The need to develop exposure-led human relevant testing strategies for the assessment of human health risks that are based solely on new approach methods (NAM) is rooted in the principles of the three R’s; to reduce, replace and refine the use of animals in scientific experiments, and EU regulation 2010/63/EU, which promotes the development, validation and implementation of alternative methods to animal experiments. The broad application of these new approaches is shown through the numerous legislations that make the provision of information on repeated dose toxicity and developmental and reproductive toxicity (DART) mandatory in the EU. In addition to ethical concerns, screening large libraries of chemical compounds of concern using traditional in vivo tests is very costly and time consuming, and might not always well represent the effects in human. There is a need for NAMs that can provide quantitative toxicological data – importantly based on mechanistic understanding - for many chemical compounds in a reliable, fast and economical manner.
Under several pieces of EU legislation information on repeated dose toxicity and developmental and reproductive toxicity (DART) represents a standard information requirement in the assessment of human health hazards. Namely, the regulation on the registration, evaluation, authorization and restriction of chemicals (REACH) for chemicals, the biocidal product regulation (BPR) for biocides, the regulation on classification, labelling and packaging (CLP), the plant protection product (PPP) regulation for pesticides, the Cosmetics regulation for finished cosmetic products and the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) for human medicines. Generally speaking, these legislations ask for information on 28-day and/or 90-day repeated dose toxicity studies via at least one route of administration (mostly oral) and in at least one species. Also, repeated dose chronic exposure is mandatory in some of the legislations. For the DART endpoint there is usually the request for one reproductive toxicity study and a developmental toxicity study in at least one species and sometimes a two-generation or extended one-generation reproductive toxicity study.
It is important to note that all legislations provide circumstances under which it is not necessary to carry out some of the animal experiments. It is often encouraged to evaluate all existing available information on a substance also from in silico and in vitro studies. In addition, it is expected that approaches developed in EU-ToxRisk have the potential to strengthen current read-across (RAX) practice. Structural and physicochemical similarity data will be linked in defined, quantifiable ways to adverse outcomes by incorporating mechanistic and toxicokinetic knowledge gained from NAMs. Incorporation of similarities on the key event activation level (termed ‘biological RAX’) will bring the RAX concept forward to a robust process of assessing toxicological properties of chemicals that will be of practical regulatory use. Most notably, amongst the legislation listed above is the cosmetics regulation, which prohibits the testing of finished cosmetic products and cosmetic ingredients on animals.
Chemicals: For chemicals the regulation (EC) No 1907/2006 on the registration, evaluation, authorization and restriction of chemicals (REACH), specifies the different testing requirements. Testing requirements are set according to the amount of a chemical (tonnes per year) that is either produced in the EU or imported to the EU. The higher the amount of a chemical, the more thoroughly it will be tested. Both repeated dose toxicity tests and DART tests start to be required from 10 tonnes per year and more, with more rigorous tests required at each incremental step.
Biocides: For biocides, that is active substances that protects humans, animals, materials and articles against harmful organisms such as bacteria and pests, the Biocidal Product Regulation (BPR, (EU) 528/2012) sets out testing requirements. For active substances the toxicological profile for humans and animals needs to be defined and amongst other data requirements there are requirements for repeated dose toxicity tests (28 day and/or 90 day), chronic exposure and reproductive toxicity tests (pre-natal developmental toxicity studies, and/or a two generation toxicity test).
Classification, labelling and packaging: The regulation (EC) No 1272/2008 on the classification, labelling and packaging of substances and mixtures (CLP Regulation) ensures that hazards posed by chemicals are clearly communicated so that appropriate risk management measures can be taken.
Pesticides: For pesticides, the Plant Protection Product regulation (PPP) (EU) No 1107/2009, the Commission Regulation (EU) No 283/2013 set out the information requirements for active substances. These are very extensive; where repeated dose toxicity tests in two species, chronic exposure, developmental toxicity in two species and reproductive toxicity test are mandatory.
Cosmetics: The cosmetics regulation (EC) 1223/2009 for finished cosmetic products sets out the information requirements for cosmetic products that are made available in the EU. As of March 2013, the use of animals in the testing of both cosmetic products and ingredients is prohibited.
Medicines: The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) sets out the information requirements for human medicines. Repeated dose systemic toxicity studies are required under document S3A, “Note for guidance on toxicokinetics: the assessment of systemic exposure in toxicity studies.”, while requirements for reproductive toxicity tests are outlined in document S5 “Detection of toxicity to reproduction for Medicinal products & Toxicity to male fertility”.