WI Tissue hypo fate--O-Cl or toxic chloride?

[ttweed@wildrockies.org (Tony Tweedale)]

A new WI Tissue, Inc. mill plans to deink w/ hypochlorite [how on earth can
hypo be cheaper than peroxide for this 100% deinked fiber source mill, when
every deink mill I've heard of uses only peroxide because it is a good enuf
oxidant, yet is extremely cheap to install and use?!],

My question is, what does hypo (OCl-) largely end up as after being reacted
w/ the cellulose & ink?  Hypo starts as the salt sodium-hypochlorite
(NaOCl, but the bond is ionic and it dissolves in water into its
constituent ions (Na+ , OCl-).  Hypo, as w/ Cl-dioxide, bleaches w/ the
important participation of oxygen, but the details are beyond my knowledge.
As a result perhaps the amnt. of dioxins and AOX from hypo are
significantly less, as industry claims is the case w/ Cl-dioxide.  If the
oxygen atom is more unstable and thus gets closest to the organic molecule
to be torn apart (bleached), does the Cl- (chloride) ion not react as
easily to form an organochlorine?  (in the natural environment, chloride is
extremely stable, does not form covalent bonds, so it exists as a salt (ie
ionized w/ a cation such as NaCl).  Perhaps this is why less AOX is said to
be formed.

However, lets turn their argument on its head.  If hypo, OCl-, does not
react w/ the organic matter, it, (or Cl-, assuming that the oxygen is gone,
reacted w/ the organic matter) must then persist, so is it toxic when it
gets into the body?

ed. Taylor et al. _Physiology of Oxygen Radicals_ Amer. Physiological Soc.,
Bethesda MD, 1986

In reading the intro chapter of this text on oxidative damage, I came
across a neat bit of toxicol. info that has helped the MT RailLink Alberton
MT Cl2(g) exposed citizens (because Cl2 gas reacts completly w/ water/vapor
into ionic forms (Cl- and OCl-) or their salts).  See pages 3-9, titled
'peroxidase catalyzed, H2O2-dependent formation of cytotoxic oxidants'

The body creates peroxide in free radical reactions all the time, which w/
the aid of common peroxidase enzymes this section explains, can turn
chloride (Cl-) into hypochlorous acid (HOCl -- an ionic salt again, but
partly or largely OCl- at neutral body pH).  Then,:  "HOCl (or OCl-) is
~100 times more reactive than H2O2 and thus reacts rapidly with several
biological compounds ... reacts extremely rapidly [e.g. 10E6 moles/second
rate!] with the unprotonated form of primary amines [proteins] (RNH2) to
yield N-chloramine derivatives (RNHCl).  ...certain forms of lipophilic
chloramines are the [likely] final mediators of toxicity".

[Note that either unreacted ionic form of chlorine from the bleaching (Cl-
or OCl-) can lead to this oxidative damage by reactive yet lipophilic
chloroamines (chloride first has to be converted into hypo w/ the common
peroxidase enzymes and peroxide).]

Yes, chloride is already ubiquitous in the body.  I don't know the answer
to how harmful *additional* chloride or hypo are, but I do know that with
oxidative damage, it's a sliding scale (eventually it kills us all, of "old
age").  So workers at the bleach plant are likely accelerating thei rate of
oxidative damage, which includes mutations (DNA damage) that lead to some
cancers and possibly to birth defects.  And if there is ionic chlorine (ie
if they're claiming it doesn't react covalently w/ organic matter) in the
ww discharge, greater rates of oxidative damage will be occuring in many
other species.  BTW, in drinking water disinfection, not only would this
chloramine mechanism of oxidative damage occur (to an unknown (to me)
degree), but chloramines themselves are used to disinfect!  This tells you
how broad-spectrum toxic they are, that they are used to kill microbes.  I
suspect their lipophilicity is another reason they are disinfection agents,
ie they have some persitence and attraction to biologic tissue.  They are
famous in chlorinated drinking water for their potency as mutagens, so I
guess they are also formed when only chlorine or bleach is used for
disinfection.

Tony Tweedale

Causality is a concept not subject to empirical demonstration. -David Hume
(1711-'76)

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