the community if it were delisted from the SARA 302 ExtrerneIy Hazardous SubstanceList. Would you kindly insert Attachments 3 and ~nto the tabs sent with 

### the of Paraquat Dichloride at its Decomposition Point." 

# k

Augustpackage. 

### Also 

### enclosed is a report entitled 

### "AnEstimation ofthe Vapor 

### Pressure

We 

### hope that your questionsand concerns have been addressed, However,ifyou need any additional information 

### or discussion, Syngenta

### would be pleased to 

### respond further. Sincerely,

Heather 

### C.Winett Environmental 

### Counsel
CC: 

### Nina Rivera, Esq. 

### (EPA) Alan Carpien, Esq. 

### @PA) Peter Gray, Esq. 

### Sueanne Pfifferling Richard 

### ReissQuestion 5: Would the proposed change to Paraquat dichloride's status in EPCRA affect all solids in solution? Are many other pesticides solids in solution?
Answer There appear to be only 18 other chemicals (pesticides and non-pesticides) classified by EPA as "solids in solution" on the EPCRA 302 list, and therefore assigned dual TPQs. At least three of 

### these chemicals have been discontinued in recent years. 

### See Attachment 3. However, paraquat1can be distinguished, because it has both an extraordinarily 

### low vapor pressure and 

### no boiling point, key properties in 

### assessing offsite release concerns. Compounds with very low vapor pressure 

### do not volatize at atmospheric temperatures. As temperatures rise (e.g., in 

### a fire), the vapor pressure of a chemical 

### increases until it reaches that chemical's boiling point, and the chemical becomes 

### a gas. Paraquat, however, 

### does not have a boiling point, but 

### rather decomposes 

### at between 320-340'c.~
For purposes of comparison, Attachment 3 lists the chemicals (pesticides and nonpesticides) classified 

### as solids in solution on the EPCRA 302 list with 

### vapor pressures equal to or 

### lessthan 

### Paraquat. For each chemical, the table includes the vapor pressure, boiling point, 

### TPQ, and uses! Ofthe 1 5 chemicals still in use, only 

### four others [Coumaphos, Phenol, 

### 2,2'-Thiobis(4,6-Dichloro), Strychnine sulfate and Thallous sulfate] have 

### a vapor pressure equal to or lessthan Paraquat's also have 

### no boiling points. 

### None ofthese three compounds iswidely used 

### for agricultural purposes and are

### not generally used as liquids; therefore, the lower 

### TPQ for 

### each of those is not relevant. Additionally, Strychnine sulfate may no longer be registered for use 

### as a bait in rodent control. Thallous sulfate is used as a solid for rodent control; its use 

### as a reagent in analytical chemistry 

### as a liquid would 

### be only 

### in very small 

### quantities. Coumaphos, 

### an insecticide, 

### is not widely used in the

## u.s.~
For non-pesticides, 1998usage volumes are reported in EPA's Inventory Update Rule 

### (IUR) report if the usage is above 10,000 lbs per year. The IUR does not contain usage data for any ofthe non-pesticides on Attachment 3, including the compounds with 

### no boiling points 

### (i.e.,

### phenol,2,2'-thiobis(4,B-dichloro), and thallous sulfate), 

### thus the usage must be 

### below 10,000lbs 

### per year.

1 Unless otherwise indicated, Syngenta's reference to "Paraquat" always refers to Paraquat dichloride.

J. I.Macnab, "An Estimation ofthe Vapor PressureofParaquat Dichloride at its Decomposition Point." 15 August 2001

3 Accordingto annual Pesticide Use Data from the National Centerfor Food and Agricultural Policy 1997National Pesticide Use Database, only 71,000 Ibsofcournaphos wm used in the U.S. in 1997,comparedwithnearly 7million Ibs ofParaquat.