Corn, steep liquor

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 28 June 2010 and 13 July 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Corn Steep Liquor

IUPAC Name:

Corn Steep Liquor

Details on test material:

Sponsor's identification : Corn Steep Liquor
Description : opaque brown liquid
Batch number : E108C
Date received : 15 June 2010
Expiry date : 02 October 2010
Storage conditions : approximately 4°C in the dark

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca (CBA/CaOlaHsd)

Sex:

female

Details on test animals and environmental conditions:

Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Harlan Laboratories UK Ltd, Oxon, UK.

On receipt the animals were randomly allocated to cages. The animals were nulliparous and non pregnant.

After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink
marking on the tail and a number written on a cage card.

At the start of the study the animals were in the weight range of 15 to 23 g, and were eight to twelve weeks old.

The animals were individually housed in suspended solid floor polypropylene cages furnished with softwood woodflakes.

Free access to mains tap water and food (2014 Teklad Global Rodent diet supplied by Harlan Laboratories UK Ltd, Oxon, UK) was allowed throughout
the study.

The temperature and relative humidity were controlled to remain within target ranges of 19 to 25°C and 30 to 70%, respectively. Any occasional
deviations from these targets were considered not to have affected the purpose or integrity of the study.

The rate of air exchange was approximately fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06.00 to 18.00) and twelve hours darkness.

The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have
affected the purpose or integrity of the study.

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Remarks:

Please see below for Vehicle Determination Record

Concentration:

Each group was exposed to concentrations of 100% (undiluted), 50% or 25% v/v (in dimethyl sulphoxide)

No. of animals per dose:

Groups of four mice were treated

Details on study design:

RANGE FINDING TESTS:
As no toxicological information was available regarding the systemic toxicity/irritancy potential of the test material, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µl of the undiluted test material to the dorsal surface of each ear for
three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of
toxicity or excessive local irritation noted during this period were recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6.

- Lymph node proliferation response:
Clinical observations, bodyweight and mortality data are give in the results section (table 1).

No signs of systemic toxicity were noted.

Based on this information the dose levels selected for the main test were 25% and 50% v/v in dimethyl sulphoxide and 100%.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT

- Name of test method:
Local Lymph Node Assay in the Mouse. The assay has undergone extensive inter-laboratory validation and has been shown to reliably detect test
materials that are moderate to strong sensitisers.

- Criteria used to consider a positive response:
The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node(dpm/node) and as the ratio of 3HTdR incorporation in lymph node cells of test nodes relative to that recorded for the control nodes (stimulation Index).

The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non-sensitier".

TREATMENT PREPARATION AND ADMINISTRATION:
For the purpose of the study, the test material was used undiluted and also freshly prepared in dimethyl sulphoxide. This vehicle was chosen as it
produced the most suitable formulation at the required concentration. The concentrations used are given above.

Determination, by analysis, of the concentration, homogeneity and stability of the test material preparations was not appropriate because it was not
specified in the Study Plan and is not a requirement of the Test Guidelines.

The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest
suitable concentration. The mice were treated by daily application of 25 µl of the appropriate concentration of the test material to the dorsal surface
of each ear for three consecutive days (Days 1, 2 and 3). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.

3H-Methyl Thymidine Administration:
Five days following the first topical application of the test material (Day 6) all mice were injected via the tail vein with 250 µl of phosphate buffered
saline (PBS) containing 3H-methyl thymidine (3HTdR: 80 µCi/ml, specific activity 2.0 Ci/mmol, GE Healthcare UK Ltd) giving a total of 20 µCi to each mouse.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

None provided.

Results and discussion

Positive control results:

Current Positive Control Study for the Local Lymph Node Assay

Introduction. 
A study was performed to assess the sensitivity of the strain of mouse used at these laboratories to a known sensitiser. The methodology for the LLNA is detailed in the OECD Guideline for the Testing of Chemicals, No. 429, and Method B.42 of CommissionRegulation (EC) No. 440/2008. The study described in this document is based on these test methods but has been refined in order to reduce the number of animals required. The reduced LLNA (rLLNA) has been endorsed by the non‑Commission members of the European Centre for the Validation of Alternative Methods (ECVAM) Scientific Advisory Committee (ESAC) at its 26thmeeting held on 26 – 27 April 2007 at ECVAM,Ispra, Italy.

Test Material:                                    α‑Hexylcinnamaldehyde, tech., 85%
Project number:                        0039/1154
Study dates:                                      09 June 2010 to 15 June 2010

Methods. 
A group of five animals was treated with 50 µl (25 µl per ear) ofα‑Hexylcinnamaldehyde, tech., 85%as a solution in dimethyl sulphoxideata concentration of 15% v/v. A further control group of five animals was treated with dimethyl sulphoxide alone.

Results. 
The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group is as follows:

Concentration (% v/v) in dimethyl sulphoxide Stimulation Index Result
15 3.25 Positive

Conclusion. 
α‑Hexylcinnamaldehyde, tech., 85%was considered to be a sensitiser under the conditions of the test.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: A stimulation index of less than 3 was recorded for the undiluted test material and the test material at concentrations of 50% and 25% v/v in dimethyl sulphoxide. The stimulation index (SI) results are given in Table 2.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: The radioactive disintegrations per minute (dpm) per lymph node and the stimulation index (SI) are given in Table 2.

Any other information on results incl. tables

Interpretation of Results

The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of³HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).

The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in³ HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in³HTdR incorporation will be classified as a "non-sensitiser".

Preliminary Screening Test

Clinical observations, bodyweight and mortality data are given in Table 1.

No signs of systemic toxicity were noted.

Based on this information the undiluted test material and the test material at concentrations of 50% and 25% v/v in dimethyl sulphoxidewere selected for the main test.

Main Test

Estimation of the Proliferative Response of Lymph Node Cells

The radioactive disintegrations per minute per lymph node and the stimulation index are given in Table 2.

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in dimethyl sulphoxide	Stimulation Index	Result
25	1.54	Negative
50	1.15	Negative
100	1.35	Negative

Clinical Observations and Mortality Data

Individual clinical observations and mortality data for test and control animals are given in Table 3.

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test. Fur loss was noted, on Days 5 and 6, in animals treated with the undiluted test material.

Bodyweight

Individual bodyweights and bodyweight changes for test and control animals are given in Table 4.

Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.

Table 1              Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration	Animal Number	Bodyweight (g)		Day
				1		2		3		4	5	6
		Day 1	Day 6	Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
100%	S-1	21	21	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 2              Disintegrations per Minute, Disintegrations per Minute/Node and Stimulation Index

Concentration (%v/v) in dimethyl sulphoxide	dpm	dpm/Node^a	Stimulation Index^b	Result
Vehicle	6959.39	869.92	na	na
25	10721.12	1340.14	1.54	Negative
50	8003.55	1000.44	1.15	Negative
100	9417.81	1177.23	1.35	Negative

dpm=  Disintegrations per minut

a=      Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

b=      Stimulation Index of 3.0 or greater indicates a positive result

na =    Not applicable

Table 3              Individual Clinical Observations and Mortality Data

Concentration (% v/v) in dimethyl sulphoxide	Animal Number	Day 1		Day 2		Day 3		Day 4	Day 5	Day 6
		Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
Vehicle	1-1	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0
25	2-1	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0
50	3-1	0	0	0	0	0	0	0	0	0
	3-2	0	0	0	0	0	0	0	0	0
	3-3	0	0	0	0	0	0	0	0	0
	3-4	0	0	0	0	0	0	0	0	0
100	4-1	0	0	0	0	0	0	0	0Fl	0Fl
	4-2	0	0	0	0	0	0	0	0Fl	0Fl
	4-3	0	0	0	0	0	0	0	0Fl	0Fl
	4-4	0	0	0	0	0	0	0	0Fl	0Fl

0=      No signs of systemic toxicity

Fl =     Fur loss

Table 4              Individual Bodyweights and Bodyweight Changes

Concentration (% v/v) in dimethyl sulphoxide	Animal Number	Bodyweight (g)		Bodyweight Change (g)
		Day 1	Day 6
Vehicle	1-1	17	16	-1
	1-2	18	18	0
	1-3	21	22	1
	1-4	19	18	-1
25	2-1	21	20	-1
	2-2	20	21	1
	2-3	21	22	1
	2-4	17	18	1
50	3-1	20	20	0
	3-2	21	21	0
	3-3	21	20	-1
	3-4	18	19	1
100	4-1	20	19	1
	4-2	19	19	0
	4-3	17	18	1
	4-4	21	22	1

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

The test material was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The method was designed to meet the requirements of the following:

        OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted)

        Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Directive 2004/73/EC

Methods. 

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 100%, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µl (25 µl per ear) of the undiluted test material or the test material as an emulsion in dimethyl sulphoxide at concentrations of 50% or 25% v/v. A further group of four animals was treated with dimethyl sulphoxide alone.

Results. 

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in dimethyl sulphoxide	Stimulation Index	Result
25	1.54	Negative
50	1.15	Negative
100	1.35	Negative

Conclusion. 

The test material was considered to be anon-sensitiser under the conditions of the test.