Threats to Human Health: Use of Chlorine, an Obsolete Treatment Technology - Global Drinking Water Management and Conservation - page 200

four national Laboratories or Centers of the US Environmental Protection Agency ' s

(EPA ce of Research and Development. The purpose of the project is to

develop (a) a new procedure for producing chlorinated drinking water concentrate
for animal toxicology experiments, (b) comprehensive identi

' is Of

cation of at least 100

DBPs, and (c) quanti cation of 75 of the priority and regulated DBPs (Pressman

et al. 2010 ).
The results from studies on risks to human health by the use of chlorine reviewed
above seem to suggest that the Health Canada guideline for total THMs of 100

g/L

μ

(Health Canada 2006 ) and of 80 g/L (Health Canada 2008 ) for HAAs is out of

date. Even the reduction of MAC for THMs to 80

μ

g/L in Ontario may be unsafe.
For some Ontario municipalities, the total THMs far exceed the regulatory limit,
with the average of the 90th percentile being 93.8. The 95th and 99th percentile
values for Ontario are 106.02 and 152.88, respectively.
In 2009, Health Canada issued a national consultation document on chlorine in
drinking water (Health Canada 2009 ). Its primary concern was with disinfection,
and while Health Canada brought in a limit for BDCM of a maximum of 16

μ

μ g/L

(Health Canada 2006 ), the maximum limit of THMs remained unchanged (at

“

100 Disinfection is essential to safe-

guard drinking water; the health risks from disinfection byproducts are much less
than the risks from consuming water that has not been disinfected

μ g/L), But Health Canada 2009 states that:

”

(Health Canada
2009 , p.1) This is largely a “ benet-cost ” conclusion rather than a serious assess-
ment of risks. In fact the document states that the Guideline

…“ does not review the

bene ts or the processes of chlorination, nor does it assess the health risks related to

exposure to byproducts formed as a result of the chlorination process. ” How can a

“ Health Canada ” guideline fail to assess the health risks … of exposure to disin-

fection byproducts? The document goes on to state: ed

chlorine as unlikely to be carcinogenic to humans. Studies in laboratory animals
and humans indicate that chlorine exhibits low toxicity, regardless of the route of
exposure (i.e. ingestion, inhalation, dermal). Studies in animals have not been able
to identify a concentration of chlorine associated with adverse health effects, in part
because of aversion to its taste and odor. No adverse health effects have been
observed in humans from consuming water with high chlorine levels (up to 50 mg/
L) over a short period of time.

“ Health Canada has classi

g/L in
the distribution system to prevent regrowth of bacteria. It concludes boldly that:
“

” It supports a free chlorine residual of 200

μ

Because chlorine is not stable under environmental conditions, exposure is not
expected to be signi

cant, and there are few data available ” (Health Canada 2009 ,

p.16). It contains the following statement: “ [T]here have not been any epidemio-

logical studies that have speci cally examined free chlorine concentrations in water

and long-term health effects in the human population. This assertion is completely

out of date, as shown above; the study by Hwang et al. ( 2008 ) raises important
questions and suggests that any level greater that 4

”

μ g/L carries serious risk for the

nursing mothers.
In contrast, some developed countries in the EU have applied alternative
approaches for drinking water disinfection to minimize the use of chlorine. For
example, France and Italy use Ozone as a primary disinfectant. In Germany, the