Department of Defense Comments on 

Benzoapyrene IASC draft Toxicological Review.pdf

Comments submitted by: Chemical Material Risk 

Management Directorate

Organization: Department of Defense Date Submitted: 7/7/2011

*Comment categories: Science or methods (S); Editorial, grammar/spelling, clarifications needed (E); or Other (O). Also please indicate if Major i.e. affects the outcome, 

conclusions or implementation of the assessment.

Comment 

No.

Section Pages Comment

Suggested Action, Revision and References 

(if necessary)

*Category

1 2 3, line 27 References needed for these statements Please provide references. E

2 2 3, line 31 Same reference provided twice in one sentence. Please eliminate one of the references. E

3 2 4, lines 8 and 12

The text should mention that the percent 

absorbed depends on the concentration.

Please add that the amount absorbed is 

concentration dependant.

S

4 2 4, line 12

The antecedent of a pronoun should exist within 

the same paragraph.

Either reference “these studies” or connect with 

previous paragraph.

E

5 2 5

These inhalation exposures in Table 2-2 and 

associated pages do not indicate an exposure 

problem when compared with the RfC of 5 

ng/m3. A reference to this fact would be 

appropriate to frame the exposure 

concentrations.

As per NAS (2009), EPA should start with a 

problem formulation statement: What is the 

problem with BaP, given these minimal 

exposures?

S

6 2 6

These oral exposures in Table 2-3 do not 

indicate an exposure problem when compared 

with the RfD of 500 ng/kg-day. A reference to 

this fact would be appropriate to frame the 

exposure concentrations.

EPA should start with a problem formulation 

statement here as well. What is the problem 

with BaP, given these minimal exposures?

S
7 Global

This document frequently assumes that results 

for any or every PAH are relevant to BaP. This 

document reviews the toxicity of BaP only; EPA 

has another document that demonstrates the 

differences among PAHs

All references to data that are not specifically 

about BaP should be deleted.

S/M

8 Global

DoD has documented in the comments below 

many instances where (1) the summary of a 

section is inconsistent with the statements in 

that section or (2) the conclusion in one section 

is inconsistent with that of another section. 

Given that the interagency review group was 

told to expect this draft in early January, it is 

unfortunate that a better quality review has not 

occurred prior to this release.

Improvements in internal consistency are 

necessary. It should not be left to readers to 

attempt to locate when conclusions either 

misstate or contradict the findings. The 

document should have undergone a quality 

review prior to release for interagency review. In 

particular, if people read only summaries of 

sections, they should have the same conclusion 

as those who read the whole section.

S/M

9 Global

Adjectives and adverbs are imprecisely used. 

Frequently, for example, a form of "rapid" is 

used when "increased amount" is meant. On 

page 38 of the text there are several more 

examples of sloppy presentation of information.

The document should be edited before it is 

released for interagency review to ensure the 

text is not misinterpreted.

S/M

10 Global Global

EPA's 2005 cancer guidelines require quality 

human data to use the characterization 

"carcinogenic to humans.” In this document, 

EPA has clearly stated that there are no quality 

studies of BaP alone that demonstrate human 

carcinogenicity. EPA has presented no data 

that the carcinogenicity of the PAH-containing 

mixtures is due to the BaP and not the combined 

effects of the other PAHs or other chemicals in 

those mixtures or both. EPA has a different 

EPA should clearly present the data available on 

BaP alone with regard to the characterization of 

the weight of the evidence for carcinogenicity, as 

well as the requirements of its 2005 cancer 

guidelines. If EPA continues to include data on 

other PAHs and PAH-containing mixtures, it 

should clearly justify why this determination 

should be made in this document, rather than in 

its document on PAH mixtures.

S/M
document that reviews PAHs. It also uses BaP 

as the index chemical. This means that if EPA 

determines that BaP is a human carcinogen, all 

PAHs will be determined to be human 

carcinogens as BaP-equivalents. Using data for 

PAH mixtures to determine information on BaP's 

weight of evidence for carcinogenicity and then 

using the BaP determination to assess PAH 

toxicity is circular reasoning that borders on a 

tautology.

11 All All

Please address the following editorial 

comments.

Page 246, line 24. “..divided by a total 

uncertainly factor of 1000 (factors of 3 for animal 

to human extrapolation, 10 for human 

interindividual variability, and 3 for database 

deficiencies)” Please correct the factors to 

make a multiple of 1000 i.e., 10 for animal to 

human extrapolation etc).

Page 204, line 28 and following page. Please 

move the top half of the table onto the next page 

so that Table 5.1 is all on one page.

Page 218, line 18. “s(1998) udies” should be 

changed to “(1998) studies”

Page 235, line 5. “Average dose/day = 

(ug/application) x (number of exposures/week ÷ 

7 days/week. Please add parenthesis to number 

of exposures /week) and make “7 days/week the 

E
sole denominator. 

Page 8, line 6. “samples. .” delete the second 

period

Page 32, line 21. “benzo[a]pyrene should be 

capitalized at the beginning of the paragraph.

This error occurs throughout the document

Page 139, line 5. As above.

Page 161, line4. As above.

Page 166, line 36. As above.

Page 38, line 3. There are three enzymes, 

"either" is incorrect.

Page 32, line 15. The sentence is not written in 

proper English and needs editing.

Page 170, line10. “caspace” should be spelled 

“caspase”.

Page 176, line 7. “subchronicly” should be 

“subchronically”

Page 178, line 5. Paragraph beginning with “In 

addition...” should be indented, for consistency.

Page 181, line 32. “.Carfi e al.” please remove 

the leading period.
Page 181, line 21. “Spleen cell cultures...” 

should be indented.

Page 186, line 20. “an alternant” should be “an 

alternate”.

Page 244, line 6. Capitalized “b” in 

benzopyrene. Please search the document for 

this recurring error.

12 Global NA

1. Given that this is an updated profile of 

benzo[a]pyrene and that the EPA has 

promulgated the potential use of genomics in 

toxicology, it is surprising that there is no 

mention of microarrays or genomics in this 

review. There are 37 hits using the keywords 

benzopyrene and microarray in Pubmed many 

of which examine the carcinogenicity of BaP. 

See EPA Interim Genomics Policy: 

http://www.epa.gov/spc/genomics.htm

“Genomics data may allow EPA to enhance its 

assessments and better inform the decisionmaking process”.

Luo, W. et al. Phenotypic anchoring of global 

gene expression profiles induced by N-hydroxy4-acetyaminobiphenyl and benzo[a]pyrene diol 

epoxide reveals correlations between 

expression profiles and mechanism of toxicity.

Review EPA Genomics Policy and studies for 

applicability.

S
 Chem Res Toxicol. 2005 18(4): 619-29.

Bartosiewicz, M. et al. Applications of gene 

arrays in environmental toxicology: fingerprints 

of gene regulation associated with cadmium 

chloride, benzo[a]pyrene, and trichloroethylene.

2001. Environ Health Perspect. 109(1): 71-4.

13 References 285

It would appear that the critical study for 

derivation of the RfD (Xu et al., 2010) is missing 

from the list of references

Please insert Xu et al., 2001 into references S

14 3.1.1.1 9, line 27

If the concentration of BaP is low in the air, there 

is no particular reason to believe that either oral 

or dermal exposure will occur. Oral exposure 

would either be through consumption of food or 

water or via the mucociliary escalator, the latter 

of which is unexpected unless insoluble particles 

are involved. Dermal exposure, to the extent it 

occurs, would not only depend on the 

concentration but also the clothing of the person.

This statement should either have a reference or 

include data to support the assertion. Broadbased assertions with significant implications 

should be accompanied by a reference or 

primary data supporting them.

S

15 3.1.1.1

10, lines 1 

through 28

The information about absorption of other PAHs 

is not relevant to the discussion of BaP unless 

the presence of other PAHs affects the 

absorption of BaP, in which case these data are 

confounded.

Please clarify the purpose of presenting 

information on other PAHs in a document that is 

only on BaP. IRIS has already released a 

document on PAH mixtures, and extra and 

redundant information unnecessarily lengthens 

an already long document. Please delete this 

and other references to PAHs unless their 

relevance is established.

S/M

16 3.1.1.1

11, lines 1 

through 26

As the metabolism of BaP has not been 

discussed by this point in the document, please 

Please add the requested information, and if this 

metabolite is related to other PAHs, please 

S
indicate the relevance of “transantibenzo[a]pyrene-tetrol in the urine” with 

regard to BaP absorption. Is this metabolite 

related to exposure to any other PAH?

explain how this confounding information was 

handled.

17 3.1.1.1 11, line 28

Please explain the relevance of the comparison 

with other PAHs. Please also explain the 

conclusion that “benzo[a]pyrene is absorbed in 

an unpredictable fashion” given that, in all of the 

examples provided, there were significant 

confounders and the presence of materials that 

might affect the absorption of BaP, i.e., the 

presence of organic matter as discussed on 

page 9, line 8.

Please substantiate or remove the assertion that 

the absorption of BaP is “upredictable.” We 

believe that a more complete analysis of the 

data discussed in this section would 

demonstrate that the absorption of BaP can be 

reasonably and consistently predicted if the 

conditions of the absorption and the presence of 

other chemicals are included in the analysis.

S

18 3.1.1.1 11, line 33

We believe that instillation experiments are of 

limited value for assessing toxicokinetics and 

should not be used when inhalation data are 

available.

Please explain how the instillation data have 

been quantitatively adjusted or, preferably,

merely reference them and indicate that they are 

of limited quantitative utility if inhalation data are 

available.

S

19 3.1.1.2

11, line 38 

through 13, line 6

Please explain how a bolus administration of a 

very high concentration of BaP is relevant to 

absorption of ambient levels, as the previous 

discussions indicate that the extent of absorption 

is concentration dependant. Extensive 

discussions of data that are not relevant serve 

only to lengthen the document. Furthermore, 

the use of instillation limits the utility of these 

data.

Please explain or limit discussion of these 

experiments to one sentence.

S

20 3.1.1.2 12, line 6

The statement that “the clearance rate [from the 

lungs] was limited by diffusion through the 

As recommended by several, recent external 

review panels, DoD recommends that EPA 

S
alveolar septa for highly lipophilic compounds 

such as benzo[a]pyrene” might also explain the 

asserted “unpredictability”of BaP that was 

discussed in the previous section. Since the 

majority of the experiments measured 

absorption as the appearance of urinary 

metabolites, the retention of BaP in the lungs 

(which is expected to be dose dependant as 

dose would affect the diffusion gradient) might 

cause lags and otherwise influence the 

appearance of urinary metabolites.

include more integration of the data it has been 

reviewing. As the toxicologists involved in these 

reviews have more time and knowledge about 

the chemical under review, DoD would expect 

that they would notice these correlations and 

present them in their analyses.

21 3.1.1.2 14, line 11

It is not clear why dose administered as an 

aerosol concentration creates a limitation for the 

study.

As the cancer potency and RfD/Cs will be 

expressed as concentration in the air, please 

explain why “administered aerosol 

concentration” is a limitation of the study.

S

22 3.1.1.2 14, line 17

Use of triethylene glycol as the solvent will be a 

confounder, given all of the effects that have 

been discussed previously.

EPA should state that the differences between 

these results and those of saline – including the 

biphasic nature of the absorption – are likely due 

to the solvents, i.e., hydrophilic versus 

hydrophobic.

S

23 3.1.1.2 16, line 8

The word “particles” should be qualified, as 

EPA’s definition of particles is quite broad.

Statement should read “some, insoluble 

particles.”

S

24 3.1.1.2 17, line 21

Because most of the animal data presented are 

from instillation or other nonconventional 

methods, e.g., application to nasal tubinates, the 

conclusion that “absorbed rapidly (within 

minutes) and extensively” is insufficiently 

supported and should be qualified. Data from 

these non-conventional methods can not be 

The text and associated conclusions should be 

appropriately qualified.

S
used to quantitatively support absorption from 

inhalation. Similarly, the “more rapid absorption 

in the pulmonary regions” in line 23 can not be 

supported by instillation experiments, as the 

instillation procedure bypasses the nose.

25 3.1.1.2 17, line 17

The statement that the variation in results is due 

to interindividual variability is neither referenced 

nor supported. As stated in previous comments, 

the perceived variability could be due to the lack 

of analysis on the part of EPA. None of the data 

presented in this document demonstrate that 

differences in subjects caused the variability.

Furthermore, the statement that this is “most 

likely the result of different genetic makeups” 

has no support thusfar in the document. If they 

are discussed later, the section should be 

referenced here.

EPA should either provide data or a references 

of primary data to support these statements. If 

not, such speculation should be deleted.

S

26 3.1.2.2. Global

As with inhalation, the experiments reported 

depend on non-conventional exposures, e.g., 

gavage (Ramesh et al., 2001b; O’Neill et al. 

1990) or bolus (Foth et al., 1988)

The results from these experiments should be 

appropriately qualified and not used for

quantitative analyses.

S

27 3.1.3.1. 21, lines 1 - 15

As reported, this study only reports results for 

“PAHs” not BaP, and therefore is not relevant to 

this document.

The study should be deleted from this section. S

28 3.1.3.1

21, lines 33 and 

37

The percentage absorbed is meaningless since 

the document does not report the dose applied 

and absorption of BaP is dose dependant.

The dose should be provided or the “results” 

should be deleted.

S

29 3.1.3.1 22, line 25 The adverb “rapidly” seems inappropriate, since Perhaps the document means to say that not S
none of the studies examined uptake over time. much was absorbed, at least as BaP.

30 3.1.3.1

23, line 18, 

repeated on page 

24m line 21

It is not clear whether this is the conclusion one 

of the authors” or that of EPA? Moreover, does 

the person who is speculating have data to 

differentiate the difference in viscosity versus a 

difference in hydrophobicity being the likely 

effecter? Hydrophobicity seems more likely, as 

the viscosity of soil should prevent any 

absorption.

The text should be clear as to which conclusions 

are those of the authors of the experiment and 

which are those made by EPA scientists. 

Moreover, speculations that are not supported 

by data should not be included.

S

31 3.1.3.1 23, line 30

It is highly unlikely that the soil, much less the 

BaP, was in a “monolayer”.

The characterization should be corrected S

32 3.1.3.1 23, line 38

Given that, in other radio-labeled experiments, 

not all of the radioactivity was recovered, if 34% 

was excreted, more than 34% was likely 

absorbed. The EPA authors should be careful 

about how they present the data and should not 

make their own, unsupportable conclusions.

The text should be corrected to reflect the 

reported data, not inferences.

S

33 3.1.3.1 24, line 7

Given that only metabolites were released and 

that this section is concerned with absorption, 

retention of the metabolites by the skin is not 

relevant for this section.

This document should avoid inference and 

speculation, especially that which is not relevant 

to the topic under discussion.

S

34 3.1.3.1 24, line 15

The “and” should be “or” or “and/or” as the 

experiment can not distinguish whether it is one 

or both that are saturated. Indeed, the next 

sentences suggest it is a saturation of 

metabolism, not absorption per se.

Change “and” to appropriately reflect the results 

of the experiment.

S

35 3.1.3.1 25, line 12

This sentence does not appear to be supported 

by the information provided in EPA’s document.

The statement should be edited to accurately 

reflect the text it is summarizing.

S
If “abundant” data are available, why is only one 

study presented. Furthermore, the data from 

that study are only given in terms of “PAHs” and 

as such provide no quantitative evaluation of 

human dermal absorption of BaP.

36 3.1.3.1 24, line 18

The data do not indicate a change in rate, only 

amount.

The text should accurately reflect that more BaP 

was absorbed after induction; this document 

says nothing about a change in rate.

S

37 3.1.3.1 22, line 37

These tissues qualify as “dermal”, furthermore 

the text states that this data is not comparable to 

human skin data.

Discussion of these experiments should be 

moved to the appropriate section, or deleted.

S

38 3.1.3.1 25, line 15

As the dermal absorption is dose-dependant, the 

percent absorption should reflect this.

Add “dose-dependant” to this sentence. S

39 3.1.3.1 25, line 17

Unless this sentence is specifically applicable to 

BaP, it should be deleted. The data 

demonstrate that absorption differs among 

PAHs; therefore, generalizations cannot be 

made.

The sentence should either replace “PAHs” with 

“benzo(a)pyrene”, if that is accurate, or it should 

be deleted.

S

40 3.1.3.1

26, line 26; 27, 

line 25; 31, line 

38

The text should indicate if this is the authors’ or 

EPA’s conclusion. It appears that all three may 

be EPA’s speculations, as the data are open to 

other interpretations.

If the speculations about the mucocilary 

clearance are EPA’s speculations, they should 

either be deleted or clearly stated as such. If 

this is the case, the “is” in the last citation should 

be changed to “may” as it is speculative, not 

demonstrated.

S

41 3.2 31, line 8

This sentence is speculative and has no data to 

support it.

This sentence should be deleted. S

42 3.2 31, line 8 Is EPA stating as a fact that particles (in this As these documents all originate from NCEA, S
case with BaP adsorbed) do not circulate from 

the lungs to other parts of the body? If so, is this 

in agreement with EPA’s conclusions regarding 

the distribution of particles in its documents on 

particulate matter? For example, section 4.3.3. 

“Particle Translocation” of EPA’s “Integrated 

Science Assessment for Particulate Matter” 

(EPA/600/R-08/139F, December 2009) states, 

“There is evidence that particles may cross cell 

membranes and move from their site of

deposition by other mechanisms [than 

mucociliary and macrophage mediated 

clearance].”

EPA should ensure agreement among their 

documents.

43 3.2 31, line 34

It seems that “limited” be “absence of”; given 

(page 25, line 6) that there are “No adequate 

quantitative studies of benzo[a]pyrene tissue 

distribution in exposed humans.”

Correct the the text to make it internally 

consistent.

S

44 3.2 31, line 36

Given that the previous section indicated that 

very little is absorbed, we are confused how 

“significant levels” can be in the tissues.

Recommend correction so the document is 

internally consistent.

S

45 3.2 32, lines 4 and 6

The dependent clause should be deleted, as 

EPA has already concluded that most of the 

BaP is metabolized as it is absorbed. Similarly, 

given the statement at line 4, shouldn’t line 6 be 

about the metabolites?.

The independent clause makes the dependent 

clause unnecessary. Line 6 should say 

“metabolites”.

S

46 3.3 32, line 10

Even if secondary sources are used, they should 

be referenced, as not all of the reviews will 

agree on all issues.

Please add the references. S
47 3.3 32, line 34

Both steps in the metabolism should get 

equivalent treatment.

Phase II metabolism should also be displayed, 

perhaps in 3.3.2. Phase II Metabolism.

S

48 3.3.1.1 Global

Many statements in this section have specific 

references from the 1970s and 1980s, 

contradicting the earlier statement that “Key 

concepts have been adapted largely from these 

reviews and supplemented with recent 

findings.” Do these statements disagree with 

the reviews? Is this information based on what 

the reviews say about the articles (in which case 

the reference should so indicate) or based on a 

review of the primary article by EPA scientists?

The text should accurately reflect whether the 

EPA scientist read a review or the primary 

article. Disagreement between the introductory 

text and the main text should be resolved.

S

49 3.3.1.1 37, line 10

The singular in the parenthetical implies the 

lethality is only for one dose, but the sentence 

has 3 dose levels.

The sentence should be corrected to state 

clearly whether all or only the highest dose is 

lethal to the knock-out mice in 30 days.

S

50 3.3.1.1 37, line 27

This experiment is misplaced, as it addresses 

potential effects of the metabolites rather than 

metabolism.

The paragraph should be moved. E

51 3.3.1.2 38, line 9

The term “bioactivation” either assumes 

metabolites are more active than the parent 

compound, which is demonstrably false for BaP, 

or that EPA is only concerned about metabolites 

that are more active, which would be 

unfortunate.

The text should be edited to reflect accurately 

the intention.

E

52 3.3.1.2 38, line 10

As the previous sentence stated that this 

paragraph would be about CYP-independent 

processes, the inclusion of “via CYPs” in the 

parenthetical is inconsistent.

The text should be carefully edited to avoid such 

apparent contradictions.

E
53 3.3.1.2 38, lines 11-18

This experiment is misplaced, as it addresses 

potential effects of the metabolites rather than 

metabolism.

The text should be moved, E

54 3.3.1.2

38, line 24 

through page 40, 

line 22

Without information about the concentration of 

BaP, it is not possible to judge whether these 

experiments were conducted at biologically 

relevant concentrations.

All in vitro data should be presented with a 

discussion of whether the doses are biologically 

relevant.

S/M

55 4.5.3 167-170

The discussion regarding AhR’s role in BaPmediated carcinogenesis is poorly written and 

inadequate. BaP-specific information needs to 

be clearly distinguished from general AhR 

biology and from evidence that was from PAH 

mixture studies. Figure 4-1 can be dramatically 

improved with more sophisticated and BaPspecific information; it is unnecessary to provide 

basic AhR biology. There are numerous 

sentences that are not clear within this section. 

AhR may be involved in regulating BaP 

metabolism AND/OR involved in the 

upregulation of genes involved in cell cycle and 

differentiation. These two distinct roles of AhR 

are not clearly described nor evaluated.

Recommend significant edits to improve the 

evaluation of BaP-mediated AhR activation, as it 

relates to both tumor initiation and promotion. A 

molecular biologist with expertise in nuclear 

receptor signaling should review this section and 

improve the accuracy and clarity of statements 

within.

S/M

56 4.5.3 169, line 21

It is unclear how the following statement is 

concluded: “The high levels of benzo[a]pyrene 

DNA adduct in organs other than the liver of 

AhR–/– mice may be the result of slow 

detoxification of benzo[a]pyrene in the liver, 

allowing high concentrations of the parent 

compound to reach distant tissues." It is also not 

Recommend delete the sentence beginning on 

line 21.

S
clear why this type of pontification is necessary 

or appropriate in the current section.

57 4.6.2 179

According to EPA (1994) guidelines, the 

database shown in Table 4-28 is insufficient to 

develop an RfC. Specifically, lung effects were 

not sufficiently monitored, and the duration is too 

short. In addition to the studies shown in Table 

4-28, Wolff et al., 1989 assessed lung injury 

after only a 4 week exposure, and Thyssen et 

al., 1981 did not report histological examination 

of the lung. A reproductive/developmental RfC 

could be developed, but it must be annotated as 

such and the lack of a general RfC must be 

clearly stated.

An RfC cannot be developed. Recommend 

removing the RfC development from the 

document, or deriving a 

reproductive/developmental RfC.

S/M

58 4.7.3.1 187

Figure 1 shows more than just the 4 key events 

described in the text, and yet is also missing 

other information discussed in the text. How 

does cytotoxicity play a role in tumor formation, 

for example? If it does not have a role, it is not 

clear why it was included it in the Figure. The 

arrows and boxes (key events) of the process 

should be specific to BaP, with supporting 

information to justify why the step is necessary

in BaP-induced neoplasm formation. Figure 1 

also does not differentiate between several 

potential MOAs (i.e. cytotoxicity versus mutation 

and promotion).

Figure 1 needs to be modified to represent the 

known key events specific to BaP-mediated 

carcinogenicity, as distinct from general steps in 

the carcinogenic process. Discuss cytotoxicity 

as a possible MOA for the cancer endpoint.

S/M

59 4.7.3.2 189

Section titled “Dose-response concordance 

and temporal relationship.” Adduct formation 

Please discuss specific data on mutations as a 

possible MOA for the cancer endpoint.

S/M
does not equal mutation as EPA (2007) clearly 

states. EPA needs to provide information on 

how adduct formation’s dose-response 

concordance and temporal relationship is 

relevant to the mutagenic MOA. There is no 

data presented for dose-response concordance 

and temporal relationship for mutations.

60 4.7.3.2 190, line 21

It is agreed that there is temporal consistency 

between BPDE-DNA adducts and forestomach 

tumors, however a comparison of the dose 

response behavior of these two endpoints is 

inconsistent. If tumors were based on adduct 

formation, one questions why there is a sharp 

increase in tumor incidence between doses, and 

not a linear increase as for adducts. Moreover, 

EPA has not shown a temporal and dose 

response concordance between mutations and 

tumor formation.

The discussion amongst the various possible 

MOAs for the cancer endpoint needs to be 

balanced.

S/M

61 4.7.3.2 190, line 36

EPA has not demonstrated temporal and dose 

concordance between tumors and mutations. It 

is very unclear why these arguments are being 

made against alternative MOAs.

Please balance the discussion amongst the 

various possible MOAs for the cancer endpoint.

S

62 4.7.3.2 191, line 6

EPA needs to take all of the evidence on 

relevant MOAs, through the MOA/Human 

Relevance (MOA/HR) framework. Production of 

inflammatory cytokines and inhibition of GJIC 

should be analyzed for temporal and dose 

response concordance. Without doing this, the 

overall MOA conclusions made by EPA, 

Balance the discussion amongst the various 

possible MOAs for the cancer endpoint. Apply 

the MOA/HR Framework to all potential MOA 

evidence.

S/M
including the determination of inadequate 

information, cannot be evaluated.

63 4.7.3.2 191, line 15

Not believed by whom? Please use a citation 

for this sentence. If it is speculation by the 

author, please state it as such.

Incorporate appropriate citation. S

64 4.7.3.2 191, line 29

While support exists for gene mutations, the 

authors have not linked these mutations to 

tumor formation through the MOA/HR 

framework. For example, the section on "Doseresponse concordance and temporal 

relationship" only gives evidence for DNA 

adducts.

Balance the discussion amongst the various 

possible MOAs for the cancer endpoint. Clearly 

differentiate between DNA adduct formation and 

mutagenicity.

S

65 4.8.1 192, line 11

This statement is not true. The expectation 

depends entirely on the full underlying MOA.

EPA (2005, page 1-17) states that:

"These empirical results are consistent with 

current understanding of the biological 

processes involved in carcinogenesis, which 

leads to a reasonable expectation that children 

can be more susceptible to many [not all is 

implied in EPA’s BaP text] carcinogenic 

agents."

Furthermore, EPA (2005, page 2-29) also 

states:

"Identifying and comparing metabolic process 

differences by age, sex, or other characteristic 

so that susceptible subpopulations can be 

Revise the ADAF discussion to be consistent 

with EPA cancer guidelines. Incorporate 

specific data that indicates that an ADAF for oral 

cavity tumors is not needed.

S/M
recognized. For example, metabolic capacity 

with respect to P450 enzymes in newborn 

children is extremely limited compared to that in 

adults, so that a carcinogenic metabolite formed 

through P450 activity will have limited effect in 

the young, whereas a carcinogenic agent 

deactivated through P450 activity will result in 

increased susceptibility of this lifestage (Cresteil, 

1998). A variety of changes in toxicokinetics and 

physiology occur from the fetal stage to postweaning to young child. Any of these changes 

may make a difference for risk (Renwick, 1998)."

BaP metabolites are formed in part by P450 

enzymes, and thus, such metabolites are less 

likely to be formed in younger animals. So why 

is the ADAF for BaP being proposed?

66 4.8.1 193, line 6

The authors lead this section off with the phrase 

"Increased childhood susceptibility..." 

presumably in comparison with adults, but then 

do not show any comparative data between 

adults and children. Without comparative 

information, any difference (i.e. increase) in 

susceptibility is impossible to evaluate. The 

data within section 4.8 merely demonstrates 

childhood susceptibility.

The comparative data between adults and 

children needs to be shown.

S

67 4.8.1 194, line 9

DoD does not agree with EPA’s conclusions of 

the epidemiological studies assessing cigarette 

smoke. It is possible that exposure to other 

compounds within the cigarette smoke, such as 

Evaluate the epidemiological studies of cigarette 

smoke to discuss the milieu of compounds 

within the smoke, not just PAHs. Clarify text.

S
carbon monoxide, could cause the observed 

effect; the effects cannot be ascribed to PAHs 

alone without additional clarification or 

information. Also, the last sentence (line 14) 

does not make sense. Do the authors mean 

"missed period"?

68 4.8.1 194, line 18

Clarify how overt toxicity or depression in fertility 

of F1 can be compared to parental toxicity when 

the exposure to the parental animals starts at 

GD 7.

Recommend correcting the summarization 

sentences to accurately reflect the available 

data; do not over interpret the data.

S

69 4.8.1 195, line 31

Rather than using default procedures, EPA 

needs to show these data (Vesselinovitch et al., 

1975), since they appear to be a solid basis for 

the age dependent adjustment factor (ADAF).

Note that these data may be useful to explore 

different ADAFs with different tumor types.

Please revise the ADAF discussion to be 

consistent with EPA cancer guidelines by 

incorporating specific data that indicates that an 

ADAF for oral cavity tumors is not needed.

Such an ADAF may be needed for other tumors.

S/M

70 5.1 201

The document is lacking a candidate RfD array.

These arrays are extremely useful in illustrating 

the variety of studies, the impact of POD and 

UF, and the range of potential values.

Please generate a candidate array for the 

potential RfDs to illustrate the PODs, UF and 

resulting potential RfDs for comparison.

S

71

5.1.2. Methods of 

Analysis

205, line 13

The reference cited is an External Review Draft 

that, in more than a decade, has not been 

finalized. Therefore, citing this guidance as a 

reason for any particular action is problematic.

Only final guidance or guidelines should be 

cited, or if EPA wishes to continue to cite this 

reference, the text should clearly state that this 

is not EPA guidance, i.e., "based on procedures 

suggested in EPA’s draft technical guidance". 

Otherwise, some readers might assume that (1) 

this is formal, EPA guidance and (2) EPA must 

follow these procedures unless it can justify its 

deviance based on the weight of the evidence of 

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scientific studies.

72

5.1.2. Methods of 

Analysis

205, line 14

EPA’s BMD software calculates a one-sided 

95% lower limit that is equal to the more 

appropriate 90% two-sided confidence interval.

EPA should state the qualifications on this 

calculation clearly and transparently.

S

73 5.1.2 205, line 26

The rationale for the choice of principal study 

and critical effect(s) is clearly and logically 

presented. However, the decisions regarding 

principal study and the critical effect for 

developing the oral RfD for benzo[a]pyrene are 

not justified. The appropriate principal study and 

critical effect(s) were not selected. EPA's IRIS 

defines a "critical study" as "The study that 

contributes most significantly to the qualitative 

and quantitative assessment of risk. Also called 

Principal Study". The EPA also defines a "critical 

effect" as "The first adverse effect, or its known 

precursor, that occurs to the most sensitive 

species as the dose rate of an agent increases". 

Several studies [e.g., De Jong et al. (1999) 35-

day rat gavage study, Kroese et al. (2001) 5-

week, 90-day and 2-year rat gavage studies, 

Beland and Culp (1998) and Culp et al. (1998) 

mouse studies) have all reported dosedependent and statistically significant increases 

in the incidence of forestomach hyperplasia in 

both rats and mice. Table 4-27 shows the 

NOAEL/LOAELs for this endpoint in both 

species. In several instances (e.g., pages 178, 

201, etc), EPA has acknowledged that 

forestomach hyperplasia is a sensitive effect in 

EPA does not provide sufficient justification for 

discounting forestomach hyperplasia as the 

critical effect, and needs to answer the question; 

how do the reproductive and fertility 

effects better characterize noncancer low dose 

effects? Please revise the critical effect choice 

and discussion to be consistent with EPA 

guidelines. Without appropriate justificatio to 

exclude forestomach hyperplasia, Beland and 

Culp (1998) would be the principal study and 

forestomach hyperplasia from this study would 

be the critical effect for developing the oral RfD 

for benzo[a]pyrene. EPA should appropriately 

qualify its discussion of this endpoint.

If forestomach hyperplasia were chosen as the 

critical effect, then the toxicokinetic factor for 

experimental animal to human and within human 

variability might not be needed as per EPA’s 

Acute Exposure Guideline Level methods. EPA 

authors need to explore this alternative or more 

clearly justify the selection of Xu et al. (2010) as 

the principal study and decreases in ovary 

weight, estrogen, and primordial follicles, and 

altered estrus cycling as the critical effects.

S/M
the two chronic-duration studies in rats and 

mice. In addition, modeling results also identify 

increased forestomach hyperplasia in female 

B6C3F1 mice (Beland and Culp, 1998) (see 

Table 5-2) as the critical effect, i.e., observed at 

the lowest dose level.

However, EPA did not select the forestomach 

effects as the most sensitive measure (p. 208, 

parag. 1). Instead, EPA selected the Xu et al. 

(2010) study as the principal study (see also 

page 245, line 7, and elsewhere). This latter 

study observed biologically and statistically 

significant decreases in ovary weight, estrogen, 

and primordial follicles, and altered estrus 

cycling in treated animals (see p. 208, parag. 

1). The BMDL<sub>1SD</sub> from the Xu et 

al. study is 1.5 mg/kg-day, a value that is 10x 

higher than the BMDL<sub>10</sub> of 0.115 

mg/kg-day identified for forestomach effects in 

the Beland and Culp (1998) study.

We acknowledge selection of rat forestomach 

hyperplasia as the critical endpoint for 

evaluating human non-cancer effects of BaP is 

problematic. DoD believes, based on EPA’s 

definition of principal study and critical effects, 

the appropriate study and effect may not have 

been selected and therefore requires additional 

justification. It may be argued that rodent 

forestomach hyperplasia following gavage 
administration of BaP is not relevant to humans; 

not only do humans not have a forestomach, but 

they also do not have an equivalent organ where 

ingested material is stored for long periods of 

time. Also, gavage may increase the 

concentration in the forestomach beyond that 

which would occur from an exposure through 

food or drinking water. The combination of the 

high concentration of BaP concurrent with the 

potential for gavage to cause physical irritation, 

may contribute to the hyperplasia. We 

understand that EPA has selected forestomach 

hyperplasia as a critical effect for other 

chemicals. If EPA feels these that the 

quantitative analysis of effects observed in the 

forestomach after exposure by gavage is not 

reasonable, this needs to be appropriately and 

transparently discussed. If EPA has used this 

endpoint for noncancer risk assessment for 

other chemicals, EPA should discuss why the 

conclusions differed for this chemical.

74 5.1.2 209

EPA has recently recommended the use of 

animal to human body weight scaling as the 

default method in the development of the oral 

RfD for benzo[a]pyrene (see Risk Assessment 

Forum guidance, EPA/100/R11/0001). However, 

the Agency has not used this approach in 

calculating the human equivalent doses (HEDs) 

upon which the dose-response modeling can be 

based. In deriving an RfC (EPA, 1994), EPA 

routinely conducts dosimetric conversion of the 

The corresponding HEDs for all noncancer 

effects data need to be calculated prior to the 

dose-response modeling as is done in deriving 

RfC. In this way, the principal study and the 

critical effect can be evaluated and compared 

and the appropriate HED-based POD selected 

for deriving the oral RfD.

S/M
concentration to a human equivalent 

concentration (HEC) before the different adverse 

effects in the data array are evaluated and 

compared.

75 5.1.2-5.1.3 209-210

Although EPA’s rationale for the choice of UF 

values for derivation of the oral RfD is clearly 

and logically presented, it is based on the wrong 

critical effect. EPA has used a total UF of 3000: 

10 each for UFA, UFH, and UFS, 1 for UFL, and 3 

for UFD. Furthermore, UFA can be reduced to 3, 

if HEDs are calculated and used in the doseresponse modeling to estimate the POD (e.g., 

BMDL10). If the forestomach effects are used as 

the critical effect for benzo[a]pyrene (Beland and 

Culp, 1998), the total UF will likely be 30 to 100, 

instead of the 3000 used for the less sensitive 

endpoint of decreased ovarian weight (Xu et al., 

2010).

Using the derived HED-based BMDL10, for 

hyperplasia, the total UF will be 100, which is 

comprised of UFA of 3 for the toxicodynamic 

component given that HED has been calculated, 

UFH of 10 for human variability, UFS of 1 

because the principal study (if the Beland et al., 

1998 turns out to produce the critical effect after 

HED calculation and BMD modeling) is a chronic 

study, UFL of 1 for use of BMR for BMD 

modeling, and UFD of 3 for lack of a standard 

multigeneration reproductive toxicity and a 

neurodevelopmental toxicity study.

EPA scientists need to read the cancer bioassay 

reports, not just the published papers, for 

monitoring of other effects; this will aid in the 

judgment of UFD. The overall factor should be 

either 30 or 300, depending on judgment of UFD, 

and the toxicokinetic component of UFD and 

UFH. For example, if the hypeprplasia, the 

critical effect by EPA’s own definition, is an 

irritant effect (EPA has not demonstrated this), 

then the toxicokinetic factor for experimental 

animal to human and within human variability 

might not be needed as per EPA’s Acute 

Exposure Guideline Level methods.

S
76

5.1.3. RfD 

Derivation

Global

Selection of a subchronic study when EPA lists 

a number of high quality chronic studies in Table 

5-2 that fit all of its criteria appears to be a 

method to increase the estimated toxicity of BaP 

for the following reasons:

1. Several of the chronic studies have

BMDLs that are greater than the 

selected BMDL after the UF of 10 for 

subchronic to chronic is applied.

2. Reproductive studies, with the exception 

of mutigenerational studies, are of a 

duration appropriate to the chemical and 

the reproductive cycle of the animal. 

Thus, 60 days is sufficient for this type 

of study.

EPA must justify its deviation from standard, 

scientific practice, i.e., using a subchronic study 

to estimate a chronic RfD when high quality, 

chronic studies are available.

S/M

77 5.1.3 210, line 5

The database uncertainty factor may be 3-fold or 

it could be 10-fold, pending review of the chronic 

rat and mouse studies and determining the 

extent of noncancer effects monitoring. For 

example, if the chronic bioassays had little in the 

way of noncancer modeling, then a full factor of 

10 might be needed. The key determinant here 

is to read the original research reports, and not 

just the published papers, since the authors of 

the published papers may have emphasized 

reporting on cancer endpoints, despite the fact 

that non cancer endpoints were monitored.

We recommend that the EPA authors evaluate 

the original research reports to make this 

determination.

S
78 5.2.3 214

The net difference in RfD and RfC is 380-fold. 

This difference is hugely problematic and needs 

to be addressed, especially since the critical 

effects, as determined by EPA, are both 

systemic and reproductive. Specifically:

RfC vs RfD

RfC= 4.6x10-6 mg/m3per day 

Assume inhalation rate of 20m3/d

 = 92x10-6 mg/d = 0.92x10-4 mg/d

RfD = 5x10-4 mg/kg-d

 = 350x10-4 mg/d

RfD/RfC (assuming equivalent absorption 

between routes) = 380

Consider the huge difference in RfD/Cs, which is 

not anticipated based on toxicology of BaP. Our 

initial analysis supports that the RfC is 

incorrectly derived and, as suggested in other 

comments, should be dropped.

S/M

79 5.2.3 215, line 8

UFD may need to be 10-fold if a review of the 

database suggests that the available bioassays 

in two species are insufficient for monitoring 

noncancer effects.

If the RfC is retained, recommend revising the 

UFD to a 10 to reflect the lack of standard 

bioassays in two species.

S/M

80 5.4.1.3 221, line 8

One of the principal arguments EPA makes for 

mutagenic mode of action is early tumor 

occurrence in multiple tissues. In contrast, the 

forestomach tumors do not occur in the 

expected linear fashion (e.g., Neil and Rigdon; 

Culp et al., 1998, page 122). Moreover, Kroese 

et al (2001, page 32) state that adducts may not 

Several MOAs may be operating to cause the 

tumor response. Authors need to follow EPA 

guidelines and explore joint action.

S/M
be enough for tumor formation. EPA needs to 

discuss these possibilities, and perhaps judge 

that multiple modes of action may be occurring 

at different dose response areas. EPA's 

guidelines (page 3-22) allow for this:

"Both linear and nonlinear approaches may be 

used when there are multiple modes of action. If 

there are multiple tumor sites, one with a linear 

and another with a nonlinear mode of action, 

then the corresponding approach is used at 

each site. If there are multiple modes of action at 

a single tumor site, one linear and another 

nonlinear, then both approaches are used to 

decouple and consider the respective 

contributions of each mode of action in different 

dose ranges. For example, an agent can act 

predominantly through cytotoxicity at high doses 

and through mutagenicity at lower doses where 

cytotoxicity does not occur. Modeling to a low 

response level can be useful for estimating the 

response at doses where the high-dose mode of 

action would be less important."

81 5.4.2.4-5.4.2.1 223-225

There are no quantitative mathematical errors in 

concept or execution with the oral slope factor, 

and the approaches seem consistent with EPA 

2005 Cancer Guidelines and the EPA report on 

the time-to-tumor model. The statistical method 

for combining tumor sites assuming 

independence and summing MLEs seems 

appropriate and correctly calculated, including 

No action needed. S
the variance estimates, and in accord with the 

EPA report on use of the multistage-Weibull 

model for time to tumor data. In addition, the 

separate SFs (per species/sex/tumor type) are 

presented. This follows EPA cancer guidelines 

recommendations for displaying alternatives to 

express uncertainty ranges.

82 5.4.2.4 227, lines 27-32

The inhalation slope factor matches very nicely 

with that derived from oral exposures, unlike for 

the oral RfD and inhalation RfC.

No action needed. S

83 5.4.3.3 235, line 17

Disagree with the relaxation of the p≥0.1 rule for 

choosing models. The multistage model should 

not be preferred if it does not fit the data.

Further justification is needed.

EPA needs to explain/further justify this 

exception to EPA methods, especially since 

other models, with p values greater than 0.1, are 

available as the basis of the slope factor. These 

models would result in lower risk, perhaps as 

much as 9-fold.

S/M

84 5.4.3.3 236, line 8

Agree with the point about incomplete mortality; 

however, the bolus dosing of the experimental 

protocols needs to be discussed, since such 

dosing may actually serve to decrease this same 

risk. Defense mechanisms might be more easily 

overwhelmed with bolus dosing when compared 

to dietary exposures, especially at higher doses.

EPA needs to balance conflicting science 

issues. Recommend adding a discussion 

regarding potential impact of bolus dosing 

protocols on cancer risk calculations.

S

85 5.4.3.3 236, line 11

The selected study is Sivak et al. (1997), 

C3H/HeJ male mice. There is no figure or text 

output in Appendix F for that sex and strain. Fig. 

F-12 on p 393 has the right data but wrong 

figure caption/title. The animal should be 

C3H/HeJ male mice. The BMD and BMDL 

EPA needs to correct these errors. S
values in the text do not agree with those in 

Appendix F:

Table 5-12: BMD = 0.12; BMDL = 0.066

Fig. F-12: BMD =0.109; BMDL = 0.058

86 5.4.3.3 238, line 16

In the 2005 supplemental guidance (EPA/630/R03/003F), Figure 3 shows that the assumption of 

early-life susceptibility is to be made only after 

five previous steps were completed that involve 

evaluations of MOA information. EPA needs to 

follow their guidanc and show these previous 

steps in order to properly evaluate early-life 

susceptibility.

Authors need to follow EPA guidelines; evaluate 

the carcinogenic MOA fully before determining 

early-life susceptibility.

S/M

87 5.4.3.3 238, line 17

The oral slope factor is reported as 1 per mg/kgday elsewhere; the dermal slope factor is shown 

as 0.005. Be consistent regarding the number of 

significant figures shown.

Assign appropriate precision to all wrought 

values, and then be consistent with summary 

statements.

S

88 5.4.3.3 238, line 19

We disagree with the use of ADAF. The 

Vesselinovitch et al (1975) study---not 1984---

clearly shows that the older experimental 

animals are similarly, or perhaps even more, 

sensitive to stomach tumors than younger 

animals (Vesselinovitch et al., Table 5, page 

2951; this EPA text page 195). This argues 

contrary to the use of an ADAF here, since 

EPA's slope factor is based on tumors of the 

alimentary canal, including stomach tumors. An 

ADAF factor might be needed if liver tumors 

were the basis of the EPA slope factor.

The data clearly show that oral tumors are not 

more prevalent in the young. We recommend 

that the ADAF for this tumor endpoint be 

removed from the document.

S/M
89 5.4.5 240, line 8

The studies selected for use in the calculations 

do not have any data support provided; i.e., they 

are stand-alone data sets. For the oral slope 

factor, there is one rat study, one mouse study. 

For inhalation unit risk, there is only the study on 

Syrian golden hamsters. A much better sense of 

uncertainty would exist if there were calculations 

on studies by different researchers: a second rat 

and mouse study for oral, a different species for 

inhalation. Using only a single study falls within 

EPA guidelines, but it is still statistically weak.

The text needs to state the weaknesses of using 

limited data.

S
Department of Defense Comments on 

Benzoapyrene IASC draft charge to peer reviewers.pdf 

Comments submitted by: Chemical Material Risk Management Directorate Organization: Department of Defense Date Submitted: 7/7/2011 *Comment categories: Science or methods (S); Editorial, grammar/spelling, clarifications needed (E); or Other (O). Also please indica

conclusions or implementation of the assessment. 

Comment No. 

Section Pages Comment Suggested Action, Revisio

(if necessary) 

1 General Charge 

Question 1 

1 

The question asks about the clarity of EPA’s synthesis, but not about accuracy nor relevance. 

While clarity and transparenneither is useful if the analysand relevant. Please add arelevance to the charge que

2 A.1 1 

This question does not specifically highlight the issue of using a subchronic study when high quality, chronic studies are available. 

DoD believes that this issue specifically teed-up for the r

3 A. 2-4 1-2 

These questions assume that the reviewers will agree that EPA chose the correct study. If the reviewers agree with DoD that a chronic study should have been selected, EPA will not have information necessary for completion of the document. 

After the first question, EPA branched series of questionwould continue with the exisquestions. The second branreviewers to identify the studthey recommend that EPA uwould be applied. Without twould not be able to say thaanother study had been pee

4 B 2 Both oral and inhalation noncancer toxicity 

values for BaP are based on systemic 

The external reviewers shouconsider the difference betw
reproductive critical effects, yet there is an 

approximate 380 fold difference between the two values (after unit conversion). 

inhalation noncancer values has appropriately evaluated effects, the noncancer MOAuncertainties within the RfD 

5 B.1 2 

Given the database used for the RfC development we believe it should be teed up for the external reviewers. 

Please add to the second sequestion: "Please comment the inhalation database usethe selection of this study as study...." 

6 C.1 2 

DoD understands this document to be evaluating BaP alone, as another IRIS document evaluates PAHs. Therefore, we believe that the reviewers should specifically be asked whether this WOE judgment is based on BaP alone or on all PAHs. 

EPA should separate this qureviewers would agree with only data from BaP and thebased on all data provided i

7 C.2 2 

DoD suggests that EPA specifically ask its external reviewers to consider whether the evaluation of the mutagenic MOA data followed the "Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens" and is sufficient to apply an ADAF to the derivation of cancer slope factors. 

Please add a sub-question basking external reviewers to whether EPA appropriately "Supplemental Guidance foSusceptibility from Early-Life Carcinogens" in evaluating tapplying an ADAF for oral, icancer risk. 

8 C. 3-12 3 

The wording of these questions assumes that the reviewers agree that a linear extrapolation should be used. If the reviewers were to disagree, the cancer potency would be determined by an RfD, and all of the questions 

In this set of charge questioDoD strongly recommends tthe “cancer potency” rather factor” to allow the questionif the reviewers do not agree 
regarding “slope factor” could not be answered 

reasonably as written. DoD mentions this issue because it was the subject of much discussion during the external peer review of hexavalent chromium where most of the reviewers did not believe that a linear-to-zero extrapolation was appropriate, but felt compelled to answer the question as asked, i.e., that the procedure was appropriately done even if it should not have been done. 

threshold extrapolation – or has occurred in several receshould be presented.