Improving structure and transparency in reliability evaluations of data under REACH: suggestions for a systematic method

Figures & data

Table 1. Peer-reviewed studies included in this investigation. Studies have been listed according to the assigned reliability category by the registrant: category 1 = Reliable without restriction, category 2 = Reliable with restriction, category 3 = Not reliable and category 4 = Not assignable.

Reliability category	Study	Adequacy	Bibliographic reference	Type of study	Route of exposure	EC-number
1	1	Supporting	Whelton et al. 1997	Oral toxicology study in mice (714 days)	Oral	231-152-8
2	2	Key	Zissu 1995	Repeated inhalation study in mice (14 days) Testing 14 substances (10 chemical families)	Inhalation	201-126-0
	3	Key	Maltoni et al. 1986	2-year oral carcinogenic study in rat (52 weeks exposure)	Oral	201-167-4
	4	Key	Loeser and Lorke 1976a	Semi-chronic oral toxicity study in rat (90 days)	Oral	231-152-8
	5	Key	Loeser and Lorke 1976b	Semi-chronic oral toxicity study in dog (90 days)	Oral	231-152-8
	6	Key	Gaunt et al. 1968	Short-term feeding study in rat (90 days)	Oral	234-186-1
	7	Key	Condie et al. 1988	Oral toxicity study in rat (90 days)	Oral	905-588-0
	8	Supporting	Goldberg et al. 1964	Repeated inhalation study in rat (10 days). Testing nine substances	Inhalation	203-539-1
	9	Supporting	Ballantyne et al. 2006	Repeated inhalation toxicity study in rats (9 days, whole-body)	Inhalation	203-953-2
	10	Supporting	Leber et al. 1990	Dermal toxicity study in rabbit (21 days)	Dermal	203-962-1
	11	Supporting	Lake et al. 1983	Oral toxicity study in hamster (14 days) Testing main substance, primary metabolite and a third substance	Oral	204-211-0
	12	Supporting	Detwiler-Okabayashi and Schaper 1996	Acute inhalation toxicology study in mice (180 min exposure)	Inhalation	204-709-8
	13	Supporting	Penninks and Seinen 1982	Oral toxicity study in rat (2-weeks)	Oral	234-186-1
	14	Supporting	van der Ven et al. 2006	Oral dose toxicity study for investigating endocrine disrupting effects in rats (28 days)	Oral	247-148-4
	15	Supporting	Fairhurst et al. 1989	Dermal toxicity in rat (28 days)	Dermal	252-104-2
3	16	Disregarded study	Cranch et al. 1942	Dermal toxicity study on major wounds in rabbit (9–23 days)	Dermal	203-919-7
	17	Disregarded study	Colerangle and Roy 1996	Oral toxicity study investigating endocrine disrupting effects in rat (11 days)	Oral	284-325-5
	18	Not specified	Crocker et al. 1988	Oral toxicity study in rat (12 months) Testing leachate and substance	Oral	204-211-0
4	19	Supporting	Innis and Nixon 1988	Dermal toxicity study in rabbits (91 days) (Abstract)	Dermal	225-878-4
	20	Supporting	Barnes and Stoner 1958	Repeated oral toxicity study in rats (54–55 days). Summarize different tests on 20 substances by several routes of administration (oral, dermal, intraperitoneal and intravenous) to different species (rats, mice, rabbits and guinea-pigs) ranging from single dose tests to exposure duration of several months.	Oral	234-186-1

Figure 1. Overview of selected studies from each reliability category fulfilling the criteria (1) the bibliographic reference was stated as “publication”, (2) the reference could be identified, (3) the study summary only referred to one bibliographic reference and (5) the adequacy was stated. One of the three studies in reliability category 3, was exchanged as the information in the summary did not correspond to the study stated as reference. Instead, another study assigned reliability category 3, but with no assigned adequacy was included. The numbers in bold indicate the number of included studies in each category (in total 20).

Figure 2. Screen shot of the online SciRAP tool, showing part of the form for evaluating methodology quality. The evaluation is recorded by selecting a pre-defined evaluation statement (fulfilled, partially fulfilled, not fulfilled or not determined) and justifying the assessment with a comment.

Table 2. SciRAP reporting and methodology criteria considered key for evaluating reliability based on expert judgment and “red criteria” in ToxRTool.

Key reporting criteria

The chemical name, ID or CAS-number of the test compound was given.

The animal model (species, strain, age or life stage and sex) was described.

The administered dose levels or concentrations were stated.

The total number of animals per dose group was stated.

The route of administration was stated.

The frequency and duration of dosing/administration of the test compound was stated.

The test and/or analytical methods used were sufficiently described to allow for evaluation of the reliability of results.

The statistical methods and software used were described.

Key methodology criteria

A concurrent negative control group was included.

A reliable and sensitive animal model was used for investigating the test compound and selected endpoints.

The route of administration was appropriate and not likely to interfere with the study results.

Reliable, and sensitive test methods were used for investigating the selected endpoints.

Measurements were collected at suitable time points in order to generate sensitive, valid and reliable data.

A sufficient number of animals per dose group were subjected to separate tests/data collection/measurements to generate reliable and valid results.

Table 3. Principles for categorizing studies into reliability categories 1–4 based on the SciRAP evaluation.

Reliability category	Criteria
1. Reliable without restrictions	Well designed and performed study. All key reporting and methodology criteria are judged as fulfilled and there are no deficiencies in the other non-key criteria that are considered to affect the reliability of the study or make the study not assignable.
2. Reliable with restrictions	Generally well designed and performed study. All key reporting and methodology criteria are judged as fulfilled or partially fulfilled. Minor deficiencies in the other non-key criteria may be present.
3. Not reliable	The study has serious flaws in the study design or conduct affecting its reliability, i.e. one or several of the key methodology criteria are judged as not fulfilled, or there are serious deficiencies in the other non-key criteria that have considerable impact on study reliability,
4. Not assignable	The study is insufficiently reported for evaluating reliability. The study is either published as an abstract or in secondary literature (books, reviews), or important information for assessing reliability in the study is missing, i.e. one or several key reporting criteria have been judged as not fulfilled.

Table 4. Reliability category and rationale for reliability as registered in the REACH registration dossier for the 20 selected studies and resulting reliability evaluation with the SciRAP tool.

Study	Author (Year)	Registrant's reliability category	Registrant's rational for reliability	Reliability category based on SciRAP evaluation	Comment
1	Whelton et al. (1997)	1	Reliable without restriction. Well documented and scientifically acceptable	2	The study was assigned reliability category 2 as the key methodology criteria regarding sufficient number of animals per dose group was evaluated as partially fulfilled. The number of animals killed in each interim test were given as a range and the lower range was sometimes considerably lower than the recommended number in the test guidelines. The other key reporting and methodological criteria were fulfilled.
2	Zissu (1995)	2	Study well documented, meets generally accepted scientific principles, acceptable for assessment	3	The study was assigned reliability category 3 since the key methodology criteria for appropriate route of administration was evaluated as not fulfilled. Nose-only exposure is the preferred mode of exposure in inhalation studies according to guidance and particularly for studies of liquid aerosols. The study uses whole-body exposure without justification, which may affect the dose.
3	Maltoni et al. (1986)	2	Non-GLP, non-guideline study, however well documented and scientifically acceptable.	2	The assigned category did not differ from the registrant’s categorization. Key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
4	Loeser and Lorke (1976a)	2	Reliable with restriction. Well documented. Not according to GLP Method not in compliance with ER 67/548/EEC, Annex V and OECD test guidelines.	4	The study was assigned reliability category 4 since the key reporting criteria on statistics was not fulfilled. It was not reported to what extent the majority of the results had been statistically analyzed (except for accumulation of substance in organs) and no description of variation was provided for the results.
5	Loeser and Lorke (1976b)	2	Reliable with restriction. Well documented. Not according to GLP Method not in compliance with ER 67/548/EEC, Annex V and OECD test guidelines.	3	The study was assigned reliability category 3 since the key methodology criteria regarding number of animals per sex and dose group was evaluated as not fulfilled. Only 2 animals/sex/dose had been used, which deviates from the recommended 4 animals/sex/dose in the OECD guideline for non-rodents (ref). Key reporting criterion on statistics was evaluated as not fulfilled since no statistical analysis of the results (except for accumulation of substance in organs) was reported and no description of variation was provided.
6	Gaunt et al. (1968)	2	Preferred study for this SIDS endpoint. Study predates GLP; however, method was comparable to OECD Guideline 408. The effect of DBT exposure on the thymus of was not assessed in this study. No information on the stability or homogeneity of the test material in the DBTC-prepared diets.	3	The study was assigned reliability category 3 since the key criteria regarding collecting measurements at suitable time point was evaluated as not fulfilled. The study investigated development of bile duct lesions, but a longer exposure time was likely needed for such effects to develop according to the authors of the study (ref).
7	Condie et al. (1988)	2	GLP status not known, near guideline study, published in peer reviewed literature, limitations in design and/or reporting but otherwise adequate for assessment.	2	The assigned category did not differ from the registrant’s categorization. Key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
8	Goldberg et al. (1964)	2	The report (publication) contains sufficient information to permit a meaningful evaluation of study results.	2	The assigned category did not differ from the registrant’s categorization. Key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
9	Ballantyne et al. (2006)	2	Acceptable, well-documented publication which meets basic scientific principles.	3	The study was assigned reliability category 3 since the key methodology criteria regarding appropriate route of exposure was evaluated as not fulfilled. Animals were exposed whole-body in the inhalation chamber, but due to the chemical’s physical properties resulting in vetting of the fur, it was likely that the observed toxicity was attributed to combined inhalation and oral ingestion.
10	Leber et al. (1990)	2	Acceptably documented study which meets basic scientific principles and contains sufficient detail to be able to judge the results reliable as a contribution to the understanding of the repeat dose toxicity of this substance.	4	The study was assigned reliability category 4 since the key reporting criteria regarding statistics was evaluated as not fulfilled. No information on the type of statistical tests or statistically significant levels that had been used were reported. The criteria regarding reporting all results for the investigated endpoints was also evaluated as not fulfilled. Certain results were not reported with figures although statistically significant differences to the controls were seen.
11	Lake et al. (1983)	2	Study well documented, meets accepted scientific principles, acceptable for assessment. Special focus on hepatic peroxisome proliferation.	2	The assigned category did not differ from the registrant’s categorization. All key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
12	Detwiler-Okabayashi and Schaper (1996)	2	meets generally accepted scientific standards, well-documented, and acceptable for assessment	4	The study was assigned reliability category 4 since the key reporting criteria regarding number of animals per dose group was evaluated as not fulfilled. The number of animals used were not clearly reported.
13	Penninks and Seinen (1982)	2	Short-term feeding study. No information on the stability of the test substance in the diet or homogeneity of the test diets is provided. Purity of the test substance is not reported.	2	The assigned category did not differ from the registrant’s categorization. All key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
14	van der Ven et al. (2006)	2	Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results.	1	The study was assigned reliability category 1 since all key reporting and methodology criteria were fulfilled and no other aspects were considered to impact the reliability of the study.
15	Fairhurst et al. (1989)	2	This study was conducted similar to OECD guideline 410.	2	The assigned category did not differ from the registrant’s categorization. All key reporting and methodology criteria were either evaluated as fulfilled or partially fulfilled and no other aspects were considered to make the study unreliable.
16	Cranch et al. (1942)	3	Significant methodological deficiencies. Details on results not provided. No details on systemic examinations conducted. No information on total amount of substance applied. No data on impurity of test substance.	3	The study was assigned reliability category 3 since the key methodology criteria regarding number of animals per dose group was evaluated as not fulfilled. Only two wounds per dose groups were used in the study. The majority of the other reporting criteria were not fulfilled due to insufficient documentation.
17	Colerangle and Roy (1996)	3	Ashby and Odum (Environ Health Perspect, 106, A315-316, 1998) draw attention to the fact that the positive control (DES) data reported for this study also appear in two other reports by Colerangle and Roy (1995 and 1997), and that the vehicle control data of the nonylphenol study is duplicated in the 1997 study. This raises some uncertainties as whether the control data were generated concurrently with the nonylphenol data and questions the validity of this study.	4	The study was assigned reliability category 4 since the key reporting criteria regarding number of animals per dose group was evaluated as not fulfilled. The study was assigned category 3 by the registrant due to uncertainties regarding concurrent control groups. This uncertainty was clarified in this investigation through correspondence with one of the authors of the study (ref). However, the uncertainty regarding number of animals per dose group could not be resolved as the author responsible for the laboratory protocols could not be reached (ref).
18	Crocker et al. (1988)	3	Other: significant methodological deficiencies (no purity, only 4 animals per group, no data on the experimental conditions, gavage 3 times a week, special focus on kidney but no data on the other organs…).	2	The study was assigned reliability category 2, since all critical reporting and methodology criteria were judged either as “fulfilled” or “partially fulfilled” and no other aspects were considered to make the study unreliable.
19	Innis and Nixon (1988)	4	Only abstract available.	4	The assigned category did not differ from the registrant’s categorization. One of the key methodology criterion regarding sufficient number of animals per dose group was evaluated as not fulfilled and consequently should have been assigned to reliability category 3. However, the study was assigned to reliability category 4 since insufficient information was available to make an overall reliability assessment of the study (abstract).
20	Barnes and Stoner (1958)	4	Limited information on methodology; documentation insufficient for assessment.	4	The assigned category did not differ from the registrant’s categorization. The study was assigned reliability category 4, since the key reporting criteria regarding sufficiently described test and/or analytical methods were evaluated as not fulfilled.

Table 5. SciRAP evaluation of reporting quality criteria for the 20 studies included in this investigation listed according to the assigned reliability category with the SciRAP tool. Each criterion was evaluated as either F = fulfilled, PF = partially fulfilled, NF = not fulfilled, ND = not determined or NA = not applicable.

				Key criteria									Other criteria
Reliability category	Study	Publication		The chemical name, ID or CAS-number of the test compound was given.	The animal model (species, strain, age or life stage and sex) was described.	The administered dose levels or concentrations were stated.	The total number of animals per dose group was stated.	The route of administration was stated.	The frequency and duration of dosing/administration of the test compound was stated.	The test and/or analytical methods used were sufficiently described to allow for evaluation of the reliability of results.	The statistical methods and software used were described.		The purity of the test compound was stated or is traceable according to information given regarding manufacturer and lot/batch number. In case of mixtures, the composition of different constituents was stated.	The vehicle was described.	It was stated that a negative control group was included.	Any positive control, if used, was described.	The method for individual identification of animals was described.	The housing temperature was stated.	The relative humidity was stated.	The light-dark cycle was described.	The number of animals per sex in each cage was stated.	The cage materials were described.	Any materials used for physical enrichment were described.	Water bottle materials were described.	The bedding material used was described.	The type and source of feed were reported.	The source of drinking water was reported.	The method for allocating animals to different treatments was stated.	The sex and age (or life stage) of the animals at start of dosing was stated or is obvious from the information given, e.g. pregnant rats were used” is enough information that animals are female andsexually mature/adult.	The method for allocating animals to different tests and measurements(e.g. tissue collection or evaluation of functional or behavioral endpoints) was stated.	The sex, age and number of animals per dose group subjected to separate tests and measurements was stated.	The statistical unit, e.g. the individual or the litter, was stated.	All results for the investigated endpoints were reported. The most critical results were presented in tables and figures, including description of variation and statistically significant results.	The funding sources for the study were stated.	Any competing interests were disclosed or it was explicitly stated that the authors did not have any competing interests.
1	14	van der Ven et al. (2006)		F	F	F	F	F	F	F	F		F	F	F	NA	NF	PF	PF	F	NF	F	NF	NF	F	F	NF	NF	F	NA	F	NA	F	F	NF
2	1	Whelton et al. (1996)		F	F	F	F	F	F	F	F		NF	F	F	NA	NF	F	F	F	PF	NF	NF	NF	NF	PF	NF	PF	F	PF	F	NA	F	F	NF
	3	Maltoni et al. (1986)		F	F	F	F	F	F	F	PF		F	F	F	NA	F	F	PF	PF	F	F	NF	NF	NF	NF	NF	F	F	NA	F	NA	F	PF	NF
	7	Condie et al (1988)		F	F	F	F	F	F	PF	F		F	F	F	NA	NF	F	F	F	F	NF	NF	NF	NF	F	NF	F	F	NA	F	NA	F	F	NF
	8	Goldberg et al. (1964)		F	F	F	PF	PF	F	F	F		NF	NA	F	NA	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	F	F	NA	PF	NA	PF	PF	NF
	11	Lake et al. (1983)		F	F	F	F	F	F	F	PF		PF	F	F	NA	NF	F	F	NF	NF	PF	NF	NF	NF	F	NF	NF	PF	NA	F	NA	F	F	NF
	13	Penninks and Seinen (1982)		F	F	F	F	F	F	F	F		PF	F	F	NA	NF	F	F	F	PF	PF	NF	NF	NF	F	F	F	F	NA	F	NA	F	NF	NF
	15	Fairhurst et al. (1989)		F	PF	F	F	F	F	F	PF		PF	NA	F	F	NF	NF	NF	NF	PF	NF	NF	NF	NF	NF	NF	F	PF	NA	PF	NA	PF	NF	NF
	18	Crocker et al. (1988)		F	PF	F	F	F	F	PF	F		PF	F	F	NA	NF	NF	NF	NF	NF	NF	NF	F	NF	PF	NF	F	PF	NF	PF	NA	PF	F	NF
3	2	Zissu (1995)		F	PF	PF	F	F	F	PF	ND		F	NA	F	NA	NF	F	PF	F	F	PF	NF	NF	NF	NF	NF	NF	PF	NA	PF	NA	PF	NF	NF
	5	Loeser and Lorke (1976b)		F	F	F	F	F	F	PF	NF		NF	F	F	NA	NF	NF	NF	NF	F	NF	NF	NF	NF	PF	F	NF	F	NA	F	NA	PF	NF	NF
	6	Gaunt et al. (1968)		F	F	F	F	F	F	PF	PF		F	F	F	NA	NF	NF	NF	NF	F	NF	NF	NF	NF	PF	NF	NF	F	NF	F	NA	PF	NF	NF
	9	Ballantyne et al. (2006)		F	PF	F	F	F	F	PF	F		F	NA	F	NA	NF	F	F	F	F	F	NF	NF	NF	F	NF	F	PF	NA	PF	NA	F	NF	NF
	16	Cranch et al. (1942)		F	PF	F	NF	F	F	F	ND		NF	NA	F	NA	NF	NF	NF	NF	F	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NA	PF	NF	NF
4	4	Loeser and Lorke (1976a)		F	PF	F	F	F	F	PF	NF		F	F	F	NA	NF	PF	PF	PF	F	NF	NF	NF	NF	F	NF	NF	PF	NF	PF	NA	PF	NF	NF
	10	Leber et al. (1990)		F	F	F	F	F	F	PF	NF		F	NA	F	NA	NF	PF	PF	PF	NF	NF	NF	NF	NF	NF	NF	F	F	NA	F	NA	NF	F	NF
	12	Detwiler-Okabayashi and Shaper (1996)		F	PF	PF	NF	F	F	F	F		NF	NA	F	NA	NF	PF	PF	F	F	F	NF	NF	NF	F	NF	NF	PF	NA	PF	NA	PF	F	NF
	17	Colerangle and Roy (1996)		F	F	F	NF	F	F	F	F		PF	F	F	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	F	NA	PF	NA	F	NF	NF
	19	Innis and Nixon (1988)		F	PF	F	F	F	F	NF	NF		NF	F	F	NA	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	NF	PF	NA	PF	NA	NF	NF	NF
	20	Barnes and Stoner (1958)		F	PF	F	F	F	PF	NF	PF		NF	F	F	NA	NF	NF	NF	NF	F	NF	NF	NF	NF	PF	NF	NF	NF	NA	PF	NA	PF	NF	NF

Table 6. SciRAP evaluation of methodology quality criteria for the 20 studies included in this investigation listed according to the assigned reliability category with the SciRAP tool. Each criterion was evaluated as either F = fulfilled, PF = partially fulfilled, NF = not fulfilled, ND = not determined or NA = not applicable.

			Key criteria							Other criteria
Reliability category	Study	Publication	A concurrent negative control group was included.	A reliable and sensitive animal model was used for investigating the test compound and selected endpoints.	The route of administration was appropriate and not likely to interfere with the study results.	Reliable, and sensitive test methods were used for investigating the selected endpoints.	Measurements were collected at suitable time points in order to generate sensitive, valid and reliable data.	A sufficient number of animals per dose group were subjected to separate tests/data collection/measurements to generate reliable and valid results.		The test compound or mixture was unlikely to contain any impurities that may significantly have affected its toxicity.	An appropriate vehicle was used that is not expected to interfere with the absorption, distribution, metabolism, excretion or toxicity of the test compound.	An appropriate positive control group was included, and the expected result was observed from this treatment.	Animals were individually identified.	Housing conditions (temperature, relative humidity, light-dark cycle) were appropriate for the study type and animal model.	The number of animals per sex in each cage were appropriate for the study type and animal model.	The test system is unlikely to contain contaminants that could affect study results, such as organic pollutants, pesticide residues, heavy metals, and mycotoxins, as well as phytoestrogens.	The allocation of animals to different treatments was randomized.	The timing and duration of administration were appropriate for investigating the included endpoints.	The frequency of administration is appropriate for investigating the included endpoints.	The allocation of animals to different tests and measurements was randomized.	The statistical methods have been clearly described and do not seem inappropriate, unusual or unfamiliar.
1	14	van der Ven et al. (2006)	F	F	F	F	F	F		F	F	NA	ND	F	F	ND	ND	PF	F	NA	F
2	1	Whelton et al. (1996)	F	F	F	F	F	PF		ND	ND	NA	ND	F	ND	ND	PF	F	F	ND	F
	3	Maltoni et al. (1986)	F	F	F	F	PF	PF		F	F	NA	F	PF	F	ND	F	PF	PF	NA	PF
	7	Condie et al. (1988)	F	PF	F	PF	F	F		F	F	NA	F	F	F	ND	F	F	F	NA	F
	8	Goldberg et al. (1964)	F	F	PF	PF	F	F		ND	NA	NA	ND	ND	NF	ND	F	F	F	NA	F
	11	Lake et al. (1983)	F	F	F	F	F	F		ND	F	NA	ND	PF	ND	ND	ND	F	F	NA	PF
	13	Penninks and Seinen (1982)	F	F	F	F	PF	F		ND	F	NA	ND	F	ND	ND	F	PF	F	NA	F
	15	Fairhurst et al. (1989)	F	F	PF	F	F	F		ND	NA	ND	ND	ND	NF	ND	F	PF	PF	NA	PF
	18	Crocker et al. (1988)	F	PF	F	F	F	PF		ND	F	NA	ND	ND	ND	ND	F	PF	F	ND	F
3	2	Zissu (1995)	F	PF	NF	F	F	F		F	NA	NA	ND	PF	ND	ND	ND	F	F	NA	ND
	5	Loeser and Lorke (1976b)	F	F	F	F	PF	NF		ND	F	NA	ND	ND	ND	ND	ND	F	F	ND	ND
	6	Gaunt et al. (1968)	F	F	F	PF	NF	F		F	F	NA	ND	ND	F	ND	ND	PF	F	ND	PF
	9	Ballantyne et al. (2006)	F	F	NF	F	F	F		F	NA	NA	ND	F	F	ND	F	PF	F	NA	F
	16	Cranch et al. (1942)	F	F	F	F	F	NF		ND	NA	NA	ND	ND	ND	ND	ND	NA	F	NA	ND
4	4	Loeser and Lorke (1976a)	F	F	F	PF	F	PF		F	F	NA	ND	F	F	ND	ND	F	F	ND	PF
	10	Leber et al. (1990)	F	F	PF	PF	PF	F		F	NA	NA	ND	F	ND	ND	F	F	F	NA	NF
	12	Detwiler-Okabayashi and Shaper (1996)	F	PF	F	F	F	ND		ND	NA	NA	ND	PF	F	ND	ND	PF	F	NA	F
	17	Colerangle and Roy (1996)	F	F	F	F	F	PF		ND	F	ND	ND	ND	ND	ND	ND	ND	F	NA	F
	19	Innis and Nixon (1988)	F	F	PF	ND	ND	NF		ND	ND	NA	ND	ND	ND	ND	ND	PF	F	NA	ND
	20	Barnes and Stoner (1958)	F	F	F	ND	ND	PF		ND	F	NA	ND	ND	F	ND	ND	ND	F	NA	PF

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