Article
#1:
Evaluating Iodine-based drinking water
systems.
As the use of iodinated resins for the disinfection of drinking
water grows more popular, there is also more investigation into the
iodine levels needed for proper disinfection, as well as the maximum
iodine tolerable for human consumption.
Iodinated resins are exceptionally effective at disinfecting water
and are generally assumed to be fast-acting and long-lasting.
Nonetheless, more work must be done to verify current assumptions and
to encourage similar scrutiny of other forms of water treatment.
Despite the obvious benefits of various water treatment methods-
chlorination, ultraviolet irradiation, reverse osmosis, etc.- valid
safety and other concerns surround each. The carcinogenic by-products
they may produce, the excessive system failure rates that may be
attributed to them, the ineffectiveness of various techniques against
certain problems and misrepresentation of product performance are all
issues the water treatment industry continues to deal with.
While some manufacturers acknowledge these issues and design devices
to address them, others unfortunately don't. By understanding
iodine-based treatment systems and how they should (and can) operate,
you can better select those iodinated resin systems that do address
performance and safety concerns.
Iodine Types
In water, iodine is most often found either as "free iodine" (I2) or
one form or another of "iodide" (I-minus). The panoply of
iodine-related chemicals, including free iodine, iodides, iodites and
iodates, is often referred to as "total iodine." When discussing the
disinfection of drinking water, free iodine is or other accepted
label pathogens, and incorporates steps to protect against the risk
of post-treatment recontamination.
Iodine Safety
The critical safety issue that iodinated resin system users must
consider is what level of total iodine is permitted to remain in
drinking water, and what health effects can be anticipated if a
system exceeds those levels.
A recent article in Water Technology reported that chronic exposure
to up to 1.19 ppm total iodine "has been adopted as the adjusted
acceptable daily intake." This level appears generally safe, but
available literature doesn't support a claim that manufacturers
should strive for systems that consistently allow 1.19 ppm of total
iodine in drinking water.
First, parts per million is a relevant measure only if you make
certain assumptions about the quantities of water consumed. Someone
drinking 1 liter of water per day containing 1.19 ppm iodine
concentration consumes only 1.19 milligrams total iodine; another
person drinking 4 liters per day of the same water would ingest
nearly 5 mg per day.
Moreover, according to Jean A.T. Pennington, Ph.D., RD, of the Food
and Drug Administration's Division of Nutrition, Center for Food
Safety and Applied Nutrition, some individuals tolerate large intakes
without side effects, whereas others may respond adversely to levels
close to recommended intakes.
Pennington concludes that total iodine amounts less than or equal to
1 milligram per day (mg/day) are probably safe for most people,
according to an article published in the Journal of the American
Dietetic Association in November 1990.
The Food and Nutrition Board, beginning with its 10th revised edition
of the Recommended Dietary Allowance (RDA) publication released in
1989, indicates that at 2 mg/day for adults and 1 mg/day for
children, there are no adverse effects.
Various other studies report conclusions within this general range.
Therefore, if the commonly used figure of 2 liters per day is a fair
estimate of the average adult's water consumption (with young
children presumably consuming lesser amounts), prudent manufacturers,
cognizant of these recommendations, should strive for no more than
0.5 ppm to 1 ppm of total iodine content so that total adult iodine
consumption from water doesn't exceed 1 to 2 mgs/day.
Even somewhat higher total iodine intake has shown few adverse
effects. As an example of routinely high iodine intake, those on high
seaweed diets (such as many Japanese consumers) can consume more than
40 mg/day from this source.
In one published study, seemingly healthy American soldiers consumed
32 mg/day of iodine from tetraglycine hydroperiodide tablets
dissolved in water for 7 consecutive days. Although sensitive thyroid
tests were marginally outside of normal ranges, the soldiers
exhibited no clinically evident symptoms, according to an article
published in Military Medicine in December 1993. In this context, you
wouldn't expect iodine-treated drinking water to cause any health
problems because most reputable, commercially available iodinated
resins are designed to elute 2 to 6 ppm of total iodine under
ordinary operating conditions.
Residual Iodine
However, total iodine levels may "spike" under some conditions to 10
ppm or even considerably higher. While most systems attempt to
re-move some or all of this total iodine, success varies from system
to system. Selecting a system with adequate removal is, therefore,
every bit as important as selecting a system with adequate
disinfection capabilities. Based on the available literature and the
opinions of medical advisors, and despite several anecdotal reports
(which may or may not be sta-tistically significant), small levels of
iodine consumption by healthy individuals appear to be neither
life-threatening nor seriously debilitating.
To be sure, iodine (like every other disinfectant) can cause harm, or
even kill, at extreme levels. For example, there have been nine
recorded cases of suicide by iodine ingestion where the iodine level
was known. However, the amounts consumed were enormous, ranging from
1,184 to 9,472 mg. Lesser amounts of iodine from a variety of sources
have caused thyroid dysfunction in patients already suffering from
thyroid disease, and pregnant women and infants may be particularly
sensitive to iodine intake.
Indeed, Pennington's work re-viewed 1,256 cases and found that 49
people (3.9 percent) exposed to iodine intakes of no more than 10
mg/day suffered adverse effects. All 49 also had known thyroid
problems. However, water consumption is too ubiquitous and
unpredictable.
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Article
#2:
Is There a Market for RO Post
Treatment?
There's little debate about the quality of treatment reverse
osmosis (RO) affords. The difference in rejection rates of leading
membranes probably matters more for marketing than for performance.
For most uses, the difference between 92 and 95 percent rejection,
for example, is marginal at best.
What may be more important than the performance of the membrane
itself is what happens to water afterward, when it must often be
stored before use.
Posttreatment Protection
Even pristine RO product water may need to be protected from
recontamination. Because almost all RO systems remove chlorine before
the product water is stored, the water is often devoid of anything to
protect it from bacteria, viruses and algae. There's also a growing
concern that even water that's been properly treated with RO using a
top-caliber membrane can harbor microbiological contaminants picked
up from storage tanks and plumbing.
Until recently, this debate has been muted in the U.S., presumably
because of the prevailing assumption that the feedwater to most RO
systems is already microbiologically safe. This premise has been
jeopardized, however, following outbreaks of various waterborne
diseases, including the Cryptosporidium outbreak that struck
Milwaukee, WI, in 1993.
Coupling this with the realization that posttreatment contamination
can be introduced through human contact, and with the growth in
international markets for water treatment (where often no presumption
of water safety can be made), some RO system makers are paying closer
attention to the practical and marketing appeal of preserving
RO-treated water downstream of the membrane.
Commercial First
Because of the extra expense that such a regimen entails, industrial,
commercial and other large-scale RO systems were among the first to
react. There, the added cost can be amortized over larger volumes of
water and users.
However, the POU segment of the market has been slow to react. Adding
even the cost of a small UV module to systems that retail for about
$500 represents a significant percentage cost increase.
Unfortunately, POU systems are more likely to benefit from
posttreatment disinfection because their volume limitations usually
necessitate the use of storage tanks.
What's Being Done
Several products have emerged to address the posttreatment issue.
Perhaps the least attractive approach has been to install
bateriostatic materials at key points within a system. The theory
behind this approach is that if bacteria can't reach stored water,
they can't infect it. However, bacteriostatic media inhibit the
growth of bacteria within them; they don't ensure bacteria are
removed from water passing through them.
"Bacteriostatic" is also a somewhat vague term because it says little
about a medium's effect on non-bacterial pathogens like viruses. The
most common of these media, silver-impregnated carbon, will kill
viruses as well as bacteria, but silver is so slow in acting it's
unlikely to kill all viruses during a pass through a carbon
filter.
A more successful approach has been to emulate the success of larger
systems using UV. This approach has only recently become practical at
the POU as a result of advances in UV technology that enabled
manufacturers to construct small UV modules.
RO treated water is fed through a chamber containing a UV lamp, which
kills any microbes that may be present. This may be the ideal
circumstance for UV treatment because these systems have already
removed sediment, total dissolved solids and, at a minimum, the
larger clumps of bacteria. Thus, there's little risk of
microorganisms evading the UV light by "hiding" behind larger
materials. The only obvious problems with this approach are the need
for a reliable supply of electricity (which can't be taken for
granted in some underdeveloped nations) and the added cost.
Another successful approach is to leave one of the more stable
halogens (chlorine or iodine) in the RO-treated water to guard
against downstream contamination. This method can be virtually
foolproof and exceptionally cost-effective.
Where the RO feedwater is adequately disinfected with chlorine, the
use of a chlorine-tolerant membrane can enable you to bypass normal
chlorine removal and keep residual chlorine in the storage tank at no
added cost. Where source water isn't adequately chlorinated, an
iodinating or chlorinating system can be added downstream for about
the same cost as a small UV unit.
Of course, taste, odor and safety considerations require that you
remove the halogen disinfectant after storage and before water is
consumed. This requires a post-filter (granular activated carbon for
chlorine, a scavenger for iodine) that can be used during the
dispensing process itself.
The debate continues regarding the actual risk of recontamination of
RO product water. What's clear already, however, is that there are at
least some microbiological risks, and that the market is growing more
concerned about them.
The demand for secondary disinfection following RO treatment, whether
it's the result of a universal need within the industry or simply an
escalated awareness of the risks of pathogens, is growing. The market
needs to adapt to satisfy that demand.
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Article
#3:
Facing World Water Disinfection
Challenges.
Where microbiological water quality is questionable and modern
conveniences rare, iodine-based water disinfection systems may be the
wisest way to make water potable.
Yet while iodine offers an attractive alternative, its use alone
isn't enough. As with any water disinfection method, iodine-based
systems must offer an intelligent treatment regimen, not merely a
disinfecting agent.
Disinfecting Can Be a Problem
Many purification technologies common in the U.S. don't adequately
address conditions most common in the developing world. Each has its
merits, but each also suffers from drawbacks that make iodine a good
choice in areas without reliable, microbiologically safe drinking
water.
Unfortunately, the need for effective and economical disinfection
devices is the most acute in these areas.
According to a UNICEF study, 1.2 billion people in the developing
world are denied access to safe drinking water. In some countries,
nearly 80 percent of the population lacks access to safe water. That
portion can exceed 98 percent in some rural areas.
The problems with drinking water in these nations are numerous,
dynamic and often unpredictable. In Mexico, for example, there's an
enormous variance between microbiological water quality in major
cities (with large-scale municipal treatment) and the microbiological
water quality in rural areas.
There's also extraordinary inconsistency within a single city. In
Mexico City, for example, chlorine levels vary dramatically from zone
to zone and day to day. Some days, an incredible 200 parts per
million (ppm) chlorine can reportedly be present at a tap. Water at
that same tap may be nearly devoid of chlorine just one week
later.
While water pressure and turbidity can also vary from zone to zone
and day to day, pressure is almost universally low and turbidity is
almost universally high when measured against U.S. standards. In many
of the most needy regions, funds for capital-intensive systems are
scarce, and energy for pump-based systems is expensive and
unreliable.
Moreover, in much of the developing world even "adequate"
disinfection isn't enough. In many areas a lack of access to safe
drinking water is coupled with a lack of access to adequate
sanitation. This compounds the risk of re-infection of treated water
and creates a need for systems that mitigate such risks.
Addressing these challenges is difficult for many types of systems.
Sub-micron sediment filtration (primarily ceramics), while
theoretically effective against microorganisms, can be impractical
where heavy turbidity is present. Frequent filter replacement is
costly, while frequent cleaning of reusable filters is inconvenient
and increases the risk of contaminating the filter itself.
Likewise, reverse osmosis (RO) produces excellent quality water but
requires booster pumps at lower water pressures, has volume
limitations and creates a product with a limited "shelf life" because
it contains no residual disinfectant.
Ozone also produces an end-product with limited shelf life for the
same reason; chlorine, despite its wide-spread use on the municipal
level, has come under scrutiny because it may create carcinogenic
by-products.
Iodine as a Solution
In areas of economic underdevelopment iodine is an effective and
cost-effective alternative. Moreover, if properly designed and
monitored these systems can help counter the effects of iodine
deficiency. The seriousness and extent of this worldwide problem has
been grossly underestimated.
UNICEF estimates that nearly 1.6 billion people in more than 110
nations risk iodine deficiency and that 300 million suffer from
lowered mental ability as a result. Nearly 566 million - about 10
percent of the world's population - suffer from goiter; at least
30,000 babies are stillborn every year; and more than 120,000 are
born mentally retarded, physically stunted, deaf, or paralyzed
because of a lack of dietary iodine.
By permitting regulated quantities of iodide to pass into drinking
water, systems using iodine can help address these health
problems.
Properly-designed iodine-based systems also offer an alternative for
cleaning fruits, vegetables and other perishables at risk of
contamination. In many areas, these products are commonly cleaned
with iodine or silver nitrate purchased in costly, small
containers.
To make matters worse, the consumer is often faced with a choice of
rinsing the disinfectant off with infected water or suffering with an
unpleasant taste and aroma. By passing water through an iodine-based
system's resin and removing the iodine afterward, the water can be
used to safely rinse away any residual iodine taste.
Choosing a System
Iodine-based systems have their drawbacks, too. Some people,
including pregnant women, people with thyroid problems, iodine- or
iodide-sensitive people and others, risk health consequences if they
consume iodine or iodide. You must therefore be certain the system
removes much or all of the iodine it adds and the iodide into which
it degenerates. Bear in mind that activated carbon postfiltration,
although effective at removing residual iodine, does nothing to
remove residual iodide.
Also bear in mind that not all iodine resins are alike. Some last
longer than others. Some maintain consistent iodine elution levels;
others don't. To avoid the perils of ineffectiveness from too little
iodine, the health risk from iodine levels that are too high and the
high cost of of rapidly-deteriorating resins, ensure the system you
purchase contains only resins from reputable manufacturers.
The system you select should also ensure water has adequate exposure
to iodine. Limited exposure may not kill tenacious pathogens such as
polio virus. Any iodine system should also strive to limit the risk
of post-purification recontamination and, as with any disinfection
system, should address local conditions. Iodine kills many known
pathogens by itself, but coupling it with prefiltration enables many
more to be addressed. This is especially true for water harboring
Cryptosporidium, where small-pore prefilters are required.
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Article #4:
Should There be Mandatory Third-Party Product
Certification?
Through extensive experience with various regulatory agencies,
including the U.S. Food and Drug Administration (FDA), I have come to
know that approval processes - especially those which are centralized
- are bureaucratic, slow, expensive and often politically motivated
and arbitrary. The most wealthy and influential companies often have
the greatest successes obtaining approvals, while many of the best
products will never make it to market due to lack of adequate funding
or political savvy.
Equally troubling, if the healthcare model of product testing and
certification is followed, there will be scores of unapproved
products sold regardless, with insufficient "watchdog" funds and
personnel to enforce compliance. Those acting responsibly by seeking
compliance will find themselves at a competitive disadvantage over
the "free riders."
These problems can be abated somewhat - but not completely - if
industry standards are set and, instead of centralized testing, a
wide range of third-party testing facilities were permitted to grant
approval (similar to automobile inspections in most states).
Making such a system viable, however, is not easy. How does one
protect against incompetence or "fixed" results? Must we first
certify the certifiers? If so, how much will that cost, how will the
costs be borne and what will that do to smaller or less experienced
firms?
Water Conditions Vary
Assuming that decentralized testing is desirable and feasible, I
nevertheless take issue with the whole premise of setting uniform
standards in an industry where nothing is uniform or standard. Water
conditions vary dramatically from region to region. Passing a
standardized test means nothing if the "real world" conditions in
which a system operates are different from the test control in any
material way.
Examples of source water conditions that would make such comparisons
meaningless include pH levels, water temperature, turbidity, chemical
pollution and biological contamination.
There is the argument that standardized testing will at least show
relative performance. But this is not so. If one chlorinator device
provides a 7-log kill against E. Coli while another provides a 4-log
kill, which is "better" if the former provides no prefiltration
against cysts and the latter one does? The answer of course depends
upon the source water.
If one lead-removal medium operates to NSF standards but another does
not, is the NSF-approved media "better" if appended to an inferior
carbon that allows harmful trihalomethanes to pass through?
Which reverse osmosis (RO) membrane is "better": one that removes 99
percent of all total dissolved solids (TDS) but only 50 percent of
dissolved arsenic, or one that removes 90 percent TDS and also 90
percent arsenic? Again, it depends on the source water and whether
arsenic is present. There are thousands of such hypotheticals. The
cutoff points at which products may or may not be "minimally
acceptable" are simply too nebulous, given this abundance of
variables.
Moreover, how does one factor cost into the equation? Is it better
for someone who cannot afford an optimum system to drink untreated
water, or to drink water that has been treated somewhat, however
imperfectly?
And if an inexpensive system's price doubles because of the cost of
the approval process and is no longer affordable to lower-income
consumers, who benefits?
A Company Example
Our company seeks to treat water as what it is, the ultimate
healthcare product. We test internally and attempt to double-check
claims of OEM suppliers to the extent feasible. We also convened a
medical/technical advisory board - a body of independent scientists
to provide guidance on what is and isn't safe and responsible in
areas not universally understood.
With respect to all systems other than the most basic filtration
products, we require our dealers to conduct localized, on-site
product testing to verify our claims and results under their
particular water conditions.
Also, we are very careful in the claims that we make and the warnings
we provide. For example, when asked the life span of a filter, we do
not give the standard rating, but a wide range, advising what sorts
of water conditions will affect a filter's performance and duration.
We also provide health warnings, such as the health risks attributed
to chlorine.
Address Unethical Practices
There are water treatment products currently on the market that are
simply worthless, and others that are plainly unsafe. Misleading and
unsubstantiated claims are all too commonplace, and safety warnings
are almost non existant. "Caveat emptor" is not an appropriate reply.
How then do we balance the desire for fairness, safety and
responsibility with the range of concerns stated earlier?
Unlike the proponents of mandatory testing, I offer no timely,
universal answer. And what I do propose might not be the best or only
solution. What I do know is that when stricter and more arbitrary
rules are imposed, those who do not care will continue to flout them;
those who already comply will be impacted the most.
Yet, despite my own misgivings about regulation, one thing is
certain: if this industry does not begin to police itself, government
will. And the results will be worse - less rational, more burdensome,
more expensive and less successful - than the worst solutions that
might develop from well-intentioned, industry-driven discussion.
No Mandatory Testing Until...
Thus, I oppose any mandatory testing (in favor of the elevated
disclosure obligations offered below) at least until such time
as:
> standards that are universally meaningful can be
articulated;
> appropriate exceptions and safe harbors are approved that
address the tricky issues of local conditions and price
rationing;
> an equitable and non-burdensome taxation plan can be developed
to permit adequate enforcement and, more importantly, assure equal
access; and
> plans are adopted for broad decentralization of the approval
process, to ensure inexpensive and timely approvals.
In this interim, however, the industry must not stand still. We
should adopt and enforce enhanced disclosure standards so that the
limits of each system and its safety risks are clear. Consumers
currently buy water treatment products under the false impression
&endash; some intentionally created, but mostly out of naiveté
&endash; that such products will do the impossible.
For example, the best filter system in the world will not "disinfect"
or "purify," but many comsumers do not realize this. Therefore,
appropriate information on every system sold should be required to
discuss a product's purpose, risks and shortcomings.
Enforcing proper disclosure may be as simple as requiring submission
of proposed labeling to WQA for preapproval. Only those who obtain
preapproval could have an official WQA approval logo &endash; perhaps
a "silver seal" to complement the current "gold-seal" program
&endash; appended to their product labeling and advertising. Perhaps
trade magazines could contribute by requiring evidence of such
labeling before accepting advertisements, or state "Labeling Not WQA
Approved" on ads for products which lack the required
disclosures.
Such preclearance efforts by the WQA would be far less onerous than
imagined, and would be limited exclusively to comparing the actual
labeling with that required for the submitted product.
For example, filtration systems could not imply a disinfection
capability, single-pass RO systems could not imply purity, nominal
micron filters would be forced to disclose a vulnerability to
Cryptosporidium and disinfection claims would require providing
independent clinical test results. Enforcement could be handled with
limited staffing and paid for by a modest and universally affordable
user fee of $100 to $200 per application.
The Next Critical Step
Jumping to rapid conclusions without a complete debate of the issue
serves only the interests of large testing laboratories and
influential franchises. But doing nothing is likely to lead to
equally ominous results.
Therefore, we need to begin a dialogue at the grass-roots level in
this industry, which I think the white paper has started, exposing
the errors of the past and agreeing upon meaningful standards for
disclosure and performance in the future.
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