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Substances are defined as carcinogenic if after inhalation, ingestion, dermal application or injection they induce (malignant) tumours, increase their incidence or malignancy, or shorten the time of tumour occurrence.

It is generally accepted that carcinogenesis is a multihit/multi-step process from the transition of normal cells into cancer cells via a sequence of stages and complex biological interactions, strongly influenced by factors such as genetics, age, diet, environment, hormonal balance, etc.

Since the induction of cancer involves genetic alterations which can be induced directly or indirectly, carcinogens have conventionally been divided into two categories according to their presumed mode of action: genotoxic carcinogens and non-genotoxic carcinogens.

Genotoxic carcinogens have the ability to interact with DNA and/or the cellular apparatus and thereby affect the integrity of the genome, whereas non-genotoxic carcinogens exert their carcinogenic effects through other mechanisms that do not involve direct alterations in DNA (Adler et al., 2011).

Regulatory context

EURL ECVAM validated test methods

Development and optimisation of alternative methods and approaches

Scientific tools and databases