Handbook of Solvents - George Wypych - ChemTech - Ventech!

15.2.2 A simple test to determine toxicity using bacteria 1099
the volume of the toxin is plotted. From this the log of the volume corresponding to 50% inhibition
of reduction can be determined and the antilog of this value provides the volume. In
this laboratory the data is plotted both linearly and logarithmically and the best method providing
the regression coefficient closest to 1.00 is chosen. From the concentration of the
toxic compound, the volume found to inhibit reduction of the dye could be converted to
mg/ml present in the test tube. From this the inhibitory concentration causing 50% inhibition,
the IC50, can be calculated. The test has been described in detail (Botsford et al., 1997;
Botsford 1998; Botsford, 1999).
A method to lyophilize cells has been developed and cells are active for at least a
month after being lyophilized (Robertson, 1996).
This test for toxic chemicals is very inexpensive. It can be carried out by unskilled personnel.
It is rapid, taking less than an hour to determine the toxicity of a compound. It provides
values comparable to more conventional tests (Botsford, 2000a). It provides a sort of
toxicological triage, a method to rapidly determine if something is toxic and should be investigated
further. Since it uses bacteria rather than animals as an indicator, it is acceptable
with animal rights advocates. The test has been patented and the author is seeking a firm to
market the test. In the meantime, it can be carried out by any laboratory equipped to grow
bacteria.
Since this test uses a bacterium as the indicator organism. It can be argued that the results
with a bacterium are not applicable to humans. But tests with rats and mice may not be
applicable to humans (Ruelius, 1987). For example, in a test of 10 chemicals comparing results
with mice, rats and five cellular assays, the toxicity of three of compounds differed by
at least an order magnitude when rats and mice were compared (Ekwall et al., 1989). Such
anomalies been observed with many drugs, that drugs were up to 12× more toxic for humans
than for rats and mice (Brodie and Reid, 1967). At a biochemical level, a compound that
damages the cytoplasmic membrane of a bacterium will also damage the cytoplasmic membrane
of a human or any other organism. This test has been compared with 20 other tests for
toxic chemicals and comparable results (similar IC50 values) are obtained (Botsford,
2000a). No one test finds all chemicals to be toxic. Every assay for toxic chemicals is blind
to some compounds and conversely every assay for toxic chemicals is much more sensitive
to some compounds than are other tests. Thus toxicologists desire “batteries of tests”, a
compound is not considered to be toxic until it has proven to be toxic in 3 or 4 systems.
15.2.2.4 Chemicals tested
In Table 15.2.2.1, the values for the more than 200 chemicals tested in this laboratory are reported.
This includes a series of organic chemicals, chemicals that are reported in the literature
as being toxic. It was noted that aromatics, phenol, benzene and toluene are not very
toxic. But when they have substituents, a phenoxy group, chlorine, methyl or nitro they become
quite toxic. Solvents were tested for toxicity and most solvents are not very toxic. We
have found we can dissolve toxic compounds in solvents (methanol and DMSO) and find no
change in the toxicity. Apparently the toxin is so much more toxic than the solvent that only
the toxin affects the mechanism affording the assay. Many drugs were also tested and it is
significant that many of these drugs are toxic for the bacterium and presumably would be
toxic for patients receiving them. Often it is noted that when a drug is taken, an individual
simply does not feel well. This could be due to toxicity of the drug. It was found that many
alkaloids are toxic and then it was shown that many herbs are also toxic. Presumably the
herbs contain toxic levels of some alkaloids. Some of these herbs are toxic enough that if
mega herb therapy ever becomes popular, there could be problems from the toxicity of the
herbs. It was found that divalent cations are toxic for the system. It was found that small
amounts of EDTA could relieve this toxicity in soil and water samples. This will be dis-