Lecture 11 (Bioavailibility & Toxicology

8/8/2019 Lecture 11 (Bioavailibility & Toxicology

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INDUSTRIAL & ENVIRONMENTAL

BIOTECHNOLOGY

Course # KIBGE-707

AFSHEEN AMAN, Ph.D.

Assistant ProfessorIndustrial Biotechnology Section

Dr. A.Q. Khan Institute of Biotechnology & GeneticEngineering (KIBGE)University of Karachi

Pakistan11


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BIOAVAILABILITY &

TOXICITY OF POLLUTANTS

Course # KIBGE-707


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ECOTOXICOLOGY

The termThe term ecotoxicologyecotoxicology was coined bywas coined byRene Truhaut in 1969in 1969

Branch of toxicology concerned withBranch of toxicology concerned withthe study of toxic effects, caused bythe study of toxic effects, caused bynatural or synthetic pollutants, to thenatural or synthetic pollutants, to theconstituents of ecosystems, animalsconstituents of ecosystems, animals

(including human), vegetables and(including human), vegetables andmicrobesmicrobes

Ecology in the presence of toxicantsEcology in the presence of toxicants33


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A 5-steps understanding process useful for

research/regulation

Release of pollutant into the environment

Transport and fate into biota (with/out chemical

transformation)

Exposure to biological and ecological system Understanding responses and/or effects

(molecular to ecological systems)

Design experiments, remediation, minimization,

conservation, and risk assessment plans tounderstand, eliminate, prevent or predict

environmental and human health pollutions

situations.44


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Ecotoxicity

Subject of study of the field of ecotoxicologyrefers to the potential for biological, chemical or

physical stressors to affect ecosystems.

Such stressors might occur in the naturalenvironment at densities, concentrations or

levels high enough to disrupt the natural

aspects that comprise the ecosystem.

Biochemistry

Physiology

Behavior

Interactions of the living organisms55


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Bioavailability of a pollutant

The extent to which a pollutant is availableThe extent to which a pollutant is available

to living things. Some compounds are veryto living things. Some compounds are very

bioavailable to plants and animals becausebioavailable to plants and animals because

they are soluble in water; differentthey are soluble in water; different

compounds are soluble to differentcompounds are soluble to different

degrees.degrees.

If a substance is insoluble in water, orIf a substance is insoluble in water, or

hydrophobic, it is generally nothydrophobic, it is generally not

bioavailable.bioavailable.


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Hydrophobic compounds have an

affinity for lipids and thus do not

associate with water.

Bioavailability will vary with soil

structure and organic matter content.

The higher the clay content of a soil,

the more likely a pollutant is to bebound to the soil and therefore

unavailable for plant uptake.77


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Clay soils have a smaller particle size,

and thus more surface area. This high

surface area provides for more exchangesites.

Organic compounds that have a chargeare subject to these exchange sites and

become less bioavailable.

High organic matter content in the soilwill bind lipophilic (i.e. hydrophobic)

compounds, making petroleum

hydrocarbons less available.88


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TYPES OF POLLUTANTS

Greenhouse Gases:Carbon dioxide and methane are two of themost important of these gases, calledgreenhouse gases because they trap heat

in the earth's atmosphere.This is already causing severe problemsaround the world and the situation willonly get worse.

The rising temperatures will likely lead tomore severe weather events, cause shiftsin natural communities, and probably leadto greater species extinction rates, among

numerous other effects.


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Pesticides:

A broad group of chemicals that enable

us to live more comfortable lives by andlarge, but whose main purpose underlies

the central problem with pesticide

pollution.

A lot of these chemicals will wash into our

rivers and streams and cause directtoxicity to fishes, and may work their way

up the food chain to affect birds, bears,

whales, and other predatory wildlife,

including humans.


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Insecticides

Fungicides

Herbicides

Plant-growth regulator

Other compound

They are all poisons

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Some of these pesticides will persistfor long periods of time in the

environment.

DDT was a pesticide used for along

time in the US (and is still beingused in parts of the world formosquito control), but has beenbanned in the US since 1972.

Yet we still find DDT in ourenvironment, sometimes at veryhigh levels.


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Heavy metals:

Metals are continuously released into theMetals are continuously released into the

biosphere by volcanoes, natural weatheringbiosphere by volcanoes, natural weathering

of rocks but also by numerousof rocks but also by numerous

anthropogenicanthropogenic acitivitiesacitivities, such as mining,, such as mining,

combustion of fuels, industrial and urbancombustion of fuels, industrial and urbansewage and agricultural practices.sewage and agricultural practices.

On a global scale there is now abundantOn a global scale there is now abundant

evidence that anthropogenic activities haveevidence that anthropogenic activities havepolluted the environment with heavy metalspolluted the environment with heavy metals

from the poles to the tropics and from thefrom the poles to the tropics and from the

mountains to the depths of the oceans.mountains to the depths of the oceans.1313


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Most heavy metals, such as mercury, are

a natural part of the earth's crust, and

would be slowly released into the

environment over time just by weathering

of soils and rocks. However, our consumption of fossil fuels

has greatly increased the introduction of

heavy metals into our environment.

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The world-wide emissions of metals to

the atmosphere by natural sources is

estimated as (thousand t yr-1):

Ni: 26, Pb: 19, Cu: 19, As: 7.8,

Zn: 4, Cd: 1.0, Se: 0.4

Whereas, from anthropogenic sources

(thousand t yr-1):

Pb: 450, Zn: 320, Ni: 47, Cu: 56,

As: 24, Cd: 7.5, Se: 1.11515


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It is estimated that half of the mercury

introduced into the environment today

is due to human sources.

The problem is mercury, as well as

other heavy metals, that cannot bedetoxified.

Once it is in the environment, it is herefor good. Toxic effects of heavy metals

vary.1616


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Mercury is a potent toxin in people

targeting nervous tissue, but targets

other tissues in other animals.

The effects of heavy metals can also be

quite severe, since plants and animalshave no natural ability to deal with

heavy metals specifically and heavy

metals do not have any functions in ourbodies.


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List of Environmental Issues Climate change Global warming Fossil fuels

Sea level rise Greenhouse gas Oceanacidification

Conservation Species extinction Pollinator

decline Coral bleaching Holocene extinction

event Invasive species Endangered species Dams Environmental impacts of dams

Energy Energy conservation Renewable

energy Efficient energy use Renewable energy

commercialization

Intensive farming Overgrazing Irrigation

Monoculture Environmental effects of meat

production


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Land degradation Land pollution

Desertification

Soil Soil conservation Soil erosion Soil contamination Soil salination

Land use Urban sprawl Habitat

fragmentation H

abitat destruction Nanotechnology Nanotoxicology

Nanopollution

Nuclear issues Nuclear fallout Nuclear

meltdown Nuclear power Radioactive

waste

Overpopulation Burial

Ozone depletion CFC


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Toxins Chlorofluorocarbons DDT

(dichlorodiphenyltrichloroethane)ichlorodiphenyltrichloroethane) Endocrine disruptors Dioxin Heavy

metals Herbicides Pesticides Toxic

waste Bioaccumulation

Waste E-waste Litter Waste

disposal incidents Marine debris

Landfill Recycling Incineration

Genetic engineering Genetic pollution Genetically modified food

controversies


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THANK YOU

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Lecture 11 (Bioavailibility & Toxicology