Endocrine disruptors and Endocrine disruptors and animal-free toxicologyanimal-free toxicology

Teuta Murati, Ivana Kmetič, Jasna Kniewald, Branimir Šimić

Zagreb, May 11, 2013

ENDOCRINE DISRUPTING COMPOUND (EDC)ENDOCRINE DISRUPTING COMPOUND (EDC)

“an exogenous agent that interferes with synthesis, secretion, transport, metabolism, binding action, or elimination of natural blood-borne hormones that are present in the body and are responsible for homeostasis, reproduction, and developmental process” (EPA)

synthetic chemicals:• industrial chemicals and their byproducts (PCBs, PBBs, TCDD) • plastics (BPA) • plasticizers (phthalates) • pesticides (methoxychlor, chlorpyrifos, DDT) • fungicides (vinclozolin) • pharmaceutical agents (DES)....

natural chemicals found in human and animal food (phytoestrogens)

ENDOCRINE DISRUPTING COMPOUND (EDC)ENDOCRINE DISRUPTING COMPOUND (EDC)

Frye, C. (2012) J. Neuroendocrinol. 24, 144-159.

DES

DDT

BPA

TCDD

PCBs genistein

Sources of EDCs

• Diet

• Environmental

Contamination

• Plastic

• Medical compounds

Effects

• Sexually dimorphic behaviors

• Reproduction

• Neurodevelopment

Critical Periods

• Intrauterine

• Perinatal

• Puberty

• AdultMechanisms

• Hormone precursors

• Metabolism of steroids

• Steroid receptors

• Steroid-sensitive

substrates

From Rachel to REACHFrom Rachel to REACH

1962 Silent Spring by Rachel Carson

2007 REACH (Registration, Evaluation, Authorisation and Restriction of Chemical substances)

source: Web of Science (May, 2013)

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1996

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year

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Number of scientific publications on endocrine disruptors published during 1996 - 2012

Source: U.S. Department of Agriculture, Animal and Plant Health Inspection Service, September 2008

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of a

nim

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used

• Safety Evaluation Ultimately Replacing Animal Testing (SEURAT)

“We are not 70 kg rats” (Hartung, T.)

• since 1986 the EU has invested some $300 million on the development and validation of alternative approaches

The 3RsThe 3Rs

1959 W. Russell and R. Burch The Principles of Humane

Experimental Technique (http://altweb.jhsph.edu/pubs/books/humane_exp/het-toc)

goal: improve existing methods so fewer animals are required

goal: refine studies so animals experience as little pain and stress as possible

goal: develop and implement alternatives to replace animal testing wherever possible

ReductionReduction

rational and efficient use of animals (pilot studies) appropriate experimental design and statistical analysis of data derived from

experiments variety of animal species (greater sensitivity)

RefinementRefinement improved housing conditions and experimental techniques use of animal species that are less sensitive to pain and suffering reducing pain and suffering of animals to a minimum (anesthesia/analgesia,

the use of the least invasive methods) improved animal welfare

'mouse house' (MRC National Institute for Medical Research)

ReplacementReplacement

alternatives include the use of:

physical and chemical analysis techniques mathematical and computer models (molecular modelling, (quantitative) structure-

activity relationship (Q)[SAR] approaches, physiologically based pharmacokinetic [PBPK] modelling)

-omics technologies in vitro systems (subcellular systems, primary cell cultures, cell lines, stem cells, whole

tissues and perfused organs) organisms not classed as protected animals early developmental stages of protected animals species, before the regulations apply

to them

ValidationValidation

Manou, I. et al. (2005) Altern. Lab: Anim. 33, 21-26.

Estimated time required to achieve the full replacement of animal testing with alternative method

http://alttox.org/ttrc/validation-ra/validated-ra-methods.html

The Dawning of a New Age of ToxicologyThe Dawning of a New Age of Toxicology

2007 Toxicity testing in the 21st century: a Vision and a Strategy

Leist, M et al. (2008) ALTEX 25, 103-114.

Approach to toxicity testing suggested by the US National Research Council

“Sometimes, in vitro is better” (Perkel, J.M.)

Thank you for your attention