Subject substantial distinction

Previous chapters have been directed primarily to the aquatic environment. The principles may, with appropriate modification, be extended to terrestrial systems. In practice, there is no distinct bonndary between terrestrial and aquatic systems. Both are influenced by the level of the water table and the possibility of leaching from the soil phase. Substantial effort has been directed to a wide range of agrochemicals, and a few of these have already been used as illustration in earlier chapters. Some important general conclusions from these studies have a direct bearing on the subject of this chapter ... 

The experiment was nonetheless instructive, and one could hardly ask human subjects to participate in a more rigorous test. Two facts stand out in addition to what has already been said (1) Substantial variation was observed among the nine individuals, and (2) this variation may have been due to differences in intestinal flora rather than to more direct differences in need. It should be pointed out, however, that differences in need based upon differences in intestinal flora may be real and just as exacting as if the differences had a different origin. Presumably differences in intestinal flora are due to the different "climates" which are distinctive for each individual (p. 149). If we take the experiments and the authors interpretation at face value, we are led to conclude that some individuals can get along with practically no thiamine in their dieta conclusion which certainly points toward high variability of needs. 

The primary (enzymatic) phase of renneting overlaps somewhat with the secondary phase of aggregation. The gel subsequently undergoes syneresis to produce curds and whey while a slow but more general proteolysis of the caseins begins, which eventually contributes substantially to the distinctive flavor and texture of cheese. The enzymatic coagulation of milk and formation of the curd has been reviewed by Dalgleish (1987). Here, attention will be confined to parts of the subject that most clearly relate to the structure and stability of bovine casein micelles. 

A facility to allow the concurrent testing of different surfaces (e.g. roughness or material) would be a distinct advantage although it may be difficult to design the probe head to accommodate several surfaces that are substantially subject to the same conditions of flow and temperature. 

As distinct from the unreasonable risk standard of 4(a)(1)(A), under 4(a)(1)(B) EPA must issue a test rule if it makes a B finding that a chemical substance is produced in substantial quantities and (i) it is, or is expected to, enter the environment or (ii) there is or may be significant human exposure. Unlike in an A finding, there is no risk-based criterion to satisfy in a B finding. However, as with the phrase unreasonable risk, the terms substantial and significant are not defined in the statute, nor are they elucidated in any way in the legislative history of TSCA. Yet, they have been the subject of litigation. 

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