When scaling elements to be summarized: Scale all elements as needed by using the "Increase Font Size" and "Decrease Font Size" buttons or manually changing the font size for editable text. Summarize the document in 3 sentences or less. The document discusses heavy metals, their sources, effects on human health and aquatic ecosystems, and ways to reduce exposure. It defines heavy metals, describes how they accumulate in organisms and biomagnify up the food chain, and explains their health impacts including effects on organs and links to conditions like cancer. Recommendations are provided to minimize exposure to heavy metals such as limiting certain fish and rice consumption, being aware of lead pipes, and stopping smoking.

1. When scaling, group all elements to be scaled. Scale as needed. Use the “Increase Font Size,” “Decrease Font Size” buttons or manually change the font size for the editable text.
Azad Uddin (sojib)
ASH1718010M
NSTU
Dept of Oceanography

2. Welcome to everyone

3. CONTENTS
Preamble 01
What are heavy metals 01-02
Source of heavy metals 02-03
Effects of human health 04-05
Effects of heavy metal on aquatic ecosystem 06-08
What is bioaccumulation 09-10
What is bio magnification 11-12
Health impact of heavy metals 13-15
How to reduce exposure of heavy metals 16-19
epilogue 19

4. Preamble:
Heavy metal are natural constituents of the earths crust .but
indiscriminate human activities have drastically altered their
geochemical cycles and biochemical balance. Any toxic metals
may be called heavy metals.
Since heavy metal have a propensity to accumulate in selective
body of organs. The average safety levels in food and water are
often misleading high.

5. What are Heavy Metals?
Heavy metals are present in earth’s crust alongside other metals,
minerals, and organic matter. Some examples include: mercury, lead,
arsenic, cadmium, chromium, copper, & thallium.
Heavy metals are defined as “heavy” in comparison to water,
meaning that they have a higher molecular weight than 18 g/mol. Heavy
metals also find their way into watersheds from concentrated
wastewater, sewage, industrial activities, and mining operations. These
metals can contaminate soil systems and water sources.

8. Effect of heavy metals on aquatic life:
Fish is high in omega-3 and protein that the human body
needs to stay healthy. However, potentially dangerous heavy
metals are absorbed into the body tissues of fish that are
transferred to humans on consumption of this affected fish.
Good quality of food for human consumption can only be
produced in an environment free from contamination and
pollution. Fish are of great economic importance, but are
affected immensely by various chemicals including heavy metals
directly or indirectly in different ways.

9. Effect of varying concentrations of heavy metal salts on normal
blood cells of fish Labeo rohita exposed for 15, 30 and 45 days
was studied. Following physiological changes in the fish were
observed:
Cell membrane may be wrinkled, damaged or totally
destroyed.
Nucleus of the cell may be damaged.
Nucleus may shift in position.
Size of nucleus may be reduced or may be enlarged.
Nucleus may be totally destroyed.
Vacillation is observed inside the cell

10. Cell membrane wrinkled and damaged.Nucleus shift in position.
Vacillation is observed inside the cell. Normal blood smears of fish Labeo rohita

11. Bioaccumulation is essentially the buildup of contaminants
such as heavy metals or pesticides in living organisms. Aquatic
organisms are often subject to bioaccumulation because they
absorb contaminants from the water around them faster than their
bodies are able to excrete them.
Humans are also subject to bioaccumulation, either from
consuming contaminated aquatic organisms or from exposure to
contaminants in our food, air, or water. Heavy metals do
not biodegrade, which means they can last for a long time in our
bodies.
What is Bioaccumulation?

13. What is Biomagnification:
Biomagnification is process by which substance become
more concentrated in the bodies of consume as move up
the food chain or tropic levels.
At every point in this process, heavy metals bioaccumulate
in the bodies of each living organism—by the time they get
to us, we consume the heavy metals in high concentrations.
The increase of heavy metals concentration up the food
chain is called biomagnification

14. Unfortunately, heavy metals can have serious health
effects for humans. Many play a role in cancer development
or cause internal organ damage, even at low concentrations.
Cadmium, cobalt, lead, nickel, and mercury are also known to
affect the formation of blood cells–the metals can react with
the surface of the cells, making them less elastic and
therefore less able to circulate throughout the body. Here
we’ve summarized five critical heavy metals and their known
health effects
Health Effects of Heavy Metals:

15. Mercury
Mercury is known to cause brain damage in developing
children, and if you’re pregnant, it can cause birth defects or
possibly a miscarriage. Methyl mercury compounds are also
known to cause cancer. There is a deep concern about mercury
exposure through predatory fish such as tuna
Lead
Lead is particularly harmful for children. It is
structurally similar to calcium and can therefore replace
calcium in the growing bones of children. Once the child is
grown, the lead can release into the body and cause brain
and nerve damage.

16. Lead can also cause anemia, reproductive issues, and renal
impairment. People are usually exposed to lead through
contaminated food or water, or in the case of children, from
ingesting objects with lead paint. Lead can be expelled at very low
levels, but at high or continuous doses, lead bio accumulates in the
body.
Cadmium
Cadmium remains in human bodies for decades, and long-term
exposure is linked to renal dysfunction. A high concentration
exposure can also lead to bone defects and lung disease, which
may eventually become lung cancer. People can be exposed to
cadmium not only through food and water, but also from tobacco
in cigarettes.

17. Arsenic
Arsenic is technically considered a metalloid, but acts like a
heavy metal in its toxicology. Arsenic exposure can cause breathing
problems, lung and skin cancer, decreased IQ, nervous system
issues, and even death at high levels.
Arsenic easily enters ground water and soils from natural
sources and industrial operations. Some crops can uptake arsenic
after irrigation or from the soil, an example being rice, leading to
exposure through food.

18. How to Reduce Exposure of heavy
metals
Though these health effects may seem frightening, there are
a few simple ways to reduce your exposure to heavy metals and
protect your health! A few include:
1. Avoid certain fish such as king marckered,marlin,tilefish
2. Stop smoking tobacco
3. Minimize rice consumption.
4. Read medicine labels.
5.Be aware of lead pipes & filter your water

19. Epilogue:
Heavy metals are the most toxic substances
because of their varied effects .metals with higher
concentration are know to cause harmful effect on the
blood and organs of the fish.

20. Thanksgiving to all