Arsenic Poisoning Clinical Trial
Official title:
Mitigating Arsenic Toxicity in Bangladeshi People by Supplementing Their Diets With High Selenium Lentils
About 45 million people in Bangladesh are chronically exposed to unacceptable levels of
arsenic in their drinking water. Chronic arsenic poisoning leads to cancers, and vascular
diseases.
This dietary trial intends to test the potential of high-selenium lentils, consumed as
lentil soup, in reducing the arsenic body burden in an exposed Bangladeshi population, and
in improving the overall health status.
Arsenic-exposed families will be assigned to one of two groups. One group will eat lentils
(50g/person/day) that are naturally high in selenium, the other group will receive lentils
with low selenium content. This 6 months trial is randomized and double-blinded.
Chronic arsenic (As) poisoning is a worldwide public health problem. Up to 100 million
people worldwide, are chronically exposed to dangerously high concentrations of As in their
drinking water and food supply. Bangladesh is facing a major public health challenge -
contamination of groundwater by arsenic (As). Since tube well water contamination by As was
discovered in Bangladesh in the 1990s, As in drinking water has been reduced by 40%, yet
approximately 45 million Bangladeshis remain at risk from high As concentrations greater
than the WHO guideline value of 10 µg/L in the well water. The annual cost to treat As
related health problems in Bangladesh is currently estimated up to $77.5 million.
Micronutrient-deficient (e.g. Selenium) soils lead to less nutritious local foods, which
becomes a partner in crime exacerbating the toxic burden incurred by As exposure.
Selenium (Se) is a trace element that is an essential component of several metabolic
pathways controlling immune function. Se and As work antagonistically in the body by
competing in many biological functions. Arsenic added to animal diets has been known to
counteract Se toxicity/activity in animals since the 1930s. Se interacts with As to form a
complex; excessive Se excretion can occur as result of Se/As complex formation under
condition of chronic As ingestion and low dietary Se ingestion. This scenario may further
accelerate Se depletion. Again, since Se can form a complex with As, Se supplementation, in
principle, can reduce As toxicity and also decrease effects of As exposure on many other
parameters, such as oxidative stress, immunotoxicity etc.
Supplementation of Se as pills is currently used to treat arsenicosis. But pills are not
often well received by people and are expensive for low-income families. Lentils are a
common food in Bangladesh and the country already imports lentils from Canada. Saskatchewan
(SK) grown lentils are rich in Se, mostly in form of L-selenomethionine, which is highly
bioavailable. The Saskatchewan lentils have mean selenium levels between 425-672 µg/kg, with
some regions where lentil selenium levels go up to 1884 µg/kg. These high Se lentils,
incorporated into the daily meals of As-exposed Bangladeshi families, may help mitigate the
symptoms of long-term As poisoning in a cost-effective, uncomplicated, and nutritionally
beneficial way.
Red lentils for this trial were grown in Saskatchewan, Canada (Se = 854 µg/kg) and Idaho,
USA (Se = 0.043 µg/kg). Other nutrients will be measured in both crops of lentils at the
UofS before dispatching to families in Bangladesh. High-Se and low-Se lentils will be packed
in two different coloured packets and will be given to the designated families. The
investigators as well as the field staff will be blinded to the types of lentils/dahl being
given to each family. 65g lentils per person/day will be measured with a cup by the female
family head, who typically cooks the moshur dahl (lentil soup) daily for the whole family.
65g high-Se lentils provide 55 µg Se, which is the recommended daily allowance of 55
µg/person/day.
Sampling procedure and Data collection: At the start, at mid-term and the end of the trial
(Table 1), household water samples, plus hair, blood, faeces and on-spot urine samples will
be collected from each individual.
Water (20 ml): Currently used drinking water for measurement of arsenic, and other toxic and
essential elements. Water will be acidified before storage at pH <2.0 in trace element free
tubes at room temperature.
Urine (15-20 ml): Urine will be collected in trace element free tubes, aliquoted and stored
in -80°C.
Stool (5-10 g): Stool will be collected in trace element free tubes and stored in -20°C.
Blood (5 ml/visit): Blood will be collected using a sterile needle and syringe in trace
element free vacutainer tubes. Blood samples will be sent to Dhaka Lab on the same day in
cool boxes and separated into plasma and cells, aliquot of plasma will be stored at -80°C.
Buffycoat cells will be stored in RNALater in -80°C freezer. Whole blood (100 ul) will be
stored in -80°C.
Hair: Hair from the back of the head will be collected (about 0.2 g) for analysis of As, as
hair As is a suitable marker for long term exposure.
Laboratory Methods:
Metals: Se will be measured in blood by Graphite Furnace Atomic Absorption Spectrometry
(GFAAS). Arsenic in hair, stool and urine samples will be measured by Hydride Generation
Atomic Absorption Spectrometry (HGAAS) after acid digestion of samples.
Oxidative stress and antioxidant status : the investigators will measure 8-oxo-7,
8-dihydro-2'-deoxyguanosine (8-oxodG), a major product of ROS-induced oxidative stress, in
urine/plasma of children using commercial ELISA kits. Reduced glutathione (GSH) is
considered as an important scavenger of reactive oxygen species (ROS), and its ratio with
oxidized glutathione (GSSG) is used as a marker of oxidative stress. The antioxidant status
(GSH/GSSG) in whole blood will be assessed by measuring GSH and GSSG using commercial kits.
Lung inflammation: The investigators will measure fractional exhaled nitric oxide (FENO) in
participants (≥9 yrs) as a marker of allergic lung inflammation. Monitoring FENO is simple
and non-invasive with the use of a hand held small equipment. FENO will be measured online
by the single breath technique according to published guidelines (ref) and manufacturer's
instructions, with a NIOX MINO®. FENO will be recorded as mean value from two successive
reproducible readouts. FENO data will be given as p.p.b. NIOX MINO uses IR communication for
transfer of participant data to a PC using the software NIOX MINO Data Manager. FENO is
usually high in individuals with current allergic asthma or rhinitis.
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