Concerns pesticides have to both humans and environment.

1. Environmental
concerns of
pesticides
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2. Outline
 Effect on human
 Pesticides resistance & resurgence
 Pesticide on target organism
 Pesticide on non-target organisms
 Pesticide on soil environment
 Pesticide on water and air ecosystem
 Pesticide biomagnification
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3. Introduction
 The use of chemicals in modern agriculture
has significantly increased productivity.
 Their has been an increase in the
concentration of pesticides in food and in our
environment, with associated negative effects
on human health and the environment.
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4. Pesticides and human health
 Annually there are dozens of million cases of pesticide
poisonings worldwide (Richter, 2002).
 Pesticide effects to human can be categorized as acute i.e
those with quick felt effects e.g. nausea or chronic i.e those
with long term felt effects such as the case of leukemia.
 Health effect on people with direct exposure
 Health effect on people with indirect exposure
 Health effect on consumers
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5. Health effect on people with direct
exposure
 Person who are most affected are the persons who are involved in
actual application or who work in areas application of pesticides takes
place e.g.
 Farm sprayers
 Farm workers
 These are the most common health effects.
 Cancers
 Depressions/neurological deficits
 Diabetes
 Respiratory diseases
 Women specific disorders
 General health/multiples diseases
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6. Health effect on people with direct
exposure
Cancers
 Studies have shown exposure to pesticides increases risk of cancer which is
high among persons or workers exposed to pesticides compared to
general population e.g.
 Prostate cancers among men has been studied to occur most among men
exposed to Organochlorine pesticides.
 Exposure of farm workers to pesticides such as Chlorpyrifos has shown some
evidence that suggest that these workers suffer a higher incidence of lung
cancer compared to control.
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7. Health effect on people with direct
exposure
Depressions/neurological deficits
 Studies suggests that high‐intensity and cumulative pesticide exposure
contributes to depression among pesticide applicators.
 E.g.
 Studies have also shown that pesticides heavily affect the neurology of
person with direct exposure.
 E.g. OPPs are inhibitory to esterase which leads to accumulation of
acetylcholine at the nerve endings causing cholinergic crises by initial
stimulation and eventually exhaustion of cholinergic synapses.
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8. Health effect on people with direct
exposure
Diabetes
 Studies have in the recent years linked pesticides to diabetes cases.
 E.g. Exposure to organochlorine/handling of organophospates compounds is
associated with increased prevalence of diabetes.
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9. Health effect on people with direct
exposure
 Respiratory disorders/ diseases
 Pesticides have been linked to respiratory related
diseases/disorders.
 E.g. Asthma in children has been associated with exposure
to pesticides such as parathion and coumaphos in 12
studies done specifically for maternal organochlorines,
organophosphates, b and fungicides exposure.
 Others include bronchitis, rhinitis disease etc.
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10. Health effect on people with direct
exposure
Women specific disorders
 Women are most vulnerable when exposed to pesticides and have effects
such as:
 Miscarriages – Exposure to pesticides such as abamectin, imidacloprid,
methiocarb, deltamethrin and pirimicarb causes miscarriage among women.
 Organochlorines pesticides that disturb the normal estrogen –progesterone
balance which is particularly important in the maintenance of pregnancy.
 Other cases include menopause and hormonal disorders among women.
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11. Health effect on people with direct
exposure
General health/ multiple diseases
 Once the immunity of the a person is
compromised the whole health of a person is
compromised.
 This allows pathogen to gain entry into the
body and cause diseases.
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12. Health effect on people with indirect
exposure
 Person can also be affected health wise by pesticides indirectly through:
 Exposure to dust/ soil contaminated with pesticides.
 Clothing contaminated with pesticides
 Toys for kids contaminated with pesticides
 Etc.
 These effect are felt in farm workers homes or among people living within
areas where pesticides are used frequently.
 All health complication mentioned above in health effect on people with
direct exposure apply also in this case.
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13. Health effect on consumers
 Pesticides need a given time to breakdown once inside the
target point e.g. in tomato.
 When the PHI i.e (pre harvest interval) is not strictly adhered
to then there are some pesticides residue left in the product
which has potential to cause harm to consumer.
 Such health complications include :
 Cancers
 General health/ multiple diseases
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14. Health effect on consumers
Cancers
 Presence of pesticide residue in products such as fish,
milk, vegetables have contributed to cancer cases.
 Pesticides such as DDT, DDD
(dichlorodiphenyldichloroethane),PCB
(polychlorinated biphenyls) present a higher cancer
risk to consumers.
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15. Health effect on consumers
General health/multiples diseases
 Persons health is compromised once he/she
consumes products with pesticide residues.
 E.g. Parathion has a high case of pesticide residue in
vegetables in areas which experience winters because
its highly used during that time.
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16. Pesticide residue in foods 16

17. Effect of pesticide on the environment
 Once a pesticides is released into the environment it has effects on two
broad areas i.e
Effect on target organism e.g. insect pest, weeds etc.
Effect on non-target organisms e.g. earthworms,
pollinators, humans etc.
 On the target organism also their can be cases such:
Resistance to pesticide
Resurgence of pest
 Pesticides and soil environment
 Pesticide in water and air ecosystem
 Pesticide & bio-magnification
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18. Effect on target organism
 In the recent past their has been an increase in pesticide application
targeting a broad spectrum of pests.
 This has lead to the pest adapting or moving to new environments.
 This is attributed to gene mutation, increase in no.of generations, change
in pop growth rate.
 This in turn has lead to pest resurgence & resistance to pesticides.
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19. Resurgence
 Resurgence is defined as the rapid reappearance of a pest population in
injurious numbers following pesticide application.
 Persistence & broad spectrum pesticides which kill even beneficial & natural
enemies account for resurgence of pest.
 Other factor leading to resurgence include:
 Increase in feeding and reproductive rates of insect pests.
 Application of sub-lethal doses of pesticides.
 Elimination of a primary pest.
 Some of the pests which have resurged include cotton bollworm Helicoverpa
armigera
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20. Resistance
 Resistance may be defined as a heritable change in the sensitivity of a pest
population that is reflected in the repeated failure of a product to achieve
the expected level of control when used according to the label
recommendation for that pest species.
 Resistant pop continue to multiply till they become dominant proportion
of pop.
 As majority of pest is resistant pesticide appear to be ineffective when
used.
 The no of resistant species among organisms is on the increase ag in
insects and mites it stood at 600 in 1990 and rose to 700 in 2001.
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21. Pesticides and resistance development 21

22. Resistance to fungicides
 Resistance is a genetic adjustment by a fungus that results in reduced sensitivity to a fungicide.
 Reduced sensitivity is thought to be a result of genetic mutations which occur at low
frequencies (one in a million or less) or of naturally occurring sub-populations of resistant
individuals.
 The resistance trait may result from single gene or multiple gene mutations.
 The build-up of resistant strains is caused by repeated use of the fungicide which exerts
selection pressure on the population.
 This shift toward resistance occurs at different rates, depending on the number of genes
conferring resistance.
 When single gene mutations confer resistance, a rapid shift toward resistance may occur,
leading to a population that is predominantly resistant and where control is abruptly lost .
 When multiple genes are involved, the shift toward resistance progresses slowly, leading to a
reduced sensitivity of the entire population .
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23. Effect of pesticides on non-targets
 Pesticide effect on non-target has become a worldwide point of
discussion.
 E.g. The reduction of natural enemies and pollinator numbers by some of
the insecticides in the recent years.
 Their destruction has led to a surge in pest levels in the environment & use
of more pesticides to control the pest wrecking havoc.
 Pesticides affect both invertebrates e.g. earthworms and vertebrates e.g.
humans.
 Below are some of cases discussed including- earthworms, pollinators,
predators and humans.
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24. Effect of pesticides on earthworms
 Earthworms rep +80% of the terrestrial invertebrates and are responsible of
soil fertility by decomposing soil organic matter in humus.
 Studies have shown pesticide application lead to their decline.
 For example Carbamate insecticides are very toxic to earthworms and some
organophosphates have been shown to reduce earthworm populations.
 Pesticides affects:
 Earthworm growth
 Reproduction(cocoon production, hatchling per cocoon, incubation period)
 Neurotoxicity
 Physiological damage i.e cellular dysfunction & protein catabolism
 Earthworm general mortality to pesticide exposure
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25. Effect of pesticides on earthworms 25

26. Effect of pesticides on pollinators
 Pollinators are biotic agents that play a very important role in pollination
process.
 They include bees (honey, bumble), fruit flies, beetles, birds
(hummingbirds, sunbirds).
 Pesticides application affect various activities of pollinators such as:
 Foraging behavior
 Colony mortality
 Pollen collecting efficiency
 Application of neonicotinoid insecticides such as imidacloprids leads to the
above effects on pollinators.
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27. Effect of pesticides on bees 27

28. Effect on predators
 Predators are organisms that live by preying on other
organisms and they play a very crucial role in keeping
pest populations under control.
 These include coccinellids, braconid wasps and
predatory spiders.
 E.g. cypermethrin and imidacloprids cause high
mortality rate of the above mentioned predators than
when bio-pesticides are used such neem.
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29. Effect of pesticide on natural enemies 29

30. Effect on human
 Pesticides effect on human is a result of increase in pesticide
persistence in environment and ability to enter into food
chain.
 Pesticides can gain entry into humans through direct contact,
contaminated food/water/air.
 Pesticides effects can be either acute or chronic.
 Acute effects include -headaches, body aches, skin rashes,
poor concentration, nausea, dizziness, impaired vision, cramps
etc.
 Chronic effects include- cancers, birth defects, diabetes etc
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31. Pesticides and soil environment
 Use of pesticides in agriculture/other purpose lead to accumulation of such
pesticides in the soil.
 Indiscriminate use of pesticides further worsen the already stressed soils.
 The pesticides fate is determined by soil properties such as degradation,
transport, adsorption/desorption.
 Effects of pesticides in soil include:
1. Alter soil microbial diversity/biomass.
2. Affect soil vital biochemical reactions.
3. Affect mineralization of soil organic matter.
4. Disturb local metabolism/alter soil enzymatic activity.
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32. Pesticides and soil environment
1. Alter soil microbial diversity/biomass
 Pesticides that reach soil affect microflora/fauna in the following ways.
 Affect the growth, microbial diversity or microbial biomass of
the soil microflora. E.g sulfonylurea herbicides- metsulfuron
methyl, chlorsulfuron and thifensulfuron methyl reduce the
growth of the fluorescent bacteria Pseudomonas strains.
 Inhibit or kill certain group of microorganisms and outnumber
other groups by releasing them from the competition E.g
Endosulfan increase bacteria biomass by 76% and reduce
fungal biomass by 47%.
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33. Cont..
 Source of energy leading to increase in growth and disturbance
in soil ecosystem of some microbial groups. E.g. Bacterial are
known to use chlorpyriphos as a source of carbon for their own
growth.
 Reduce the functional structure and functional diversity of
microorganisms, but increase the microbial biomass E.g.
methamidophos and urea decreased the microbial biomass and
increased the functional diversity of soil as determined by
microbial biomass and community level physiological profiles.
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34. Pesticides and soil environment
2. Affect soil vital biochemical reactions
Pesticides affect reactions such as nitrogen fixation , nitrification
and ammonification by activating/deactivating specific soil
microorganisms and enzymes.
 The synergistic and additive interactions between pesticides,
micro-organisms and soil properties ultimately govern increase
or decrease in rate of soil biochemical reactions.
 E.g. Population of Azospirillum spp bacteria + rate of
ammonification increased at a particular pesticide
concentration (I.e 2.5 to 5.0 kg/ha) in both laterite & vertisol
soils planted with groundnuts.
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35. Pesticides and soil environment
3.Affect mineralization of soil organic matter
Pesticides have been reported to influence mineralization
of soil organic matter a key soil property influencing soil
quality and productivity.
 E.g. Significant reduction in soil organic matter was
found after the application of four herbicides (atrazine,
primeextra, paraquat, and glyphosate).
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36. Pesticides and soil environment
4. Disturb local metabolism/alter soil enzymatic activity
 Soil in general contains an enzymatic pool which comprises of free enzymes,
immobilized extracellular enzymes and enzymes excreted by (or within)
microorganisms that are indicator of biological equilibrium including soil
fertility and quality.
 E.g. phosphate (hydrolyze organic P compound into inorganic P) when
exposed to pesticides such as 2,4-D nitrapyrin, mancozeb, carbendazim and
the enzymatic activity increases but high concentration increase incubation
period leading to inhibitory effect.
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37. Pesticides in water and air ecosystem
 Pesticide residues in water and air are a major concern as they pose a serious
threat to biological communities.
 Pesticides get into water through:
 Accidental spillage, industrial effluent, surface run off and transport from pesticide
treated soils, washing of spray equipment's after spray operation, drift into water
points, aerial spray to control water-inhibiting pests etc.
 Pesticides get into air through:
 Spray drift, volatilization from the treated surfaces, and aerial application of pesticides.
 Once in these environments pesticides affect several organisms such as:
 Birds, fish, amphibians etc.
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38. Pesticides in water and air ecosystem
Fishes
 Fishes are an important part of marine ecosystem as
they interact closely with physical, biological and
chemical environment.
 Fishes provide food source for other animals such as
sea birds and marine mammals and thus fishes form an
integral part of the marine food web.
 Pesticides have been directly linked to causing fish
mortality worldwide.
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39. Effect of pesticides on fish 39

40. Pesticides in water and air ecosystem
 Birds
 Birds are a diverse group, and apart from their distinct songs and calls, showy
displays and bright colors adding enjoyment to lives of humans, they play a
very critical role in food chains and webs in our ecosystems.
 Pesticides exposure by different means such as direct ingestion of pesticide
granules and treated seeds, treated crops, direct exposure to sprays,
contaminated water, or feeding on contaminated prey, and baits cause birds
mortality.
 Carbamates, organochlorines, and organophosphates can cause a decline in
the populations of raptorial birds by altering their feeding behavior and
reproduction.
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41. Effects of pesticides on birds 41

42. Pesticides in water and air ecosystem
 Amphibians
 The global decline in the amphibian population has become an
environmental concern worldwide.
 Many amphibian species are on the brink of extinction with 7.4%
listed as critically endangered, and at least 43.2% experiencing
some sort of population decrease.
 Glyphosate has far reaching effects on non-target amphibians
juvenile frog.
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43. Effect of pesticide on amphibians 43

44. Pesticides and biomagnification
 Biomagnification is the increase of some of the pesticides due to
its persistent and non-biodegradable nature in the tissue of
organ at each successive level of food chain.
 Organisms at the higher levels of food chain experience greater
harm as compared to those at lower levels.
 For example, out of 36 species collected from three lakes of
northeastern Louisiana (USA) that were found to contain
residues of 13 organochlorines.
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45. Thank you
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