In reviewing the database PHYTOTOX we found 359 unique measurement units for reporting the values of dosage. These included units such as: um/m3 and g/m2, but also some strange mixes, g/ft3, mg/gal, and some rather obscure measures such as lb/feddan. It is true that some of those units are remnants of archaic measurement systems and don't appear in the current literature, but articles published since 1980 still contained 59 unique units. The diversity of measurement units and presentation practices makes it difficult to use some of this data and even more difficult to make comparisons among studies.
Guidelines are proposed that are designed to improve research reporting and help in planing experiments that are comparable and thus useful in the context of other studies. The adoption of SI units solves many problems, but still confusion is created when sufficient details are not reported to understand each dosage and measurement. Since toxic effects are based on chemical interactions, dosage should be based on the number of molecules (moles) applied to an area (m2 ) (soil or leaf), a volume (m3) (soil or solution), a mass (g) (soil or plant), or numbers of cells, seeds, plants, etc. Amendments such as surfactants or oils, used to increase plant contact, should be reported separately and in the same units (denominator) as the tested chemical.