1.1 al.2011). Pesticides consumption in the world


are chemical substances that are used to manage or kill pests at tolerable
levels and are used to combat the problems associated with loss in food
production.Rapid expansion in population has resulted to accumulation of toxics
to the environment due to high agricultural activities thus the production of
these xenobiotic chemicals has forced to implement new technologies to
eliminate them from the environment(equab et al.2016).The major concern about
adverse impact of pesticides on environment and human health started being
voiced in the early 1990s'(carson,1962).Despite being harmful component of
modern farming it plays a major role in maintaining high quality agricultural
productivity.The extensive use of pesticides has resulted in serious health and
environmental problems which has affected biodiversity.They pose threats to
soil,water safety and air quality.Contamination of groundwater and surface
water causes a serious threat to sorrounding ecosystem.Organserious hne and
organophosphate cause tumors irritability and convulsion and serious
environmental issues due to Biomagnifixation.It has been reported that 500
million people lack access to safe drinking water in China due to highly
polluted rivers with xenobiotic chemicals(Zhang et al.2011).

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consumption in the world has reached to 2million tonnes as per Abhilash and
Nandita in which Europe utilizes 45% followed by USA 24% and 25% in the rest of
the world.China produces highest percentage followed by Korea,Japan and India
because of warm humid climatic condition.The concept of green revolution has
played important role for utilization of various pesticides for high
yield.Presently India is the largest producer of pesticides in Asia and ranks
12th in the world(Abhilash et al.2009;Bhat et al.2009).Pesticides residual in
crops has affected the export of agricultural commodities in the last few years
therefore pesticides safety and regulation,proper application strategies and
integrated pest management are key strategies for minimizing human exposure to
pesticides and maintenance of soil fertility for proper


comprise of different variety of chemicals including
herbicides,insecticides,fungicides and rodenticides.They are classified on the
basis of the structure.The structural classification include
organochlorine,nitrogen based pesticides,organ I phosphorus
carbamates.Pesticides can also be classified by various criteria such as
functions groups,mode of action and toxicity(Garcia et al.2012).They have
differebt mode of action to control the target pest.Moreover,certain herbicides
may stimulate the function of plant growth regulators while others may control
the capacity of a plant convert light into food.Likewise fungicides may affect
cell division.Pesticides are sometimes classified according to the type of
target pest for which they are applied,example miticides are used for mite
while insecticides for insects.Insecticides kill insects by penetrating into
their bodies via direct contact(dermal entry),respiratory entry or
oral.Herbicides are used to kill plants by direct contact or by killing weeds
when they are absorbed through roots,stems or leaves.Some pesticides are
developed to influence the nervous system or to act on the endocrine or hormone
systems of pests.Others are capable of moving into untreated tissues after
being absorbed by plants and animals hence they can penetrate throughout the
plant to kill certain insects or fungi(mnif et al.2011).


farmers overuse and misuse of pesticides is major challenge in Kenya because
many farmers are unwilling to accept risks of crop loss.They lack education and
training on use of pesticides and have inadequate knowledge on related
hazards.Some research have been conducted to evaluate farmees pesticide use in
Kenya but most of this research focused on commercial farmers leaving behind
small scale farmers who are the main contributors if agriculture in Kenya and
provide security in food supply.These farmers are usually heavy pesticide
users,risk averse and resource poor.


studies have focused on quantity of pesticides on extensive farming practices
ignoring small scale farmers who are the main contributors of agriculture in
Kenya therefore my study aim at finding the impact of pesticides on environment
and human health,the quantity and type of pesticides used ,their knowledge and
attitude in regard of use of pesticides,problems associated with pesticides
especially on small scale farmers.





increasing population pressure has facilitated intensive farming in Narok
town.Farmers in Narok town of Narok county have shifted from organic farming to
inorganic farming(growing vegetables,tomatotoes,onions and fruits in
greenhouse,use of chemicals such as herbicides in crop production and machine
especially in wheat cultivation).Most farmers rely on pesticides as the primary
pest control measures(Horne et al.2008).Indiscriminate use of pesticides can
result in transimitral of pesticides residuals through the food to human
being,health impairement due to indirect or direct exposures,contamination of
ground water and surface water through seepage and surface runoff and increase
in resistance of pest population to pesticides.These impacts are linked to
unwilling of farmers to accept risk loss,lack of education and training on
pesticide use,inadequate knowledge on related hazards of pesticides and weak
enforcement of pesticide law(Khan et al.2015).In response to this my study
proposes to ensure pesticides are used in away that minimizes the adverse risks
on human,environment and animals which will be achieved through creating public
awareness and education on related hazards associated with inappropriate use of
pesticides,use lower dose rate on farms,observe buffer zones around water
bodies and human settlement and use of protectives such as
gloves,gumboots,overall and mask when handling farm produce.




usage of pesticided are increasingly gaining importance around the world
because of their potential adverse environmental and health impact.Overuse and
misuse of pesticides due to inadequate knowledge among farmers may pose harmful
impact on environment and human health therefore the aim of my study is
determine farmers source of information on use of pesticides,create public
awareness on health hazards associated with pesticides,determine quantity and
type of pesticides used in field and assess farmers knowledge,attitudes and
practices in regard to use of pesticides.




Main objectives

determine harmful impact of pesticides exposure to farmers health and the


Specific objectives

To determine the type and quantity of pesticides used by farmers

To determine signs,symptoms and problems related to pesticide exposure

To establish farmers knowledge,attitude and practices on pesticides







What are the environmental and health impact of pesticides

What is the type and quantity of pesticides used by farmers

What are the signs,symptoms and problems associated with use of

What are the farmers knowledge,attitude and practices towards
pesticides application







Farmers apply pesticides with no respect to type and quantities

There is no environmental and health effects associated with use of

Farmers have inadequate knowledge,wrong attitude and practices towards
pesticides application










 2.1 Importance of pesticides

are widely used by farmers in developed countries to combat risks associated
with pests and diseases that may lead to poor productivity.Over last 60years
farmers have achieved significant progress in production of crop yields by
using pesticides.They have done this principally to prevent agricultural losses
to pests and promote great availability of food at a reasonable price and at
any season (Cooper et al.2007). By use of pesticides,productivity has increased
dramatically in most countries. For example corn yield in the USA,Wheat yield
in the United Kingdom and total yield in the Russia and other countries were
enhanced enoumously.It hhas been believed that diets containing fresh
vegetables and fruits far overweight potential risks from eating very low
residues of pesticides in crops.Improved nutrition the quality of life and
longetivity,improved drug and medical together with hygiene have played
important role in extending lives but the value of nutritious safe and
affordable food should not be underestimated as health promoter that increases
the life expectancy.


pesticide production increased at a rate of about 11% per year to more than
5million by 2000(FAO,2017) due to rapid increase in population.The use of
pesticides has not been the same across the world due to the cost of chemicals
and the costs of manpower and the specific pests of each climatic /geographic
region.Average application rate of pesticides per hectares of arable land has
been computed by FAO and the highest average attaining 6.5_60kg/ha occurred in
Asia and in some countries at South America(Carvalho,2017).Pesticides comprises
a variety of different types of chemicals including
herbicides,fungicides,insecticides and rodenticides.They are classified on the
basis of structure which include carbonates,organochlorine,organophosphate and
nitrogen based pesticides(Uqab et al.2016).


is given to biological control of pests.This is a bioeffecfor method of
controlling pests using biocontrolling agents including other living
organisms.These biocontrolling agents are also known as bio_rational
pesticides.Example of bbiocontrolling agents pesticides is insect growth
regulators(IGR) which are the hormones that regulates growth of insects without
interfering with non_target organisms(Delaplane,2000).




Pesticide registration and safety

registration is a complex,administrative and legal processes that takes into
consideration amount of time,skills of registration authority,pesticide
manufactures and resources.In this process risks associated with use of
pesticides on environment and human health are examined(Monaco et al.2002) so
as to ensure these chemicals can be used properly and in safest manner possible
by researchers and practitioners.Registration of pesticides is important
because it ensure that the pesticides produced in market is authorised and used
for the intended purpose.According to (WHO,2010) pesticides registration
enables the authorities to control over labelling,quality,price,packaging and
labelling of those pesticides.Application of pesticides registration involves
analytical methods,proposed environmental toxicity and human health hazards and
formulated products recommended uses and labels,waste and container management
and disposal.Application is then reviewed and analysed by the registration
authority scientist offer which it is approved or rejected after
environment,human and biodiversity risk assessment.Registration of pesticides
ensure that they meet current scientific,safety and regulatory
standards(Damalas and Eleftherohorinos,2011).



Health and Environmental impact of pesticides

 Use of pesticides in modern agriculture has
significantly increased in our environment which is associated with negative
effect on the environment and human health.The fate of pesticides in the
environment is determined by pesticide characteristics(tendency to absorb to
the soil,water solubility and pesticide persistance) and soil
characteristics(sand,clay and organic matter) (Anonymous,2009).Pesticides enter
into the ecosystem by two different means depending on their solubility.Through
bioamplification,fat soluble pesticides enter the bodies of animals and get
absorbed in the tissues of animals leading in pesticides persistence in food
chain.On the hand water soluble pesticides get dissolved in water and enter
rivers,lakes,stream and ground water hence causing harm to non_target


of pesticides from the site of application to non_target location may lead to
economic loss to farmers,environment contamination and inefficient control of
pests(Merle et al.2007).The volatized pesticdes such as herbicides may
evaporate into the atmosphere and cause serious injuries to non_target
organism.Uncontrolled use of pesticides has resulted to severe decline of
terrestrial and aquatic plant and animal species.They have also endangered
survival of rare species such as perigrine falcon,Osprey and the bald
eagle(Helfrich et al.2009)



Effect of pesticides on human health

long term and indiscriminate use of pesticides has resulted in serious health
problem.According to world health organization 3000000 cases of pesticides
poisoning and 220 000 deaths are reported in developing countries each
year.900000 people worldwide die by suicide each year and in attempted suicide
poisoning result in temporary or permanent disorders.There are several problems
of intentional and unintentional middle and low income countries such as
India,China,Srilanka and Viet Nam (Lah,2011).Moreover,some people are more likely
to be affected to pesticides exposure than others such as infants,young
children,pesticides applicators and agricultural farmers(Damalas et
al.2011).Pesticides enter the body through inhalation,ingestion or penetrationa
via skin but most people get affected by taking pesticide contaminated food
where they are accumulated in the body organs leading to toxicity(Hayo and Werf
Acute effect of pesticides

effect of pesticide exposure include blisters on the skin,dizziness,diarrhoea,nose
and throat irritation,headache,stinging of the eyes and skin,nausea and
vomiting,blindness and very rarely deaths which are severe enough for someone
to seek medic help.
Chronic effects

effect of pesticides are often fatal and may not appear for several years.These
are long term effects that cause damage to the body organs.Pesticides exposure
for long period of time may result to the following consequences

Damages lungs,liver,kidney and may cause blood diseases

Damage immune system and can cause hypersensitivity,asthma and

Affect reproductive capabilities by altering the level of female and
male reproductive hormones

May result to leukamia,brain cancer,lymphoma,cancer of
breast,prostate,ovaries and testis

of organochlorine and pyrethroids may lead to an allergic of skin
response,sensitivity to sound,light and touch,dizziness,aggressiveness,tremors
and seizures,confusion,muscle and chest pain,nausea and
vomiting(Lah,2011).Organophosphate and carbamates interfere with normal nerve
signal,transduction resulting to severe headach,muscle and chest pain,vomiting
and nausea.



Effect of pesticides on the environment

of pesticides has lead to decline in population of rare species of animals and
birds and their longterm usage results to bioaccumulation(Pesticide reduce
biodiversity 2010).Accumulation of pesticides in the food chain affect the
predators and raptors directly therefore the impact of pesticides on
populations of aquatic and terrestrial plants,birds and animals is a major
Threats to terrestrial biodiversity

exposure lead to sub_lethal effect on terrestrial plant and killing of
non_target organisms.Use of broad spectrum insecticides such as
pyrethroids,organophosphate and carbonate can lead to decline of population of
beneficial insects such as bees,butterflies and beetles(Pilling and
Jepson,2006).Neonicotinoids insecticides such as clothianidin even at low doses
are very toxic to beers(Yang et al,2008).Pesticides exposure to the tissues of birds
lead to their death.Organophosphate insecticides are very toxic to birds and
can affect the nervous system leading to behavioural change.Leaching of
pesticides into the soil lead to killing of microbes which are involved in
nitrogen fixation therefore leading to disruption of nitrification and
devitrification processes(Lang and cai,2009)


cause damage to fungal species in soil where trifluralin and oryzalin inhibit
the growth of symbiotic mycorrhizal fungi that help in nutrient
uptake.Oxidiazon reduce the number of fungal spores.Pesticides exposed in soil
pore have toxic effect on earthworm which contribute to soil fertility and also
act as soil contamination bio_indicators and model of soil toxicity(Schreck et
al.2008).Glyphosphates affect feeding and viability of earthworm and have toxic
effect at the cellular level of earthworm hence causing DNA damage( Casabe et
al.2007).Goulson reported that neonicotinoids can kill earthworms such as
Eisenia foetida species due to its tendancy to accumulate in the
Threats to aquatic biodiversity

enter the water via surface runoff from agricultural field,leaching through the
soil,drift.Pesticides decreases dissolved oxygen in water,affect aquatic plants
and cause behavioural and physiological change in fish population(Scholz et
al.2012).According to Helfrich aquatic animal are exposed to pesticides in
three ways(Helfrich et al.2009).

Breathing uptake via gills during breathing

Dermally.Direct absorption via skin

Orally.Entry via drinking contaminated water

of herbicides on aquatic plants lead to decrease in oxygen level in water which
results in suffocation of fish.Pesticides reach underground water through
leakage of contaminated surface water.Atrazine pesticides is very toxic and it affect
the immune system of amphibians(Rohr et al.2008).Carbaryl is very toxic to
amphibian species whereas herbicides gyphosphate cause high mortality rate of
juvenile frogs and tadpoles low concentration of malathion changes the composition
and quantity of periphyton and plankton which disrupt the growth of frog tadpoles(Relyea
and Hoberman 2008).Dr Hayes discovered that 10% of male frog raised in a
trazine contaminated water developed into females.Male frog that were genetically
males phenotypically developed ovaries within their testes.


addition persistent organic pesticides such as DDT bioaccumulate in the body
organs of birds,animals and domestic livestock hence becoming toxic. (Liroff,2000)
reported that DDP lead to decline of Bald eagle population in the USA and it’s
metabolites.Despite being banned DDT is being experienced in upstream
agricultural and water catchment areas of river Tana and Sabaki,which flow in
to the Indian ocean.Before 1986 DDT lead to existence of a deformed animal
sanctuary in Kitale(Western Kenya Province) where it was extensitively used to
control agricultural pests.The study also revealed that the problem also extended
widely in cotton growing areas of Turkana where DDT was used extensively in the
1970’s.In water samples from the confluence of river Sabaki which flows in
central highlands,a region of extensive agricultural and human load
activities,DDT was detected(0.295ngg-1) during the rainy seasons.




Alternative Pest Management Systems

control has meant the use of chemical for many years.Pesticides can be very
effective means of pest control when used properly however can harm wildlife,people,contaminate
water and soil when misused.IPM is regarded as an effective means to pest control
that minimizes the use of pesticides.IPM involves carefully managed use of three
different pest control tactics:biological,cultural and continuous field
monitoring(Konradesen,2007).The use of IPM requires a sophisticated understanding
of the ecosystem of turf and available pest control tactics.The New Hampshire Pesticide
control Board rules prohibits the use of pesticides within 25 feet of any




have proved to be beneficial to farmers and people a around the world by increasing
agricultural yields but the issue of hazardous risks posed by pesticides to the
environment and human health have raised concerns on the safety of
pesticides.We cannot eliminate completely the risks associated with pesticides
use but we can by pass them in away that is less harmful to the environment and
human health.The harmful consequences of pesticides can be eliminated by
alternative cropping methods,production of safe,better and environmental
friendly pesticides formulation,use of pesticides in appropriate quantities and
only when required and well maintenance of pesticides equipment.


organochlorine which are used as pesticides are least biodegradable and is
banned in many countries.Besides this fact,this pesticides is highly used in
many places resulting in serious health hazards,water pollution even at low
concentration and threat to the environment(Agrawal et al.2010).Many farmers
are unaware of potential risks of pesticides,their level of poisoning,hazards
and safety measures to be taken before use of those pesticides hence leading to
harmful effects to the environment and their health.Public awareness should be
created for those farmers to decrease pesticide hazards to the environment and
human health(Sharma et al.2012)


control and remedies can be used in combination with chemical pesticides which
result in more sustainable destruction of pests and insects.This combination
lead to sustainable environment and controlling of invasive species and pests(Gentz
et al.2010).Pesticides have also fixed a serious threat on aquatic ecosystem
and biological integrity of marine.It is time to integrate studies of different
displine such as conservation biology,environmental chemistry,toxicology,ecology,population
biology so as to understand harmful effects of pesticides on human health and
the environment(Macneale et al.2010).


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