Pesticides can persist in the environment for long periods and accumulate in living organisms. They are linked to serious health effects in humans and other species. Pesticides enter aquatic environments through various pathways like agricultural use, dumping of waste, and atmospheric deposition. Their fate depends on factors like solubility, adsorption, and bioaccumulation. Pesticides can have ecological impacts like death, reproductive inhibition, immune suppression, and physiological effects in organisms as well as human health impacts through ingestion, inhalation, and skin contact. Persistent organic pollutants are resistant to degradation, can undergo long-range transport and bioaccumulation, and have impacts on health and environment.

1. BRIJESH CHAHAR
PhD Scholar
b0001chahar@gmail.com
CCS Haryana Agricultural University, Hisar
Aquatic Pollution
AEM-302
Pesticide Pollution

2. Pesticide- Any substance or mixture of substances intended for
preventing, destroying, repelling or mitigating any pest.
or
•A pesticide is any substance or mixture of substances used to destroy,
suppress or alter the life cycle of any pest.
•There are currently about 10,000 products used world over to control a
pest. These products are used extensively in both commercial and
domestic circumstances and in urban and rural environments.
Why Pesticides are a Problem?
•Break-down very slowly in soil, air, water and living organisms, and
persist in the environment for long periods of time.
•Concentrate in the food chain, building up to high levels in the tissues of
all living creatures.
•Travel long distances in global air and water currents and concentrate in
high latitude, low-temperature regions of the globe.
.
Pesticide Pollution

3. • Linked with serious health effects in human and other species
including reproductive and developmental illnesses, immune
suppression, nervous system disorders, cancers and hormone
disruption.
 Types of pesticides
 Bactericides:
These destroy, suppress or prevent the spread of bacteria. eg.chlorine
containing chemicals.
 Baits:
These are ready-prepared products which need to be mixed with a
food to control a pest.
eg. baits for cockroaches and ants.
 Fungicides:
These control, destroy, render ineffective or regulate the effect of a
fungus.Eg: Bordeaux mixture

4.  Herbicides:
These destroy, suppress or prevent the spread of a weed or other
unwanted vegetation.
eg. glyphosate.
 Insecticides:
These destroy, suppress, stupefy or inhibit the feeding of or prevent
infestation or attack by an insect.
eg. Dichlorodiphenyltrichloroethane, gammahexachlorocyclohexane.
 Lures:
These are chemicals that attract a pest for the purpose of its
destruction.
 Rodenticides:
These are used for controlling rodents
eg.zinc phosphide, warfain
 Repellents:
These repel rather than destroy a pest. eg. camphor, clove oil

5. • Anthropogenic activities provide the primary source of chlorinated
hydrocarbon input into the aquatic environments.Chlorinated
hydrocarbon enter the aquatic environment mainly by deliberate
application or accidentally, while poly chlorinated biphenyls entry into
the aquatic environment is indirect and principally accidental.
Deliberate application – spraying of pesticides on agricultural crops,
control of weeds, eradication of trash fish, etc.
•Dumping of waste/containers from public health agriculture and
industrial usage,Domestic and industrial effluents.
•Accidental spillage from agricultural and industrial sites, road and rail
vehicles and ships,Drainage and run – off from treated farm lands,
garbage and industrial solid wastes dump
•Dumping of sewage sludge, municipal and industrial solid wastes
•Atmospheric input (dry deposition and precipitation)
burning/incineration of domestic, municipal/industrial solid wastes;
industrial emissions.
Sources and Pathways of Pesticides

6.  Aerial transport/atmospheric Input
• The principal source of widespread pesticide contamination is from
the agricultural use of these compounds. In fruit and vegetable
growing areas where there is heavy use of pesticides,these are rapidly
lost to the atmosphere and forms aerosols in the presence of water
vapour, which travel long distances.
Example: 99% of HCH lost to air (India),98% of DDT lost to air
(Nigeria)
• In arid areas, the dry soil with absorbed pesticides is transported in
dust storms.
• Dioxins and Furrous-by burning /incineration of municipal waste
 River runoff
Although the total burden of pesticides carried out into the sea by
rivers is small compared with aerial input, it may be locally damaging.
Pathways of Pesticides

7. •Rain washing of pesticides from plants and soil into the river.
•Floods carry out very large quantities of silt into the sea from
agricultural lands contaminated with pesticides.
 Direct input (Effluents)
Contaminate bottom sediments
- Industrial outfalls (PCB’s)
- Sewage sludge
 Fate of pesticides in the Aquatic Environment
On entry into the aquatic environment through various pathways,
these non-polar, toxic, semi-volatile and fairly persistent substances
may remain within the water body unchanged for a period of time,
undergo degradation to simpler compounds which may be more toxic
or/and more persistent than the parent compounds (e.g DDE, dioxin)
or get reversibly transferred into the atmosphere by volatilization.

8.  Comparison of behavioral toxicity of chlorinated
hydrocarbons(CLHCs) and related compounds
 The ultimate fate of these pollutants including partitioning into
various aquatic environmental compartments (water, suspended solids,
sediments and biota) will depend on a number of factors including
concentration, dilution, water solubility, biogeochemical processes
taking place, adsorption to soils, suspended particulates and
sediments, lipophilicity and bioaccumulation in living organisms.
 The hydrophobic nature of CLHCs makes their presence in water to
be at ultra-trace level (ng/l) and their accurate determination difficult.
The adsorption of these compounds to particulate matter and
sediments is an important mechanism for their removal from the water
column.

9.  Consequently, the sediment component of aquatic ecosystems can be
the ultimate sink of CLHCs similar to metals and petroleum
hydrocarbons, and suspended particulates entering slow moving
waters such as larger water bodies settle out and their associated
CLHCs are added to the existing sediments component.
 Half-lives of Pesticides
It is the amount of time it takes for half the active ingredient to
disappear.

10.  The ecological impacts of pesticides
 The ecological effects of pesticides (and other organic contaminants)
are varied and are often inter-related. Effects at the organism or
ecological level are usually considered to be an early warning
indicator of potential human health impacts.
 The major type of effects are listed below and will vary depending on
the organism under investigation and the types of pesticide. Different
pesticides have markedly different effects on aquatic life which makes
generalization very difficult. The important point is that many of these
effects are chronic (not lethal) and are often not noticed by casual
observers, yet have consequences for the entire food chain.
• Death of the organism.
•Cancers, tumours and lesions on fish and animals
•Reproductive inhibition or failure
•Suppression of immune system
•Disruption of endocrine (hormonal) system

11. •Cellular and DNA damage
•Teratogenic effects (physical deformities such as hooked beaks on birds)
•Poor fish health marked by low red to white blood cell ratio, excessive
slime on fish scales and gills, etc.
•Intergenerational effects (effects are not apparent until subsequent
generations of the organism)
•Other physiological effects such as egg shell thinning

12.  Human Health Effects of Pesticides
Human health effects are caused by:
• Skin contact: handling of pesticide products
• Inhalation: breathing of dust or spray
• Ingestion: pesticides consumed as a contaminant on/in food or in
water.
 Farm workers have special risks associated with inhalation and skin
contact during the preparation and application of pesticides to crops.
However, for the majority of the population, a principal vector is
through ingestion of food that is contaminated by pesticides. The
degradation of water quality by pesticides runoff has principal human
health impacts. The consumption of fish and shellfish that are
contaminated by pesticides, this can be a particular problem for
subsistence fish economies that lie downstream of major agricultural
areas.

13. Persistent Organic Pollutants
• Persistent Organic Pollutants (POPs) are organic compounds that are resistant to
environmental degradation through chemical, biological and photolytic processes.
Because of this they have been observed to persist in the environment, are capable
of long-range transport, bioaccumulate in human and animal tissues and have
potential significant impacts on human health and the environment.
• In May 1995, the UNEP Governing Council decided to begin investigating POPs,
initially beginning with a short-list of twelve POPs: aldrin, chlordane, DDT,
dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, polychlorinated biphenyls,
polychlorined dibenzo-p-dioxins, polychlorinated dibenzofurans and toxaphene.
• Since then this list has generally been accepted to include such substances as
carcinogenic PAHs, and certain brominated flame- retardants, as well as some
organometallic compounds such as tributyltin (TBT).
• The groups of compounds that make up POPs are also called as PBTs (persistent,
bioaccumulative and toxic) or even TOMPs (toxic organic micro pollutants).

14.  Chemical Properties of Pesticides
• Some of their chemical characteristics include low water solubility, high lipid
solubility, high molecular masses and low volatility. One important factor of their
chemical properties results in the ability to accumulate in the fatty tissue of living
organisms.
• The mechanism of toxicity of the organophosphate pesticides is inhibition of
acetylcholinesterase, which catalyzes the deacetylation of acetylcholine.
Acetylcholine helps transfer nerve impulses between nerve cells or from a nerve cell
to other types of cells, such as muscle cells. The inhibition of the enzyme
acetylcholinesterase leads to the build-up of acetylcholine, which then over-
stimulates muscles, causing symptoms such as weakness and sometimes paralysis.
• When a crop is treated with a pesticide, a very small amount of the pesticide, or
indeed what it changes to in the plant (its ‘metabolites’ or ‘degradation products’),
can remain in the crop until after it is harvested. This is known as the ‘residue’.
 The POPs include three groups of chemicals,
a. Pesticides/insecticides: which were once commonly used to control pests in
agriculture and to protect public health. eg. aldrin, chlordance, DDT, dieldrin,
endrin, heptachlor, mirex and toxaphene, polychlorinated camphenes
b. Industrial chemicals (c.)Chemical byproducts

15. •Dichloro Diphenyl Trichloroethane( DDT)
The most notorious organochlorine is the DDT promoted as a “cure all”
insecticide in the 1940 DDT was widely used in agricultural production
around the world for many years. It was also the chemical of choice for
mosquito control. DDT was banned in many countries in the 1970’s in
response to the public concern and mounting scientific evidence linking
DDT with damage to wildlife. Since then agricultural uses of DDT have
been outlawed worldwide. DDT has been shown to cause breeding
failures in birds.
 Derivatives of DDT:
• DDE – Dichloro Diphenyl Ethane
• DDD – Diclorophenol Dichlorethane
Dichloro Diphenyl Trichloroethane ( DDT)

16.  Drins
These belong to a class of closely related, highly toxic organo chlorine
pesticides. This group of insecticides include aldrin, diedrine endrin
and heptachlor. These are used to control pests in vegetables, fruits
cereal grains and cotton. Endosulfan is applied to control pests on
cashew plantations in India.
 Lindane ( Hexachloro Cyclohexame - HCH)
Lindane has been used to protect crop seeds from insects, for pest
control in forests, on livestock and house hold pests for control of
ticks and other pests and in homes to control ants and other household
pests. It is also the active ingredient in many medicated shampoos and
soaps to control head lice and scabies.

17.  Polychlorinated Biphenyls (PCBs)
These are a group of synthetic chlorinated aromatic hydrocarbons and
residues have been identified throughout the global ecosystem with
widespread contamination. PCBs are used in commercial products
such as heat transfer agents, lubricants, insulating and cooling agents,
and flame retardants. PCBs similar to DDT and its metabolites, have
been implicated in reproductive abnormalities in both wild and
domestic birds.
There are a group of synthetic chlorinated hydrocarbons containing 1-
8 chlorine atoms per molecule. These are chemically very stable and
resist chemical attack. They have been used in electrical equipments
and in the manufacture of paints, plastics, adhesives and coating
compounds

18.  Dioxins and Furans
• Poly chlorinated dibenzo-p-dioxins (dioxins) and poly chlorinated
dibenzo furans are a group of organic chemicals that contain 210
structurally related individual chlorinated dibenzo-p-dioxins (CDDs)
and chlorinated dibenzo furans (CDFs)
• These are two groups of tricyclic compounds containing 1 to 8
chlorine atoms. Dioxins have 75 possible isomers and furans have 135
positional isomers. Both dioxins and furans are generated from a
variety of combustion, incineration of chemical processes. The most
significant sources of release to the air include accidental fires and
open burning of agricultural wastes, iron and steel wires, power
stations and vehicles. Incineration of waste used to be the biggest
single source of emission into the atmosphere. Dioxins have been
detected in soils, water, sediments, plants and animal tissues in all the
regions of the earth.

19. • The most toxic dioxine is 2,3,7,8-TCDD (tetrachloro-dibenzo-p-
dioxin)
• Dioxins and furans are crystalline solids, insoluble in water, but
readily soluble in organic solvents, fats and oils.Dioxins are highly
resistant in the environment with reported half-lives in soil and
sediment ranging from months to years. Because dioxins have very
low solubility in water and low volatility, most are contained in soil
and sediments that serve as environmental reservoirs from which
dioxins may be released over a long period of time.
• Dietary intake is the most important source of exposure to dioxins for
the general population. Meat,dairy products, fish and other sea-foods
contribute more than 90% of the daily intake for the general
population.
Dioxins and Furans

20. The wide use of organophosphates is based on several factors
They are relatively inexpensive.
•They are broad spectrum (most organo-phosphates can be used on
several crops to control a variety of insect pests)Because of this broad
spectrum of activity, one organophosphate might control the insects that
would require three or four non-organo-phosphate insecticides.
•In general, insects have not developed resistance to organophosphates as
they have to some other pesticides.
 Organophosphates affect the nervous system by reducing the ability of
cholinesterase, an enzyme, to function properly in regulating a
neurotransmitter called acetylcholine. Acetylcholine helps transfer
nerve impulses from a nerve cell to a muscle cell or another nerve
cell. If acetylcholine is not properly controlled by cholinesterase, the
nerve impulses or neurons remain active longer than they should,
over-stimulating the nerves and muscles and causing symptoms such
as weakness or paralysis of the muscles.
Importance of Organophosphates

21. Examples
Chlorpyrifos
•Diazinon
•Dimethoate
•Disulfoton
•Ethon
•Malathion
•Methyl parathion
•Parathion
•Phorate
•Phosmet
•Temephos
•Trichlofon

22. • Organophosphates are very efficiently absorbed from the skin, lungs
and gastrointestinal tract. The majority of organophosphate poisoning
occurs by accidental or occupational exposure, but poisoning may also
be due to suicide attempts, homicide attempts or chemical warfare.
• Organophosphate pesticides are active against a broad spectrum of
insects and are used on food crops as well as in residential and
commercial building and on ornamental plants and lawns. The
exposure of the general population to these pesticides occurs primarily
from ingestion of food products or from residential use.
Exposure TO ORGANOPHOSPHATES

23. •Human Exposure to Organophosphates
As organophosphates have a wide variety of uses, there are many opportunities for
exposure.
•Workers apply the pesticide or work in areas where pesticides have been used.
•Organophosphates are used in homes and office building or on lawns and gardens for
insect control.
•We drink water or eat foods that have pesticides residues.
 Organophosphates as a class have become the most frequently used pesticides
because of their rapid breakdown into environmentally safe products. However, they
have far more immediate toxicity than DDT and other related products. There are
more than 40 different organophosphate pesticides in the market today, and each
causes acute and sub-acute toxicities. They are used in agriculture, homes, gardens
and in veterinary practice. They all work by inhibiting acetylcholinesterase and
cause a similar spectrum of symptoms. In 2003, there were 6442 reported exposures
of which 6010 were unintentional. 1695 of these cases were seen in emergency
departments and there were 16 reported fatalities

24. • Bioaccumulation is a process of accumulation of chemicals in an
organism that takes place if the rate of intake exceeds the rate of
excretion. Chemicals are introduced into the organism through
exposure to the abiotic environment (soil, water, air) or as dietary
intake (trophic transfer).
• Biodegradable substances are those which can be broken down by
microbes into harmless compounds. Conservative pollutants are
unable to be broken down and will build up in the soil or marine
environment. Conservative pollutants include some pesticides,
industrial chemicals such as PCBs and heavy metals such as tin, lead
and mercury.
• Conservative pollutants can enter living organisms at any time and
accumulate in their tissues. Such organisms are able to build up very
high levels of such pollutants - eg oysters can concentrate DDT from
0.001 ppm in sea-water to 700ppm in their bodies. This is known as
bioaccumulation.Bioaccumulation occurs within a trophic level.
Bioaccumulation

25. • Biomagnification happens when toxic chemicals, like DDT, whose
remains in the environment are consumed indirectly by organisms
through food.
• Conservative pollutants are not metabolized (broken down inside an
organism) and therefore when an organism containing a pollutant is
eaten, the pollutants are simply passed on to the predator and
accumulate in its tissues. By consuming many preys an organism may
build up very high concentrations of the pollutant in its tissues. This
process may continue up the foodchain, leaving the top predator with
very high and sometimes lethal concentrations of the pollutant.
• Pollutants will enter organisms via different routes eg. though the
mouth and digestive tract or across gill surfaces. Small aquatic
organisms absorb most toxins directly from the water whereas
carnivores at the top of the food chain - eg. birds and mammals -
receive most of their pollutant uptake from their food.
Biomagnification occurs across trophic levels.
Biomagnification

26. • The Effect of the Pollutant
• Different organisms show varying degrees of sensitivity to toxins.
Even within a species, sensitivity to a particular toxin may depend on
age, sex, food availability, reproductive condition and genetic make-
up. Young larval forms tend to be much more sensitive than the adults
of the same species.
• Organisms may ingest or absorb more than one pollutant at a time.
Two pollutants may interact to produce a toxic effect which is greater
than the combined effect of the two pollutants simply added together
i.e. one of the pollutants may increase the mortality caused by the
other. This is called synergism.
• High concentrations of lead, zinc and mercury are each capable of
slightly reducing the growth rate of aquatic protozoans, but when
acting together the overall effect is much higher.
Effect of the toxic Pollutant

27. The Effect of the Pollutant
•Organochlorines
Organochlorines are hydrophobic (water-hating) and show low solubility
in water, but are readily soluble in fat (lipophilic). Consequently, they
will often accumulate in the fatty (adipose) tissue of an organism. In the
past, organochlorines have been widely used as pesticides. They have
two important characteristics:
They are chemically stable and remain active in the environment for
many years.
•They are fat-soluble and readily concentrate in adipose tissue.
Whilst there, even high concentrations may cause little if any harm.
However, in times of food shortage, fat reserves may be metabolised,
releasing the pesticide into the blood of the organism. This may be fatal.
.
.

28. • Polychlorinated biphenyls (PCBs)
• PCBs were used in the manufacture of paint, plastics and adhesives.
PCBs are chemically stable, hydrophobic and lipid soluble, hence they
can rapidly bioaccumulate. There is strong evidence to suggest that
PCBs are at least partly to blame for the seriously declining numbers
of the European Otter and for the decline in some populations of seals.
• PCBs interfere with the hormonal control of oestrous and ovulation,
seriously reducing reproductive ability and weaken the immune
system of marine mammals, predisposing them to illness. In humans,
PCBs may increase the risk of anaemia, oedema and susceptibility to
infectious diseases.
• PCBs enter the environment by leakage from landfill sites,
incineration of waste and from sewage effluent. Eventually, large
quantities of the PCBs will end up in the sea and high levels may
accumulate in sediment on the sea bed. Organisms which burrow in or
feed on such sediment may accumulate very high concentrations.
Effect of the Pollutant

29. SYMBOL OF TRUST