PPB P arts P er B illion. PPM P arts P er M illion. Pyrophoric materials ignite spontaneously in air. Since a wide variety of chemicals will burn if heated sufficiently, it is usual to define a pyrophoric material as one which will ignite spontaneously at temperatures below about 45 C. R A Reproductive Toxin , such as vinyl chloride or PCBs, is a chemical which may cause birth defects or sterility. These values, which may differ from country to country, are often backed up by regulation and therefore may be legally enforceable.
Systemic poisons have an effect which is remote from the site of entry into the body.
A TD50 can be computed for any particular type of neoplasm, for any particular tissue, or for any combination of these. The range of statistically significant TD50 values for chemicals in the CPDB that are carcinogenic in rodents is more than 10 million-fold. A Teratogen is a chemical which may cause genetic mutations or malformations in the developing foetus. These values, which may differ from country to country, are often backed up by regulation and therefore may be legally enforceable. TSCA Acronym for Toxic Substances Control Act.