## Introduction

In this vignette, CTX Hazard API will be explored.

NOTE: Please see the introductory vignette for an overview of the ccdR package and initial set up instruction with API key storage.

Data for the Hazard API come from the Toxicity Value Database (ToxValDB). ToxValDB includes data on thousands of chemicals from tens of thousands of records, with an emphasis on quantitative estimates of relevant points-of-departure from in vivo toxicology studies, such as no- and low-observable adverse effect levels, screening levels, reference doses, tolerable daily intake, etc.

The Aggregated Computational Toxicology Resource (ACToR) is currently being integrated into ToxValDB. ACToR, as described in Judson et al (2008), was designed to serve as a central location for information on chemical structure in vitro bioassays, and in vivo toxicology assays used in various Computational Toxicology efforts at US EPA.

More information on ToxValDB can be found at https://www.epa.gov/comptox-tools/downloadable-computational-toxicology-data#AT. Additional resources under “ToxVal” subtopic: New Approach Methods training.

## Functions

Several ccdR functions are used to access the CTX Hazard API data.

### Hazard Resource

#### Get Hazard Data by DTXSID

`get_hazard_by_dtxsid()` retrieves all hazard data, both human and EcoTox data.

    res_dt <- get_hazard_by_dtxsid(DTXSID = 'DTXSID7020182')

#### Get Human Hazard Data by DTXSID

`get_human_hazard_by_dtxsid()` retrieves only human hazard data.

    res_dt <- get_human_hazard_by_dtxsid(DTXSID = 'DTXSID7020182')

#### Get EcoTox Hazard Data by DTXSID

`get_ecotox_hazard_by_dtxsid()` retrieves only ecological toxicity hazard data.

    res_dt <- get_ecotox_hazard_by_dtxsid(DTXSID = 'DTXSID7020182')

### Skin Eye Resource

`get_skin_eye_hazard()` retrieves hazard data specific to skin and eye hazard.

    res_dt <- get_skin_eye_hazard(DTXSID = 'DTXSID7020182')

### Cancer Resource

`get_cancer_hazard()` retrieves cancer hazard data.

    res_dt <- get_cancer_hazard(DTXSID = 'DTXSID7020182')

### Genetox Resource

`get_genetox_summary()` retrieves summary level data for genotoxicity data associated to a chemical.

    res_dt <- get_genetox_summary(DTXSID = 'DTXSID7020182')

`get_genetox_detail()` retrieves more detailed genetox data for a chemical than is provided on the summary level.

    res_dt <- get_genetox_details(DTXSID = 'DTXSID7020182')

## Example Use Case: Comparing Hazard Data Across Chemical Lists

The fourth Drinking Water Contaminant Candidate List (CCL4) is a set of chemicals that “…are not subject to any proposed or promulgated national primary drinking water regulations, but are known or anticipated to occur in public water systems….” Moreover, this list “…was announced on November 17, 2016. The CCL 4 includes 97 chemicals or chemical groups and 12 microbial contaminants….” The National-Scale Air Toxics Assessments (NATA) is “… EPA’s ongoing comprehensive evaluation of air toxics in the United States… a state-of-the-science screening tool for State/Local/Tribal agencies to prioritize pollutants, emission sources and locations of interest for further study in order to gain a better understanding of risks… use general information about sources to develop estimates of risks which are more likely to overestimate impacts than underestimate them….”

These lists can be found in the CCD at CCL4 with additional information at CCL4 information and NATADB with additional information at NATA information. The quotes from the previous paragraph were excerpted from list detail descriptions found using the CCD links.

In this example use case, hazard data will be compared between a water contaminant priority and an air toxics list.

### Obtain Lists of Chemicals

First, confirm the chemical list to query.

    options(width = 100)
    ccl4_information <- get_public_chemical_list_by_name('CCL4')
    print(ccl4_information, trunc.cols = TRUE)
    #>    id    type                                    label visibility
    #> 1 443 federal WATER|EPA: Chemical Contaminants - CCL 4     PUBLIC
    #>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             longDescription
    #> 1 The Contaminant Candidate List (CCL) is a list of contaminants that, at the time of publication, are not subject to any proposed or promulgated national primary drinking water regulations, but are known or anticipated to occur in public water systems. Contaminants listed on the CCL may require future regulation under the Safe Drinking Water Act (SDWA). EPA announced the <a href='https://www.epa.gov/ccl/contaminant-candidate-list-4-ccl-4-0' target='_blank'>fourth Drinking Water Contaminant Candidate List (CCL 4)</a> on November 17, 2016. The CCL 4 includes 97 chemicals or chemical groups and 12 microbial contaminants. The group of cyanotoxins on CCL 4 includes, but is not limited to: anatoxin-a, cylindrospermopsin, microcystins, and saxitoxin. The CCL Chemical Candidate Lists are versioned iteratively and this description navigates between the various versions of the lists. The list of substances displayed below represents only the chemical CCL 4 contaminants. For the versioned lists, please use the hyperlinked lists below.<br/><br/> \r\n\r\n<a href='https://comptox.epa.gov/dashboard/chemical_lists/CCL5' target='_blank'>CCL5 - November 2022</a> <br/><br/>\r\n<a href='https://comptox.epa.gov/dashboard/chemical_lists/CCL4' target='_blank'>CCL4 - November 2016</a> \r\n This list<br/><br/>\r\n<a href='https://comptox.epa.gov/dashboard/chemical_lists/CCL3' target='_blank'>CCL3 - October 2009</a> <br/><br/>\r\n<a href='https://comptox.epa.gov/dashboard/chemical_lists/CCL2' target='_blank'>CCL2 - February 2005</a><br/><br/>\r\n<a href='https://comptox.epa.gov/dashboard/chemical_lists/CCL1' target='_blank'>CCL1 - March 1998</a><br/><br/>
    #>              updatedAt listName chemicalCount            createdAt
    #> 1 2022-10-26T21:14:27Z     CCL4           100 2017-12-28T17:58:36Z
    #>                                                                                                                                              shortDescription
    #> 1 The Contaminant Candidate List (CCL) is a list of contaminants that are known or anticipated to occur in public water systems. Version 4 is known as CCL 4.

    natadb_information <- get_public_chemical_list_by_name('NATADB')
    print(natadb_information, trunc.cols = TRUE)
    #>    id    type                                            label visibility
    #> 1 454 federal EPA: National-Scale Air Toxics Assessment (NATA)     PUBLIC
    #>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              longDescription
    #> 1 The National-Scale Air Toxics Assessment (NATA) is EPA's ongoing comprehensive evaluation of air toxics in the United States. EPA developed the NATA as a state-of-the-science screening tool for State/Local/Tribal Agencies to prioritize pollutants, emission sources and locations of interest for further study in order to gain a better understanding of risks.  NATA assessments do not incorporate refined information about emission sources but, rather, use general information about sources to develop estimates of risks which are more likely to overestimate impacts than underestimate them.\r\n\r\nNATA provides estimates of the risk of cancer and other serious health effects from breathing (inhaling) air toxics in order to inform both national and more localized efforts to identify and prioritize air toxics, emission source types and locations which are of greatest potential concern in terms of contributing to population risk.  This in turn helps air pollution experts focus limited analytical resources on areas and or populations where the potential for health risks are highest.  Assessments include estimates of cancer and non-cancer health effects based on chronic exposure from outdoor sources, including assessments of non-cancer health effects for Diesel Particulate Matter (PM). Assessments provide a snapshot of the outdoor air quality and the risks to human health that would result if air toxic emissions levels remained unchanged.
    #>              updatedAt listName chemicalCount            createdAt
    #> 1 2018-11-16T21:42:01Z   NATADB           163 2018-02-21T12:04:16Z
    #>                                                                                                                shortDescription
    #> 1 The National-Scale Air Toxics Assessment (NATA) is EPA's ongoing comprehensive evaluation of air toxics in the United States.

Next, retrieve the list of chemicals associated with each list.

    ccl4 <- get_chemicals_in_list('CCL4')
    ccl4 <- data.table::as.data.table(ccl4)

    natadb <- get_chemicals_in_list('NATADB')
    natadb <- data.table::as.data.table(natadb)

### Review Genotoxicity Data for a Single Chemical

Using the standard CompTox Chemicals Dashboard approach to access genotoxicity hazard data, one would navigate to the individual chemical page as shown below.

Figure 1: CCD Navigation to Hazard Data>Genotoxicity Plot

Figure 2 shows the genotoxicity section of the hazard tab for Bisphenol A. This page provides a summary of available genotoxicity data as well as individual reports and samples of such data.

Figure 2: CCD Hazard Data>Genotoxicity for Bisphenol A

The CTX APIs streamline the process of retrieving this information in a programmatic fashion. Figure 3 shows the particular set of genotoxicity resources available in the `Hazard` endpoints of the CTX APIs. There are both summary and detail resources, reflecting the information one can find on the CompTox Chemicals Dashboard Genotoxicity page for a given chemical.

Figure 3: CTX Hazard APIs for Genotoxicity Endpoints

### Review Genotoxicity Data for Chemical Lists

The function `get_genetox_summary()` is used to access summary genotoxicity information per chemical. To query a list of chemicals, rather than searching individually for each chemical, the batch search version of the function, `get_genetox_summary_batch()`, can be used to access these details.

First, pull the data.

    ccl4_genotox <- get_genetox_summary_batch(DTXSID = ccl4$dtxsid)
    natadb_genetox <- get_genetox_summary_batch(DTXSID = natadb$dtxsid)

Next, it may be helpful to examine the dimensions and column names of the output.

    dim(ccl4_genotox)
    #> [1] 71  7
    dim(natadb_genetox)
    #> [1] 153   7
    colnames(ccl4_genotox)
    #> [1] "id"              "dtxsid"          "reportsPositive" "reportsNegative" "reportsOther"
    #> [6] "ames"            "micronucleus"
    head(ccl4_genotox)
    #>       id        dtxsid reportsPositive reportsNegative reportsOther   ames micronucleus
    #>    <int>        <char>           <int>           <int>        <int> <char>       <char>
    #> 1: 16410 DTXSID0020153              26               5            1      -     positive
    #> 2: 20381 DTXSID0020446               0              12            0      -     negative
    #> 3: 21212 DTXSID0020573               3              14            0      -     negative
    #> 4: 23984 DTXSID0020600              20               0            1      -     positive
    #> 5: 23751 DTXSID0020814               1               0            0      -            -
    #> 6: 18199 DTXSID0021464               9              11            0      -     positive

The information returned is of the first variety highlighted in the Figure 2, that is, summary data on the available genotoxicity data for each chemical. Observe genotoxicity data was returned for 71 chemicals from the CCL4 chemical list and 153 from the NATA chemical list. Chemicals missing genotoxicity information are noted.

    ccl4[!(dtxsid %in% ccl4_genotox$dtxsid),
         .(dtxsid, casrn, preferredName, molFormula)]
    #>              dtxsid       casrn             preferredName    molFormula
    #>              <char>      <char>                    <char>        <char>
    #>  1: DTXSID001024118  77238-39-2               Microcystin          <NA>
    #>  2:   DTXSID0024052  55290-64-7                Dimethipin     C6H10O4S2
    #>  3:   DTXSID0032578  59669-26-0                Thiodicarb  C10H18N4O4S3
    #>  4:   DTXSID1037484 194992-44-4             Acetochlor OA     C14H19NO4
    #>  5:   DTXSID1037486 171262-17-2 2-[(2,6-Diethylphenyl)(me     C14H19NO4
    #>  6:   DTXSID1037567 171118-09-5           Metolachlor ESA    C15H23NO5S
    #>  7:   DTXSID2022333    135-98-8          sec-Butylbenzene        C10H14
    #>  8:   DTXSID2031083 143545-90-8        Cylindrospermopsin   C15H21N5O7S
    #>  9:   DTXSID2037506  16655-82-6       3-Hydroxycarbofuran     C12H15NO4
    #> 10:   DTXSID2052156    517-09-9                 Equilenin      C18H18O2
    #> 11:   DTXSID3021857  25154-52-3             n-Nonylphenol       C15H24O
    #> 12:   DTXSID3034458  99129-21-2                 Clethodim  C17H26ClNO3S
    #> 13:   DTXSID3042219    103-65-1             Propylbenzene         C9H12
    #> 14:   DTXSID3073137  14866-68-3                  Chlorate          ClO3
    #> 15:   DTXSID3074313  35523-89-8                 Saxitoxin    C10H17N7O4
    #> 16:   DTXSID4022448  51218-45-2               Metolachlor   C15H22ClNO2
    #> 17:   DTXSID4032611  13194-48-4                  Ethoprop    C8H19O2PS2
    #> 18:   DTXSID4034948 112410-23-8              Tebufenozide    C22H28N2O2
    #> 19:  DTXSID50867064  64285-06-9                Anatoxin a      C10H15NO
    #> 20:   DTXSID6024177  10265-92-6             Methamidophos     C2H8NO2PS
    #> 21:   DTXSID6037483 187022-11-3            Acetochlor ESA    C14H21NO5S
    #> 22:   DTXSID6037485 142363-53-9              Alachlor ESA    C14H21NO5S
    #> 23:   DTXSID6037568 152019-73-3            Metolachlor OA     C15H21NO4
    #> 24:   DTXSID7024241  42874-03-3               Oxyfluorfen C15H11ClF3NO4
    #> 25:   DTXSID7047433    474-86-2                   Equilin      C18H20O2
    #> 26:   DTXSID8022377     57-91-0         17alpha-Estradiol      C18H24O2
    #> 27:   DTXSID8052483   7440-56-4                 Germanium            Ge
    #> 28:   DTXSID9032113 107534-96-3              Tebuconazole   C16H22ClN3O
    #> 29:   DTXSID9032329    741-58-2                 Bensulide  C14H24NO4PS3
    #>              dtxsid       casrn             preferredName    molFormula
    natadb[!(dtxsid %in% natadb_genetox$dtxsid),
           .(dtxsid, casrn, preferredName, molFormula)]
    #>             dtxsid        casrn             preferredName molFormula
    #>             <char>       <char>                    <char>     <char>
    #>  1: DTXSID00872421 NOCAS_872421     Lead & Lead Compounds       <NA>
    #>  2:  DTXSID1020273    7782-50-5                  Chlorine        Cl2
    #>  3: DTXSID10872417 NOCAS_872417 Cadmium & Cadmium Compoun       <NA>
    #>  4: DTXSID30872414 NOCAS_872414 Antimony & Antimony Compo       <NA>
    #>  5: DTXSID30872419 NOCAS_872419 Cobalt & Cobalt Compounds       <NA>
    #>  6: DTXSID40872425 NOCAS_872425 Nickel & Nickel Compounds       <NA>
    #>  7:  DTXSID5024267    1336-36-3 Polychlorinated biphenyls       <NA>
    #>  8:  DTXSID7020687     608-73-1 1,2,3,4,5,6-Hexachlorocyc    C6H6Cl6
    #>  9:  DTXSID7023984  NOCAS_23984       Coke oven emissions       <NA>
    #> 10: DTXSID90872415 NOCAS_872415 Arsenic & Arsenic Compoun       <NA>

Now, genotoxicity details of the chemicals in each chemical list are returned using the function `get_genetox_details_batch()`.

    ccl4_genetox_details <- get_genetox_details_batch(DTXSID = ccl4$dtxsid)
    natadb_genetox_details <- get_genetox_details_batch(DTXSID = natadb$dtxsid)

If inspecting the first chemical in each set of results, DTXSID0020153, notice that the information is identical in each case as this information is chemical specific and not chemical list specific.

    identical(ccl4_genetox_details[dtxsid %in% 'DTXSID0020153', ],
              natadb_genetox_details[dtxsid %in% 'DTXSID0020153', ])
    #> [1] TRUE

Assays present for chemicals in each chemical list can be explored. First, determine the unique values of the `assayCategory` column and then group by these values and determine the number of unique assays for each `assayCategory` value.

    ccl4_genetox_details[, unique(assayCategory)]
    #> [1] "in vitro" "ND"       "in vivo"
    natadb_genetox_details[, unique(assayCategory)]
    #> [1] "in vitro" "ND"       "in vivo"
    ccl4_genetox_details[, unique(assayType)]
    #>  [1] "InVivoMN"
    #>  [2] "Overall"
    #>  [3] "bacterial reverse mutation assay"
    #>  [4] "micronucleus assay"
    #>  [5] "Ames"
    #>  [6] "InVitroCA"
    #>  [7] "InVitroMLA"
    #>  [8] "InVitroMN"
    #>  [9] "Cell transformation, clonal assay"
    #> [10] "Forward and reverse gene mutation, host-mediated assay"
    #> [11] "Histidine reverse gene mutation, Ames assay"
    #> [12] "Micronucleus test, chromosome aberrations"
    #> [13] "Mitotic recombination or gene conversion"
    #> [14] "Rec-assay, DNA effects (bacterial DNA repair)"
    #> [15] "Rec-assay, spot test, DNA effects (bacterial DNA repair)"
    #> [16] "Sister-chromatid exchange (SCE) in vitro"
    #> [17] "Unscheduled DNA synthesis (UDS) in vitro, DNA effects"
    #> [18] "In vivo carcinogenicity studies"
    #> [19] "in vitro mammalian chromosome aberration test"
    #> [20] "mammalian cell gene mutation assay"
    #> [21] "DNA damage and repair assay, unscheduled DNA synthesis in mammalian cells in vitro"
    #> [22] "in vivo micronucleus (mouse)"
    #> [23] "in vivo micronucleus (rat)"
    #> [24] "Sperm morphology"
    #> [25] "InVivoCA"
    #> [26] "InVivoUDS"
    #> [27] "transgenic"
    #> [28] "Chromosome aberrations"
    #> [29] "Forward gene mutation at the HPRT locus"
    #> [30] "Heritable translocation test, chromosome aberrations"
    #> [31] "Reverse gene mutation"
    #> [32] "Sex-linked recessive lethal gene mutation"
    #> [33] "Sister-chromatid exchange (SCE) in vivo"
    #> [34] "Dominant lethal test"
    #> [35] "Unscheduled DNA synthesis (UDS) in vivo; DNA effects"
    #> [36] "chromosome aberration assay"
    #> [37] "mammalian germ cell cytogenetic assay"
    #> [38] "bacterial forward mutation assay"
    #> [39] "sister chromatid exchange assay in mammalian cells"
    #> [40] "DNA Binding"
    #> [41] "rodent dominant lethal assay"
    #> [42] "unscheduled DNA synthesis"
    #> [43] "Bacterial Mutagenesis"
    #> [44] "Cytogenetics Other"
    #> [45] "Cytotoxicity"
    #> [46] "In Vitro Micronucleus"
    #> [47] "bacterial gene mutation assay"
    #> [48] "in vitro mammalian cell micronucleus test"
    #> [49] "Aneuploidy, chromosome aberrations"
    #> [50] "Chromosome aberrations in vivo"
    #> [51] "sister chromatid exchange assay"
    #> [52] "InVivoDNADamage"
    #> [53] "Cell transformation, viral enhanced"
    #> [54] "combined chromosome aberration and micronucleus assay"
    #> [55] "Chromosome aberrations in vitro"
    #> [56] "Forward gene mutation"
    #> [57] "Forward gene mutation at the HPRT or ouabain locus"
    #> [58] "Forward gene mutation at the thymidine kinase (TK) locus; chromosome aberrations"
    #> [59] "Specific locus test, gene mutation"
    #> [60] "Spot test, gene mutation"
    #> [61] "In Vivo Non-mammalian Mutagenesis"
    #> [62] "In Vivo Micronucleus"
    #> [63] "mouse spot test"
    #> [64] "transgenic rodent mutagenicity assay"
    #> [65] "yeast cytogenetic assay"
    #> [66] "Micronucleus and sister chromatid exchange"
    #> [67] "in vivo comet (mouse)"
    #> [68] "in vivo comet (rat)"
    #> [69] "Gene mutation"
    #> [70] "in vitro mammalian cell transformation assay"
    #> [71] "Cell transformation"
    #> [72] "Tryptophan reverse gene mutation"
    #> [73] "Cell Transformation"
    #> [74] "DNA Damage/Repair"
    #> [75] "In Vitro Chromosome Aberration"
    #> [76] "Mutation"
    #> [77] "DNA Covalent Binding"
    #> [78] "In Vivo Chromosome Aberration"
    #> [79] "In Vivo Mammalian Mutagenesis"
    #> [80] "in vitro chromosomal aberration study in mammalian cells"
    #> [81] "Mutation Other"
    #> [82] "Evaluation of metabolic activity of acute cytotoxicity"
    #> [83] "In vitro mammalian chromosomal aberration test"
    #> [84] "Forward and reverse gene mutation, body fluid assay"
    #> [85] "Forward and reverse gene mutation, chromosome aberrations, mitotic recombination and gene conversion, DNA effects, host-mediated assay"
    #> [86] "Chromosomal aberration assay"
    #> [87] "Mitotic recombination"
    #> [88] "Aneuploidy, sex chromosome gain, chromosome aberrations"
    #> [89] "Aneuploidy, whole sex chromosome loss, chromosome aberrations"
    #> [90] "fluctuation test"
    natadb_genetox_details[, unique(assayType)]
    #>   [1] "InVivoMN"
    #>   [2] "Overall"
    #>   [3] "bacterial reverse mutation assay"
    #>   [4] "micronucleus assay"
    #>   [5] "Ames"
    #>   [6] "InVitroCA"
    #>   [7] "InVitroMLA"
    #>   [8] "InVitroMN"
    #>   [9] "Cell transformation, clonal assay"
    #>  [10] "Forward and reverse gene mutation, host-mediated assay"
    #>  [11] "Histidine reverse gene mutation, Ames assay"
    #>  [12] "Micronucleus test, chromosome aberrations"
    #>  [13] "Mitotic recombination or gene conversion"
    #>  [14] "Rec-assay, DNA effects (bacterial DNA repair)"
    #>  [15] "Rec-assay, spot test, DNA effects (bacterial DNA repair)"
    #>  [16] "Sister-chromatid exchange (SCE) in vitro"
    #>  [17] "Unscheduled DNA synthesis (UDS) in vitro, DNA effects"
    #>  [18] "In vivo carcinogenicity studies"
    #>  [19] "DNA damage and repair assay, unscheduled DNA synthesis in mammalian cells in vitro"
    #>  [20] "rodent dominant lethal assay"
    #>  [21] "Chromosome aberrations"
    #>  [22] "Gene mutation"
    #>  [23] "InVivoUDS"
    #>  [24] "InVivoCA"
    #>  [25] "transgenic"
    #>  [26] "Forward gene mutation at the HPRT locus"
    #>  [27] "Heritable translocation test, chromosome aberrations"
    #>  [28] "Reverse gene mutation"
    #>  [29] "Sex-linked recessive lethal gene mutation"
    #>  [30] "Sister-chromatid exchange (SCE) in vivo"
    #>  [31] "Dominant lethal test"
    #>  [32] "Unscheduled DNA synthesis (UDS) in vivo; DNA effects"
    #>  [33] "Bacterial Mutagenesis"
    #>  [34] "Cytogenetics Other"
    #>  [35] "Cytotoxicity"
    #>  [36] "DNA Damage/Repair"
    #>  [37] "In Vitro Chromosome Aberration"
    #>  [38] "In Vitro Micronucleus"
    #>  [39] "In Vivo Non-mammalian Mutagenesis"
    #>  [40] "Mutation"
    #>  [41] "In Vivo Chromosome Aberration"
    #>  [42] "In Vivo Mammalian Mutagenesis"
    #>  [43] "In Vivo Micronucleus"
    #>  [44] "in vitro mammalian chromosome aberration test"
    #>  [45] "InVivoDNADamage"
    #>  [46] "Cell transformation, viral enhanced"
    #>  [47] "mammalian cell gene mutation assay"
    #>  [48] "in vivo micronucleus (mouse)"
    #>  [49] "Sperm morphology"
    #>  [50] "Forward and reverse gene mutation, mitotic recombination and gene conversion, host-mediated assay"
    #>  [51] "Spot test, gene mutation"
    #>  [52] "bacterial forward mutation assay"
    #>  [53] "sister chromatid exchange assay in mammalian cells"
    #>  [54] "DNA Binding"
    #>  [55] "unscheduled DNA synthesis"
    #>  [56] "bacteriophage induction in E. coli, gene mutation, UDS in mammalian cells, sex-linked recessive lethal mutations in Drosophila"
    #>  [57] "DNA damage, gene mutation, reverse mutation, gene conversion, DNA repair, chromosomal aberration, chromatid exchange, UDS"
    #>  [58] "chromosome aberration study in mammalian cells"
    #>  [59] "in vitro mammalian cell transformation assay"
    #>  [60] "Forward gene mutation at the thymidine kinase (TK) locus; chromosome aberrations"
    #>  [61] "Cell transformation"
    #>  [62] "Forward and reverse gene mutation, body fluid assay"
    #>  [63] "Forward gene mutation at the HPRT or ouabain locus"
    #>  [64] "chromosome aberration assay"
    #>  [65] "Drosophila SLRL assay"
    #>  [66] "Salmonella and Escherichia strains: bacterial reverse mutation assay (e.g. Ames test) ; Bacillus strains: recombination assay"
    #>  [67] "Cytogenetic assay in bone marrow cells"
    #>  [68] "in vivo comet (mouse)"
    #>  [69] "Chromosome aberrations in vitro"
    #>  [70] "Forward gene mutation"
    #>  [71] "Chromosome aberrations in vivo"
    #>  [72] "in vitro mammalian cell gene mutation tests using the thymidine kinase gene"
    #>  [73] "in vivo comet (rat)"
    #>  [74] "in vivo micronucleus (rat)"
    #>  [75] "mouse spot test"
    #>  [76] "Aneuploidy, whole sex chromosome loss, chromosome aberrations"
    #>  [77] "sister chromatid exchange assay"
    #>  [78] "Mouse Lymphoma Forward Mutation Assay"
    #>  [79] "mammalian erythrocyte micronucleus test"
    #>  [80] "Tryptophan reverse gene mutation"
    #>  [81] "bacterial gene mutation assay"
    #>  [82] "yeast forward mutation and mitotic gene conversion assays in Schizosaccharomyces pombe (P1 strain) and Saccharomyces cerevisiae (D4 strain)"
    #>  [83] "Micronucleus test in vitro, chromosome aberrations"
    #>  [84] "heritable translocation assay"
    #>  [85] "mitotic recombination assay with Saccharomyces cerevisiae"
    #>  [86] "Aneuploidy, chromosome aberrations"
    #>  [87] "cell transformation"
    #>  [88] "in vitro mammalian cell micronucleus test"
    #>  [89] "somatic mutation and recombination test in Drosophila"
    #>  [90] "transgenic rodent mutagenicity assay"
    #>  [91] "yeast cytogenetic assay"
    #>  [92] "Micronucleus and sister chromatid exchange"
    #>  [93] "in vitro mammalian cell gene mutation test using the Hprt and xprt genes"
    #>  [94] "bone marrow chromosome aberration assay and mammalian germ cell cytogenetic assay"
    #>  [95] "bacterial mutation"
    #>  [96] "bacterial reverse mutation assay (Salmonella typhimurium and Escherichia coli)"
    #>  [97] "Aneuploidy, partial sex chromosome loss, chromosome aberrations "
    #>  [98] "Chromosome aberrations, in vivo"
    #>  [99] "in vitro chromosome aberration study"
    #> [100] "Cell transformation, focus assay"
    #> [101] "Forward and reverse gene mutation, mitotic recombination and gene conversion, DNA effects, host-mediated assay"
    #> [102] "gene mutation assay in fungi"
    #> [103] "DNA adduct formation"
    #> [104] "Cell Transformation"
    #> [105] "DNA Covalent Binding"
    #> [106] "mammalian comet assay"
    #> [107] "Aneuploidy, sex chromosome gain, chromosome aberrations"
    #> [108] "mammalian germ cell cytogenetic assay"
    #> [109] "Forward and reverse gene mutation, chromosome aberrations, mitotic recombination and gene conversion, DNA effects, host-mediated assay"
    #> [110] "E. coli K-12 DNA repair host-mediated assay"
    #> [111] "Chromosomal aberration assay"
    #> [112] "forward mutation"
    #> [113] "mammalian cell gene mutation test"
    #> [114] "Mitotic recombination"

Next, determine the number of assays per unique `assayCategory` value, count the number of assay results and grouping by `assayCategory`, and `assayType`, and also examine the different numbers of `assayCategory` and `assayTypes` values used for both chemical lists.

    ccl4_genetox_details[, .(Assays = length(unique(assayType))),
                         by = .(assayCategory)]
    #>    assayCategory Assays
    #>           <char>  <int>
    #> 1:      in vitro     65
    #> 2:            ND      3
    #> 3:       in vivo     22
    natadb_genetox_details[, .(Assays = length(unique(assayType))),
                           by = .(assayCategory)]
    #>    assayCategory Assays
    #>           <char>  <int>
    #> 1:      in vitro     83
    #> 2:            ND      3
    #> 3:       in vivo     28

    ccl4_genetox_details[, .N, by = .(assayCategory, assayType, assayResult)]
    #>      assayCategory                 assayType assayResult     N
    #>             <char>                    <char>      <char> <int>
    #>   1:      in vitro                  InVivoMN    negative    10
    #>   2:            ND                   Overall    positive     5
    #>   3:      in vitro bacterial reverse mutatio    positive    39
    #>   4:       in vivo        micronucleus assay    negative    36
    #>   5:       in vivo        micronucleus assay   equivocal     1
    #>  ---
    #> 149:      in vitro Heritable translocation t    negative     1
    #> 150:      in vitro     Mitotic recombination    positive     1
    #> 151:      in vitro Aneuploidy, sex chromosom    negative     1
    #> 152:      in vitro Aneuploidy, whole sex chr    positive     1
    #> 153:      in vitro          fluctuation test    negative     2
    ccl4_genetox_details[, .N, by = .(assayCategory)]
    #>    assayCategory     N
    #>           <char> <int>
    #> 1:      in vitro   815
    #> 2:            ND    38
    #> 3:       in vivo   188
    ccl4_genetox_details[assayCategory == 'in vitro', .N, by = .(assayType)]
    #>                     assayType     N
    #>                        <char> <int>
    #>  1:                  InVivoMN    28
    #>  2: bacterial reverse mutatio   165
    #>  3:                      Ames    88
    #>  4:                 InVitroCA    31
    #>  5:                InVitroMLA    24
    #>  6:                 InVitroMN     6
    #>  7: Cell transformation, clon     8
    #>  8: Forward and reverse gene      7
    #>  9: Histidine reverse gene mu    19
    #> 10: Micronucleus test, chromo     8
    #> 11: Mitotic recombination or     18
    #> 12: Rec-assay, DNA effects (b    15
    #> 13: Rec-assay, spot test, DNA     2
    #> 14: Sister-chromatid exchange    41
    #> 15: in vitro mammalian chromo    22
    #> 16: mammalian cell gene mutat    42
    #> 17: DNA damage and repair ass    21
    #> 18:    Chromosome aberrations     2
    #> 19: Forward gene mutation at      5
    #> 20: Heritable translocation t     5
    #> 21:     Reverse gene mutation     9
    #> 22: Sex-linked recessive leth     9
    #> 23: Sister-chromatid exchange    13
    #> 24: chromosome aberration ass    15
    #> 25: bacterial forward mutatio     1
    #> 26: sister chromatid exchange    11
    #> 27:     Bacterial Mutagenesis    27
    #> 28:        Cytogenetics Other    26
    #> 29:              Cytotoxicity    21
    #> 30:     In Vitro Micronucleus     4
    #> 31: bacterial gene mutation a     7
    #> 32: in vitro mammalian cell m     5
    #> 33: Aneuploidy, chromosome ab     5
    #> 34: sister chromatid exchange     3
    #> 35: Cell transformation, vira    12
    #> 36: combined chromosome aberr     1
    #> 37: Chromosome aberrations in     2
    #> 38:     Forward gene mutation     5
    #> 39: Forward gene mutation at      6
    #> 40: Forward gene mutation at      2
    #> 41: Specific locus test, gene     1
    #> 42:  Spot test, gene mutation     1
    #> 43: In Vivo Non-mammalian Mut     7
    #> 44:           mouse spot test     2
    #> 45: transgenic rodent mutagen     1
    #> 46:   yeast cytogenetic assay     1
    #> 47:             Gene mutation     4
    #> 48: in vitro mammalian cell t     2
    #> 49:       Cell transformation     5
    #> 50: Tryptophan reverse gene m     8
    #> 51:       Cell Transformation     2
    #> 52:         DNA Damage/Repair     8
    #> 53: In Vitro Chromosome Aberr    11
    #> 54:                  Mutation     3
    #> 55: in vitro chromosomal aber     1
    #> 56:            Mutation Other     4
    #> 57: Evaluation of metabolic a     1
    #> 58: In vitro mammalian chromo     2
    #> 59: Forward and reverse gene      2
    #> 60: Forward and reverse gene      1
    #> 61: Chromosomal aberration as     2
    #> 62:     Mitotic recombination     1
    #> 63: Aneuploidy, sex chromosom     1
    #> 64: Aneuploidy, whole sex chr     1
    #> 65:          fluctuation test     2
    #>                     assayType     N
    ccl4_genetox_details[assayCategory == 'ND', .N, by = .(assayType)]
    #>                    assayType     N
    #>                       <char> <int>
    #> 1:                   Overall     5
    #> 2: In vivo carcinogenicity s    23
    #> 3:                transgenic    10
    ccl4_genetox_details[assayCategory == 'in vivo', .N, by = .(assayType)]
    #>                     assayType     N
    #>                        <char> <int>
    #>  1:        micronucleus assay    46
    #>  2: Unscheduled DNA synthesis     9
    #>  3: in vivo micronucleus (mou    19
    #>  4: in vivo micronucleus (rat     9
    #>  5:          Sperm morphology     9
    #>  6:                  InVivoCA    14
    #>  7:                 InVivoUDS    11
    #>  8:      Dominant lethal test     5
    #>  9: Unscheduled DNA synthesis     3
    #> 10: mammalian germ cell cytog     2
    #> 11:               DNA Binding     1
    #> 12: rodent dominant lethal as    15
    #> 13: unscheduled DNA synthesis     6
    #> 14: Chromosome aberrations in     2
    #> 15:           InVivoDNADamage     7
    #> 16:      In Vivo Micronucleus     1
    #> 17: Micronucleus and sister c     2
    #> 18:     in vivo comet (mouse)     1
    #> 19:       in vivo comet (rat)     3
    #> 20:      DNA Covalent Binding    12
    #> 21: In Vivo Chromosome Aberra     4
    #> 22: In Vivo Mammalian Mutagen     7
    #>                     assayType     N

    natadb_genetox_details[, .N, by = .(assayCategory, assayType, assayResult)]
    #>      assayCategory                 assayType assayResult     N
    #>             <char>                    <char>      <char> <int>
    #>   1:      in vitro                  InVivoMN    negative    40
    #>   2:            ND                   Overall    positive    16
    #>   3:      in vitro bacterial reverse mutatio    positive    93
    #>   4:       in vivo        micronucleus assay    negative    76
    #>   5:       in vivo        micronucleus assay   equivocal     4
    #>  ---
    #> 194:      in vitro Heritable translocation t    negative     2
    #> 195:       in vivo     mammalian comet assay   equivocal     1
    #> 196:      in vitro mammalian cell gene mutat    positive     1
    #> 197:      in vitro in vitro mammalian cell t    positive     1
    #> 198:      in vitro     Mitotic recombination    positive     1
    natadb_genetox_details[, .N, by = .(assayCategory)]
    #>    assayCategory     N
    #>           <char> <int>
    #> 1:      in vitro  2112
    #> 2:            ND   100
    #> 3:       in vivo   435
    natadb_genetox_details[assayCategory == 'in vitro', .N, by = .(assayType)]
    #>                     assayType     N
    #>                        <char> <int>
    #>  1:                  InVivoMN    89
    #>  2: bacterial reverse mutatio   362
    #>  3:                      Ames   258
    #>  4:                 InVitroCA    98
    #>  5:                InVitroMLA    85
    #>  6:                 InVitroMN    20
    #>  7: Cell transformation, clon    14
    #>  8: Forward and reverse gene     17
    #>  9: Histidine reverse gene mu    55
    #> 10: Micronucleus test, chromo    33
    #> 11: Mitotic recombination or     47
    #> 12: Rec-assay, DNA effects (b    34
    #> 13: Rec-assay, spot test, DNA     6
    #> 14: Sister-chromatid exchange    98
    #> 15: DNA damage and repair ass    50
    #> 16:    Chromosome aberrations    25
    #> 17:             Gene mutation    20
    #> 18: Forward gene mutation at     12
    #> 19: Heritable translocation t    10
    #> 20:     Reverse gene mutation    30
    #> 21: Sex-linked recessive leth    26
    #> 22: Sister-chromatid exchange    31
    #> 23:     Bacterial Mutagenesis    41
    #> 24:        Cytogenetics Other    41
    #> 25:              Cytotoxicity    20
    #> 26:         DNA Damage/Repair    27
    #> 27: In Vitro Chromosome Aberr     6
    #> 28:     In Vitro Micronucleus     8
    #> 29: In Vivo Non-mammalian Mut     7
    #> 30:                  Mutation     6
    #> 31: in vitro mammalian chromo    91
    #> 32: Cell transformation, vira    46
    #> 33: mammalian cell gene mutat   104
    #> 34: Forward and reverse gene      4
    #> 35:  Spot test, gene mutation     4
    #> 36: bacterial forward mutatio     4
    #> 37: sister chromatid exchange    50
    #> 38: bacteriophage induction i     1
    #> 39: DNA damage, gene mutation     1
    #> 40: chromosome aberration stu     1
    #> 41: in vitro mammalian cell t     2
    #> 42: Forward gene mutation at      6
    #> 43:       Cell transformation    11
    #> 44: Forward and reverse gene      7
    #> 45: Forward gene mutation at     10
    #> 46: chromosome aberration ass    24
    #> 47:     Drosophila SLRL assay    20
    #> 48: Salmonella and Escherichi     4
    #> 49: Cytogenetic assay in bone     1
    #> 50: Chromosome aberrations in     7
    #> 51:     Forward gene mutation    18
    #> 52: in vitro mammalian cell g     2
    #> 53:           mouse spot test     7
    #> 54: Aneuploidy, whole sex chr     4
    #> 55: sister chromatid exchange     7
    #> 56: Mouse Lymphoma Forward Mu     1
    #> 57: Tryptophan reverse gene m    18
    #> 58: bacterial gene mutation a    11
    #> 59: yeast forward mutation an     4
    #> 60: Micronucleus test in vitr     2
    #> 61: mitotic recombination ass     6
    #> 62: Aneuploidy, chromosome ab     8
    #> 63:       cell transformation     2
    #> 64: in vitro mammalian cell m    13
    #> 65: somatic mutation and reco     3
    #> 66: transgenic rodent mutagen     2
    #> 67:   yeast cytogenetic assay     2
    #> 68: in vitro mammalian cell g     2
    #> 69:        bacterial mutation     1
    #> 70: bacterial reverse mutatio     5
    #> 71: Aneuploidy, partial sex c     2
    #> 72: in vitro chromosome aberr     1
    #> 73: Cell transformation, focu     2
    #> 74: Forward and reverse gene      1
    #> 75: gene mutation assay in fu     5
    #> 76:       Cell Transformation     1
    #> 77: Aneuploidy, sex chromosom     1
    #> 78: Forward and reverse gene      1
    #> 79: E. coli K-12 DNA repair h     1
    #> 80: Chromosomal aberration as     2
    #> 81:          forward mutation     1
    #> 82: mammalian cell gene mutat     1
    #> 83:     Mitotic recombination     1
    #>                     assayType     N
    natadb_genetox_details[assayCategory == 'ND', .N, by = .(assayType)]
    #>                    assayType     N
    #>                       <char> <int>
    #> 1:                   Overall    16
    #> 2: In vivo carcinogenicity s    66
    #> 3:                transgenic    18
    natadb_genetox_details[assayCategory == 'in vivo', .N, by = .(assayType)]
    #>                     assayType     N
    #>                        <char> <int>
    #>  1:        micronucleus assay   105
    #>  2: Unscheduled DNA synthesis    27
    #>  3: rodent dominant lethal as    31
    #>  4:                 InVivoUDS    33
    #>  5:                  InVivoCA    37
    #>  6:      Dominant lethal test    14
    #>  7: Unscheduled DNA synthesis     5
    #>  8: In Vivo Chromosome Aberra     5
    #>  9: In Vivo Mammalian Mutagen     6
    #> 10:      In Vivo Micronucleus    11
    #> 11:           InVivoDNADamage    23
    #> 12: in vivo micronucleus (mou    51
    #> 13:          Sperm morphology    25
    #> 14:               DNA Binding     1
    #> 15: unscheduled DNA synthesis    18
    #> 16:     in vivo comet (mouse)     4
    #> 17: Chromosome aberrations in     9
    #> 18:       in vivo comet (rat)     3
    #> 19: in vivo micronucleus (rat     9
    #> 20: mammalian erythrocyte mic     2
    #> 21: heritable translocation a     2
    #> 22: Micronucleus and sister c     2
    #> 23: bone marrow chromosome ab     1
    #> 24: Chromosome aberrations, i     2
    #> 25:      DNA adduct formation     1
    #> 26:      DNA Covalent Binding     1
    #> 27:     mammalian comet assay     6
    #> 28: mammalian germ cell cytog     1
    #>                     assayType     N

Observe that there are 90 unique assays for CCl4 and 114 unique assays for NATADB. The different assay categories are “in vitro”, “ND”, and “in vivo”, with 65 unique “in vitro” assays for CCl4 and 83 for NATADB, 3 unique “ND” assays for CCL4 and 3 for NATADB, and 22 unique “in vivo” assays for CCL4 and 28 for NATADB.

One may be interested in looking at the number of chemicals for which an assay resulted in a positive or negative result. To assess this, group by `assayResult` and determine the number of unique `dtxsid` values associated with each `assayResult` value.

    ccl4_genetox_details[, .(DTXSIDs = length(unique(dtxsid))), by = .(assayResult)]
    #>    assayResult DTXSIDs
    #>         <char>   <int>
    #> 1:    negative      64
    #> 2:    positive      53
    #> 3:   equivocal      15

    natadb_genetox_details[, .(DTXSIDs = length(unique(dtxsid))),
                           by = .(assayResult)]
    #>    assayResult DTXSIDs
    #>         <char>   <int>
    #> 1:    negative     141
    #> 2:    positive     130
    #> 3:   equivocal      48

For CCL4, there are 64 unique chemicals that have a negative assay result, 53 that have a positive result, and 15 that have an equivocal result. For NATADB, there are 141 unique chemicals that have a negative assay result, 130 that have a positive result, and 48 that have an equivocal result. Observe that since there are 72 unique `dtxsid` values with assay results in CCL4 and 153 in NATADB, there are several chemicals that have multiple assay results.

Next, determine the chemicals from each chemical list that are known to have genotoxic effects. For this, examine which chemicals produce at least one positive response in the `assayResult` column.

    ccl4_genetox_details[, .(is_positive = any(assayResult == 'positive')),
                         by = .(dtxsid)][is_positive == TRUE, dtxsid]
    #>  [1] "DTXSID0020153" "DTXSID0020573" "DTXSID0020600" "DTXSID0020814" "DTXSID0021464" "DTXSID0021541"
    #>  [7] "DTXSID0024341" "DTXSID1021407" "DTXSID1021740" "DTXSID1021798" "DTXSID1024338" "DTXSID1026164"
    #> [13] "DTXSID1031040" "DTXSID2021028" "DTXSID2021317" "DTXSID2021731" "DTXSID3020203" "DTXSID3020702"
    #> [19] "DTXSID3020833" "DTXSID3024869" "DTXSID3031864" "DTXSID4020533" "DTXSID4021503" "DTXSID4022361"
    #> [25] "DTXSID4022367" "DTXSID5020023" "DTXSID5020576" "DTXSID5020601" "DTXSID5021207" "DTXSID5024182"
    #> [31] "DTXSID5039224" "DTXSID6020301" "DTXSID6021030" "DTXSID6021032" "DTXSID6022422" "DTXSID7020005"
    #> [37] "DTXSID7020215" "DTXSID7020637" "DTXSID7021029" "DTXSID8020044" "DTXSID8020090" "DTXSID8020832"
    #> [43] "DTXSID8021062" "DTXSID8023846" "DTXSID8023848" "DTXSID8025541" "DTXSID8031865" "DTXSID9020243"
    #> [49] "DTXSID9021390" "DTXSID9021427" "DTXSID9022366" "DTXSID9023380" "DTXSID9023914"
    natadb_genetox_details[, .(is_positive = any(assayResult == 'positive')),
                           by = .(dtxsid)][is_positive == TRUE, dtxsid]
    #>   [1] "DTXSID0020153" "DTXSID0020448" "DTXSID0020523" "DTXSID0020529" "DTXSID0020600"
    #>   [6] "DTXSID0020868" "DTXSID0021381" "DTXSID0021383" "DTXSID0021541" "DTXSID0021834"
    #>  [11] "DTXSID0021965" "DTXSID0024187" "DTXSID0039227" "DTXSID0039229" "DTXSID1020148"
    #>  [16] "DTXSID1020302" "DTXSID1020306" "DTXSID1020431" "DTXSID1020512" "DTXSID1020516"
    #>  [21] "DTXSID1020566" "DTXSID1021374" "DTXSID1021798" "DTXSID1021827" "DTXSID1022057"
    #>  [26] "DTXSID1023786" "DTXSID1024045" "DTXSID1026164" "DTXSID1049641" "DTXSID2020137"
    #>  [31] "DTXSID2020262" "DTXSID2020507" "DTXSID2020682" "DTXSID2020844" "DTXSID2021284"
    #>  [36] "DTXSID2021286" "DTXSID2021319" "DTXSID2021658" "DTXSID2021731" "DTXSID2021781"
    #>  [41] "DTXSID3020203" "DTXSID3020257" "DTXSID3020413" "DTXSID3020415" "DTXSID3020596"
    #>  [46] "DTXSID3020679" "DTXSID3020702" "DTXSID3020833" "DTXSID3021431" "DTXSID3025091"
    #>  [51] "DTXSID3039242" "DTXSID4020161" "DTXSID4020298" "DTXSID4020402" "DTXSID4020533"
    #>  [56] "DTXSID4020583" "DTXSID4020874" "DTXSID4020901" "DTXSID4021006" "DTXSID4021056"
    #>  [61] "DTXSID4021395" "DTXSID4039231" "DTXSID5020023" "DTXSID5020027" "DTXSID5020029"
    #>  [66] "DTXSID5020071" "DTXSID5020316" "DTXSID5020449" "DTXSID5020491" "DTXSID5020601"
    #>  [71] "DTXSID5020607" "DTXSID5020865" "DTXSID5021124" "DTXSID5021207" "DTXSID5021380"
    #>  [76] "DTXSID5021386" "DTXSID5024055" "DTXSID5024059" "DTXSID5039224" "DTXSID6020145"
    #>  [81] "DTXSID6020307" "DTXSID6020353" "DTXSID6020432" "DTXSID6020438" "DTXSID6020515"
    #>  [86] "DTXSID6020569" "DTXSID6020981" "DTXSID6021828" "DTXSID6022422" "DTXSID6023947"
    #>  [91] "DTXSID6023949" "DTXSID7020005" "DTXSID7020009" "DTXSID7020267" "DTXSID7020637"
    #>  [96] "DTXSID7020689" "DTXSID7020710" "DTXSID7020716" "DTXSID7021029" "DTXSID7021100"
    #> [101] "DTXSID7021106" "DTXSID7021318" "DTXSID7021360" "DTXSID7021368" "DTXSID7021948"
    #> [106] "DTXSID7024166" "DTXSID7024370" "DTXSID7024532" "DTXSID7025180" "DTXSID7026156"
    #> [111] "DTXSID8020090" "DTXSID8020173" "DTXSID8020250" "DTXSID8020599" "DTXSID8020759"
    #> [116] "DTXSID8020832" "DTXSID8021195" "DTXSID8021197" "DTXSID8021432" "DTXSID8021434"
    #> [121] "DTXSID8021438" "DTXSID8024286" "DTXSID9020168" "DTXSID9020243" "DTXSID9020247"
    #> [126] "DTXSID9020293" "DTXSID9020827" "DTXSID9021138" "DTXSID9021261" "DTXSID9041522"

Given the amount of genotoxicity data, consider one chemical, DTXSID0020153, to get a sense of the assays, the number of each type of result, and which correspond to “positive” results. To determine this, group by `assayResult` and calculate `.N` for each group. We also isolate which were positive and output a data.table with the number of each type.

    ccl4_genetox_details[dtxsid == 'DTXSID0020153', .(Number = .N),
                         by = .(assayResult)]
    #>    assayResult Number
    #>         <char>  <int>
    #> 1:    negative      5
    #> 2:    positive     22
    #> 3:   equivocal      1
    ccl4_genetox_details[dtxsid == 'DTXSID0020153' & assayResult == 'positive',
                         .(Number_of_assays = .N), by = .(assayType)][order(-Number_of_assays),]
    #>                     assayType Number_of_assays
    #>                        <char>            <int>
    #>  1: bacterial reverse mutatio                3
    #>  2:                      Ames                3
    #>  3:                 InVitroCA                2
    #>  4:                InVitroMLA                2
    #>  5: Rec-assay, DNA effects (b                2
    #>  6: Sister-chromatid exchange                2
    #>  7:                   Overall                1
    #>  8:                 InVitroMN                1
    #>  9: Cell transformation, clon                1
    #> 10: Histidine reverse gene mu                1
    #> 11: Mitotic recombination or                 1
    #> 12: Rec-assay, spot test, DNA                1
    #> 13: Unscheduled DNA synthesis                1
    #> 14: In vivo carcinogenicity s                1

There were five assays that produced a negative result, 22 that produced a positive result, and one that produced an equivocal result. Of the 22 positive assays, “bacterial reverse mutation assay” and “Ames” were the most numerous, with three each.

### Review Hazard Data for Chemical Lists

Hazard data associated with the chemicals in each chemical list can be retrieved. For each chemical, there are potentially hundreds of rows of hazard data, so the returned results will be much larger than in most other API endpoints. We model how one would structure such a query of the chemicals in CCL4 and NATADB, and leave it to the reader to explore the data in a similar fashion to the previous examples.

    ccl4_hazard <- get_hazard_by_dtxsid_batch(DTXSID = ccl4$dtxsid)
    natadb_hazard <- get_hazard_by_dtxsid_batch(DTXSID = natadb$dtxsid)

Next, it may be helpful to examine the dimensions and column names of the output.

    dim(ccl4_hazard)
    dim(natadb_hazard)
    colnames(ccl4_hazard)
    head(ccl4_hazard)

## Conclusion

In this vignette, a variety of functions that access different types of data found in the `Hazard` endpoints of the CTX APIs were explored. While this exploration was not exhaustive, it provides a basic introduction to how one may access data and work with it. Additional endpoints and corresponding functions exist and we encourage the user to explore these while keeping in mind the examples contained in this vignette.