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Populations Most at Risk From Drinking Water Contaminants

To better understand how the health risks of water contaminants are determined,
I would encourage you to read this discussion.

Risks to Pregnancy:

Disinfection Byproducts
A 1998 Federal Register report, National Primary Drinking Water Regulations.
Disinfectants and Disinfection Byproducts Notice of Data Availability
, listed several studies suggested pregnant women who drank water containing the disinfection byproducts, Trihalomethanes (THM) could increase the risk of neural tube defects in the developing fetus or early term miscarriage.  Another study providing similar information can be found at Water chlorination and birth defects.  
    Neural tube defects - "The authors reported elevated odds ratios (ORs), generally between 1.5 and
        2.1, for the association of neural tube defects with trihalomethanes (THMs). However, the only
        statistically significant results were seen when the analysis was isolated to those subjects with the
        highest THM exposures (greater than 40 parts per billion {or ppb}) and limited to those subjects with
        neural tube defects in which there were no other malformations (odds ratio = 2.1, meaning that the
        risk was about double what it would have been without exposure to THMs
)."  Several recent
        papers have supported the 1998 findings:  Dodds L, King WD., Relation between trihalomethane
        compounds and birth defect, in Occup Environ Med 2001 Jul;58(7):443-6; Nieuwenhuijsen MJ. et. al.,
        Chlorination disinfection byproducts in water and their association with adverse reproductive
        outcomes: a review, in Occup Environ Med 2000 Feb;57(2):73-85;  Klotz JB, Pyrch LA., Neural tube
        defects and drinking water disinfection by-products, in Epidemiology 1999 Jul;10(4):383-90

    Miscarriages - "Women with high THM exposure in home tap water (drinking five or more glasses
        per day of cold home tap water containing at least 75 micro gram (ug) per liter of THM) had an early
        term miscarriage rate of 15.7%, compared with a rate of 9.5% among women with low THM exposure
        (drinking less than 5 glasses per day of cold home tap water or drinking any amount of tap water
        containing less than 75 ug per liter of THM - {or 75 parts ppb})."  
    It is worth mentioning that the current EPA Maximum Contaminant Level (MCL) for total
        THMs is 80ug/l (or ppb).  
A link to Some medical abstracts concerning pregnancy and disinfection byproducts
    Do not drink water that has not been disinfected or cut back your water intake in an effort to
        reduce THM or other contaminant exposure.
  Based on the current state of knowledge, any
        potential risks of adverse pregnancy outcomes associated with drinking water containing THMs are
        far lower than the risks of serious illness and death that could result from consuming drinking water
        that has not been properly disinfected.  If you want to reduce exposure to THMs consider drinking
        bottled water from a NSF certified company or purchasing a treatment system (discussed elsewhere)
        that is certified by NSF to remove THMs.

There are ongoing studies that implicate a variety of other drinking water contaminants as possibly causing problems with pregnancy or the developing fetus:

Arsenic - May cause low birth weights, spontaneous abortions, and other problems.  Another discussion
    on arsenic and pregnancy can be found by clicking here

Nitrates  - Exposure during pregnancy is possibly linked to neural tube defects, although the study did
    not rule out other causes.

Other organic compounds like Dioxin have also been implicated as having harmful effects on the
    developing fetus. another article, Dioxin fact sheet

Lead - Discussed in detail here.


Risks to Children:
   National Resources Defense Council - Our Children At Risk
    EPA - Children’s Environmental Health, Children and Drinking Water Standards
                Contaminants to Which Children May Be Particularly Sensitive 

Several contaminants are of particular concern to children:
Lead - Discussed in detail here.

Nitrates - A common pollutant in water in the Midwest or other agricultural regions.  High levels of nitrites
    or nitrates in the water supply can interfere with infants' ability to absorb oxygen and can lead to
    "blue-baby" syndrome (methemoglobinemia), which can result in death. EPA has set drinking water
    standards for nitrates and nitrites.

Pesticides - Malignancies {in children} linked to pesticides in case reports or case-control studies
    include leukemia, neuroblastoma, Wilms' tumor, soft-tissue sarcoma, Ewing's sarcoma, non-Hodgkin's
    lymphoma, and cancers of the brain, colorectum, and testes. Although these studies have been limited
    by nonspecific pesticide exposure information, small numbers of exposed subjects, and the potential for
    case-response bias, it is noteworthy that many of the reported increased risks are of greater magnitude
    than those observed in studies of pesticide-exposed adults, suggesting that children may be particularly
    sensitive to the carcinogenic effects of pesticides. 
    Zahm SH, Ward MH., Pesticides and childhood cancer, in Environ Health, in Perspect 1998 Jun;106
     Suppl 3:893-908.  
    A related article,  Cancer Risk and Parental Pesticide Application in Children of Agricultural...

Biological Contaminants - E. coli, giardia and cryptosporidia cysts can all cause gastro-intestinal
    problems where dehydration from diarrhea and vomiting may be more severe and rapid than in adults. 
    These contaminants can cause death.  In 1998, EPA established the Interim Enhanced Surface Water
    Treatment Rule, which strengthens control over microbial contaminants, including the pathogen,
    Cryptosporidium. By 2002, public water systems using surface water (or ground water under the direct
    influence of surface water) and serving more than 10,000 peopl must comply with the rule. States must
    adopt the new standards by 2001.  In some people, particularly children under 5 years of age and the
    elderly, E. coli 0157:H7 infection can also cause a complication called hemolytic uremic syndrome, in
    which the red blood cells are destroyed and the kidneys fail. About 2% of infections lead to this

Disinfection Byproducts (DBPs) - According to the EPA, the risk varies depending on the DBP.
    Some epidemiological studies may indicate a link between certain DBPs and a slight increased risk of
    reproductive and developmental effects.  
    It would make sense that if drinking water contaminated with moderate levels of DBPs over a lifetime
        increases the risk of some cancers, it would be an excellent idea to remove as many of these
        compounds from the drinking water as soon in life as possible and continue the removal through

For additional information on the special sensitivity of children to drinking water contaminants, visit the
    EPA's excellent site: Children and Drinking Water Standards


Risks to the Elderly and/or Immunocompromised:
Although both populations are affected by all of the contaminants listed above, they are at special risk of
    serious injury or death from biological, pathogenic contaminants.  If there is any chance that their drinking
    water has been contaminated with harmful bacteria, or cysts, their drinking water should be disinfected
    immediately (boiling would be a good option), or they should drink a good quality of bottled water until
    the water is safe.  Since it can take as long as 24 hours to be notified of a contaminant risk, a better plan
    than continually wondering if the water were safe would be to invest in a high quality filtration system that
    is NSF certified to remove cysts and tested by independent laboratories to remove E. coli
(as described
    below).  The PDF file, Protecting Vulnerable People from Drinking Water Diseases and Illnesses, from
    the Campaign for Safe and Affordable Drinking Water (CSADW), containg some good information
    about these risks.
In some people, particularly children under 5 years of age and the elderly, E. coli 0157:H7 infection can
    also cause a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed
    and the kidneys fail.


Water Treatment Strategies for High Risk Groups
If there are members of these high-risk groups living in your home, it would be an excellent plan to
    consider a permanent water treatment strategy , since:
There is always a "lag time" between the discovery of pathogens in a water supply by water officials and
    notification of the public.
There are disinfection byproducts at some level in nearly all water that is chlorinated.  The highest
    levels are usually found in chlorinated water (municipal or private) from a surface source or water from
    an unconfined aquifer.  Water from confined aquifers typically does not have to be chlorinated as heavily
    (if at all) as water from the other sources.  This water also usually contains a lower level of the organic
    material (leaf fragments, etc.) that interacts with chlorine to form the disinfection byproducts than does
    surface water or water from an unconfined aquifer.
A high percentage of homes have the potential for lead to leach into the drinking water from the
    plumbing pipes and fixtures - this problem is discussed in detail on the previous page.
In agricultural regions, there is a good reason to expect nitrate, pesticide, and possibly bacterial
contamination, particularly in private wells using water from unconfined aquifers (or in surface water). 
    Surface water is also likely to contain cryptosporidia or giardia cysts.  Wells in these regions should
    be tested, and water quality reports should be studied carefully to see if these contaminants exist in the
    drinking water.

The simplest and most economical long- term solution to reduce the majority of the above
     contaminants (except nitrates) and chronic bacterial or viral contamination to safe levels is
     a NSF certified, high-quality, Solid Block, Activated Carbon (SBAC) filtration system with a
     sub-micron pore size
  - These systems will significantly reduce the chlorine, any DBPscysts, asbestos, and a wide range
     of pesticides and other organic contaminants from your drinking and cooking water.  Most SBAC
     filtration systems also remove lead effectively, and some are designed to remove mercury, but check
     with the manufacturer to make certain.
  - Although these filters are not recommended for continual use with bacterially contaminated water, the
     pore size is small enough to reduce the levels of many types of bacteria that might accidentally
     contaminate a normally safe water supply.  
  - NSF does not certify filtration systems for bacterial removal, so make certain that the manufacturer of
     any SBAC system you are considering provides independent lab tests that demonstrate effective
     reduction of E. Coli.
If nitrates or arsenic are known (or suspected) to be in the water, in addition to the other contaminants
     listed above, a high-quality, Reverse Osmosis (RO) system would be the most economical long-term
     solution.  Any system you purchase should have a good activated carbon solid block post-filtration
     system to remove any contaminants not removed by the RO membranes. 
Distillation is also an excellent method treating water that has contaminants not removed by activated
     carbon, but it is more expensive than reverse osmosis.