A simple change.
A serious impact.
In the case of cosmetics, the manufacturer could choose ingredients that have been used for a long time, and so are likely to be safe. If the chemical is a new one, the first test could be the QSAR computer analysis to predict its likely irritancy.
In the next stage, a number of in vitro (test tube) tests could be used. Some tests are better than others for substances of a certain form, for example liquid rather than solid, and for substances of a certain chemical class, for example alcohols rather than oils. The aim would be to choose the best set of tests for a particular substance.
Doing more than one test is not a problem because in vitro tests are so much faster and cheaper than animal tests. For example, an Agarose Diffusion Test takes 24 hours per product, whereas a Draize test takes at least three days per product and costs 10 times more to carry out.
If the product is shown to be safe by this set of tests, it can then be trialed by human volunteers. This is the final and best test of all. By going through this series of steps products can be guaranteed to be safe without the suffering that is currently inflicted on animals.
Alternative Toxicity Tests
Human cell cultures have several advantages in predicting toxicity:
They are human and so avoid species differences;
They can be taken from the tissue that a particular test chemical is most likely to affect, for example the skin, or the liver;
They allow researchers to study how a substance causes damage to the cells, that is, why it is toxic;
They avoid causing pain and death to animals.
Human tissues for testing are becoming more available in the USA and Europe, although less so in Australia.
There are companies that market cell lines from normal tissues and from tumours. For example:
The American Type Culture Collection has available over 2300 animal and human cell lines.
Companies such as Clonetics market cell cultures derived from human skin, cardiovascular system, brain, respiratory system, kidneys and muscles (visit the Clonetics web site).
Researchers can collect their own human tissue, for example, blood from volunteers or skin from plastic surgery. For many tissues, though, it is easier to use tissue banks.
In the USA, the National Disease Research Interchange in Philadelphia collects tissues removed during operations and from donors, and distributes them to researchers (visit the NDRI web site and look at About Us and Our Mission and History).
In the UK, the University of Leicester is doing the same. They use organs that are not suitable for transplantation and would otherwise be destroyed.
Alternative Irritancy Tests
h-CLAT (Human Cell Line Activation Test)
There are few validated alternative tests relating to mutagenicity/genotoxicity; referring to the mutation of cells causing degenerative conditions and heritable damage. The in vitro Mammalian Cell Micronucleus test uses cultured human cells to detect micronuclei in the cytoplasm of cells which have undergone cell division either during or after exposure to the test substance. The presence of micronuclei can demonstrate chromosomal instability and thus the hazardous nature of the test substance.
Reconstructed Human Epidermis
Corneal cell lines/strong
Neutral Red Uptake Test
Agarose Diffusion Test
Some cosmetics companies already use human volunteers to test new formulations. This is the most reliable test of all. Human irritancy can be assessed through patch testing, where test substances are placed on small areas of the upper back and covered with a patch for two days.
Microdosing is another method of testing on humans. Volunteers are given an extremely small dose of the drug before sophisticated imaging techniques are used to monitor how it is metabolised within and affects the body. This is effective in screening out drug compounds which will have no effect on humans, thus eliminating the governmental requirement for animal testing.
Functional Magnetic Resonance Imaging (fMRI) is another technique which utilises humans rather than animals in the study of the brain. fMRI uses brain imaging and recording techniques to safely study the brain. Researches are even able to temporarily and reversibly induce brain disorders through transcranial magnetic stimulation; thus eliminating the archaic method of inducing brain damage on rats, cats and monkeys.
Wyss Institute’s ‘Organs-on-chips’ is an in vitro alternative test that utilises human cells which have been grown to mimic the structure and function of human organs and their systems. The chip is made from a clear, flexible polymer which contains hollow microfluidic channels which are lined by specific living human organ cells and interfaced with a human endothelial cell-lined artificial vasculature. Mechanical forces are then applied to mimic the physical microenvironment of living organs, such as the motion of breathing for lung cells. Therefore they are able to be exposed to disease and drug testing while accurately replicating human physiology responses.
Organoids are also similar in vitro methods. These are miniature and simplified versions of human organs which are grown in a lab. They allow for the study of disease and treatment, and have been used successfully in the Netherlands to show how certain drugs affect individuals being treated for cystic fibrosis. As a specific organoid can be grown from a biopsy of an individual patient, this allows for extremely accurate testing.
CATMoS - Collaborative Acute Toxicity Modelling Suite
CATMoS is an in silico predictive modelling method which tests for acute toxicity, and can replace in vivo testing. It utilises reference animal test data and international consensus predictions of how a substance may react following oral consumption. This free resource for screening organic chemicals for acute toxicity has been effective in reducing the number of animals used for toxicity testing.
QSAR - Quantitative Structure-activity Relationships
These are in silico computer modelling techniques. Past research and our knowledge of human biology are combined to develop mathematical algorithms which are integrated with computer code to formulate the predicted behaviour and effects of a substance. This method of alternative testing is heavily supported due to its accuracy and ability to significantly reduce the use of animals in scientific testing.
KeratinoSens and LuSens Assay
These are also validated alternative skin sensitisation tests.
KeratinoSens uses a human keratinocyte cell line (HaCaT) which are transfected with a plasmid which contains the luciferase gene, which is known to be regulated by contact sensitizers. The luciferases are oxidating enzymes which emit light that can be quantified by luminescence detection. These cells are then exposed to a substance and the luciferase concentration can be used to predict sensitisation.
The LuSens assay is based on the same concepts. It utilises the same HaCaT cells and employs the same luciferans reporter gene.
It is recommended that these tests are used in combination with other in vitro and in chemico models.
DPRA – Direct Peptide Reactivity Assay
DPRA is a skin sensitisation test. This in chemico method quantifies the reactivity of test chemicals towards model synthetic peptides which contain either lysine or cysteine. Evaluating the protein reactivity by measuring the peptide depletion values allows the categorisation of a substance into one of four reactivity classes; thus determining whether the substance is a skin sensitizer or not.