Unilever: Pathway-based

approaches to safety

Carl Westmoreland, 18 June 2012

Paul Carmichael, Matt Dent, Cameron MacKay, Gavin Maxwell, Fiona

Reynolds and Julia Fentem

Safety & Environmental Assurance Centre

(SEAC)

SEAC

Safety Decisions are Risk-

Based

We use scientific evidence-based risk assessment

methodologies to ensure that the risk of adverse health

and/or environmental effects from exposure to chemicals

used in our products is acceptably low.

Hazard-based

• check-list compliance

• unnecessary testing

• doesn’t consider how product

is used

• yes / no decisions

• overly conservative

Risk-based

• expertise- & evidence-driven

• essential testing only

• product use / exposure

determines outcome

• options to manage risks

• uncertainties explicit

Ref: Terry Schultz

Application of Research to Levels of Organization

Based on Source to Outcome

Source

Environmental Contaminant

Exposure

Molecular Initiating Event

Cellular Effects

Individual

Population

Community

Mode of Action

Adverse Outcome Pathway

Source to Outcome Pathway

Toxicity Pathway

Capability building – pathways approaches

● We are currently assessing a pathways-based approach

to assessment of consumer (and environmental) safety

● Case studies

– Risk assessment for skin allergy

– A TT21C approach to risk assessment for DNA

damage

http://www.unilever.com/sustainable-living/consumer/testing/

● We risk assess to prevent skin sensitisation in consumers

– What risk does ingredient X at conc. Y in product Z pose to the consumer?

● How can we risk assess without new animal test data?

1.Identify pathways driving human adverse response = qualitative AOP

2.Develop test methods to predict key toxicity pathways

3.Will response be adverse for given exposure scenario? = qualitative AOP

Human Health Risk Assessment for Skin Allergy

Risk ?

Pro

du

ct

X

Hazard Exposure

Historical Non-animal In Vivo

Identify the toxicity pathways driving the

human adverse response

?

Epidermis Epidermis

Lymph

Node

Induction Elicitation

Modified version of flow diagram from ‘The Adverse Outcome Pathway for Skin Sensitisation initiated by Covalent Binding to Proteins’, OECD report (Draft: 14th Dec 2011)

1. Skin

Penetration

2. Electrophilic

substance:

directly or via

auto-oxidation

or metabolism

3-4. Haptenation:

covalent

modification of

epidermal proteins

5-6. Activation

of epidermal

keratinocytes &

Dendritic cells

7. Presentation of

haptenated protein by

Dendritic cell resulting

in activation &

proliferation of

specific T cells

8-10. Allergic Contact

Dermatitis: Epidermal

inflammation

following re-exposure

to substance due to T

cell-mediated cell

death

Key Event 1 Key Event 2 + 3 Key Event 4 Adverse Outcome

Chemical

Structure &

Properties

Organism

Response

Organ

Response

Cellular

Response

Molecular

Initiating

Event

Pro

du

ct

Epidermis

Lymph

Node

Induction Elicitation

No

. o

f C

D8+

sp

ec

ific

T c

ell

s

Time

X @ conc. 2

X @ conc. 1

Non-Adverse

Adverse

Chemical

Structure &

Properties

Organism

Response

Organ

Response

Cellular

Response

Molecular

Initiating

Event

What risk does ingredient X at conc. Y in product Z pose to the consumer?

Total Haptenated

Skin Protein

Exposure & Consumer Use Assessment

High-content information in vitro assays in human cells & models

Dose-response assessments

Computational models of the circuitry of the relevant toxicity pathways

PBPK models supporting in vitro to in vivo extrapolations

Risk assessment based on exposures below the levels of significant pathway perturbations

www.tt21c.org

(From Andersen &

Krewski, 2009, Tox

Sci, 107, 324)

Joint Research Program

• HCA: Cellular response to DNA damage (toxicity pathway + case study chems)

• Localization of Mn & DNA damage response proteins in single cells

• phos-p53, total-p53, p21, MDM2, Chk2, p-ATM, H2AX

• High throughput flow cytometry (FACS)

• Alterations in gene expression following DNA damage

• Time and dose-dependent changes

• Full-genome arrays + ChIP-chip + ChIP-seq

Characterizing the Cellular

Response to DNA Damage

SEAC

Flow Cytometry

High Content Imaging Assays

0.001 0.01 0.1 1 10 100 10000

20

40

60

80

uM

%M

N F

req

uen

cy

Cellomics Micronuclei

0.001 0.01 0.1 1 10 100 10000

20

40

60

80

100

uM

p-H

2A

X %

Resp

on

der

Integrate Data into Models/Networks

Basal function

Response to small perturbations

Response to larger perturbations

Assessing mechanism of underlying threshold giving rise to increased mutation

Computational modeling of

dose response for DNA

damage pathway activation

In Vitro to In Vivo (human

exposure) Extrapolation

Exposure

mg/kg/day

Target site

concentration (µM)

In vitro

adaptive/adverse

threshold

concentration (µM)

– measuring &

modelling FREE

CONCENTRATIONS

RISK21

ToxCast™

External Partnerships