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Chapter 1


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           Until today, contamination of heavy
metals in the environment is a major global concern due of its toxicity to the
human life and ecosystem. Human exposure to these heavy metals through
inhalation, skin contact and even ingesting contaminated food and beverages may
introduce some adverse effects to the body. These effects may either be toxic
(acute, chronic or sub-chronic), neurotoxic, or even carcinogenic, mutagenic or
teratogenic. Arsenic (As), considered to be a naturally occurring component of
the earth’s crust is a carcinogenic heavy metal of the Nitrogen group. Known to
be the King of Poisons, this environmental intoxicant is highly toxic in its
inorganic form and contributes to the contamination of air, agricultural soils,
and water supplies. Its presence in water irrigation and agricultural soils
increases Arsenic’s capability of finding their way in the human food chain.


(Oryza sativa), considered to be a
staple food of over half of the world’s population is one of the food crops
that are at high risk of Arsenic contamination. 
Being grown in water-flooded conditions where high levels of water
accumulation is needed for plant’s survival, rice roots  has the tendency to absorb toxic heavy metals
contained in soil and water much more effectively than most plants. Allowing
heavy metals to be more easily taken up by its roots and stored on the grains. In
numerous areas where rice is cultivated, the use of As-contaminated irrigation
water results to the build-up of Arsenic (As) levels in soil. Excessive
accumulation of this element, particularly inorganic As in rice poses a
potential health risks to population with high rice consumption such as the

presence, consumption, and long-term exposure to inorganic arsenic, mainly
through drinking-water and food, including rice can lead to chronic arsenic
poisoning that may be observed by to pigmentation changes, skin lesions and
hard patches on the palms and soles of the feet (hyperkeratosis). These occur
after a minimum exposure of approximately five years and may be a precursor to
skin cancer. In addition to skin cancer, long-term exposure to arsenic may also
cause cancers of the bladder and lungs (World Health Organization, 2017).

aforementioned cases influenced the researchers to study about the toxicity
level of Arsenic in rice grains and irrigation waters. Determining the levels
of this carcinogenic metal will aid the proponents of this study to produce
baseline data for future research.


Statement of the Problem

      This study aimed to determine the level of
toxicity in rice grains and irrigation waters at Maco, Compostela Valley.
Specifically, it seeks to answer the following questions:

What is the role of irrigation water on
Arsenic contamination in rice grains?

How can Arsenic be contained in irrigation

Is there a significant difference between
the levels of Arsenic on rice grains and irrigation waters?


Theoretical Framework

         Arsenic is a
metalloid, a natural element that is not actually a metal but which has some of
the properties of metal. It is a natural component of the Earth’s crust,
generally found in trace quantities in all rock, soil, water and air. However, is
significant when concentrations are higher leading in acute to chronic
diseases. Presence of Arsenic is more prominent in certain areas in the
industrial zone where factories and mining industries are present. Contaminated
water used for drinking, food preparation and irrigation of food crops poses
the greatest threat to public health from arsenic (World Health Organization,

          Ingestion of low dose via food or
water is the main pathway of this metalloid into the organism, where absorption
takes place in the stomach and intestines, followed by the released in the
bloodstream. In chronic poisoning, arsenic is then converted by the liver to a
less toxic form, from where it is eventually largely excreted in the urine.

         The incidence of arsenic contamination
of both rice grains and irrigation water has taken the dimension of an
epidemiological problem. It has been established that arsenic is extremely
toxic in the body when found in concentrations higher than 1 ppm (Agency for
Toxic Substances and Disease Registry, 2009). It enters into the human body
through ingestion, inhalation or skin absorption. After entering into the body
it is distributed in the large number of organs including the lungs, liver,
kidney and skin. The clinical manifestation of arsenic poisoning are myriad,
and the correct diagnosis depends largely on awareness of the problem.


Conceptual Framework

Variable                                                         Dependent




Figure 1: Conceptual Framework

          The figure shown above depicts the
determination of the amount of Arsenic in rice grains and irrigation waters as
the independent variable having effect to the levels of Arsenic in rice grains
and irrigation waters as the dependent variables.

Significance of the Study

        The study aimed to measure the levels
of toxicity brought by Arsenic in Maco, Compostela Valley and would dwell on
the possible arsenic contents of rice grains and irrigation waters in the said
area. In addition, the study would provide awareness on the toxicity level of
this heavy metal in our most consumed food and how threatening is its effects
in our body. Furthermore the study would provide data on the arsenic content in
rice grains that could be used in future arsenic related studies. The result of
this study would be important to the following:

To the government : The
result of this study may be used by the government in checking whether the varieties
of rice that would be examined in this study is safe for human consumption.

To the society :
The result of this study would give awareness to the society about the possible
arsenic content of rice grains and irrigation waters.

To the future researchers : This
study will lay the recommendations that may bridge the current research and
future research about the determination of heavy metal Arsenic in other food
source of humans to avoid any serious health conditions that it might bring.

Scope and Delimitations

This study will be focusing and delimiting only to selected
rice fields in Maco, Compostela Valley. Irrigation waters and rice grains
samples will then be utilized as the source of As in this study. Both water and
rice samples will be processed at the Chemistry Laboratory of the UIC Main
Campus and would be examined and read using the silver diethyldithiocarbamate
spectrophotometric method at the Science Resource Center of the University of
the Immaculate Conception located at Fr. Selga St., Davao City.







Definition of Terms

following are terms that are being defined as per its operational use in the

Atomic Absorption Spectrometry (AAS) –
A spectroanalytical procedure whose principle involves the absorption of
optical radiation by free atoms in the gaseous state, that would be used in
this study to identify and quantify the presence of Arsenic in the samples of
rice grains and irrigation waters that would be utilized in this research.

Rice grains –
A crop that would be utilized in this study as a source of Arsenic

Irrigation water – A
potential source of Arsenic that would be tested in this study for its Arsenic

Inorganic arsenic-
A toxic form of Arsenic naturally found in ground and surface water however can
be at higher concentrations due to mining and industrial wastes.



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