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TITLE: The relationship between E. coli indicator
bacteria in well-water and gastrointestinal illnesses in rural families.
AUTHORS: Raina PS; Pollari FL; Teare GF; Goss MJ; Barry DA; Wilson JB
SOURCE: Can J Public Health 1999 May-Jun;90(3):172-5
ABSTRACT: OBJECTIVES: To determine the relationship between consumption of
E. coli contaminated well-water and gastrointestinal illness in rural families.
METHODS: One hundred and eighty-one families with well-water as a drinking
source participated in a one-year follow-up study. Water was tested for E.
coli bacteria and health outcomes were monitored for house-hold members.
RESULTS: E. coli in well-water was significantly associated with gastrointestinal
illness in family members, however the relationship was modified by the distance
from the septic tank to the well. E. coli had an odds ratio of 2.16 [95%
CI 1.04, 4.42] if the septic tank was greater than 20 metres from the well
and 0.46 [95% CI 0.07, 2.95] if the septic tank was within 20 metres.
CONCLUSIONS: Consumption of contaminated well-water is associated with
gastrointestinal illness. E. coli can be a useful marker for detecting wells
that pose a potential public health problem in rural areas.
TITLE: Epidemic and endemic seroprevalence of
antibodies to Cryptosporidium and Giardia in residents of three communities
with different drinking water supplies.
AUTHORS: Isaac-Renton J; Blatherwick J; Bowie WR; Fyfe M; Khan M; Li A; King
A; McLean M; Medd L; Moorehead W; Ong CS; Robertson W
SOURCE: Am J Trop Med Hyg 1999 Apr;60(4):578-83
ABSTRACT: This study was carried out to compare cryptosporidiosis and giardiasis
seroprevalence rates in residents of three communities. Community (Com 1)
uses drinking water from deep wells, community 2 (Com 2) uses surface water
from a protected watershed, and community 3 (Com 3) uses surface water frequently
containing Cryptosporidium oocysts and Giardia cysts. Unfiltered drinking
water from each community was collected at the tap and tested for Cryptosporidium
oocysts and Giardia cysts during the 12 months in which sera were collected
for testing. No oocysts or cysts were detected in the water from the Com
1 deep wells; oocysts and cysts were detected intermittently in the drinking
water from the other two communities. A waterborne outbreak of cryptosporidiosis
occurred in a municipality adjacent to Com 3 six months into this 12-month
study. Sera from residents of each of the communities were collected
proportionately by month and by population size. Coded sera were tested for
IgG to Cryptosporidium using a previously developed Western blotting method.
The presence or absence of bands at 15-17 kD and/or 27 kD was recorded for
the 1,944 sera tested. Definite bands at 15-17 kD and/or 27 kD were detected
in 981 (50.5%) of the sera. A total of 33.2% of sera from Com 1 (community
using deep wells) were positive using the same criteria compared with 53.5%
(Com 2) and 52.5% (Com 3) of sera from the two communities using surface
drinking water. Both bands (15- 17 kD plus 27 kD) were detected in 582 sera
(29.9%) from the three communities: 14.1% of sera from Com 1 compared with
32.7% from Com 2 and 31.5% from Com 3. These findings are consistent with
a lower risk of exposure to Cryptosporidium from drinking water obtained
from deep well sources. However, analysis of results by calendar quarter
showed a significant (P < 0.001) increase in the number of Com 3 positive
sera (compared with Com 1) following the waterborne outbreak. Without this
outbreak-related observation, a significant overall difference in seropositivity
would not have been seen. We also observed that in sera from the community
affected by the outbreak, the presence on immunoblots of both Cryptosporidium
bands appeared to be the best indicator of recent infection. Seroprevalence
rates using an ELISA to detect IgG to Giardia were estimated using the same
sera. Overall 30.3% (590 of 1,944) of sera were positive by the ELISA. A
total of 19.1% of sera from Com 1, 34.7% from Com 2 and 16.0% from Com 3
were seropositive. Rates for both Com 3 and Com 1 did not change significantly
over time. In Com 2, rates decreased significantly (P < 0.001) during
the last half of the study period (third and fourth calendar quarters). The
reasons for the decrease in seroprevalence in Com 2 sera are presently not
known. These studies show intriguing associations between seroprevalence,
outbreak-related laboratory serologic data, and patterns of parasite
contamination of drinking water. Further studies are required to validate
the serologic approach to risk assessment of waterborne parasitic infections
at a community level.
TITLE: Microbiological quality of drinking water
from office water dispensers.
AUTHORS: Hunter PR; Barrell RA
SOURCE: Commun Dis Public Health 1999 Jan;2(1):67-8
ABSTRACT: A survey of the microbiological quality of water sampled from office
dispensers in Merseyside found half of the samples to be either unsatisfactory
(23/56) or unacceptable (5/56) in terms of guidelines from the Automatic
Vending Association of Britain. Factors that appeared to be linked to
unsatisfactory microbiological quality were time between filling and sampling
and filling on site.
TITLE: Solar disinfection of drinking water
contained in transparent plastic bottles: characterizing the bacterial
inactivation process.
AUTHORS: McGuigan KG; Joyce TM; Conroy RM; Gillespie JB; Elmore-Meegan M
SOURCE: J Appl Microbiol 1998 Jun;84(6):1138-48
ABSTRACT: A series of experiments is reported to identify and characterize
the inactivation process in operation when drinking water, heavily contaminated
with a Kenyan isolate of Escherichia coli, is stored in transparent plastic
bottles that are then exposed to sunlight. The roles of optical and thermal
inactivation mechanisms are studied in detail by simulating conditions of
optical irradiance, water turbidity and temperature, which were recorded
during a series of solar disinfection measurements carried out in the Kenyan
Rift Valley. Optical inactivation effects are observed even in highly turbid
water (200 ntu) and at low irradiances of only 10 mW cm-2. Thermal inactivation
is found to be important only at water temperatures above 45 degrees C, at
which point strong synergy between optical and thermal inactivation processes
is observed. The results confirm that, where strong sunshine is available,
solar disinfection of drinking water is an effective, low cost method for
improving water quality and may be of particular use to refugee camps in
disaster areas. Strategies for improving bacterial inactivation are discussed.
TITLE: Decontamination of drinking water by
direct heating in solar panels.
AUTHORS: Fjendbo Jorgensen AJ; Nohr K; Sorensen H; Boisen F
SOURCE: J Appl Microbiol 1998 Sep;85(3):441-7
ABSTRACT: A device was developed for direct heating of water by solar radiation
in a flow-through system of copper pipes. An adjustable thermostat valve
prevents water below the chosen temperature from being withdrawn. The results
show that it is possible to eliminate coliform and thermotolerant coliform
bacteria from naturally contaminated river water by heating to temperatures
of 65 degrees C or above. Artificial additions of Salmonella typhimurium,
Streptococcus faecalis and Escherichia coli to contaminated river water were
also inactivated after heating to 65 degrees C and above. The total viable
count could be reduced by a factor of 1000. The heat-resistant bacteria isolated
from the Mlalakuva River (Tanzania) were spore-forming bacteria which exhibited
greater heat resistance than commonly used test bacteria originating from
countries with colder climates. To provide a good safety margin it is recommended
that an outlet water temperature of 75 degrees C be used. At that temperature
the daily production was about 501 of decontaminated water per m2 of solar
panel, an amount that could be doubled by using a heat exchanger to recycle
the heat.
TITLE: Linking research and policy to ensure
children's environmental health.
AUTHORS: Goldman LR
SOURCE: Environ Health Perspect 1998 Jun;106 Suppl 3:857-62
ABSTRACT: The U.S. Environmental Protection Agency (U.S. EPA) has made protecting
children's environmental health its highest priority. Data on how and when
children may be at risk are vital for accomplishing this goal. Recent examples
of the link between research and policy include U.S. EPA actions to carry
out the recommendations of the National Academy of Sciences on pesticides
in children's food, reduce and prevent childhood lead poisoning, and revise
national ambient air quality standards for ozone and particulate matter.
Today, the Food Quality Protection Act (FQPA), which makes protecting children
from pesticide residues in food a national priority, is contributing to the
growing need for data for decision making. Further impetus comes from provisions
in the FQPA and 1996 Safe Drinking Water Act Amendments for establishing
a screening and testing program for potential risks from endocrine disruptors.
Another factor is the analysis that will be required under President William
J. Clinton's executive order directing all federal agencies, for the first
time, to reduce environmental health and safety risks to children. Success
of the U.S. international commitment to protect children is directly tied
to the strength and availability of environmental data. To meet such challenges,
the U.S. EPA is revising key science policies, expanding research opportunities,
and adding to the public's right-to-know tools. In this dynamic climate,
there are growing opportunities for the research community to play a greater
role in helping ensure the well-being of children living today and in generations
to come.
TITLE: Need to revise the national drinking
water regulation for copper [see comments]
AUTHORS: Sidhu KS; Nash DF; McBride DE
SOURCE: Regul Toxicol Pharmacol 1995 Aug;22(1):95-100
ABSTRACT: Copper is an essential micronutrient and a potential toxic metal.
The USEPA current maximum contaminant level goal (MCLG, a nonenforceable
aspirational health goal) and the required treatment technique action level,
both set at 1.3 mg/liter of copper are not adequately protective for infants
and children under 10 years of age. Infants and children up to 10 years of
age have increased susceptibility to copper toxicity. The two main reasons
for the high sensitivity in this population subgroup are the presence of
a normally high concentration of copper in the liver during early life and
the lack of a fully developed homeostatic mechanism of copper in children
under 10 years of age. This sensitive group of infants and children represents
approximately 17% of the total U.S. population. The adverse health effects
caused by drinking water contaminated with copper are abdominal pain, nausea,
vomiting, diarrhea, headache, and dizziness. The proposed drinking water
guideline of 0.3 mg/liter for copper was derived by the application of the
risk assessment procedures approved by the USEPA. Drinking water containing
0.3 mg/liter of copper will provide approximately 26% of the nutritional
requirement of copper. This proposed drinking water guideline (0.3 mg/liter)
for copper will adequately protect health of infants, children, and adults.
TITLE: Silica and aluminum in drinking water
and cognitive impairment in the elderly.
AUTHORS: Jacqmin-Gadda H; Commenges D; Letenneur L; Dartigues JF
SOURCE: Epidemiology 1996 May;7(3):281-5
ABSTRACT: We studied the relation between silica and aluminum levels in drinking
water and the risk of cognitive impairment using data from a population-
based survey of 3,777 French subjects age 65 years and older. We also studied
the effect of pH and the concentrations of calcium, magnesium, fluorine,
zinc, copper, and iron. We used a mixed effects logistic regression adjusting
for age, sex, educational level, and occupation of the subjects. We confirmed
the inverse relation previously found between calcium level and cognitive
impairment. We found no important association between cognitive impairment
and fluorine, magnesium, iron, copper, or zinc. The association between cognitive
impairment and aluminum depended on the pH and the concentration of silica:
high levels of aluminum appeared to have a deleterious effect when the silica
concentration was low, but there was a protective effect when the pH and
the silica level were high. The threshold for an aluminum effect, however,
was very low (3.5 micrograms per liter) and did not support the hypothesis
of a deleterious effect for only high levels of aluminum. |
