  SEQ CHAPTER \h \r 1 

DATA EVALAUATION RECORDS (DER) for Estimated Drinking Water
Concentrations in the Environment

MEMORANDUM						July 2, 2004

SUBJECT:		PROPYLENE GLYCOL AND DIPROPYLENE GLYCOL: Estimated Drinking
Water Concentrations

TO:			Connie Welch, chief

			Regulatory Management Branch II

			Antimicrobials Division (7510C)

		

FROM:		A. Najm Shamim, Ph.D., Chemist

			Regulatory Management Branch II

			Antimicrobials Division (7510C)

					And

			Faruque Khan, Environmental Fate Sceintist

			Environmental Fate and Effects Divison, Branch ERB V

SUMMARY

		Background:

		This DER outlines the assessment of estimated environmental
concentrations of Propylene Glycol and, if applicable for Dipropylene
Glycol,  for their possible use as an active or an inert  in
agricultural settings (fungicidal use).

Label search shows that Diporpylene Glycol has no agricultural
applications as an active or as an inert ; Propylene Glycol, however, is
used as inert in of the products (Quintec) for fungicidal application on
Cherry, Grapes and Hops (preharvest setting).

Application Rates of Quintec: 1) For cherries, a maximum of five
applications are made, and cumulatively (for all five applications), the
toal amount of quintec used is 35 fluid ounces/acre  (approximately 2.2
lbs/acre; 2) For grapes, a maximum of five applications are made and
cumulatively the total amount of Quintec  is not exceeded from 33 fluid
ounces/acre  ( approximately 2.1 lbs/acre) and 3) for Hops, no more than
four applications of Quintec are made and the amounts of the product are
not exceeded from 33 fluid ounces/acre (approximately 2.2 lbs/acre). For
all thre pre-harvest crops, a maximum of 6.4 lbs/acre of the product
Quintec is applied.

The physical and related environmental fate properties of Propylene
Glycol were obtained from published open literature. Table I oultines
these, and for comparision purposes, the properties of Dipropylene
Glycol and Triethylene Glycol (TEG) are also listed in Table I

					Table I

Triethylene Glycol	Propylene Glycol	Dipropylene Glycol

v.p. : 1.32 x 10-2 mm Hg1	v.p: 0.129 mm Hg1	v.p: 3.19 x10-2 mm Hg1

log Kow = -1.75	Log Kow = -0.92	Log Kow = -1.07

Solubility: highly miscible	Solubility: highly miscible	Solubility:
highly miscible

Does not hydrolyze	Does not hydrolyze	Does not hydrolyze

Koc = 10	Koc = low2	Koc= 6

Does not photolyze (> 290 nm, no absorbance)	Does not photolyze (> 290
nm, no absorbance	Does not photolyze (> 290 nm, no absorbance)

Henry  Constant: 3.1 x10-11 atm m3/mole 1	Henry Constant:1.31x10-10 atm
m3/mole 1	Hnery Constant:3.88x10-9 atm m3/mole 1

BCF: Not reported	BCF: <1	BCF: Not reported

Estimated half life in air: 11 hours3	Estimated half life in air: 32
hours3	Estimated half life in air:13 hours3

Biodegradation: aerobic(fresh water): 7 to 11 days(river-die away test)
Biodegradation: aerobic: 4 days; anaerobic: 9 days	Does not biodegrade
as fast as Triethylene or propylene glycols (river die-away test)4

Highly mobile (weak binding with soils)	Highly mobile (weak binding with
soils)	Highly mobile(weak binding with soils)



Notes: 1. At 25 o C;  2) No data available; 3) measured against the
hydroxy radical reaction.

	A comparison of the three glycols indicate: 1) their physical/chemical
properties and fate chemistries are very similar to each other; 2) All
three of them do not hydrolyze as these do not contain hydrolyzable
groups All three are highly miscible with water and also are  highly
mobile in soils and hence have potential of surface and ground water
contamination concerns; 3) All three have short half lives in air ( 11
to 32 hours);4) All of them have low Kow  and hence are not likely to
bioaccumulate in aquatic organisms (fish etc.); 5) degradation pathway
for triethylene glycol and propylene glycol appears to be biodegradation
aerobically and anaerobically with a maximum half life of 4 days for
propylene glycol and 7 days for triethylene glycol and maximum half life
of 11 days for triethylene glycol and 9 days for propylene glycol; for
dipropylene glycol biodegradation data is inconclusive in terms of half
lives; however, it does appear to biodegrade more slowly than the other
two glycols.

Key Assumptions for the Application of FIRST ( FQPA Index Resorvior
Screening Tool) to estimate the concentrations of Propylene glycol at
the intake of a community water system  and SCI-GRO to estimate the
concentrations of Propylene Glycol in ground water and drinking water
resources (shallow ground water and surface water) are as follows: 1)
For Qunitec use as a fungicide a high end application rate of 10
lbs/acre was assumed; 2) in the absence of soil data on Propylene
Glycol, data on inoclum on sludge was applied and uncertainty factor of
3x was assumed; 3) it is also assumed that mineralization of Propylene
Glycol is attained in 28 days; hence assumed soil metabolism will be 28
x 3(uncertainty factor) = 84 days; 4) it is also assumed that no more
than 10% of the Propylene glycol is removed from the wastewater
treatment plants and enter into the house-hold drinking water; 5) No
value is assigned in literature for Koc for propylene glycol, assume Koc
= 10 (same as triethylene glycol) and for dipropylene glycol Koc = 6

	Because of highly miscibility of TEG in water and its hydrolytic
stability (abiotic conditions) and high mobility in water, the Agency
estimated the concentration of TEG in surface and ground water by using
some assumptive parameters. FIRST and SCI GRO were used to calculate
these concentrations. Since the in put parameters used were on the
conservative sides, the EEC’s found were to be lower than the level of
concern for TEG; we are applying the same approach for the propylene and
dipropylene glycols to estimate the EECs in water.  Table II outlines
the Input Parameters for Propylene Glycol.

					Table II

				     Propylene Glycol

Input Parameters for Propylene Glycol for FIRST Program For Preharvest
Crops of Cherries, Grapes, and Hops.

Parameter	Scenario #1

Application Rate	1 lb/acre

Soil Koc	10

Water solubility	100,000

Hydrolysis	Stable

Aq. Photolysis	Stable

Soil Metabolism T1/2 (days)	84 

Aquatic Aerobic  metabolism T1/2 (days)	4

Anaerobic Aq. Metabolism T/12 (days)	9

No of applications	1

% Crop Area Covered 	87

													

Outputs: 1) Untreated Water Concentrations of Propylene Glycol
(micrograms/liter, ppb) at the peak day (Acute) concentration = 887.538
ppb and 2) Untreated Water Concentrations ( in ppb) at the annualized
average (chronic) = 11.068 ppb

For Ground Water Screening by use of SCI-GRO, the concentrations of
Propylene Glycol in the ground water = 107 ppb

					Table III

				    DiPropylene Glycol

		In Put Parameters for Dipropylene Glycol for FIRST Program

Parameter	Scenario #1

Application Rate	10  lbs/acre

Soil Koc	6

Water solubility	100,000

Hydrolysis	Stable

Aq. Photolysis	Stable

Soil Metabolism T1/2 (days	84

Aerobic Aq. Metabolism : T/12 (days)	20



OutPuts for Dipropylene Glycol, using the parameters listed in Table III
would be: 1) Untreated Water Concentration of Diproylene Glycol ( in
micrograms/liter, ppb): peak day (acute conc: 900.469 ppb; 2) annualized
average (chronic): 52.177 ppb

For Ground Water Screening by use of SCI-GRO, the concentrations of
Dipropylene Glycol in the ground water = 153 ppb

