1. PESTICIDES
The US Environmental Protection
Agency (EPA) defines pesticides as
any materials manufactured or
formulated to kill a pest.

2. As defined by the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA), the federal low that
regulates the manufacture, sale, and use of pesticides
in USA, a pesticide is “any substance or mixture of
substances intended for preventing, destroying, repelling,
or mitigating any insects, rodents, nematodes, fungi or any
other forms of life declared to be pests; any substance or
mixture of substances intended for use as a plant
regulator, defoliant or desiccant.”

3. The principal goal of pesticide application
in commercial agriculture is to reduce
crop loss or decrease growing or
cultivation costs in order to enhance
economic returns.

4. There are over 1200 chemical
compounds used as pesticides and
marketed in over 30 000 formulations
and under different brand names.
Prior to World War II, most pesticides
were inorganic chemicals.
Since then, most have come to be
synthetic organic chemicals.

5. Most of these can be divided into
categories, or families, according to
structure or use, with certain
properties in common – including
health effects on workers and others
exposed to toxic quantities by various
routes.

6. Classification by usage:
- herbicides – (weeds)
- fungicides – (fungi)
- rodenticides (rats and other rodents)
- repellents (insects)
- growth regulators (plants and insects)
- bactericides (bacteria)
- virucides (viruses)
- acaricides or miticides (mites)
- nematocides (nematodes)

7. Classification by chemical type
Helps to determine similarities of mode of
action and metabolism in target organs.
examples of different compounds are:
- organophosphate
- carbamate
- thiocarbamate
- chlornitrophenol derivates
- pyridyl derivates
- pyretroid

8. The Farm Chemical Handbook is a useful
source of identification of a pesticide by
common name, chemical name, trade
name, and manufacturer or marketer.

9. Classification by HAZARD
Recommended by IPCS (International
Program on Chemical Safety)
Based primarily on the acute oral and
dermal toxicity in rats (LD50), four groups
are proposed. Substances with LD50 lower
than characterized in Class III are thought
unlikely to present acute hazard in normal
use.

10. Distinction should be made between toxicity –
innate capacity of a substance to cause damage
and
- hazard – the risk of poisoning arising in
practice.
Hazard is based on the toxicity of the compound
and its formulation.
Hazard is also a function of two variables other
than toxicity – contamination and time.

11. Hazard (Risk) = Toxicity x Exposure
(Contamination x Time)
- Hazard = risk of poisoning
- Toxicity = ability to cause damage
- Contamination = prerequisite for
entering the body
time – duration of contact

12. In all cases the toxicity is dose-
related.
The aim of pesticide use is to apply
an amount that is non toxic for humans
and other animals but is poisonous for
the target pest. When this is impossible
additional precautions and preventive
measures are needed.

13. Toxic effects due to pesticides
exposure may result from a single
exposure (acute toxicity) or from
repetitive exposures (chronic toxicity).
LD50 values are standard
measurements (cited in mg/kg of body
weight), often used to compare acute
toxicity of pesticides.

14. LD50 values provide measures of acute
toxicity when test animals are fed with
pesticide-treated feed or water (oral LD50) or
in case of dermal pesticide application
(dermal LD50).
The toxicity of a pesticide is related
with the route of entry into the organism.
Pesticides toxic effects vary significantly
among species. The aim is to produce
pesticide with low mammalian toxicity and
sufficiently toxic to the target pest.

15. Table 30-6. Environmental protection agency
(EPA) labeling toxicity categories.
Toxicity Categories
Hazard 1 II Ill IV
Indicators
Oral LD50 < 50 mg/kg 50-500 mg/kg 500-5000 mg/kg > 5000 mg/kg
Inhalation LD50 < 0.2 mg/L 0.2-2 mg/L 2-20 mg/L > 20 mg/L
Dermal LD50 < 200 mg/kg 200-2000 mg/kg 2000-5000 mg/kg > 5,000 mg/kg
Eye effects Corrosive; corneal Corneal opacity No corneal opacity; No irritation
opacity irreversible reversible in 8-21days; irritation reversible
irritation in 7 days
Skin effects Corrosive Severe irritation at 72 Moderate irritation at Mild or slight
hours 72 hours irritation at 72
hours
Signal word "Danger" "Warning" "Caution" "Caution"
Precautionary Fatal (poisonous) if May be fatal if swal­ Harmful if No
state­ments swallowed, inhaled, lowed, inhaled, or swallowed, inhaled, precautionary
or absorbed through absorbed through or absorbed through statements
skin. Do not breathe skin. Do not breathe skin. Avoid required.
vapor, dust, or spray vapor, dust, or spray breathing vapor,
mist. Do not get in mist. Do not get in dust, or spray mist.
eyes or on skin or eyes or on skin or Avoid contact with
clothing. clothing. skin, eyes, or cloth­
ing.

16. The toxicity of a pesticide product is
expressed by signal words DANGER,
WARNING and CAUTION.
- DANGER – highly toxic
- WARNING – moderately toxic
- CAUTION – slightly toxic.
Signal words could also reflect
formulation’s lethal effects such as skin
and eye irritation.

17. However, a highly toxic
pesticide could be specially
formulated (microencapsulated) to
reduce its toxicity if compared to a
similar, non-encapsulated product.
The aim of the signal words is to
alert the user about the toxicity of
the product.

18. HAZARD
Hazard in pesticide use should be
considered on the toxicity of a given
pesticide or pesticide product.
Therefore, hazard (risk) depends on the
toxicity of the compound and the
probability of exposure.
The hazard could be reduced by
- use of products with lower toxicity or by
- proper preventive measures.

19. A pesticide as applied consists of the
technical grade chemical (“active”
ingredient), formulated with diluents (often
organic solvents), additives (“adjuvants”),
and other “inert” ingredients, and then
applied mixed or unmixed, as sprays, dusts,
aerosols, granular or impregnated
preparations, fumigants.
"Inert" ingredients are not necessarily
nontoxic; many are organic solvents such as
methylene chloride.

20. The degree of hazard depends on the:
- toxicity of the active ingradient
- concentration of the active ingradient
- type of formulation
- rate and frequency of application
- method of application
- type of protective clothing worn
- persistence in the environment

21. HEALTH EFFECTS
Studies report association of pesticides use and
non-Hodgkin lymphoma, leukemia, prostate cancer,
multiple myeloma, soft tissues sarcoma and other
types of cancer.
The application of organophosphate pesticides is
associated with abdominal pain, dizziness,
headache, nausea, vomiting, skin and eye problems.
Long-term effects as respiratory problems, memory
disorders, neurological deficits and depression,
birth defects also have been reported to follow
pesticide exposure.

22. Occupational and environmental
pesticide exposure
Typical occupational and no
occupational pesticide exposure
situations are listed below.

23. Occupational and environmental pesticide
exposure situations.
Occupational exposures
 Research and development
 Manufacturing: Technical grade material produced.
 Formulation: Technical grade material mixed with "inert"
ingredients such as solvents, adjuvants.
 Transportation
 Pest control
 Mixing: Commercial material diluted with water or other
material.
 Loading: Into tanks in planes, ground rigs, backpacks, or
hand-held sprayers.

24. Occupational exposures
 Application
 Flagging: Standing at the end of fields to mark the
rows to be sprayed by crop-dusting aircraft.
 Farm work: Field workers, pickers, sorters, packers,
and others who come into contact with pesticide
residues on leaves and fruit.
 Emergency and medical work: Personnel exposed to
con-taminated persons and equipment in the process
of responding to spills, accidents, and poisonings.

25. Environmental and consumer
exposures
 Accidents and spills: Especially ingestion
by children
 Suicide and homicide
 Home use: House and garden
 Structural use: Residents and occupants
of buildings
 Bystanders
 Contamination: Food, water, air

26. The highest exposures and highest
incidence of poisoning occur in those
involved in agricultural pest control
operations:
- mixing,
- loading and
- applying.

27. Mixers and loaders are exposed to
concentrated pesticides and large
volumes, respectively.
The use of closed systems for mixing
and loading has reduced these
exposures and poisoning
considerably.

28. The exposure of applicators varies
with the type of application - from
leaking sprayers to enclosed-cab
vehicles with filtered cooled air.
Exposures in formulating facilities
may be much higher, particularly if
dusty formulations (dusts, powders,
granules) are produced in open
systems.

29. The most important route for most
occupational exposures is dermal, though
in some occupations such as
manufacturing inhalation may be
equally significant.
A high percentage of pesticides are absorbed
across intact human skin to a significant
degree, since they must be absorbed through
the coverings of insects or plants to be
effective.

30. The ratio of dermal LD50 to oral LD50
– values that are available for most
pesticides – can provide a rough
indication of degree of dermal
absorption.

31. The nature of exposure depends on
whether exposure is to
- commercial formulation of pesticide,
as applied in a field or structure, or
- only to the active ingredient, as
occurs in manufacturing facility.

32. Environmental effects of pesticides
Over 95% of sprayed pesticides could spread
to destination other than their target species,
including non-target species, air, water and
soil.
When pesticides are suspended in the air as
particles they are carried by wind to other
areas, potentially contaminating them.
Pesticides could be a water pollutant, and
some of them are persistent organic pollutants
contributing to soil contamination.

33. Prevention
 Work Practices:
Manufacturing and formulation workers,
mixers, loaders, applicators are directly
exposed to the concentrated or diluted
product and can only be protected by
- engineering controls and
- personal protective clothing and devices.

34. Field workers are exposed primarily
to residues on plants and in soil.
They are protected primarily by
reentry intervals – the minimum time
allowed between application of
pesticide on a field and entry into that
field.

35. The rate of degradation and the toxicity
of the degradation products are
important determinants of the extent
and effect of exposure in this group.
Pesticide degradation rates often vary
among geographic regions, so that
reentry intervals may need to be specific
to an area or climate.

36. Since skin contamination is the most
important route of most occupational
exposures, the focus of prevention is to
reduce dermal exposure, though the use
of respirators by manufacturing of
formulation workers or pesticide
applicators is often necessary.

37. Contamination of clothing, irritated skin, heat,
and sweat are all factors common in
agricultural work that promote absorption
through the skin. The use of protective
clothing in agricultural work is impeded by
the fact that most agricultural works takes
place in hot and frequently humid
environments. Therefore, need for skin
protection, which is difficult to quantify,
must be balanced against the risk of heat-
related disorders.

38. Medical surveillance
Chronic exposure to organophosphate and
carbamate pesticides may suppress the
levels of acetylcholin-esterase resulting in
endogenous acetylcholine poisoning.
Specific medical and biologic monitoring is
available for cholinesterase-inhibiting
pesticides.

39. Different types of analytic methods are
used to measure plasma cholinesterase,
with results usually reported in different
units.
Accurate methods for express determination
of both serum and erythrocyte
cholynesterase activity have been used for
diagnosis of acute and subacute poisoning
(Colortest, Merk, Boeringer).

40. As the individual baseline cholinesterase activity
may vary up to 22% from day to day even when
measured by the same method and by the same
laboratory, these levels must be established prior
the exposure.
Therefore, 25-30 % inhibition of the baseline
level during periodic monitoring (Kaloyanova,
Izmirova) can be taken as a warming level of
biological response to chronic exposure to
organophosphate and carbamate pesticides,
approaching a level likely to produce
intoxication.

41. Removal of workers at this level (30 % of
baseline) and prevention of further exposure
until levels return to approximately baseline is
likely to prevent the development of clinical
signs and symptoms of toxicity.
For most other pesticides, surveillance is
limited to general and occupational histories
and physical examination with available
laboratory tests.

42. Treatment
Treatment of pesticide poisoning in
general proceeds in 3 steps, as described
below.
1. Decontamination: this is the first priority
unless life-saving measures are required. In
the case of acute dermal overexposure, the
skin and clothing are reservoirs for
continued exposure, as is the
gastrointestinal tract in the case of
ingestion.

43. All clothings should be removed and
placed in double plastic bags for
latter analysis, decontamination, or
disposal. The skin and, if necessary,
the hair should be washed with soap.
Contamination should be looked for
under the fingernails.
If the eyes have been contaminated,
they should be irrigated.

44. The need for gastrointestinal lavage or
activated charcoal instillation should be
determined case-by-case basis, i.e., depending
on the pesticide, on whether vomiting or
diarrhea has occurred, and the level of
consciousness.
All procedures should be done in such way as to
minimize the contamination of medical personnel
and equipment without compromising patient
care.

45. 2. Specific Antidotes: they are
available only in the form of atropine
for cholinesterase-inhibiting pesticides,
and chelating agents for heavy metal
pesticides such as arsenic and mercury,
which rarely result in the need for
treatment except for cases of ingestion.

46. 3. Supportive care: it may be the only
treatment indicated and may be
lifesaving.
Assessment of respiratory status and
provision of appropriate ventilatory
support are critical, since most fatal or
serious poisonings are mediated at least
in part through respiratory
embarrassment or arrest.

47. REGULATION OF USE OF
PESTICIDES
The pesticide industry is regulated
differently in most countries that have
chemical regulatory system.
- Labeling,
- application to plants and soil,
- training in pesticide use and
- transportation are controlled.

48. When a pesticide is approved for use, its use is
specified as either general or restricted (many
pesticides can only be spread by licensed
applicators).
Labels contain useful information such as use
instruction, application methods, first-aid
recommendations, hazard information. The
use of pesticide in any way other than as
specified by the label is illegal.

49. Another problem is the disposal of
empty containers. It is not advisable,
and in many places it is illegal, to reuse
pesticide containers. Many advances
have been made to mitigate this
problem.
Plastic containers have been collected
by the distributors and reprocessed into
plastic pipe. Bulk, reliable containers
have been used.

50. Triple rinsing the container into the
solution tank gives the applicator a
method to decontaminate the container
before landfilling or recycling.
Hand lances that can pierce the
container are used to assure proper
cleaning and destruction of the
container so that it can not be reused.

51. Preventing pesticide exposure
 Select the safest formulation – granular or
microencapsulated materials
 Reduce the rate of application to the lowest effective
level
 Mix only enough pesticide to complete the assigned
task
 Select a method for application to minimize the
personal contact
 Wear all protective clothing noted on the label
 Avoid direct contact when mixing and filling the
equipment

52. -
- Use pesticides only in well-ventilated areas
- Consider the safety of others around you
during application
- Dispose the pesticide containers properly
- Be attentive to the re-entry intervals specified
on the label
- Keep pesticides in their original, labeled
containers
- Avoid pesticide drift
- Avoid conditions that might lead to ground
water contamination

53. Pesticide safety tips
- Always read the label before use
- Pesticides requiring special protective
equipment should be used by trained,
experienced applicators
- Do not eat or smoke or eat during application
- Never spray pesticides outdoors on a windy
days
- Store pesticides under lock in original
containers with proper label.
- Never transfer pesticide to another container
(e.g. soft drinking water)

54. Health control in pesticide use – most important
assignments of medical specialists
1. To become acquainted with the list of approved
pesticides for use via the running year, with their
categorization and the instructions for first aid in
poisoning.
2. To carry out health instructions for persons working
with pesticides.
3. To supply the tractor drivers and aviators applying
pesticides with first-aid medicine chest with atropine,
sodium bicarbonate, carbon medicinally, magnesium
sulfate and other antidote substances at the beginning
of the campaign of pesticide use.

55. 4. To organize and participate in the
preliminary and periodical medical
examinations and perform a dispensary system
for people working with pesticides.
5. To organize health control about the storage,
transportation and application of pesticides and
provision of workers with protective clothing
and personal protective devices.
6. To render a first aid in case of poisoning.
7. To carry out health education among people
about prevention of pesticide poisoning.