Response to Comments from

External Peer Review of the

“Technical Review of Ethylene Glycol Mono-Butyl Ether (EGBE)”

September 2009

Environmental Analysis Division

Office of Information Analysis and Access

Office of Environmental Information

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW

Washington, DC 20460
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Peer-Review Comments and Responses on

Technical Review of Ethylene Glycol Mono-Butyl Ether (EGBE)

Charge to Peer Reviewers 

EPA has prepared a technical review document to assess the chemistry, environmental fate, and the 

potential environmental impacts associated with releases of and exposures to EGBE. The purpose of this 

peer review is to seek comment on the accuracy and completeness of EPA’s assessment.

Peer Review Questions:

Chemistry and Fate

1. Are there any other chemical properties of EGBE that should be included?

2. Does the technical review accurately address the fate of EGBE in the environment including 

transformations resulting in the formation of toxic chemicals?

Environmental Effects

1. Does the summary statement and review of the literature present a clear rationale and 

accurately reflect the conclusions regarding the ecological hazards of EGBE?

1. CHEMISTRY AND FATE

Comment 1-1: The Technical Review summarizes the salient properties of EGBE. While there are other 

properties that can be identified (e.g., surface tension), I don’t believe they are germane to the subject of 

this review. The EU risk assessment cited above identifies a somewhat high vapor pressure value (1.41) 

vs. the Dow Chemical value of 0.88 used in the review. Probably a more important difference is Henry’s 

Constant. The Technical Review identifies 1.6  10-6as Henry’s Constant based on Johanson and 

Dynesius (1988). Kim et al. (2001) using two different experimental methods reported a value of 0.082 

Pa.m3/mol or 0.82  10-6atm m3/mol. This value is roughly half that used in the Technical Review. The 

EU report notes that direct measurement of Henry’s Law Constant is preferable for water miscible 

compounds such as EGBE. EPA should consider this information. It will not change the overall 

conclusions of EPA’s review. 
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Kim, B. R., E. M. Kalis, T. DeWulf and K. M. Andrews (2000). "Henry's law constants for paint solvents 

and their implications on volatile organic compound emissions from automotive painting." Water 

Environment Research 72(1): 65-74. (peer reviewer 1)

EPA Response: The Henry’s law constant value cited in the Technical Review has been replaced with 

the value of 8.16×10-7atm-m3/mol at 25°C from Kim et al. (2000).

Comment 1-2: The physical, chemical and biological processes influencing EGBE environmental fate 

are well described and for the most part quantified. Additional information that would help give the 

reader a better idea of the environmental behavior of EGBE would be details on how it gets into the 

environment. While uses are described in section 1.5 no discussion of how the material gets into the 

environment is given. This is important because if the environmental processing data are exhaustive, the 

discussion in section 1.6.4 should provide the reader with where in the environment the risk of effects is 

greatest. This discussion concludes with the results of an equilibrium distribution model suggesting that 

the majority of the EGBE would be on the land surface and in the water. If for example, the primary 

route of EGBE entry into the environment is through wastewater release (not really likely since 96% of 

EGBE is degraded in sewage sludge after 14 days) the results of this generalized modeling would be 

irrelevant. (peer reviewer 2)

EPA Response: Specific information regarding the release of EGBE into the environment has not been

located in the available literature. Emission inputs used for the new fugacity calculation in Section 1.6.4 

are based on TRI data for the “certain glycol ethers” category as provided on page 2 of the assessment. 

The assumption that the release data reported for this category are representative of EGBE releases is also 

noted.

Comment 1-3: Another apparent inconsistency is the discussion in section of 1.6.1 discussing the slow 

volatilization of EGBE from moist soil and water surfaces with the discussion of toxic transformation 

product formation in section 1.6.5. If the reader is to believe the information from section 1.6.1 and the 

resulting model predictions of section 1.6.4 that says that less than 3% of EGBE will be found in the 

atmosphere, why the emphasis on toxic transformation product formation in the atmosphere in section 

1.6.5? (peer reviewer 2)

EPA Response: The EPIWIN fugacity model predictions have been revised based on the use of actual 

environmental release values reported to EPA by industry in response to the TRI Program. The revised 
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environmental distribution values indicate that the atmosphere will be a significant sink (47%) for 

released EGBE. Based upon this revision, the emphasis on atmospheric transformation products in the 

report will remain. 

Comment 1-4: Other questions that come to mind as I read the document include the following:

1. Does the indirect photooxidation of EGBE occur on moist soil surfaces?

2. Does photoxidation occur in surface waters that contain natural organic matter (NOM)? NOM has 

been shown to mediate oxidation in aquatic systems. (peer reviewer 2)

EPA Response: Information regarding indirect photooxidation of EGBE on moist soil surfaces and 

photooxidation in surface waters containing neutral organic matter was not located in the available 

literature. 

Comment 1-5: Considering the high water solubility of EGBE and fugacity models, the major sink for 

this compound is aquatic ecosystems, especially water. This compound is expected to be dissociated in 

water depending on the pH of the water and the dissociated forms are expected to have environmental fate 

different from the neutral form. Acid-dissociation constant (pKa) provides information regarding this 

property. It will be useful and important to report pKa of EGBE. (peer reviewer 3)

EPA Response: Acid-dissociation constant (pKa) is not relevant for EGBE. EGBE does not contain any 

functional groups that will dissociate under environmental conditions.

Comment 1-6: All the relevant properties are included. There is some ambiguity about the solubility in 

water. It is given as “infinite” in Table 1.1 but as 1 x 106 mg/L in Table 2.1. In reality the later figure is 

the density of water and is used as a “dummy value” in the EPIWIN program. It would be better to have 

one Table and with SI units. (peer reviewer 4)

EPA Response: Table 2.1 has been removed from the document. The units used in Table 1.1 are 

commonly used and accepted units. For the sake of clarity, SI units will not be added to the table.

Comment 1-7: The Review accurately addresses the fate of EGBE. According to the EU risk 

assessment, the theoretical distribution of EGBE is even more concentrated in water than that reported in 

EPA’s Review (99 vs. 41.7%). Obviously, different models were used and Henry’s Law Constant is 

higher in the EU model (although all other model inputs were apparently the same). While this disparity 
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does not drastically alter interpretations in EPA’s Review, this analysis should perhaps be checked. (peer 

reviewer 1)

EPA Response: The fugacity calculation has been performed again using a different Henry’s law 

constant (8.16×10-7atm-m3/mol at 25°C from Kim et al. (2000)), a different Koc value (7.6), and different 

emission input values (82% to air, 8% to water, 7% to soil, and 0% to sediment). The emission inputs 

were chosen based on the TRI data for the “certain glycol ethers” category, with the assumption that 

reported releases for this category are representative of EGBE releases. These changes result in 

partitioning values of 20% to air, 33% to water, 47% to soil, and 0% to sediment. The inputs used for this 

calculation are similar to those used for the EU risk assessment fugacity calculation. The major 

difference is that the EU assessment used a Level I model whereas a Level III model was used for this 

assessment. The Level III fugacity model is considered to be more appropriate than the Level I model for 

the purposes of this Technical Review assessment.

Comment 1-8: The review discusses transport, degradation, transformation, and distribution of EGBE in 

the environment. While the major topics related to environmental fate of EGBE have been covered, there 

is no information on the fate of EGBE in terrestrial and aquatic environments. For example, atmospheric 

fate, degradation, and transformation products in the atmosphere have been discussed. However, fate of 

this compound in the terrestrial environment (soil) and aquatic environment are not addressed. What are 

the degradation products in soil and water? What is the half-life in soils and water? What is the fate of 

the degradation products in soil and water? Are the degradation products toxic? This information is 

especially important because fugacity models have shown that the environmental sink for EGBE is water 

and soil. (peer reviewer 3)

EPA Response: Very limited information regarding actual residence times of EGBE in soil and water 

has been located in the available literature. One study has been located that indicates that butoxyacetic 

acid is a product of EGBE biodegradation. This information will be included in Section 1.6.5 along with 

a brief description of the toxicity of this product. Information regarding the fate of butoxyacetic acid in 

the environment is not readily available.

Comment 1-9: Degradation and metabolism in biota (e.g. fish or rat or any rodent models) is not 

discussed. The reviewer has searched the literature and found out that the biological metabolism of 

EGBE can lead to the formation of butoxy acetic acid and this compound is hemolytic. In addition 

glycolic acid (which is nephrotoxic) and several toxic metabolites are formed in animals. It is important 
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to discuss the biological fate of EGBE including transformation products and toxicity? The study of Price 

et al. 1974 is too old to draw any reliable conclusion. (peer reviewer 3)

EPA Response: Information about the biological transformation of EGBE to 2-butoxyacetic acid was 

added to Section 1.6.5. Toxic Transformation Products. Detailed discussion about the toxicity of

transformation products is beyond the scope of this assessment. Regarding the comment about the Price 

et al. (1974) study, the study has value despite its age, and therefore it remains in the assessment.

Comment 1-10: It is important to indicate the major pathways of EGBE released into the environment 

(section 1.4, lines 16-17) i.e., mention whether the major release is through air or water or soil? Such 

information may be available from TSRI (toxic substances release inventory). This would dictate the 

reliability of fate assessment for any chemical released into the environment. (peer reviewer 3)

EPA Response: Specific information regarding the release of EGBE into the environment has not been 

located. EPA’s toxics release inventory (TRI) contains data for the “certain glycol ethers” category of 

which EGBE is a member, but it does not contain data for EGBE specifically. The following paragraph 

in section 1.1 is revised in an effort to clarify TRI release information reported relevant to EGBE:

“In 2007, releases of glycol ethers reported to the Toxic Release Inventory (TRI) (U.S. EPA, 

2009) under the “certain glycol ethers” category totaled approximately 18,476,000 pounds. 

Reported releases to air, surface water, and land were approximately 16,416,000, 87,000, and 

1,311,000 pounds, respectively. Approximately 126,000 pounds were released via underground 

injection. Approximately 7,902,000 pounds were transferred to publicly-owned treatment works 

(POTWs). EGBE is one of the glycol ethers reportable under the “certain glycol ethers” 

category (specific release information for EGBE is not available in the TRI database). It is not 

known how much of these amounts are attributable to EGBE releases; however, this may be a 

large percentage since EGBE is the single most widely produced glycol ether (Dow, 2006).” 

Comment 1-11: Several of the literature surveyed for this review is based on industry sponsored 

research and some bias has been introduced. (peer reviewer 3)

EPA Response: See response to comment 3-15 below.

Comment 1-12: For any of the above comments, if the authors think that there is no information in the 

literature (for smog/groundwater problem/biological fate/degradation in soil/water), it should be 

mentioned accordingly, in summary. (peer reviewer 3)
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EPA Response: Statements indicating that relevant data have not been located in the available literature 

have been included in the Technical Review text where appropriate. 

2. ENVIRONMENTAL EFFECTS

Comment 2-1: The EU risk assessment reports a valid chronic (21d) EC20 = 175 mg/L (INERIS, 1999). 

INERIS (1999d). Détermination de la toxicité chronique du 2-butoxyethanol vis-à-vis de Daphnia 

Magna, Ba746a-CGR21427. Verneuil-en-Halatte, France, 15 décembre 1999, INERIS: 13. (peer 

reviewer 1)

EPA Response: Because “INERIS (1999)” is an unpublished report, EPA was unable to obtain it. 

Instead the EC50 value, which is more standard than an EC20, are reported and cited as being from 

“INERIS (1999), as cited in the EU Risk Assessment Report on EGBE.”

Comment 2-2: Given this chronic value, one can compute an acute:chronic ratio (ACR) = 1815 (48h 

EC50)/175 or approximately 10. This ACR is fairly moderate also suggesting that EGBE is unlikely to 

elicit high long-term toxicity. (peer reviewer 1)

EPA Response: No further action was taken since the ACR supports the available experimental and 

predicted chronic values already included in the assessment.

Comment 2-3: Note that the EU Report cites valid freshwater fish acute data for rainbow trout and 

fathead minnow. This report also cites valid acute data for the freshwater invertebrate Brachionus 

calcyiflorus using a method identical to the approved ASTM standard method. This acute value (EC50 = 

164) is lower than any cited in EPA’s Review. The EU Report also cites a valid Daphnia magna chronic 

data (21d) = 175 mg/L (EC20, an endpoint typically used by EPA in their water quality criteria 

development). This is nearly 3 times EPA’s predicted value of 52 mg/L (p. 16). I would also note that a 

16d EC50 is not considered an acceptable chronic endpoint for Daphnia by either EPA OPPT or EPA OW. 

(peer reviewer 1)

EPA Response: The rainbow trout and fathead minnow acute data, as well as the chronic daphnid EC 

value, are from unpublished industry reports (e.g., “INERIS, 1999” or “Dow Chemical Company, 1979”). 
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Because they are unpublished, EPA was unable to obtain the reports. The data are now referenced as “as 

cited in the EU Risk Assessment Report on EGBE.”

The source of the Brachionus calyciflorus data (Devillers et al., 2002) was retrieved, evaluated and 

included in the assessment. In addition DeVillers et al. (2003) and Dill & Millazzo (1988), both cited in 

the EU Report, were also retrieved, evaluated, and included in the assessment. 

The predicted 16-day EC50 value was replaced with chronic predicted values that are available from the 

latest version of ECOSAR (released in 2008).

Comment 2-4: For chemicals like EGBE that have few valid data, EPA should consider using EPA’s 

Interspecies Correlation Estimation (ICE procedure) http://www.epa.gov/ceampubl/fchain/webice. This 

procedure might be informative in this case because valid data are available for several commonly tested 

species (e.g., Daphnia, fathead minnow, trout, bluegill, silverside). (peer reviewer 1)

EPA Response: The available experimental toxicity data (as well as predicted values) are sufficient for 

the purposes of this assessment.

Comment 2-5: The literature search appears to be thorough and the conclusion that EGBE is not 

expected to present a significant concern for adverse effects is sound. All of the aquatic toxicology data 

were for acute bioassays. The lack of chronic data resulted in the use of quantitiative structure activity 

relationships (QSARs) and EPA’s Ecological Structure Activity Relationship Program (ECOSAR) to 

supplement existing data and predict chronic effects. While this appears adequate, the extrapolation of 

individual effects to population level effects should be explored. Can the Daphnia magna data in Table 

2.2 be extrapolated to population level effects? What is the implied endpoint in the chronic effects 

prediction for D. magna? If it is reproduction then population level effects could be inferred. (peer 

reviewer 2)

EPA Response: The extrapolation to population effects is beyond the scope of this assessment. The 

focus of these types of assessements is to present acute and chronic toxicity data for individual effects.

Comment 2-6: The summary statement is focused heavily on chemical properties, production and usage 

of EGBE rather than environmental fate. Some of the important information regarding toxic products 

formed in the atmosphere, and potential health effects from exposure to such toxic products are not 
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mentioned in the summary. I would suggest that a paragraph on different atmospheric transformation 

products of EGBE and the formation of peroxyacyl nitrates (PANs) should be given in the summary. I 

would also add a statement to note that PANs are components of photochemical smog. Mutagenic 

property of PAN (P9, line 10), formation ozone and its effect on human health are not mentioned in the 

summary. (peer reviewer 3)

EPA Response: The following has been added to the summary section of the report to provide the reader 

additional information on the toxic transformation product of EGBE in the atmosphere and the associated 

adverse effects.

“EGBE may contribute to the formation of tropospheric ozone (Derwent et al., 1996; 

U.S. EPA, 1996). Degradation products can result in the formation 2-butoxyacetic acid (BAA) 

(see section 1.6.5) as well as peroxyacyl nitrates, (Atkinson, 2000; LOOP, 2003). In mammals

2-butoxyacetic acid is thought to be responsible for EGBE’s toxic hematological effects (U.S. 

EPA, 1999). Peroxyacyl nitrates (PAN) have been reported to be eye irritants, mutagenic, 

phytotoxic, and possible agents of skin cancer (Singh and Salas, 1989; Williams et al. 1993). 

PAN has been shown to be mutagenic in Salmonella and in the lungs of mice exposed nose-only 

to PAN generated from non-mutagenic precursors (DeMarini et al., 2000).”

Comment 2-7: Information on the high water solubility and potential for groundwater contamination by 

EGBE is not mentioned in the summary. (peer reviewer 3) 

EPA Response: The following has been added to the report summary:

“EGBE released to soils and sediments is not expected to strongly absorb and has the potential to

migrate into underlying groundwater systems (Hansch et al., 1995; HSDB, 2007; Staples et al., 

1998; U.S.EPA, 2008).”

Comment 2-8: I would also add statement regarding soil and biological degradation products. If there is 

no information regarding soil degradation products, that should be mentioned. For biota, there are studies 

that show that EGBE degrades to produce butoxy acetic acid which can cause hemolysis and this should 

be mentioned in the summary. (peer reviewer 3) 

EPA Response: There is no reliable information regarding soil degradation products for EGBE in the 

environment. This statement can be added to the summary. The degradation of EGBE to butoxyacetic 

acid (a biomarker of EGBE exposure) is a mammalian toxicology issue, and thus was not addressed in the 

ecological hazard assessment.
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Comment 2-9: The summary statement appears to be biased, overall, as information regarding toxic 

effects or ecological hazards are not mentioned. Very few studies have reported aquatic toxicity of 

EGBE. The available aquatic toxicological data are not from systematic studies with standard protocols. 

The data are inadequate to draw conclusion on ecological hazard. This needs to be mentioned in the 

summary. (peer reviewer 3) 

EPA Response: The summary statement for Chapter Two does in fact mention ecological toxicity – and 

cites Table 2-2 for the summary of values. The summary further states that toxicity is not high – “... 

indicating low to moderate aquatic toxicity (Table 2-2).” 

Comment 2-10: Some of the literature selected for this review is not up to date and some are biased. A 

cursory look at literature of EGBE has shown several new literature including toxic effects. For example, 

there is a review on ecotoxicity of EGBE. See TOXICOLOGY MECHANISMS AND METHODS 

Volume: 12 Pages: 255-263 (2002). Also see, ENVIRONMENTAL TOXICOLOGY Volume: 14 Issue:

5 Pages: 481-522 (1999). (peer reviewer 3)

EPA Response: Devillers et al. (2002) was retrieved, evaluated and included in the assessment. 

The second reference the peer-reviewer mentions (Kent et al., 1999) was evaluated and it was determined 

not appropriate for inclusion in the assessment because it’s a review that only covers ethylene glycol, 

propylene glycol, and diethylene glycol – not EGBE. 

As for other new literature that may exist on the ecological toxicity of EGBE, another ECOTOX search 

was conducted and the search resulted in one new “hit.” The ECOTOX search conducted in preparation 

for the original assessment on October 25 2007 resulted in 35 hits; the subsequent ECOTOX search 

conducted in April 2009 had 71 hits, and the additional 36 hits are all from one additional reference --

Adema, D.M.M. 1985 . Aquatic Toxicity of Compounds that may be Carried by Ships (Marpol 19733 

Annex II). A Progress Report for 1985. Source: Tech.Rep.No.R85/217, TNO, The Hague, Netherlands 

:40 p. Thus there is not much additional ecological toxicity data available.

Comment 2-11: The summary is excellent, but I would replace “infinitely soluble” with “completely 

miscible” on p1 line 12. Overall it is well done and with these minor changes should be acceptable. (peer 

reviewer 4)
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EPA Response: The phrase “infinitely soluble” will be replaced with “miscible”.

3. ADDITIONAL COMMENTS

Comment 3-1: The information presented in the Review of EGBE is accurate and interpretations are 

generally accurate as well. EPA should consider including the European Union’s (EU) recent draft Risk 

Assessment of EGBE (2005): http://ecb.jrc.it/documents/Existing-Chemicals/ 

RISK_ASSESSMENT/DRAFT/R408_0712_env_hh.pdf.

This risk assessment includes more recent environmental effects data as well as possible updates to 

certain properties such as Henry’s Law Constant. (peer reviewer 1)

EPA Response: Data reported in the EU Risk Assessment have been reviewed and included in the 

Technical Review where appropriate.

Comment 3-2: p. 2, lines 5-6: Releases to water are reported to be 128,000 lbs but 5,061,000 lbs were 

transferred to POTWs. Not clear how you can have 5 million lbs to POTWs (i.e., water) and only have 

128,000 lbs released to water. (peer reviewer 1)

EPA Response: Data reported to TRI as transferred to a POTW is not counted as released directly to 

water since no data on the treatment efficiency of the POTW is reported to the TRI. TRI data users can 

assume no treatment or some percentage treatment depending on what happens to the chemical at the 

POTW and then include those quantities as released to water from the POTW.

Comment 3-3: p. 6, line 1: The model lake is only 3m deep? I would call that a pond at best. What is 

the volatilization half-life for a lake 10-20m deep (i.e., more representative lake in North America)? (peer 

reviewer 1)

EPA Response: The model defaults for a “model lake” were used for this calculation. The purpose of 

this calculation is to provide a general comparison between a flowing body of water (model river) and a 

relatively stagnant body of water (model lake). This model was not designed for the increased 

complexities involved with chemical volatilization from deeper lake systems. 

Comment 3-4: p. 8, line 3: Lack of anaerobic biodegradation information should be acknowledged as a 

critical data gap because EGBE has a propensity to move to groundwater where volatilization is 
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negligible. Spills of EGBE to groundwater could pose a health risk to drinking water supplies perhaps.

(peer reviewer 1)

EPA Response: Data gap statements will be limited to a brief indication that the information was not 

located. The statement on p. 8, line 3 has been modified to indicate that anaerobic conditions include 

groundwater.

Comment 3-5: p. 13, line 7: ...effects occur at relatively high concentrations that are never observed 

under normal circumstances (i.e., EGBE degrades rapidly). (peer reviewer 1)

EPA Response: Italicized text added to the Chapter Two Summary to reflect the reviewer comment as 

“Such high concentrations are not expected to be observed under typical environmental conditions.” The 

parenthetical comment was not added because it is not clear that rapid degradation is the sole cause of the 

observed environmental concentrations.

Comment 3-6: This review appears to be pretty thorough and should provide information (with the 

caveats discussed below) required for section 313 of the Emergency Planning and Community Right-ToKnow Act. However, the review appears to be a quick compilation of fragments from manuscripts and 

documents without attention to a methodical discussion of the salient information. For example, the 

summary is a series of sentences largely taken from the different section and gives the reader the 

impression that little effort was spent in editing this document and making it more readable. Having said 

that, it may be that the readability of this document may not be important. If so, disregard the above 

remarks. (peer reviewer 2)

EPA Response: General edits were made to the document to improve the readability from one 

discussion to the next.

Comment 3-7: Page 4, Column 1 of Table 1-1: “Molecular Formula” should be “Molecular formula” 

and “Molecular Weight” should be “Molecular weight”. (peer reviewer 3)

EPA Response: These changes have been made as suggested.

Comment 3-8: P6, lines 9-10: It has been stated that EGBE has a potential to move from soil to 

groundwater. However, further details regarding groundwater pollution or distribution of this compound 
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in groundwater is lacking. This should be highlighted in the summary and should be stated as an area for 

future investigation. (peer reviewer 3)

EPA Response: The following sentence was added to the text of this section: “Additional information 

regarding the transport of EGBE through soil, surface water, and groundwater has not been located in the 

available literature.” As mentioned above, data gap statement is limited to a brief indication that the 

information was not located. 

Comment 3-9: P8, line 17- P9, line 11: Atmospheric transformation of EGBE has been discussed. 

While it is stated that EGBE photooxidizes to produce several air pollutants including peroxyacyl nitrates 

(PANs). The PANs are important constituents of Photochemical smog. This is not mentioned either in 

summary or in the environmental fate section. If direct release of EGBE into air was higher than that in 

soil or water, then discussion on photochemical smog is important. (peer reviewer 3)

EPA Response: Information on the formation of the EGBE degradation products resulting in the 

production of PAN and BAA has been placed in both the summary and the Toxic Transformation 

Products sections of the report

Comment 3-10: P7, line 9: ‘Topospheric’ should be “Tropospheric”. (peer reviewer 3)

EPA Response: This change has been made as suggested.

Comment 3-11: P5, line 21 and P6, line 2: “slowly” is a subjective term. How slowly? I would avoid 

such subjective terms. A similar problem on P7, line 15: “rapidly” How rapidly?? Such subjective 

terms introduce bias to this report. (peer reviewer 3)

EPA Response: The volatilization classification scheme in Lyman (1990) is now cited to provide further 

support for the statement regarding slow volatilization; estimated volatilization half-lives are also 

provided in the next sentence. The phrase “biodegrades rapidly” has been changed to “is readily 

biodegradable” with references added to support this classification.

Comment 3-12: P13: Line 6-7: This statement reads biased. There is no strong evidence to support this 

statement. First we do not have systematic studies with standard protocols to measure aquatic toxicity. 

Second, no chronic, long term exposure end points have been measured. The reported values are all 
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LC50 or LOEC; no NOEC is reported. Given these problems, the statement on P13, line 6-7 is not right. 

(peer reviewer 3)

EPA Response: The sentence was modified to read “Based upon available acute toxicity data, EGBE 

does not appear to present a significant concern for adverse effects on the aquatic environment since 

effects occur at relatively high concentrations that are have not been observed under normal 

circumstances.” EPA believes that the available toxicity data and estimated toxicity values are sufficient 

to conclude that EGBE has low to moderately low ecological toxicity.

Comment 3-13: P15, Table 2-1: Column 1, “Henry’s law constant” check the spelling.

(peer reviewer 3)

EPA Response: The spelling has been changed to “Henry’s law constant”.

Comment 3-14: P2, line 20: “rapid” How rapid? It is a subjective term. I would avoid or be specific.

(peer reviewer 3)

EPA Response: The phrase “expected to undergo rapid biodegradation” has been changed to 

“considered to be readily biodegradable” with references added to support this classification.

Comment 3-15: This review appears biased and incomplete. More information is available in the 

literature on the fate and toxicity of EGBE. An unbiased review of the available information is needed. 

EGBE is a very high production volume chemical and is used in large quantities in several products that 

we come in contact in our daily lives. There is a great potential for human and environmental exposures. 

(peer reviewer 3)

EPA Response: A search of the available literature was performed for EGBE. The relevant information 

has been summarized and presented in a factual manner in this review. No further changes will be made. 

Comment 3-16: The report is well written and appears to be up to date. The interpretations are 

consistent with the reported data although at times they are a little loose and sweeping, e.g. EGBE does 

not bioaccumulate. (A BCF of 3 represents small or slight but not zero bioaccumulation) There is some 

repetition, notably of Table 1.1 of chemical properties. (peer reviewer 4)
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EPA Response: The phrase “not expected to bioaccumulate” has been changed to “not expected to 

bioaccumulate significantly”.

Comment 3-17: In other reports the EPIWIN output has been supplied with the report on the CD. This 

was not the case with EGBE. I suggest that in view of the heavy reliance on that software the actual 

output be appended to the report. (peer reviewer 4)

EPA Response: A pdf file was generated from the EPI Suite output for reference.

Comment 3-18: Correlations between KOW and KOC and BCF are used but it should be noted that these 

correlations are largely based on substances with log KOW ranging from 2 to 6. Since log KOW of EGBE is 

0.83 there is a real possibility of poor correlation. This is apparent in the KOC estimated. A cautionary 

note should be included to this effect. (peer reviewer 4)

EPA Response: A calculated value of 7.6 from the new EPI Suite software (version 4.00) is now used 

instead of the value of 67 currently in the Technical Review. The new Koc model can perform a 

calculation based on the measured log Kow which was not possible with the previous versions of EPI 

Suite where a separate calculation was required. In addition, the new model contains a larger training set 

and improved equations compared to the older method.

Comment 3-19: P1 line 9 I believe the correct name is n-butyl not N butyl. N implies nitrogen. (see p3 

line 29). (peer reviewer 4)

EPA Response: This change has been made as suggested.

Comment 3-20: P1 line 12 I prefer “completely miscible” to “infinitely soluble”. (peer reviewer 4)

EPA Response: The phrase “infinitely soluble” has been replaced with “miscible”.

Comment 3-21: P1 line 26 delete “greater than”? (peer reviewer 4)

EPA Response: This change has been made as suggested.
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Comment 3-22: P4 Table 1.1 Can I suggest that the SI units be given as well for each property including 

vapor pressure, solubility and HLC? (peer reviewer 4)

EPA Response: For the sake of clarity, SI units will not be added to the table.

Comment 3-23: P5 line 21 I suggest that the air-water partition coefficient KAW be given as well. This is 

H/RT with R in units of atm.m3/mol.K. R is 8.314 Pam3/mol K or 82 x 10-6atm m3/mol K KAW is then 

65.5 x 10-6. (peer reviewer 4)

EPA Response: The nature of EGBE volatilization has been captured through the use of the Henry’s law 

constant value. There is no need to include the air-water partition coefficient (KAW).

Comment 3-24: P6 log KOW is 0.83 so KOW is 6.76. A BCF of 3 is thus reasonable but the KOC of 67 

seems very high. Usually KOC is about 35% of KOW. It would be more accurate to state that ‘EGBE is not 

expected to adsorb (or sorb) strongly to soils.... (peer reviewer 4)

EPA Response: The new Koc value of 7.6 will be used as discussed above. The language on p.6 has 

been changed as requested.

Comment 3-25: In the fugacity model was KOC input or KOW? Most models assume KOC is 

approximately 0.4 KOW. It may be that the model uses a different KOC from that suggested in the report, 

i.e. one calculated from KOW. (peer reviewer 4)

EPA Response: The fugacity calculation has been performed again. The new Koc value of 7.6 

mentioned above was used for this calculation.

Comment 3-26: Line 3 It would be clearer to state that Bidleman suggests that only x% of EGBE will be 

associated with aerosols. It would help to calculate KOA as KOW/KAW. It is about 105so sorption to 

aerosols at normal aerosol concentrations of 10-11 volume fraction is minimal, i.e. about 10-6. The 

conclusion is correct. (peer reviewer 4)

EPA Response: This sentence was replaced with the following: “Using this vapor pressure value, a 

calculated particle/gas partition coefficient of 2.05×10-6indicates that any EGBE that is released into the 

air will exist primarily as a vapor (Biddleman, 1988; U.S. EPA, 2008).”
Page 17 of 17

Comment 3-27: p13 the concern for adverse effects in aquatic systems depends on the prevailing EGBE 

concentration as well as toxicity. It does seem unlikely that environmental concentrations will reach 

about 1000 mg/L (which is 0.1%) except near spills or leakages. The sentence in line 6 is perhaps a bit 

broad and sweeping. Toxicity could occur under extreme conditions. (peer reviewer 4)

EPA Response: See response to comment 3-12 above.

Comment 3-28: P15 Table 2.1 is essentially Table 1.1. Why repeat it? (peer reviewer 4)

EPA Response: Table 2.1 has been removed from the document.