1. Pesticide residues in food
Dr Nik Nor Ronaidi bin Nik Mahdi

2. Content
• Introduction
• Pesticide residue
• Susceptible population
• Principle of pesticides risk assessment
• Health effect of pesticides
• Prevention and control

3. Introduction
• A pesticide is any substance or mixture of
substances intended for preventing, destroying,
repelling, or mitigating any pest.
(US EPA)
• Pests include insects, plant pathogens, weeds,
molluscs, birds, mammals, fish, nematodes
(roundworms), microbes and people that destroy
property, spread or a vector for disease or cause
a nuisance

4. Pesticides are often referred to according to the:
1) Type of pest they control
2) Derived from a common source or production
method
- chemical pesticides
- biopesticides
- antimicrobials
- pest control devices

5. Chemical pesticides:
• Organophosphate Pesticides - These pesticides affect the nervous
system by disrupting the enzyme that regulates acetylcholine, a
neurotransmitter. Most organophosphates are insecticides. However,
they usually are not persistent in the environment. (e.g. parathion,
malathion, and methyl parathion)
• Carbamate Pesticides affect the nervous system by disupting an
enzyme that regulates acetylcholine, a neurotransmitter. The enzyme
effects are usually reversible. There are several subgroups within the
carbamates. (e.g. Bendiocarb, Carbaryl, Methomyl, and Propoxur)
• Organochlorine Insecticides were commonly used in the past, but
many have been removed from the market due to their health and
environmental effects and their persistence (e.g. DDT and chlordane).
• Pyrethroid Pesticides were developed as a synthetic version of the
naturally occurring pesticide pyrethrin, which is found in
chrysanthemums. They have been modified to increase their stability
in the environment. Some synthetic pyrethroids are toxic to the
nervous system. (e.g. permethrin, resmethrin, and sumithrin )

6. • Biopesticides:
– Pesticides derived from such natural materials as
animals, plants, bacteria, and certain minerals.
1. Microbial pesticides consist of a microorganism (e.g. a
bacterium, fungus, virus or protozoan) as the active
ingredient. For example, there are fungi that control certain
weeds, and kill specific insects.
2. Plant-Incorporated-Protectants (PIPs) are pesticidal
substances that plants produce from genetic material that
has been added to the plant.
3. Biochemical pesticides are naturally occurring substances
that control pests by non-toxic mechanisms (e.g. insect sex
pheromones that interfere with mating, and various scented
plant extracts that attract insect pests to traps).

7. • National trends in the amount and composition of
pesticides use:
– For the year 2006, Malaysia experienced a 1% growth in
pesticides usage. With increases in growth of 2% each
for the chemical insecticides and fungicides compared
the usage in 2005.
– The composition of pesticides used in 2006 are 68%
herbicides, 20% insecticides, 8% fungicides and 4%
others and of these Class III and IV make up the most
number of registered products.
[The 25th Session Of The Asia And Pacific Plant Protection Commission
(Apppc), 27- 31 August 2007, Beijing, China]

9. • Vegetable comprises about 15 % of the daily food
intake of the Malaysian population (Ding et al., 1981).
• Consumers generally demand for better quality
vegetables. Quality vegetable to them means healthy,
succulent and fresh looking vegetables with no visible
rashes or holes caused by pests or diseases.
• The use of agrochemicals including pesticides has been
found to be the immediate and cheaper way to
produce unblemished vegetables and increased farm
productivity.
• This practise has unfortunately created numerous
problems associated with pesticide abuse such as
accidental poisoning to man, upset of natural
environment balance and toxic residues that are
hazardous to health in the environment (Tay, E.B et al.,
1984).

10. Pesticide Residue

11. What are residues and why do they turn up in our
food?
• Pesticides may be used in a variety of different ways
during the production of food:
– used by farmers to control the growth of weeds, or
prevent crop damage by insects, rodents and molds.
– used on food crops after harvest to prolong their storage
life.
– used on animal farms to control insect pests
• When a crop is treated with a pesticide, a very small
amount of the pesticide, or its 'metabolites' or
'degradation products', can remain in the crop until
after it is harvested. This is known as the 'residue'.

12. • Residues can arise from:
– the use on a crop of legally allowed pesticides according
to good agricultural practice – (leave smallest and
acceptable amount of residue)
– overuse of a pesticide, or use too close to harvest, of a
legally permitted pesticide
– illegal use of a pesticide that is not approved for that
crop
– incorrect use of pesticides after harvest, to reduce pest
infestation in storage or in transit.

13. • Pesticide residues may be present in:
– fresh or tinned fruit and vegetables, or
– processed food and drink made from the crop (e.g. juice,
bread or any other manufactured food or drink), or
– fresh or processed animal products (if the animals have
been fed on crop treated with pesticide).
• Occasionally, residues may also result from
environmental or other ‘indirect’ sources. (e.g.
residues of old pesticides, such as DDT )

14. Do Processed Foods Have Less Pesticides Than Fresh
Foods?
• Generally, yes.
• Reason:
– Growers who have contracts with processors often don’t
need to ensure that their foods are cosmetically perfect,
and this allows them to omit some pesticide treatments,
including some late-season insecticide applications.
– Many processors, responding to consumer demand for
foods with minimal pesticide residues, have contracts
with growers that specifically limit pesticide applications.
– Processing itself also often involves washing, peeling and
cooking the food, steps that all tend to reduce pesticide
residues.

15. What about organic food?
“When present, residues in organic foods are likely
to be at lower levels than those in non-organic
foods.” (Baker et al.)

16. (The Organic Centre, 2004)

17. NDR = no detectable residue
(The Organic Centre, 2004)

18. zd
CPDP = Crop Pesticide Data Pairs
(The Organic Centre, 2004)

19. (Edward Groth et al, 1999)

20. (Edward Groth et al, 1999)

21. Common pesticide residue exceeding MRL in
Sarawak from 2000 to 2006:
• Organophosporus pesticide (OP) – 70%
• Organochlorine pesticide – 15.3%
• Synthetic pyrethroid – 11.6%
• Ethylenebisdithiocarbamates (EBDCs) – 2.9%
(Margaret Abat and Alvin Chai Lian Kuet, 2006)

22. (Margaret Abat and Alvin Chai Lian Kuet, 2006)

23. Susceptible population
• The most vulnerable population - pregnant women,
infants, and children:
– children are much less able than adults to detoxify most
pesticides
– because they are growing and developing rapidly,
processes that are vulnerable to disruption by toxic
agents.
– Since children’s bodies are smaller than adults’ bodies,
they get greater doses of residues by consuming a given
food than an adult would.
– Children also eat fewer foods, and eat more of certain
foods that tend to be relatively heavily contaminated
with pesticides, than adults do.

24. Risk assessment
1. Hazard identification:
– The possible adverse health effects of the chemical are
identified from toxicological studies.
2. Hazard assessment:
– The toxic effects and characterization of the biological response
in terms of the dose ( i.e. the dose–response relationship, are
considered and acceptable levels of dietary intake are derived).
3. Exposure assessment:
– Referred to as the ‘dietary intake estimate’, (i.e. the dietary
exposure of residues resulting from the consumption of food
and drinking water containing residues is estimated).
4. Risk characterization:
– the estimated dietary intake is compared with the acceptable
levels of dietary intake or dose that were derived as part of the
hazard assessment. In simple terms, if the dietary intake is less
than this dose, then the risk is acceptable.

25. Health effects of pesticides
• Birth Defects
– A study in Minnesota found significantly higher rates of
birth defects in children born to pesticide applicators
and in regions of the state where chlorophenoxy
herbicides and fungicides are widely used. (Garry, 1996)
– In California, mothers living and working in agricultural
areas with high pesticide use had a higher risk for giving
birth to children with limb reduction defects.
(Schwartz, 1988)
– A study of pregnant women in Iowa and Michigan found
that women exposed to multiple pesticides had an
increased risk of giving birth to a child with cleft palate.
(Gordon, 1981)

26. Health effects of pesticides
• Neurological effects
– Long term exposure can result in reduced IQ and
learning disability, associated with permanent brain
damage.
– A study in Mexico shows that children living in area with
high levels of pesticide exposure had less
stamina, poorer eye-hand coordination, poorer memory
and were less skilled in drawing figures. (Guillette, 1998)
– The risk of developing Parkinson's disease is 70% greater
in those exposed to even low levels of pesticides
(Ascherio et al, 2006)
– There are also concerns that long term exposures may
increase the risk of dementia. (Baldi I et al, 2010)

27. Health effects of pesticides
• Cancer
– Associations have been found with: leukemia,
lymphoma, brain, kidney, breast, prostate, pancreas,
liver, lung, and skin cancers
– Sheila Zahm and Mary Ward, summarized the studies of
pesticides and childhood cancer and concluded that the
following childhood cancers were linked to pesticide
exposure: leukemia, neuroblastoma, Wilms tumor, soft-
tissue sarcoma, Ewing's sarcoma, non-Hodgkins's
lymphoma, and cancers of the brain, colorectum and
testes. (Zahm and Ward, 1998, Environmental Health
Perspectives, vol. 106)

28. Health effects of pesticides
• Fertility
– A number of pesticides including dibromochlorophane
and 2,4-D has been associated with impaired fertility in
males. (Sheiner EK et al, 2003)

29. Prevention and control
• Consumer’s education:
– Choose foods frequently that have low TI values.
– Choose foods with the highest TI values, such as
peaches, less often. Eating these foods occasionally is
unlikely to do much harm, but eating multiple servings in
a short time probably should be avoided.
– Look for organically grown food.
– Remove the peel. Many pesticide residues are on the
outside of a fruit. Removing the peel can dramatically
lower pesticide exposure associated with these foods.
– Choose processed foods more often, especially those for
which TI are substantially lower than for fresh varieties
of the same foods, such as canned peaches.

30. • Legislative approaches:
– Pesticides Act 1974 which is implemented by a Pesticides
Board, that has the Department of Agriculture (DOA) as
its secretariat is the main Act that controls pesticides
– the Food Act 1983 and The Food Regulations 1985 and
(Amendment 1995) control pesticide residues in food
and are enforced by the Ministry of Health;
– Pesticides (Registration) Rules 1976 will ensure that the
pesticides imported, manufactured, and sold in the
country are of acceptable quality not causing
unacceptable, adverse effects on human health and the
environment.

31. – Monitoring residue:
• Food Quality Control (FQC) unit and DOA – collect fresh
produce at farm gate selling points and send it for residue
testing
• If exceed MRL, growers could be charged under Food Act and
Regulations
– Standards for residue:
• National standards – Food Regulations 1985(Sixteenth
schedule)
• International standards – CODEX Alimentarius

32. Plant Protection Profile (2006)

33. • Malaysia continues to implement the Good
Agriculture Practice as an effort to manage all
hazards associated with agricultural production
through such programs as the:
– SALM (Malaysian Farm Certification Scheme For Good
Agricultural Practice)
– SOM (Organic Certification Scheme).

34. • Non-legislative and other approaches:
– research into biopesticides by research institutions;
– implementation and promotion of integrated pest
management (IPM), such as the use of barn owls to
control rats in paddy fields;
– research into alternative pest control methods;
– introduction of better pesticide application technology;
and
– promotion of alternative farming methods, including
organic farming and hydroponics for the production of
vegetables.

36. Factors on Persistent Occurrence of Contamination
(Jinius Jipanin et al, 2001)
• The DOA does not have any authority to take legal action against
vegetable producers who do not comply with the standards
• Immigrant workers with high turn over rate
• The practice of profit-sharing in vegetable production between the
workers and the land owners.
– The land owners will provide all inputs, including PESTICIDES and
marketting, while the workers are responsible to produce as much
vegetable as possible.
– The owners and workers work independently but with the common aim
to maximise profit margins by whatever means.
– This factor led to PESTICIDE ABUSE.
• There is no proper control on the local vegetable marketing
network. Practically anyone can grow vegetables and sell.
• The current enforcement of the Food Act by the agency concern
have been very sparse and the operation does not deter the
potential pesticide abusers.

37. Factors on Persistent Occurrence of Contamination
(Jinius Jipanin et al, 2001)
• Farmer’s ignorant and misconduct:
– Ignorant of the biological aspects of insects and microbial
agents
– Unable to choose the correct type of active ingredient (a.i)
with regards to the pest problems.
– Failed to follow directions on labels like dosage, application
frequency and pre harvest interval (PHI).
– Unaware of other pest control techniques
– Wrongfully mixing a few active ingredients or “trademarks”
to produce a “cocktail”
• Most farmers prefer to use insectic ides in the
organophosphorus (OP) group regardless of their
toxicity and longer persistence in the environment
because these chemicals are highly effective in
knocking off the pests and are cheaper.

38. Thank you