Mutagenicity test requirements

Subcllnlcal effects clinical laboratory test alteration (liver function, nerve conduction velocity), mutagenicity testing, cytogenetic testing Requires estimation of eventual likelihood of clinical disease predicted by subcllnlcal abnormalities ... 

ECHA (2008) REACH Guidance on information requirements and chemical safety assessment, Chapter R.7a Endpoint specific guidance. See chapter R7.7.1 Mutagenicity testing. Available at http //guidance.echa.europa.eu/docs/guidance document/information requirements r7a en.pdf vers=20 08 08... 

The dangerous properties of acute toxicity, irritation, corrosivity, sensitisation, repeated-dose toxicity and CMR are evaluated in terms of their potential toxic effects to workers, consumers and man exposed indirectly via the environment, based on the use for each stage in the lifecycle of the substance from which exposure can occur. Risk assessment is also required if there are reasonable grounds for concern for potential hazardous properties, e.g., from positive in vitro mutagenicity tests or structural alerts. The risk assessment involves comparing the estimated occupational or consumer exposure levels with the exposure levels at which no adverse effects are anticipated. This may be a quantitative risk assessment, based on the ratio between the two values, or a qualitative evaluation. The principles of human health risk assessment are covered in detail by Illing (a.30) and more briefly in Chapter 7 of (73). 

Two mammalian mutagenicity tests are generally required to support the lack of mutagenic or carcinogenic potential. Some well known tests are... 

Before administration of a NME to man, a mutagenicity test in bacterial cells (Ames test), with and without metabolic activation, and tests for chromosomal aberrations in mammalian cells should be negative. Any positive or equivocal results will require additional tests to be performed before proceeding to man. Studies of embryo-foetal toxicity should be performed before administration of a NME to women of reproductive potential. Studies of fertility, early embryonic development and pre- and post-natal development are not required at this stage of development neither are carcinogenicity studies. 

The studies with AFB serve to emphasize the importance of using sensitive toxicology test systems. The human cell system is sensitive to ng/ml concentrations of AFB, whereas bacteria mutagenicity test systems require Atg/ml AFB concentrations for a detectable response. The lower concentra-... 

They must provide end products that meet minimal input requirements for Ames mutagenicity testing. 

The panel meeting participants unanimously agreed that the air particulates protocol is a proven method with an adequate data base to demonstrate applicability to the preparation of air particulates for mutagenicity testing. However, the participants agreed that several areas require method validation. 

Soils and Sediments. This protocol (Figure 5) was developed for the preparation of soil and sediment samples for mutagenicity testing. It was designed to provide samples that accurately represent the mutagenic potential of the soil or sediment sample initially extracted and, if necessary, sufficiently fractionate the original material to isolate bioactive materials. Fractionation should be required only if the toxicity of the crude extract prevents determination of the mutagenic potential. 

In this study, a homogeneous bacterial suspension was employed and mutagens were added to the homogeneous suspension. The complete medium containing amino acids, vitamins, and mineral salts was used for experiments. Furthermore, employment of the electrode system makes possible a large injection of bacterial suspension. As a result, the time required for mutagen test was shortened to 10 h. 

Captan had one ambiguous result and one positive result in the two Tier I tests used. It was also positive in the, mouse dominant-lethal test. Because results in the Drosophila test were negative, captan is a doubtful mutagen that requires more testing. 

There is an urgent need to extrapolate data to intact animal systems and human situations to develop a more pragmatic approach and suitable remedial measures for human protection. This should not, however, disqualify scientific data but develop more evidence about the adverse effects of chemicals. The testing requirements that identify the mutagenic potential of a substance, based on USEPA, are shown in Tables 2-11 and 2-1 la. A number of experimental data suggest that different pesticides, both as technical and formulations, caused clas-togenic effects in the bone marrow system of intact rats. Reports have indicated... 

Mutagenicity (genotoxicity). A bacterial mutagenicity test that demonstrates the induction of point (gene) mutations is always required. Some mutations result in the development of cancer. 

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