INTERACTION BETWEEN SOPP AND CHLORINE
Zbozinek, J.V. (Residue Reviews 1984; v.92 p 113 [43pp])
OPP (o-phenylphenol) was introduced by Dow Chemical as Dowicide 1 in 1936
to prevent fruit rot; SOPP is sold under trade names of Dowicide A, Topane,
Preventol-On and Stopmold. SOPP crystallizes with 4 molecules of water;
its solubility in water at 25 Centigrade is about 10 g/100g, forming a
solution with a pH of 12 to 13.5 . (very alkaline) The author found that
an extensive literature search yielded little information specifically on
SOPP metabolites. He assumes similarity to other phenolic compounds in his
analysis which follows.
Phenols are highly reactive and unstable compounds; they can be chemically
oxidized to quinones and free radicals to spontaneously produce various
kinds of polymers. These chemical reactions are encouraged and favored by
alkali and oxygen. Oxidation and the accompanying formation of free
radicals can also lead to the formation of peroxides, occurring on
prolonged storage and exposure to air and light. OPP can form condensation
products as a result of hydrogen bonding.
Chlorination of OPP would result in the formation chlorine derivatives of
OPP. Further reactions can produce chlorinated acids, such as chloro-acetic
acid and chloroform.
OPP was readily decomposed by soil bacteria and was the poorest of 4
preservatives on wood buried in soil. The pathway of biodegradation by
microorganisms in the soil is assumed to be analagous to that of biphenyl
and diphenyl methanes. Similarities between benzene, toluene, biphenyl
and diphenyl methane metabolism lend credibility to that comparison.
"Another metabolic pathway of OPP in soil may be its transformation into
stable polymers which eventually become part of the humus." (p.124)Various
fungi naturally produce lactases and polyphenol oxidases which can
assimilate phenols at a neutral pH.
If OPP wastes are cycled through sewage treatment
plants, there is the possibility of the formation of PCBs
(polychlorobiphenyls) as a result of the chlorination system.
Note: On December 21, 2000, Omya requested permission from the Department of Agriculture to add VeriChem N-909 Sodium Hypochlorite Solution to the list of pesticides used by Omya.