Definitive relationships among chemical structure, carcinogenicity and mutagenicity for 301 chemicals tested by the U.S. NTP.

229

Mutation Research, 257 (1991) 229-306 © 1991 ElsevierSciencePublishers B.V. 0165-1110/91/$03.50 ADONIS 016511109100060S

MUTREV 00072

Definitive relationships among chemical structure, carcinogenicity and mutagenicity for 301 chemicals tested by the U.S. NTP John Ashby

a

and Raymond

W. Tennant

b

a ICI Central Toxicology Laboratory, Alderley Park, Cheshire (Great Britain) and b National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709 (U.S.A.)

(Accepted 9 October 1990)

Keywords:

Rodent carcinogenicitybioassay; DNA reactivity; Classification according to chemical structure/nautagenicity

Summary An analysis is presented in which are evaluated correlations among chemical structure, mutagenicity to Salmonella, and carcinogenicity to rats and mice among 301 chemicals tested by the U.S. NTP, Overall, there was a high correlation between structural alerts to DNA reactivity and mutagenicity, but the correlation of either property with carcinogenicity was low. If rodent carcinogenicity is regarded as a singular property of chemicals, then neither structural alerts nor mutagenicity to Salmonella are effective in its prediction. Given this, the database was fragmented and new correlations sought between the derived sub-groups. First, the 301 chemicals were segregated into six broad chemical groupings. Second, the rodent cancer data were partially segregated by target tissue. Using the previously assigned structural alerts to D N A reactivity (electrophilicity), the chemicals were split into 154 alerting chemicals and 147 non-alerting chemicals. The alerting chemicals were split into three chemical groups; aromatic amino/nitro-types, alkylating agents and miscellaneous structurally-alerting groups. The non-alerting chemicals were subjectively split into three broad categories; non-alerting, non-alerting containing a non-reactive halogen group, and non-alerting chemicals with minor concerns about a possible structural alert. The tumor data for all 301 chemicals are re-presented according to these six chemical groupings. The most significant findings to emerge from comparisons among these six groups of chemicals were as follows: (a) Most of the rodent carcinogens, including most of the 2-species a n d / o r multiple site carcinogens, were among the structurally alerting chemicals. (b) Most of the structurally alerting chemicals were mutagenic; 84% of the carcinogens and 66% of the non-carcinogens. 100% of the 33 aromatic a m i n o / n i t r o - t y p e 2-species carcinogens were mutagenic. Thus, for structurally alerting chemicals, the Salmonella assay showed high sensitivity and low specificity (0.84 and 0.33, respectively). (c) Among the 147 non-alerting chemicals < 5% were mutagenic, whether they were carcinogens or non-carcinogens (sensitivity 0.04). Correspondence: Dr. John Ashby, ICI Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire SK10 4TJ (Great Britain).

230 From these facts we conclude that the concepts of genotoxic and non-genotoxic rodent carcinogenicity are worthy of continued attention. Also, that it is meaningless to discuss the sensitivity/specificity of the Salmonella assay without defining the broad chemical classes under discussion. This last conclusion is important to any model for screening environmental chemicals for potential carcinogens. Some rodent tissues, such as the lung and Zymbal's gland, are uniquely associated with genotoxic carcinogenesis, while others are equally susceptible to non-genotoxic carcinogenesis. Four such tissues are currently studied as possible sites of non-genotoxic carcinogenicity, and these were separately considered; male rat kidney-specific carcinogenic effects, rodent leukaemogens, rodent thyroid gland carcinogens and mouse liver carcinogens (the latter being the largest group, 97 of the 301 chemicals having increased tumor incidences in this tissue). Chemicals inducing tumors in these tissues were of disparate chemical classes and were predominantly non-mutagenic. These facts, together with the specificity of the carcinogenic effects, is indicative of carcinogenicity resulting from a specific interaction between the chemical and the tissue, rather than it being an intrinsic and unique property of the chemical. Even when tumours in these four tissues were eliminated from the database, the Salmonella assay was only positive for 67% of the remaining 113 carcinogens (derived from a total of 162 carcinogens in the database). This indicates that a range of additional sites are subject to tissue-specific carcinogenesis by putative non-gen0toxins. A distribution chart is presented which represents the 301 chemicals according to the 6 chemical groupings and the level of carcinogenic effect. From this it becomes apparent that the N T P database is dominated by two major groups of chemicals. First, a group of structurally-alerting and mutagenic carcinogens that are predominantly active in both species a n d / o r at multiple sites, and second a group of non-alerting, non-mutagenic non-carcinogens. In between these two groups is a diffusely spread group of species/sex/tissue specific carcinogens, only some of which are mutagenic a n d / o r structurally alerting. It is among the last group of carcinogens that research is required to understand their mechanism of action and their significance to man. The in vitro mammalian cell genotoxicity database of the N T P failed to distinguish these last carcinogens from the non-carcinogens, and this endorses that research into the mode of action of these carcinogens should not be concerned with their genotoxicity. Our overall conclusion is that rodent carcinogenicity can no longer be regarded as a single entity. Structural alerts and mutagenicity to Salmonella are useful but non-definitive indicators of the overt carcinogens in the database, and the activity of the remaining (putative non-genotoxic) carcinogens is not predictable using current techniques. To pool rodent carcinogens and to attempt to find a single method for their prediction is no longer tenable. Rather, it is suggested that genotoxic carcinogens should be predicted by reference to chemical structure and the intelligent use of in vitro and in vivo genotoxicity assays, and that non-genotoxic carcinogens require basic studies to understand the subtle effects that occur in rodents upon protracted dosing with chemicals. It will also be necessary to consider which of these effects may be ancillary and which are critical to increases in tumor incidences. Some such indicators are emerging (e.g. peroxisome proliferation in the rodent liver), but much uncertainty remains in this area. The suspected nature of non-genotoxic carcinogenesis indicates that studies into its mechanisms and prediction will be most effectively progressed in vivo, rather than in vitro.

The conduct and interpretation of rodent carcinogenicity bioassays commissioned by the U.S. National Toxicology Program (NTP) have been described (Huff et al., 1985; Chhabra et al., 1990). The full data for each chemical is presented as an N T P Technical Report (TR) whose number is given with the chemical structure in Tables 3, 5,

7, 9, 13 and 15 herein. Three recent papers have summarized the test data for 301 of these chemicals that have been adequately evaluated for carcinogenicity in rats and mice (Ashby and Tennant, 1988; Ashby et al., 1989; Tennant and Ashby, 1990). These papers included information on the chemical structure of each agent, an assess-

231 ment of each chemical for structural alerts (SA) to D N A reactivity, their mutagenicity to Salmonella (Salm), the bioassay dose levels and duration of dosing, and a summary of the carcinogenicity data in the case of the carcinogens. Carcinogenicity data on these 301 chemicals from other sources was not considered. It was implied in texts that accompanied those three papers that the majority of the carcinogens identified in rodents could be recognized in terms of their D N A reactivity, as determined by their chemical structure and genotoxicity. However, a significant portion of the carcinogens ( - 36%) appeared to have no structural precedent for their carcinogenic activity, and they were tentatively classed as non-genotoxic carcinogens, in fine with early proposals made by Malling and Chu (1974) and Weisburger and Williams (1981). Another aspect of the database was that about one-third of the substances with no evidence for carcinogenicity were genotoxic in vitro. The carcinogenic inactivity of these chemicals was suggested to be associated with their non-absorption or preferential metabolic detoxification in rodents, or less likely, to their production of genetic changes in rodents of no relevance to cancer aetiology. The total number of chemicals now summarized is 301, and it is possible to analyze further the trends and conclusions derived in the three earlier studies. The stimulus for a further analysis was provided by three factors: first, although the earlier analyses had provided useful correlations between chemical structure and biological effects, none exceeded - 75%. Second, no attempt has so far been made to consider the effect on these correlations of segregating the chemicals into broad classes based on chemical reactivity. Third, confidence grows in the general concept that some chemicals can increase the tumor incidence in certain rodent tissues in the absence of a direct chemical modification of the genome of the tissue, and it therefore became of interest to evaluate the extent to which putative non-genotoxic carcinogenic responses had confounded the correlation between genotoxicity and carcinogenicity. In order to expidite this analysis, the tumor data for all 301 agents are represented in the present paper in the form of condensed tables. This has the additional advantage of gathering the

chemicals in one publication and of bringing together the chemical name and the chemical structure of each agent. The presentation of 301 chemicals in tabular form had the potential of rendering this paper unintelligible due to the enforced separation of the text from the accompanying and often extensive tables. Consequently, we have adopted a novel method of presentation. Each of the m a n y tables is preceded by a text which introduces it, describes the critical points it is considered to establish, and links it to the preceding and subsequent table. The whole analysis is then linked in a brief discussion. Methods

The compilation of the 301 chemicals in this paper uses the 3 earlier tabulations of 202 agents (Ashby and Tennant, 1988), 42 agents (Ashby et al., 1989) and 39 agents (Tennant and Ashby, 1990). Some minor corrections were made in the second paper to the database of the first paper, and these have been carried into the present paper. Structural alerts to D N A reactivity have been assigned to each of the 301 chemicals in the earlier papers and are indicated by bold type in the chemical structure of each chemical (Tables 3, 5, 7, 9, 13 and 15 herein). The model multi-electrophile chemical used to identify the structural alerts to D N A reactivity has been modified as the 3 papers developed, and the final form is shown in the preceding paper in this issue (Tennant and Ashby, 1990). The segregation of the test chemicals into six levels of carcinogenicity ( A - F ) has been maintained here although some have been usefully combined for statistical reasons (see later). These categorizations are as follows: Group A (80 chemicals): Agents found to be carcinogenic to both rats and mice at one or more sites. G r o u p B (21 chemicals): Agents found to be carcinogenic to only a single species but to be active at 2 or more sites in that species, in one or both sexes. G r o u p C (29 chemicals): Agents found to be carcinogenic at only a single site in both sexes of a single species.

232 G r o u p D (32 chemicals): Agents found to be carcinogenic at only a single site in a single sex of a single species. G r o u p E (39 chemicals): Agents evaluated for carcinogenicity in adequate studies but for which only equivocal evidence of carcinogenicity was observed. G r o u p F (100 chemicals): Agents evaluated for carcinogenicity in adequate studies and concluded to be non-carcinogenic. The 39 chemicals found equivocal for carcinogenicity (Group E) have the relevant tumor data shown in Tables 3, 5, 7, 9, 13 and 15. However, in cases where a chemical gave clear evidence (CE) or some evidence (SE) of carcinogenicity, tumor data for equivocal effects in other test groups are not shown. Between the earlier 3 surveys, 303 entries are made, however, only 301 discrete chemicals are involved. Thus, dichlorvos was entered as a noncarcinogen in the first survey [166] and as a carcinogen upon its re-evaluation for carcinogenicity in the second survey [227]. Likewise, the entry [272] is used here to replace the earlier data entry for hexachloroethane [85]. Entries [85] and [166] have therefore been eliminated from consideration in the present analysis.

Segregation of the 301 chemicals into six chemical classes A key feature of the present analysis is the separation of agents into chemical classes. These classes are broad and somewhat unusual, and are therefore discussed here. Several attempts have been made to consider correlation between shortterm test results and carcinogenicity by chemical class. Perhaps the most detailed is the Genetox analysis which recognizes from 21 to 69 different chemical classes (Kier et al., 1986; Ray et al., 1987). The major problem with such classification is that a name defines the class and multiple entries for a single chemical can ensue. For example, chlorobenzene can be entered into both 'chlorinated compounds' and 'benzenoid compounds'. Further, no distinction is possible between methyl chloride and chlorobenzene as each is formally a

'chlorinated compound'. In the present analysis a value judgment based on expected chemical properties is used to connect a chemical to a single chemical class. Thus, 4-chloroaniline is entered into the 'aromatic amine' class as the amino group is predicted to dominate biological activity. It follows that this chemical will be omitted from the non-reactive chlorinated aromatic class instituted, for example, to group chlorobenzene with T C D D . The classifications adopted here are therefore subjective but underpinned by known or projected chemical reactivity. Only six chemical classes were used to segregate these 301 chemicals, as follows:

Aromatic amino/nitro-type compounds. These 84 chemicals contained a nitrogen atom joined to an aromatic ring system, and in each case this was considered to present the major, if not unique, site for potential or actual D N A reactivity. Substituents included in this group were as follows: - N H 2 , - N H A c , - N ( O H ) N O , -NO2, N H C H 3, NH-NH-, -NO, -N=N-, -NCO, -NHOH, - N H P h , - N H E t . Dialkyl nitrogen substituents were omitted. Natural electrophiles including reactive halogens. These 46 chemicals are considered to be naturally electrophilic, i.e., do not require metabolic conversion to a DNA-reactive species. The following sub-structures were included in this category: _CH2C1 , - C H 2 B r , - N C H 2 C H 2 C 1 , epoxides, - p ( o ) O C H 3 , -P(S)OCH3, -P(S)OEt, propiolactones, - N C S , - N = C = N - , - P C H 2 O H , - C H 2 I , - O C H 2 C H 2 C I and -COCH2C1. Some of these presumed electrophiles may not be reactive, as evidenced by their non-mutagenicity to Salmonella, as discussed later.

Compounds containing a non-reactive halogen. Reactive and non-reactive halogen derivatives are often grouped together, e.g., CH3C1 and C H C I 3. Here, however, reactive halogens were placed in the preceding category and non-reactive halogen derivatives in the present group. Admission to this group of 50 chemicals implies that no other feature of the molecule is structurally alerting. In a way this is a contrived group, but 'chlorinated hydrocarbons' are often discussed so it was decided to form this separate sub-group of non-alert-

233 ing chemicals. In fact, this decision proved useful (see Fig. 3, herein). Compounds devoid of actual or potentially electrophific centers. These 61 chemicals appear to have no alerts to D N A reactivity. Compounds classed as non-alerting in structure, but with minor concerns. These 36 chemicals have been classed as non-alerting to D N A reactivity based on the megastructure shown in the preceding paper. However, aspects of the structure of each chemical may alert some investigators to possible electrophilicity (e.g., the allylic double bond in [1], the blocked nitrosamine in [87], etc.). Thus, this class and the two preceding ones (a total of 147 chemicals) are classed as non-alerting, but are segregated into 3 groups for purposes of discussion. Minor groups of structurally alerting chemicals. The remaining 24 chemicals (of the total 301) are spread between nfinor classes, or common groupings. The complete set of 301 chemicals, together with their tumor data, is represented herein in Tables 3, 5, 7, 9, 13 and 15. The order of presentation of chemicals in these six tables is in the originally used order of A - F . However, as the tables are condensed, the A - F labels have been omitted and each new group is indicated by a break in the respective tables. An index is provided at the end of this paper (Table 32) which allows a chemical to be located among Tables 3, 5, 7, 9, 13 or 15. The classification of four chemicals was specifically discussed in the previous paper (Tennant and Ashby, 1990; [268], [269], [275] and [300]). The first three were entered into the 2-species carcinogen category and are treated as such in the present calculations; the third of these, pentachlorophenol [275], was also assumed to be a rat-liver carcinogen. Epinephrine [300], an agent classified as being inadequately tested, is retained as a noncarcinogen in the present calculations. These decisions are justified in the previous paper (Tennant and Ashby, 1990) and have no influence on the conclusions drawn herein.

Results and their discussion

Sensitivity values for structural alerts and salmonella mutagenicity In keeping with the earlier analyses, sensitivity and concordance figures (%) for the Salmonella assay (Salm.) and structural alerts (SA) to DNA reactivity, for the several levels of carcinogenicity (A-F), are shown in Table 1. The following points are suggested to be the most important. (1) The percentage of Salmonella mutagens (42%) among the 301 chemicals is surprisingly high. This probably reflects a bias towards testing structurally alerting chemicals in the early days of the program (pre-1980; see Discussion section of this paper). (2) By use of the levels of carcinogenicity ( A - D ) the overall Salmonella sensitivity figure of 56% for the 162 carcinogens can be separated into the extremes of 70% for the 80 trans-species carcinogens and 34% for the 29 single-species/singletissue carcinogens. (3) As discussed in earlier analyses, the proportion of SA positive and Salmonella positive chemicals decreases when proceeding from trans-species carcinogens through to non-carcinogens ( A - F ; Fig. 1). Groups 4 and 5 in Fig. 1 (rat- and mousespecific carcinogens) are an innovation of this study (see 4 below). Concordance between SA and Salm. is high (87% over 301 agents) and SA alerts to more potential carcinogens than does Salm. (4) Splitting single-species carcinogens ( B - D ) into separate rat and mouse groups, as done for the first time in these analyses in Table 1, reveals similar numbers in each group and a similar proportion of genotoxins. (5) Chemicals found equivocal for carcinogenic activity (39 of 301; 13%) align closely with the 100 non-carcinogens in terms of Salm. and SA sensitivity values. This favours their classification as non-carcinogens (Tennant et al., 1987). (6) 25% of the 100 non-carcinogens are mutagenic to Salmonella. This observation is severely qualified in the subsequent analysis. Conclusions 1-6 above reflect earlier inferences (Ashby and Tennant, 1988; Ashby et al., 1989; Tennant and Ashby, 1990). Additional conclusions, such as the selective sensitivity of certain rodent tissues to genotoxic carcinogens (Ashby et

234

100 7

%

~ SA+ve

5o

0 All Chemical (301 )

All Carcinogens (162)

Rat]Mouse Carcinogens (80)

Rat-specific carcinogens (43)

Mouse-specific Equivocal Non-carcinogens carcinogens carcinogens (100) (39) (39)

Fig. l. Overall sensitivity values (%) for the Salmonella assay (Salm.) and structural alerts to D N A reactivity (SA) for the groups of chemicals shown. N u m b e r s in parentheses are n u m b e r s per group and data are based on those shown in Table 1.

al., 1989) are pursued later herein, but are endorsed among the last 39 chemicals (Tennant and Ashby, 1990) by the remarkable carcinogenic activity of the 3 genotoxins 3,3'-dimethoxybenzidine [268], 3,3'-dimethylbenzidine [269] and glycidol [271]. Among these 3 chemicals, 19 tissues were subject to carcinogenesis, including 11 of the 16

tissues associated earlier with genotoxic carcinogenesis.

Analysis of the database by chemical class The analyses presented in the following pages are of two types. First, presentation of the database of 301 chemicals according to 6 groupings

TABLE 1 C O R R E L A T I O N F I G U R E S (%) F O R T H E S A L M O N E L L A ASSAY (Salm.) A N D S T R U C T U R A L A L E R T S T O D N A REACTIVITY (SA) F O R T H E G R O U P S O F C H E M I C A L S S H O W N The level of effect codes ( A - F ) have been maintained, but some pooling of groups has been done to increase group sizes. Part of these data are shown in Fig. 1. Group (level of effect, A - F )

No. in Group

% SA positive

% Salm. positive

Concordance S A / S a l m . (%)

All chemicals ( A - F )

301

51

43

87

All carcinogens ( A - D ) All non-carcinogens (F)

162 100

64 33

56 25

89 86

Equivocal evidence (E)

39

41

31

85

Carcinogens to both species (A) Carcinogens to a single species ( B - D ) rat ( B - D ) mouse (B-D)

80 82 43 39

73 56 63 51

70 43 47 39

94 84 79 89

Carcinogens to 1 species at 2 or more sites (B) Carcinogens in 1 species at a single site (C) Carcinogens to a single s p e c i e s / s e x / s i t e (D)

21 29 32

67 52 47

45 34 47

80 86 84

235

based on critical features of the chemical structure/reactivity of each agent. Second, consideration of carcinogenicity in 6 major tissues, again across the whole database. Four of these tissues are subject to non-genotoxic carcinogenesis and two are uniquely associated with genotoxic carcinogenesis. These two avenues of inquiry culminate in a consideration of carcinogen prediction by chemical class, with separate attention to prediction of carcinogenesis in the above 4 nongenotoxic sites, chief among which is the mouse liver [81 (50%) of the present 162 carcinogens gave significant increases in tumor incidence in this organ].

Aromatic amino/nitro-type chemicals. 84 chemicals, classed here as structurally alerting aromatic a m i n o / n i t r o - t y p e compounds, are listed in Table 3. Entries are in sequence according to the level of carcinogenic activity (A-F). 59 of the 84 chemicals are rodent carcinogens (70%), and 72 (86%) are mutagenic to Salmonella. The sensitivi t y / specificity figures for the Salmonella assay are dramatic in their implications (Table 2). The conclusions that can be drawn from Tables 2 and 3 are as follows: (a) The aromatic a m i n o / n i t r o class contains a high proportion of carcinogens and mutagens (70% and 86%, respectively).

TABLE 2 SALMONELLA DATA FOR 84 AROMATIC A M I N O / NITRO-TYPE CHEMICALS Fractions shown because of low group numbers Group (A-F)

No. in group

% Salm. positive

All carcinogens (A-D)

59

Two species carcinogens (A) Single species carcinogens (B-D) Equivocal evidence (E)

33 26 8

100 85 (5/8) 63

Non-carcinogens (F)

17

71 (Specificity 29)

93

(b) The Salmonella assay is capable of detecting as positive the large majority of such carcinogens, and it detected all of the 33 two-species carcinogens. (c) Mutagenicity continues into the group of equivocal carcinogens and non-carcinogens, the specificity of the Salmonella assay being only 29% for this class of chemical, which is significantly less than for the entire database (75%; Table 1). (d) As a corollary to point (c), this class of chemical is responsible for a disproportionately high number of the false-positive Salmonella responses in this study (of the 38 equivocal agents among the 301, 11 are mutagenic, and 5 of these are of this class; of the 100 non-carcinogens, 25 are mutagenic, and 12 of these are of this class). (e) The 4 of 59 carcinogens of this class that are non-mutagenic to Salmonella ([56], [59], [67] and [75]) provide useful compounds for evaluating complementary short-term tests, i.e. assays that can distinguish such carcinogens without concomitantly detecting the non-carcinogens. (f) All of the tissues associated with genotoxic carcinogenesis in earlier reviews (Ashby et al., 1989) were affected by the present carcinogens. (g) The 17 non-carcinogens of this broad chemical class are probably the least secure among the 100 discussed in this paper. If any of the N T P non-carcinogens are found to be carcinogenic upon changing the test species or route of administration, it is most likely to be from these 17. Subtle differences in the disposition or metabolism of these chemicals may thus have limited their carcinogenic potential in the rodent strains used by the NTP. Such is unlikely to apply to the many non-mutagenic and non-structurally alerting noncarcinogens discussed later herein. The SA/Salm. columns of Table 3, with their high proportion of positive responses, are in sharp contrast to these same columns in the next 6 tables.

236

Table 3

AROMATIC AMINO/NITRO-TYPE CHEMICALS

[Code No] CAS No NTP Tech Report No (Year)

Structural alert

Structure or trivial name (alerting substructure in bold)

Salmonella assay response

CARCINOGENICI'FY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA) Tumor OJ ~ O~ (~ site

cl,I,

Chemical Name

cI,L.

cL,I.

cl,I.

CARCINOGENS TO BOTH RAT AND MOUSE [2] 117-79-3 144(1978) ~

+

O H

N

+

CL C. HS L L*

2

0

37

L

H

26 13 43 73

CL CH L H 4 0 8 16 9 2 11 26

CL C,

CL C.

39

o 2-Aminoanthraquinone +

[3] 6109-97-3 93(1978)

+

C C IS L L* U ZG

NH:z

L H C 13 0 0 0 1 4 18 17 1 0 2 29 46 5 11 0 0 11 15 0

CH L 0 9

H 8

L

H

15 14 73 84

2

L

H

2 86 88

0 2 13 2 26 22 0 23 24

I Et 3-Amino-9-et hylcarbazole.HCI [4l 82-28-0 111(1978)

~

O

NH 2 CH3

K L L•

0 4

12 14

21 21

K TG UB

0 0 0

5 17 96

13 15 100

AG

9

15

29

2

7

C

H

H

9

13

28

0

2

44

0 0

18 25

11 18

23

O 1-Amino-2-methylanthraquinone [5] 134-29-2 89(1978)

~H2

O

0

94

98

0

4

42

OCH

o-Anisidine.HCI [9)

5131-60-2

85(1978)

NH 2 ~ N H 2

CI 4-Chloro-rn-phenylenediamine [10] 95-83-0 63(1978)

NH 2 [ ~ N H

2

"h-"

L L °" S UB

0 0 0

9 0 36

8 4 51

0 0 0

0 0 33

4 2 71

L L*° SB SK TG ZG

0 10 4 0 0 2

4 28 40 2 11 2

16 12 32 20 41 26

0

30

20

0 0

4 4

12 14

L L**

2

39

20

20

37

55

0

8

13

20

40

54

6

38

76

4 0

8 12

10 24

cI 4-Chloro-o-phenylenediamine [11] 569-61-9 285(1986) CI-

CI Basic Red 9.HCI [12] 2832-40-8 222(1982) OH

H3C CI Disperse Yellow 3

237

Table 3

(Continued)

{Code No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)

Structural alert


CARCINOGENICITY DATA Tumor data identified in Summary of N rP Technical Report Rats (% TBA) Mice (% TBA) Tumor site

o"

?

o"

£

Chemical Name

[14] 120-71-8

+

+

NH2

142(1979) H3C~}

L L* N UB

0 0 O

27 2 63

4 45 94

0

78

0 0

17 4O

0 0

0 63

22 93

0

95

80

0

62

79

2 0

7 7

9 45

2 0 2

55 33 11

23 51 8

O

30

15

100

0

91

98

18 10

2 0 4

11 4 20

13 13 29

0

0

4

/ OCH3

p-Cresidine +

[15] 135-20-6 100(1978)

+

HO % INI** NO

©

CS HG L S ZG

Cupferron +

[16] 39156-41-7 84(1978)

+

NH=

CG PG SK TG ZG

[

CL C.

L

0 0 6 0

4 16 4 14 4 35 2 16

0 0 0 0

H

CL C. L H O 6 10 16

C, C.

L

5 0

2

0 24

2 0

2 20 0 14

0

H

Ct C.

L

H

0

0

18

0

~NH2 OCH 3 2,4-Diaminoanisole Sulfate +

[171 95-80-7 162(1979)

+

NH2

[

HS IS L L* MG

5

30

0

11

62

24

O

28

39

38

10

20

0 5

0 76

12 82

~NH2 OH3 2,4-Diaminotoluene [25] 2784-94-3 271(1985)

HC Blue 1

+

+

N(CH2CH2OH)2

L L** LU TG

2

6

22 8

40 34

60 20

O

0

10

2 4

50 23

96 8

14

~ N O 2 NHCH 3 +

[27] 122-66-7 92(1978)

+ L Lo* MG ZG

{2>-""-""-O

Ct

C. L H

0

2

10 63

2

0

4

14

Ct

C. L H

Ct

C. L H

CI

4 0 2

0 0

0 6

CH L H 2 10 47

12 12

Hydrazobenzene +

[291 13552-44-8 248(1983)

H=N ~

CH2~ ' ~

+

NH2

AG BD HS L L** LU O TG UB

0

0

2

2

24

50

0

0

15

0 0 0

6 4 4

4 35 2

2 0 6

10 0 20

18 2 69

0 0 2 0

0 0 0 7

6 6 27 9

4

24

29

20

66

58

0

6

33

2

98

98

26 2

56 12

58 22

2

4

12

0

2

26

O

92

100

4,4'-M ethylenedianiline.2HCI

[30] 129-15-7 29(1978) Int. J. Cancer, 19, 117(1977)

+ O NO2 ..~...~ ....J~ . . , ~ . OH 3

O 2-Methyl-1 -nitroanthraquinone

+

CS L S SB UB

238 Table 3

(Continued)

[Code No} CAS No NTP Tech Report NO (Year)

Structural alert



CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA) Tumor site

Chemical Name 4-

[32] 2243-62-1 143(1978)

4-

clLI"

c]'lR

CG L LU TG U

4

6

8

29

42

IS L L*

5

10

30

clLL"

cl'l"

0

17

37

2 0 0

10 20

13 33

28 58

26 51 21 4

35 11 18

NH2

1,5-Napht halenediamine

4-

[33] t 39-94-6 146( 1979 )

4-

N CH3CH2NHCONH ~ - - - ~

,O2

S Nithiazide 4-

[35] 602-87-9 118(1978)

4-

C[

CG L LU MG O SK

L

CH

H

CL CH

0 0

2

14 0

2

0 50 43

0

L

H

13 13

0 0

2 0

17 10 11 16

0

0 55 74

C

L

H

4

49

95

0

10

19

NO2

5-Nitroacenaphthene [36] 99-59-2 127(1978)

Ct CH L

NHI O2N~

CG IS L SK ZG

OCH3

H

2

0

14 63

0 2

0 0

10 38 4 21

CL C. 0 0

L H 2 20

0

6

0

CA Ce A

B

4

19

2

0

15

5-Nitro-o-anisidine [37]a 1836-75-5 184(1979) [37]b 1836-75-5 26(1978)

+

4-

CI

L

0

CS L P

C~, C

L

H

0

4

14

0

27

42

0

10

26

C~, C L H 0 0 2 8 12 20 73 96

Cr 3 0

C L H 6 0 11 0 88 98

C

L

Nitrofen

[38] 156-10-5

L L° LU

190(1979)

0 0 5

20 0

24

--

38 18

O O-.=o p- Nitrosodiphenylamine

[39]

t01-80-4 205(1980)

+

C

4CS HG L* PTG TG

L

M

H

C

L

2 26 82 78

6

0 48 34

2

0

8

13 37 55

M

H

60 46

C L M H 0 0 10 10 2 34 27 34 58 80 69 72 3 0 0 20

M

H

4

30 28 24 16 27 31 58 0

0

0

15

4-4' -Oxydianiline [40] 136-40-3 99(1978)

Phenazopyridine.HCI

I/C L L*

0

12

26

0

9

16 13 13

18 32

44 59

239 Table 3

(Continued)


Structural Salmonella alert assay response


"Tumor site

Chemical Name

[491

+

139-61-1 47(1978)

+

I/C L L" TG U ZG

CARCINOGENICITYDATA Tumor data identified in Summaryof NTP Technical Report Rats (% TBA) Mice (% TBA)

?

ol'l.

o"

cl'J.

0 0

19 64

3 30

0

85

97

0

45

24

0

56

55

0 0

30 20

76 5

35 0 0 0

40 6 18 20

71 43 24 47

L

0

6 22 0

0

18 22

K

6

22

0 0 0 0

?

ol'l

19 9 73 100 94 72 18 9

el'l"

8

94

92

0

94

97

0

45

87

0

9

50

5

4

24 0

8

26

0

37

80

0

6

4

2

8

18

0 4

2 6

10 24

4,4'-Thiodianiline +

[50] 636-21-5 153(1979)

NH= [ ~

CH3

+

CS IS L" MG MS SP UB

o-Toluidine.HCI

[52] 137-17-7 160(1979) _NH= .~l~ ell3 H3C "

LU

0

7

~ CH3

2,4,5,-Trimethylaniline

[231] 67-20-9 341(1989)

O

40

O

O=N~CH

-----N ~N.'J~NH

Nitrofurantoin

[232] 59-87-0 337(1988)

O=N

MG

16

72

CS L** MG P SB

6 30 0 4

16 42 12 2

0

72

C H = I I " N N --C --NH2

Nitrofurazone

[234] 26471-62-5 251(1986) CH3 NCO

~'~

CH3

80% O C : N ~ O

NCO

2 6

6 12

14 24

17 36 4 10

20%

2,4-/2,6-TolueneDiisocyanate

[267] 20265-96-7 351(1989)

p-Chloroaniline .HCI

NH:I

CI

C L M H 0 2 6 761 27 29 31 53 i

SP AG L• CS

C

L M H

22 43 40 42 8 8 2 20

2,40 Table 3

(Continued)


CARCINOGENICITY DATA Structural alert



Tumor data identified in Summary of NTP Technical Report

site

Chemical Name

[268]

20325-40-0 372(1990)

il2il ~

N

H

2

CH30

MG SK ZG PG OC I/C L* MT B CG U

.2HCI OCH 3

Rats (% TBA)

Tumor

Mice (% TBA)

o"

?

c['IH

o"

cILI"

C

L

M

H

0 0 27 2 0 2 3 0

29 22 28 18 2 9 2 5

37 33 45 13 11 9 9 4

37 50 49 18 13 13 10 2

?

° I L l H cI ' 1 "

C L M H 2 4 19 33 0 9 4 3 2 27 28 27 3 0 0

4 2 2

8 1 0

8 5 5

SEE TEXT

12 61 65 75 0 9 3 3

3.3'-Dimethoxybenzidine .2HCI

[269]

612-82-8 390(1990)

il2N ~

N

H

2

CH 3

SK ZG PG L* OC I/C LU MT CG MG

.2HCl

CH3

C 0 2 3 0 0 0 2 0

L M H 4 23 45 7 43 60 9 8 15 0 47 55 0 5 8 0 8 25 0 11 10 0 4 7

C 0 0

L M H 7 12 20 13 43 70

0 0 0 2

0 7 2 2

0 0

31 56 54 2 4 10

9 7 12 22 8 7 4 7 SEE TEXT

3,3'-Dimethylbenzidine .2HCI

CARCINOGENSAFFECTINGA SINGLESPECIESAT MULTIPLESITES [56] 142-04-1 130(1978)

Nil=

CS MS SP

0 0 0

38 10 38

44 38 43

0

2

14

0

12

63

0

10

42

Aniline.HCI [57} 103-33-3 154(1979)

+

+

MS

+

--

CS L

O--N:"--O Azobenzene

[52

95-79-4 187(1979)

5 20

Nil 2

CI~ C H 3 5-Chloro-~toluidine

[60]

5160-02-1

225(1982)

{C NS)Cl

D and C Red 9

HO

so

+

+

SP

0

0

L**

0

12

54 14

22 38

77 53

0 0

12 39

51 60

241 Table 3

(Continued)




CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA) Tumor o~ (2 0~ ? site

cl'l"

Chemical Name +

[61] 91-93-0 128(1979) OCN ~

~

'

=

+

HS SK ZG

0 0 0

38 35 10

°1'1"

35 30 17

or,j.

5

16

31

0

16

13

cl,I

R

2 4

6 44

NOO

H3CO

OCH 3

3,3'-Dimathoxybenzidine-4,4'-diisocyanate CL C. L

[63] 121-14-2 54(1978)

MG SB

OH 3

~NO2

H

0 0 14 27

CL C. L H 19 17 24 45

NO= 2,4-Dinitrotoluene +

[66]

99-55-8 107(1978)

+

NH 2

CS L

2 24

0 27

8 64

11 15

O=N ~ C H 3

5-Nitro-o-toiuidine

[67] 80-08-0 20(1977)

IS SP

H2N " - ~

SO2---~

C, Cp L H 0 0 14 18 0 0 18 44

NH 2

4,4'-Sulfonyidianiline +

[69] 1582-09-8 34(1977)

+

O2N

C. 0 0 0

L LU S

N(Pr)2

~NO2

C L H 0 2648 0 14 10 0 9 2

CF3

Trifuralin

CARCINOGENSAFFECTINGA SINGLE SPECIESAT A SINGLE SITE [75] 3165-93-3 165(1979)

NH2 [ ~ CH 3

+

--

+

+

CS

0

CI 4-Chloro-o-toluidine.HCI [76] 2475-45-8 299(1986)

O

NH 2

0

NH 2

UB

CLML 0 0 4 8

UB

0

C L M H 0 0 2 23

CI Disperse Blue 1 +

[77] 102-50-1 105(1978)

N.H= ~

m-Crasidine

CH3

OCH3

0

11

0

2

5

12

82

6

90

78

242 Table 3

(eontinu,d)

[Code No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)

Structural alert

Tumor

Chemical Name

,+,e

+

[80] 609-20-1 219(1982)

CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA)


+

NH= CI.~CI

O!

ct~l

"

?

°ILl

"

O"!

°ILl

38 14

58

"

L* L**

32 8

L

CL C. L H 24 13 32 42

30

?

°ILl

"

12

32

12

NH= 2,6-Dichloro-p-phenylenediamine

[86]

+

94-52-0 117(1979)

+

H

Ct C. L H 4 2 5 23

5(6)-Nitrobenzimidazole +

+

L**

10

20

60

4

6

21

226(1982) N=N

C.I. Solvent Yellow 14

CARCINOGENSAFFECTINGA SINGLESPECIES/SEX/SITE [96] 17026-81-2 112(1978)

N.HCOCH3

+

+

C, C. L H 0 0 0 16

TG

~NH= OEt 3-Amino-4-athoxyacetanilide

[97] 119-34-6 94(1978)

+

+

UB

0

0

28

+

+

HS

26

38

57

+

+

UB

+

+

CS

Nil=

OH 4-Amino-2-nitrophenol [96] 121-66-4 53(1978)

2-Amino-5-nitrothiazole

[96] 105-11-3

0

7

25

179(1979) OH'BN ~

= N--OH

p-Benzoquinone Dioxime

[100]

2185-92-4 233(1982)

H~ 2-Biphenylamine.HCI

0

2

14

243 Table 3

(Continued)

[Cede No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold) Chemical Name [102] 133-90-4 25(1977)


4-

Tumor site

CARCINOGENICITYDATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA)

o"

?

°J'l"

o"

ci'J"

?

cl'l"

cl'l"

+

C~ C~ L H 0 3 15 20

L

(~O2H

Ctlloramben [109] 1777-84-0 133(1979) N HA©

+

+

L"

22

+

+

L"

+

+

K

0

2

6

+

+

P

2

20

6

+

+

K

32

53

OEt 3-Nitro-p-acetophenetide [110] 5307-14-2 169(1979)

~

5

20

35

0

6

19

.NH2 NO 2

NH 2 2-Nitro-p-phenylenediamine [242] 99-57-0 339(1988)

~

OH NH=

NO2

2-Amino-4-nitrophenol [2431 121-88-0 334(1988)

OH O:IN ~ N H : !

2-Amino-5-nitrophenol [244] 6373-74-6 335(1988) ,/~O2

0

0

12

,SO3N;~

C.I. Acid Orange 3 CHEMICALS WITH EQUIVOCAL EVIDENCE OF CARCINOGENICITY

[1161 20265-97-8 116(1978) [~2

p-Anisidine.HCI

+

LU SK PG

0 0 2

0 0 11

5 5 2

+

+

CS SP

0

0

"/4

OCH3

[1201 106-47-9 189(1979)

p-Chloroaniline

+

CI

10

20

28

244 Table 3

(Continued)



Structure or trivial name (alerting substructure in bold}

Tumor site

Chemical Name +

[133) 56-38-2 70(1979)

+ AG


o" C[LIH

? CIL[H

c~ ? C I L I H CI L]H

C, C L H 4 0 14 24

Cp C L H 5 10 13 31

S

O2.,.~O__

pI-- (OEt)2

Parathion +

1136] 952-23-8 5(1977)

H 2 N ~ ' ~ N N

+

I/C L

0

0

6

41

57

60

8

41

44

0

0

4

=

ProflavinHCI

{247]

34 50 22

L L* L**

2871-01-4 281 (1986)

18 42 30 70 12 32 Hist. (Lab) L* 37 Hist. (NTP) L* 31

H.C. Red 3 [251] 135-88-6 333(1988)

+

D

K

+

--

P

2

2

10

+

--

IS AG

2

4

16

H

U2r'© N-Phenyl-2-Naphthylamine

[253}

121-19-7 345(1988)

OH

I O= As-- OH ~NO2 OH

Roxarsone [295] 989-38-8 364(1989)

H3C /~

NCiM.

6

6

20

C2H500C

Rhodamine 6G

.HC~ Nc~a RATAND MOUSENON-CARCINOGENS


Structural alert


Chemical Name [152] 140-49-8 177(1979)

[Code No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold) Chemical Name

+

NHCOCN 3

COCH=Ct 4-(C hloroacetyl)acetanilide

+

[156] 61702-44-1 113(1978) ~ C I

Nil= 2 Chloro-p-phenylenediamine Sulfate

Structural alert


245

Table 3

(Continued)

[Code No] CAS No NTP T~h Report No (Year) Structure or trivial name (alerting substructure in bold) Chemical Name


+

[157] 95-74-9 145(1978)

[161] 6358-85-6

.ooH,O

m

+

+

+

÷

N= N--OH--CONH

Diarylanilide Yellow +

~

+

N-H2 OCH 3

[191] 298-00-0

HC Blue 2 +

#S

157(1979)

[179] 33229-34-4 293(1985) N(CH2CH2OH)2 ~'~NO 2

OCH 3 2,4-Dimethoxyaniline.HCI +

NH(CH2CH2OH)

[1931 1465-25-4 168(1979)

NHCH2(~H2NH2

o5

NO2

Methyl Parathion

+

coc.3©

OH3 3-Chldro-.o-toluldine 171(1979)

Structural Salmonella aled assay response

N=N--CH--CONH

3o(197s)

~ C I

[169] 54150-69-5


N-(1-Naphthyl)ethylenediamine.2HCI

[194] 619-17-0 109(1978)

+

+

[195] 86-57-7 84(1978)

+

+

[200] 624-18-0

HO2C'~

~NO2 4-Nitroanthranilic Acid [196] 99-56-9 180(1979)

1-Nitronaphthalene

N H~,

~

174(1979)

NH2

~ a

NH2

NO2 4-Nitro-o-phenylenediamine

p-Phenylenediamine.2HCI

[202] 101-54-2 82(1978)

+

[210] f 27-69-5 138(1979)

G..-O-...

H

H,N = ~ - "

SO2-- / /O.,,~

)li .

=

H3C N-Phenyl-p-phenyllenediamine [218] 15481-70-6 200(f 980)

OH3

Sulfisoxazole +

+

[219] 6369-59-I 126(1978)

CH 3

CH 3

~

,,NH=

H2N ~ 2,6-Toluenediamine.2HCI

[256]

1936-15-8 211(1987)

2,5-Toluenediamine Sulfate HO

.

Agents classified as structurally-alerting by virtue of possession of a nitrogen atom attached to an aromatic ring and having the potential to N-oxidize (ie, tri-substituted nitrogens excluded). Also encompasses azo compounds. Compounds are arranged in order for the groupings shown, and as used in the three publications describing these 301 chemicals.

NaO3S ~ - - ~ C.I. Acid Orange 10

SO3Na

246

Non-alerting chemicals containing a halogen substituent. In order to illustrate the trend of this chemical class analysis, the next 50 chemicals to be considered are those classified as non-alerting agents containing a halogen substituent (Table 5). These were classed SA negative in the earlier tabulations of the 301 agents. 26 carcinogens (52%) are contained in this class, but only 2 of the 50 chemicals are mutagenic to Salmonella. The validity of these two mutagenic responses (for [125] and [204]) has been questioned in the earlier analyses, in particular, [204] ( - 60% pure photodieldrin). It is therefore possible that none of these 50 chemicals is constitutively mutagenic. The correlation figures for the Salmonella assay are shown in Table 4. The conclusions that can be drawn from Tables 4 and 5 are as follows: (a) Non-alerting chemicals containing an unreactive halogen can be carcinogenic to rodents (52% of these 50 are), but mutagenicity is not associated with this class. (b) The Salmonella assay has zero sensitivity for this class of carcinogen, and an almost perfect, but meaningless, specificity of 94%. (c) False-positive mutagenicity responses are low or perhaps even non-existent among this class of chemical. (d) The detection (prediction) of these 26 carcinogens, unlike with the arylamine class (Ta-

TABLE 4 SALMONELLA DATA FOR 50 NON-REACTIVE HALOGEN DERIVATIVES Fractions shown because of low group numbers. Group (A-F)

No. in group

% Salm. positive

All carcinogens (A-D)

26


10 16 8

0 0 (1/8) 13

Non-carcinogens (F)

16

(1/16) 6%

0

ble 3, earlier), is probably not a task for complementary genetic tests, but an incentive to mechanistic studies from which non-genetic screening tests may emerge. (e) These 26 carcinogens and the 8 equivocal carcinogens produced 85 separate reports of carcinogenicity (Table 5). 83 of these 85 (98%) were at sites discussed later in this analysis (and in Ashby et al., 1989) in connection with non-genotoxic carcinogenesis (58 liver, 7 haemopoietic tissue, 6 thyroid gland, 6 kidney, 4 adrenal gland). The above conclusions are confirmed and extended by the data presented for the next two classes of structurally non-alerting chemicals.

247 Table

5,

C O M P O U N D S CONTAINING A NON-REACTIVE H A L O G E N


Structural alert

Structure or tdvial name (alerting substructure in bold)


Tumor site

Chemical Name

CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report I Rats (% TBA) Mice (% TBA) I O" (~ O" (~

cr,I.

clL/H

ci'l"

cUrB"

CA.C,NOG~NS TO ~ O T . . A T AND "OUSE --

[7] 63449-39-8 308(1986)

--

Chlorinated paraffins (C12 : 60% CI)

[26]a 57653-85-7 198(1980) [26]b 57635-85-7 202(1980)

ct Hexachlorodibenzodioxins cl

o +

24 14

28 6

22

44

32

0 22

20 44

33 35

0

8

14

0

12

12

L*

22 22

30 40

34 58

6 0

8 36

18 44

16

24

31

C2 L M H 7 20 24 60

C~ L M H 21 28 29 50

C2 L M H 4 8 13 21

C L 0 0 0 0

C L M H 48 30 48 95

C L M H 0 0 18 88

cl ci

o

cl

[42] 67774-32-7 244(1983)

L C

Br n

14 0

NT

cl c'c ~ e ~ C ' cl

HS K L L** P TG

C L M H 0 5 3 23 0 0 0 6

M H 0 35 0 35

Br m

n+m=5-7 Polybreminated Biphenyl 5

[47]a 1746-01-6 201(1982) [47]b 1746-01-6 209(1982) C l ~

C~ L O - ~ C I

L L* TG

M H

1 10 12 20

C~ L M H 7 4

2 4

6 24 2 13

C~ L M H 11 18 16 34

30

C~ L M H 1 4 4 13 0

6

2 11

2,3,7,8 -Tetrechlorodibenzo-p-dioxin [51] 86-06-2 155(1979) OH Cl.~CI

HS L*

20

50

58

L L** P

4 0

42 8

46 12

K L Lo*

2

6

14

HS L L**

56

20

65

83

5

24

50

18 10

35 18

40 22

28 10

22 27

64 32

10 20

10 13

38 42

14 24

51 16

52 38

2

26

72

CI 2,4,6,-Tdchlorophenol [224] 115-28-6 304(1967)

CI CI ./~CO2

H

0 2

6 6

10 22

CI~)'---~./C O2H CI Chlorendic Acid [226] 106-46-7 319(1987)

CI

CI 1,4-Dichlorobenzene [233] 127-18-4 311(1986)

Cl\

/CI

cI/C=C\cI Tetrachloroethylene

74

74

36

60

58

248

Table 5

(Continued)


Stru~ural alert



CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TRA) Tumor site

Chemical Name K L*

[272] 67-72-1 361(1989) 68(1978)

CI I

ct

o"

?

°1'1"

CILl"

2

4

14

cl 15

30

?

l.

cl'l.

63

10

40

31

CI I

CI-- C-- C--CI I

I

CI

CI

Hexachloroethane

[275] 87-86-5 349(1989)

C L M H 17 40 44 69 3 8 44 92

L" AG CS

OH

C 3 0 0

L M H 8 12 65 4 4 78 2 6 16

SEE TEXT

cI Pentachlorophenol C A R C I N O G E N S A F F E C T I N G A S I N G L E S P E C I E S AT M U L T I P L E S I T E S

[68] 79-00 5 74(1978)

C~ C, L H 0 0 0 17 12 10 37 76

C C, L H 0 0 0 28 10 0 33 89

C C. L H 12 10 33 88

C C. L H 0 0 6 69

21

0

AG L

CH2CI

I CHCI 2 1,1,2 Trichloroethane [236]

150-68 5

0 H_N_~_N/CH3

266(1988)

K

0

6

L L* L**

0 2 2

2 12 12

30 6 18 14

\CH3

CI

Monuron

C A R C I N O G E N S A F F E C T I N G A S I N G L E S P E C I E S AT A S I N G L E SITE

[72] 12789-03-6 8(1978) CI

L

CI

cI

Chlordane

m

[73] 510-15-6 75(1978)

L

OH

c O,Oc CO2Et Chlorobenzilate [74] 1897-45-6 41(1978)

K

CI

C~ C, L 0 0 7

H 8

C~, C, L H 0 0 2 10

CI..~CN

/

CN Chlorothalonil --

[78] 1163-19-5 309(1986)

--

L**

2

14

31

2

6

18

Oo© Br 5

Oecabromodiphenyl Oxide

Br 5

I

67

49

22

26

249 Table 5

(continued)

]Code No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)

Structural alert


CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA) Tumor site

Chemical Name [79]

--

72-55-9

--

o"

cl[I.

?

cl[I.

L

d

?

cl[IH

cl[l"

0

0

17

38

40

71

Dichlorodiphenyldichloroethylene

[84] 76-44-8 9(1977)

CI

Cp C, L H 11 40 24 72

CI

Cp C, L H 4 20 6 71

01 CI

Heptachlor [88] 78-01-7 232(1983)

L L**

8

59

16

2 4

67 19

29 42

L*° L

13

30

42

8 2

17 11

50 13

CI CI I I CI--C--C--H I I CI CI Pentachloroethane

[90] 630-20-6 237(1983)

C~ I CI - - C - - C H2CI I

CI 1,1,1,2-Tetrachloroethane [911 79-34-5 27(1978)

C C, L H 5 8 26 90

C Cp L H 0 3 63 91

5

0

CI CI \ / H--C--C--H I I CI CI 1,1,2,2-Tetrachloroethane [931 79-01-6 2(1976)

CI...

52

65

/H

C:C CI /

"CI

Trichloroethylene CARCINOGENS

[94] 309-00-2 21(1978)

AFFECTING

A SINGLE SPECIES/SEX/SITE

C Cp L H 15 18 33 56

CI

~" "CI el

Aldrin [103] 63449-39-8 305(1986)

Chlorinated paraffins (023 : 43% CI) Chlorinated Paraffins (C~; 43% CI)

HS

12

24

32

8

23

250 Table 5

(Continued)

[Code Nol CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)


Chemical Name

Tumor site


ct

cl~l.

cl~l.

?

olLt.

tILl.

17 44 74

115-32-2 90(1978) [106]

CCI3

I

Dicofol MG

54-31-9 356(1989) [287]

COOH

0

4

10

5

6

23

U

NH2SO2" " ~ CI Furosemide C H E M I C A L S W I T H E Q U I V O C A L E V I D E N C E OF C A R C I N O G E N I C I T Y

[121] 108-90-7 261(1985)

--

--

L**

cI

C, C~

L

8

8 16

4

H

0 Chlorobenzene 0 0 16

CS HS L*

33857-26-0 123(1979)

[123]

c'

10 14 40

2 7 40

2,7- Dichlorodibenzo-p-dioxin [124]a 60-57-1 21 (1978) [124]b 60-57-1~ 22(1978)

C C,, L H 16 18 24 36

CI CI

o cI cI Dieldrin +

[125] 72-56-0 156(1979)

L"

CHCI 2

H Di(p-ethylphenyl)dichloroet hane [135] 1918-02-1 23(1978)

C,, C L H 0 0 10 14 3 O 7 15

L*o TG

NH2

CI.~CI CI~'~N/~

C02 H

Picloram TG

[138] 7772-99-8 231(1982) SnCI 2

Stannous Chloride

4

27

16

251 Table 5

(Continued)

[Code No] GAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold) Chemical Name


Tumor site TG

[139] 72-54-8 131(1978)

CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Rats (% TBA) Mice (% TBA) o"

5

o~

?

°1'1" 33

?

clLI"

cILI"

°l'I"

22

CHCI 2 I

CI " ~

CH'~cI

Tetrachlorodiphenylethane 15

[293] 58-93-5 357(1989)

20

42

O~ /.O

NH 2 S O 2 - , ~

S~'NH

H

Hydrochlorothiazide

RAT AND MOUSE NON-CARCINOGENS



[Code No] CAS No NTP Tech Report NO (Year) Structure or trivial name (alerting substructure in bold) Chemical Name [151] 77-65-6 173(1979)

[143] 101-05-3 104(1978)

cI

N'~N

Br O [ II Et-- C -- C-- NHCONH2 I Et

CI

Anilazine

Carbromal

[154] 999-81-5 158(1979)

[158] 94-20-2 45(1978)

+ .CH3 CICH2CH 2 - N # CH 3 CH3

o PrNHCONH--i-~ O

CI2-Chloroethyltrimethylammonium Chloride

Chlorpropamide

[164] 95-50-1 255(1985)

[165] 50-29-3 131(1978)

@c, CI

CI

COl 3 I

CI~ J ~ C ~ c I

DDT [183] 58-89-9

1,2-Dichlorobenzene [171] 72-20-8 12(1979)

Endrin [190] 72-43-5 35(1978)

CI

14(1977)

cI

CH30~] f CH~I~ OCH3 Methoxychlor

CI

Lindane CCI3 I

~

CI

[197] 82-68-8 61(1978)

CI~CI cty

cl

Pentachloronitrobenzene

c~

iStructural Salmonella alert assay response

252 Table 5

(Continued)

[Code NoI CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)



Chemical Name

Chemical Name

13366-73-9 17(1977) H

[2"13l 2438-88-2 114(1978) OCH 3 CI-~CI

[204]

H

H

~'~i

~ H

H

CI

°1

CI

CI GI I c~

H

Photodieldrin 1222] 75-35-4 228(1982)

Structural alert


CI" " ~ "CI NO2 2,3,5,6-Tetrachloro-4-nitroanisole 1255] 113-92-8

CINc=c/ H CI / " H Vinylidene Chloride

[288] 2698-41-1 377(1990)

CH2GH2N -- CH 3 Chlorpheniramine Maleate [299}

/CN

o-Chlorobe nzalmelanonit rile

CH 3

120-83-2

353(1989)

2,4- Dichlorophenol

OH

CI

Compounds classed as non-alerting to DNA-reactivity but which contain a non-reactive halogen substituent. Order of presentation as in Table 3.

Non-alerting chemicals not containing a halogen substituent. Consideration of chemicals of benign structure that do not contain a halogen atom yields a further 61 non-alerting chemicals (Table 7). Of these 61, 15 (25%) are rodent carcinogens and only one chemical, the non-carcinogen tolazamide [216], is mutagenic to Salmonella. The Salmonella correlation figures are shown in Table 6. The major conclusion to draw from Tables 6 and 7 is that when a group of chemicals is devoid of potential or actual DNA-reactive sub-structures, Salmonella mutagenicity is also absent. The only mutagen among these 61 chemicals (tolazamide [216]) has been queried as to its validity earlier (Ashby et al., 1989). Table 6 will be combined with Table 4 and Table 8 in the next section in order to review the mutagenicity profile for all of the 147 chemicals of benign structure among the 301. The tissues subject to carcinogenesis by these 15 carcinogens (Table 7) are, with the exception of benzene [6] and benzyl acetate [235], confined to

those associated earlier with non-genotoxic carcinogens (Ashby and Tennant, 1988; Ashby et al., 1989). Benzene is a unique chemical carcinogen and is difficult to place in any chemical class (cf. discussion of toluene in preceding paper). Benzyl acetate was characterized as inducing tumors of the mouse stomach, an uncertain effect discussed in detail in both the NTP technical report (TR 250, 1986) and in Ashby et al. (1989). TABLE 6 SALMONELLA DATA FOR 61 NON-REACTIVE CHEMICALS NOT C O N T A I N I N G A H A L O G E N SUBSTITUENT Fractions shown because of low group numbers. Group ( A - F )

No. in

group

% Salm. positive

All carcinogens ( A - D )

15

0


5 10 10

0 0 0

Non-carcinogens (F)

36

(1/36) 3

253 Table 7

COMPOUNDS DEVOID OF ACTUAL OR POTENTIALLY ELECTROPHILIC CENTRES


Structural

Salmonella

alert

assay response

CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report Tumor site

Chemical Name CA.C,N

[6] 71-43-2 289(1986)

--

E.S TO

I

O~,

°ILl

(~

o"

R °1'1

R cl'l"

C

--

L

M

H

C

L

M

H

AG

Benzene [23] 117-81-7 217(1982) O II C

--

--

--

Mice (% TBA) ~)L

I.

cl

OT. RAT AND . O U S E

L L"

C

L

M

H

2 2 14 2 0 20 27 23 8 19 18 31

HS L• LU MG O OC PG S SK ZG

[~

Rats (i/o TBA)

10 23 24 29

2 18 32 38

O 10 6 16 6 13 24 40 6

12

24

UT

0

2

15

K

C 0 0 0

2

C

L

M H

10 31 8 0 0 2

14 53 27 7 4 2

2

7 0

20 48 26 t2 10 12

21 41 14 12 20 15

10 24 18 0 4

11 62 80 5 7 13

0

3

10 54

0

18

29

38

0

14

34

0

10

55

0

0

8

0

14

15

0

2

10

5

29

24

0 7

4 5

14 31

0 10 11 30 0

4

16

0 0

4 4

25 28

13 12 3

10

OCH2CH(Et)(CH2)3CH 3

C - - OCH2CH(Et)(CH2)3CH3

II O

Di(2-ethylhexyl)phthalate K

[34]a 139-13-9 (acid) 6(1977) [34]b 18662-53-8 (tri-Na salt)

UB

/CH2CO2H N --

U8 UT

CH2CO2H

M H O 38 0 4 0 58

C 0 0 4

L 0 0 0

M H 0 17 0 21 8 54

\CH2CO2H

Nitrilot riacetic Acid 144] 50-55-5 193(1980)

CH30 ~

L 0 0 0

HH N O 6

O

AG MG SV

6

K HS L*

0

37

50

OCH3

-~ ~-0~.3

OCH~ " - ~

Reserpine

OCH3

123-31-9 366(1989) [273]

OH

7

15 16

27

40

ON Hydroquinone CARCINOGENS AFFECTING A SINGLE SPECIES AT MULTIPLE SITES --

[55] 2432-99 7 216(1982)

H2N-

--

L'*

2

UB

0

18 O

16 14

(CH2)10CO2H

11 -Aminoundecanoic Acid [70] 17924-92-4 235(1982) OH

L *o PTG O

CH 3

v

Zearalenone

v

"0

0

9

14

2.54

Table 7

(Continued) I

[Cede No] CAS No NTP Tech Report No (Year)

Structural alert



Tumor site

Chemical Name

[235] 140-11-4

--

O II 2OC0H3

250(1986)

--


o"

?

cl,I.

o"

cl,I,

L** S S* S**

Benzyl Acetate [237] 149-30-4 332(1988)

--

--

I~N SH

AG HS P PG PTG

36 14 4 2

PG CG

6

50 32 26 12

45 6 12 10

2

10

12

31

48

50

11

33

34

?

cl,[.

cl , I .

O

10 26 Hist. (Lab.) L 0-22 2 2 4 8 8 22 6 6 18 Hist. (Lab.) S*0.7(n=296) Hist. (NTP) S'1.3(n=1.070)

0

26

41

55

6 2

38 28

37 24

33

62

92

6

8

14

0 12 Hist. (Lab,) L 0-8 0 0 0 0

0 8 Hist. (Lab.) S'0.7(n=297) Hist. (Lab.) S*0.3(n=1.073)

2-Mercaptobenzothiazole

[280] 389-08-2

--

368(1989)

--

OH 2 C H 3

39

43

HaC . . , ~ N - . : ~ II O

O

Nalidixic Acid

CARCINOGENS AFFECTINGA SINGLE SPECIES AT A SINGLE SITE [81] 103-23-1

--

--

212(1982)/CO2CH2CH(Et)(CH2)3CH3 /

L* L

(CH2)4 ~ CO2CH2CH(Et)(CH2)3CH3 Di(2-ethylhexyl)adipate

CARCINOGENS AFFECTING A SINGLE SPECIES/SEX/SITE [101]

85-68-7 213(1982)

O II C -- OBu

--

--

12

HS

14

36

[~ c-ocR2O

Butyl Benzyl Phthalate

O

[111] 1:>0-62-7 124(1978)

o

C~-To>

CH3(CH2)6--CH2--S--CH-- C H 2 ~ k . ~ O CH3 Piperonyl Sulfoxide

[114] 76-42-2 274(1984) (CH3CH2C H2CH2CHCH20)3PO Et Tris(2-ethylhexyl)phosphate K

[2~]

98-85-1 369(1989)

OH I HC -- CH 3

© ec-Methylbenzyl Alcoho~

0

4

10

255 Table 7

(Continued)



CARCINOGENICITY DATA Tumor data identified in Summary of NTP Technical Report ] Rats (% TBA) Mice (% TBA) Tumor I °J (~ Cr" site

cl,IH

ClLIH C ] ' [ "

clLJ"

CHEMICALS WITH EQUIVOCAL EVIOENCE OF CARCINOGENICITY --

[119] 80-05-7 215(1982) _ _ C H 3

--

HS

26

24

46

CH3 Bisphanol A LU

[126] 120-61-6 121( 1 9 7 9 )

2 16 27

~_L~2Me

CO2Me Dimathyl Terephthalate [137] 121-79-9 240(1982)

CO2Pr

AG P PG HS MG

8 4 2 32

AG

26

25 18 16 14

16 8 0 12

22

4

10

2

6

16

2 O

4 8

10 6

0

4

2

HO " ~ O H

OH Propyl Gallate [246] 7177-48-2 318(1987)

?H20

CO2H O%_,~ N , " J ~ CH3

[~c.-c-..

|1

sI'c"=

HS

24 47 Hist. (Lab.) 22.3, highest41 10 28 26 Hist. (NTP) -gav.2-28 -ctrL10-46

3H20 Ampicillin Trihydrate [248] 136-77-6 330(1988)

AG HG

OH

CH2(CH2)4CH3 4-Hexylresorcinol [249] 41372-08-1 348(1988)

c.,-c-c-o. 1.5N20

NH2

MethyldopaSesquihydrate AG

2058-46-0 315(1987) HO CH3 OH N(CH3)2 [250]

20

PEG

36 48 Hist. (NTP) (n=1,702) 21¢10

ONH2 HO

O

OH O

Oxytetracycline Hydrochloride PAG

[282] 83.79-4 320(1988)

CH3H ~ / / c H

H2 Rotenone

I:t \CH3

2

0

9

40 48 64 Hist. (NTP) (n=1,704) 47:kl1

?.56 (Continued)I

Table 7

[Cede No] CAS No NTP Tech Report No (Year) Structure or trivial name (alerting substructure in bold)


Tumor site

CARCINOGENICITY DATA Tumor data identified in Summary of NTP TechnicalReport Mice (% TBA) R=s(%TBA)

Chemical Name [292]

2

B

147-24-0

2

LU PTG

355(1989) 355(1989)

?

o[LI. 0

6

12

o"

olLI ~ cl,I. 10

46

52

?

cl,i.

70

H /CH3 C--O--CH2--CH2- N\ ~L~0 CH3

Diphenhydramine .HCI 7681-49-4 393(1990) [296]

CLMH 0 0 2 4

OST

NaF

Sodium fluoride RAT A N D M O U S E NON-CARCINOGENS



Chemical Name

Chemical Name --

968-81-0 50(1978)

[140]

o II CPI3--C~ - -

[Code No] CAS No NTP Tech ReportNo (Year) Structure or trivial name (alerting substructure in bold)

--

[141] 9002-18-0 230(1982)

O II SO2--NH-- C-- NPI-"~

Agar

Acetohexamide 119-53-9 204(1980) [146]

[145] 50-81-7 247(1983)

CH2OH

I

HO -- C ~ =

OH O

O

CH-- C - ~ _ ~ ~

L-Ascorbic Acid

HO

[147] 128-37-0 150(1979)

OH

Benzoin [150] 105-60-2 214(1982)

C,H3

(CH3)3C~'~C(CH3)3

OH

H

Caprolactam

Butylated Hydroxytoluene

NT

[163] 262-12-4 122(1979)

[172] 134-72-5 307(1966) ~

Ephedrine Sulfate

Dibonzo-p-dioxin 150-38-9 11(1977)

CHOHCH(CH3)NHCH3

[174]

/ CH2CO2Na

[177] 9000-30-0 229(1982)

CH2--N \

Guar gum

CH2CO2Na /CH2CO2Na

CH 2 - N EDTA (tri-Na salt)

\CH2CO2H Guar Gum


257 Table 7

(Continued)



[Code No] CAS No NTP Tech Report NO(Year) Structure or trivial name (alerting substructure in bold)

Stru~ural Salmonella aled assay response

Chemical Name {184] 434-13-9 175(1979)

[178] 9000-01-5 227(1982)

CH3 CH3 CH-- CH2CH2- CO2H

H3C

Gum Arabic

Gum Arabic

Lithocholic Acid

[185] 9000-40-2 221(1981)

[188] 69-65-8 CH2OH 236(1982) HO-- C -- H I HO--C--H I H--C--OH I

Locust bean gum

H--C--OH

Locust Bean

I

Gum

D-Mannitol

[189] 15356-70-4 98(1979)

CH2OH

114-86-3 7(1977) [198]

( ;H3

[ ~

CH2CH2-- NH-- C -- NH-- C--NH 2 NH

H3C

dI-Menthol

CH3

NH

Phenformin

[199] 108-95-2 203(1960)

88-96-0 161(1979)

[205]

OH

©

[ ~

CONH2 CONH 2

Phenol

Phthalamide

85-44-9 159(1979)

[206]

51-03-6 120(1979)

{207]

o

CH3CH2(CH2CH20)3CH2M ~ - , ~ ' ~ " O

o Phthalic Anhydride

Piperonyl Butoxide

[212] 39300-88-4 224(1982)

[215] 13463-67-7 97(1979)

Tara gum

TiO2

Tam gum

Titanium Dioxide

1156-19-0 51(1978)

[216]

H3C--

Correlations between bioassay dose-level, mutagenicity to Salmonella, chemical structure and sites of carcinogenesis among 226 chemicals evaluated for carcinogenicity by the U.S. NTP.

Classification according to chemical structure, mutagenicity to Salmonella and level of carcinogenicity of a further 39 chemicals tested for carcinogenicity by the U.S. National Toxicology Program.

Salmonella mutagenicity and rodent carcinogenicity: quantitative structure-activity relationships.

Data selection and treatment of chemicals tested for genotoxicity and carcinogenicity.

Chemical structure, reactivity, and carcinogenicity of halohydrocarbons.

Mutagenicity of nitroxyl compounds: structure-activity relationships.

Mutagenicity of metronidazole: structure-activity relationships.

Mutagenicity of azo dyes: structure-activity relationships.

Implications of newly recognized relationships between mutagenicity, genotoxicity and carcinogenicity of molecules.

Structure-activity relations: maximizing the usefulness of mutagenicity and carcinogenicity databases.

Mutagenicity, carcinogenicity and teratogenicity of procarbazine.

NTP.

Coordination chemistry and the carcinogenicity and mutagenicity of chromium(VI).

Mutagenicity-carcinogenicity as related to teratogenic activity.

Relationship between chlorofluorocarbon chemical structure and their Salmonella mutagenicity.

Mutagenicity, carcinogenicity and teratogenicity of cobalt metal and cobalt compounds.

Vinyl chloride and vinyl benzene (styrene)--metabolism, mutagenicity and carcinogenicity.

Quantitative structure-activity relationships for chemical toxicity to environmental bacteria.

Nitroaromatic compounds: Environmental toxicity, carcinogenicity, mutagenicity, therapy and mechanism.

Mutagenicity of sumithion tested in Drosophila somatic and germ cells.

Predicting the carcinogenicity of chemicals with alternative approaches: recent advances.

The Use of Chemical-Chemical Interaction and Chemical Structure to Identify New Candidate Chemicals Related to Lung Cancer.

Social relationships and health related behaviors among older US adults.

Dangerous and cancer-causing properties of products and chemicals in the oil refining and petrochemical industry--Part II: Carcinogenicity, mutagenicity, and developmental toxicity of 1,3-butadiene.