Comparison of pesticide exposure and physical examination, neurological assessment, and laboratory findings between full-time and part-time vegetable farmers in the Philippines
Environ Health Prev Med
Comparison of pesticide exposure and physical examination, neurological assessment, and laboratory findings between full-time and part-time vegetable farmers in the Philippines
Jinky Leilanie Lu 0
0 J. L. Lu (&) National Institutes of Health, University of the Philippines Manila , P Gil Street, 1100 Manila , Philippines
Objectives This study aimed to compare the work practices and health effects of pesticide exposure between fulltime and part-time vegetable farmers. Methods Data was gathered via structured personal interview using a 9-page questionnaire, physical examination, and blood extraction for complete blood count and serum creatinine. Results Pyrethroid was the pesticide type most used by both groups. The risk for full-time farmers was related to both the amount of exposure and the type of pesticide. There were more full-time farmers who complained of falling ill because of work. This difference was statistically significant (P = 0.05). The level of those seeking medical attention was also significantly different between the two groups (P = 0.01). In assessing the individual components of the neurologic examination, 5.22% of full-time and 8.63% of part-time farmers had abnormal cranial nerve function, and 22 (5.7%) and 9 (6.47%) had abnormal motor strength. All farmers tested for reflexes, meningeals, and autonomics from both groups were normal. Based on hematologic examination, full-time farmers had higher mean values for creatinine, white blood cell, red blood cell, hemoglobin, and hematocrit. Activity of cholinesterase enzymes in blood can be utilized as a biomarker for the effect of organophosphates; of the 232 blood cholinesterase results, 94 (40%) were abnormal. Conclusion The study showed certain differences between full-time and part-time farmers in terms of farming practices and health-related problems. Education on safe pesticide use and handling and better health monitoring of the farmers are recommended.
Vegetable farmers; Farming practices; Pesticide exposure; Pesticide-related health problems; Full-time and part-time farmers
Agriculture is one of the primary economic sectors in the
Philippines, contributing about 20% of the gross domestic
product. Crops comprise about 47.56% of the total
agricultural sector and contribute about 510 billion pesos (USD
10.6 billion) to the country’s national income.
The majority of farmers in the Philippines still use
pesticides, some of them banned in more developed
countries. However, in Philippine agriculture, there is
increasing reliance on pesticide use without thought for its
deleterious effects on community, health, and environment.
Although alternative methods for pest control, organic
farming, and integrated pesticide management have been
initiated, they are not strongly sustained.
Given that there exists an inherent risk in these farming
practices, this paper attempts to elucidate differences in
farming communities of Benguet Province with differing
levels of pesticide exposure.
Benguet is a province in the northern portion of the
Philippines belonging to the Cordillera Administrative
Region. There are about 27.5 thousand farms covering
30,000 ha of agricultural land in Benguet. The province is
known as the ‘‘salad bowl’’ of the Philippines as its major
crops are tubers, roots and bulbs, and leafy vegetables,
stems, and flowers. Of the 27,000 farms present in Benguet,
14,349 are involved in tubers, roots, and bulbs; 11,515 are
involved in vegetables; and 9,868 are involved in legumes.
In 2005, Benguet was the top producer of broccoli and
carrots, producing about 1,200 and 13,700 metric tons,
contributing 87.4% and 81.4%, respectively, of the national
The crops grown in the study include mainly vegetables
such as cabbage, potato, carrots, wombok, lettuce, sweet
pea, onion leak, celery, beans, and tomato. The other major
crops of the Philippines, including rice, sugarcane,
coconut, corn, and banana, are grown elsewhere.
This study aimed to compare the health effects of
pesticide exposure between four municipalities identified as
having high exposure to pesticide and two municipalities
having low exposure to pesticides.
Materials and methods
Five hundred forty-two farmers from six communities
formed the target population: 73 from community 1, 104
from community 2, 52 were from community 3, 90 from
community 4, 73 from community 5, and 150 from
community 6. They were selected via cluster sampling.
Physical examination was carried out for 533
respondents. Complete blood count was done for 510
respondents, while serum creatinine was performed for 404
The full-time farmers consisted of communities 1 and 6
(both located in the central part of the province) and
communities 2 and 5 (both located in the northeastern part
of the province). They are identified as full-time farmers, as
farming is done as a full-time job, vegetable production is
produced for commercial purposes, and harvest is
yearround. The crops produced by this group included cabbage,
potato, carrots, wombok, lettuce, sweet pea, onion leak,
celery, beans, and tomato. Meanwhile, the part-time
farmers came from communities 3 (located in the
southeastern part of the province) and 4 (located in the
midwestern part). These are part-time farmers, as farming is a
secondary occupation, and vegetables are grown for
personal rather than commercial use, i.e., the farmers had the
side-job of seasonal vegetable harvesting. The crops
produced by this group included cabbage, lettuce, coffee, and
Data collection methods
Methods included structured survey interviews by field
workers, who interviewed farmers in situ using a prepared
questionnaire. The 9-page questionnaire contained
information on demographics, past and present medical
histories, family medical histories, obstetric and
gynecological history for females, pesticide use and practices, and
Physical, hematologic, and neurological examinations
were also carried out, adopted from the standard form used
by the National Poisons Control and Information Service
(NPCIS) of the UP-Philippine General Hospital in its
The physical examination, including examination of
various body parts (head, eyes, ears, nose, throat, oral
cavity, neck, lungs, heart, abdomen, extremities, and
integument), were performed by 20–30 doctors. The
neurologic examination assessed all cranial nerves (I–XII).
These cranial nerves were assessed by a neurologist by
classifying clinical findings as abnormal or normal.
For the hematologic examination, the following blood
indices were measured and mean readings were referenced
to the standard reading for such parameters: red blood
cells, hemoglobin, hematocrit, mean corpuscular volume
(MCV), mean corpuscular hemoglobin (MCH), mean
cellular hemoglobin concentration (MCHC), white blood
cells, platelets, creatinine clearance, and red blood cell
Table 1 presents the hematologic parameters measured
and their corresponding normal values. Blood extraction
was done by a licenced medical technician.
Hematocrit reflects concentration of packed red blood
cell (RBC) volume. It increases in cases of dehydration or
increased blood cellularity. mean corpuscular volume
(MCV) is an index of RBC size and is computed by
dividing the hematocrit by the RBC count. MCHC is the
average concentration of hemoglobin in a given volume of
red blood cells; MCH is the average weight of hemoglobin
of red blood cells. All three give an insight into the type of
anemia a person has, if present.
White blood cells are part of the immune system. Their
values tend to increase during infectious or allergic
processes and decrease in cases of typhoid fever; a decrease in
production by bone marrow can also occur secondary to
diseases such as neoplasm. Creatinine is a byproduct of the
metabolism of muscles and is produced in a constant
amount in the body. As such it is often used as a marker for
renal function, wherein its clearance is used to estimate the
glomerular filtration rate of the kidneys. Some pesticides
adversely affect renal function by producing acute tubular
Based on the blood parameters, certain types of anemia
were analyzed. Microcytic anemia is most commonly
caused by iron deficiency through inadequate intake, poor
absorption, excessive iron requirements or chronic blood
loss. Normocytic anemia is seen among patients
experiencing acute blood loss, hemolytic disorders or suffering
from a chronic disease.
Red blood cell cholinesterase was also measured in
this study. Two hundred thirty-two respondents submitted
for this examination while the others refused to
participate. Cholinesterase corresponds to two enzymes:
acetylcholinesterase and butyrylcholinesterase (also called
plasma cholinesterase). Activity of cholinesterase
enzymes in the blood can be utilized as a biomarker for
the effect of organophosphate and carbamate exposure.
The normal value for cholinesterase reference used is
D 0.75–1.0 ph/h.
Blood (10–15 ml) was extracted from each respondent for
blood cholinesterase, blood count, and serum creatinine by
a licenced medical technician. Blood vials were transported
on ice and analyzed within 24 h of extraction in the
The health and work practices data, including the
physical and neurological examinations and blood
examination results, were encoded and analyzed using SPSS 13.0
software. Data analysis included descriptive and inferential
Participants were informed about the nature of study,
including the research objectives, purposes, and goals.
They were also informed about the blood extraction
procedure and its purposes and risks. They have written
informed consent. Participants were also assured of data
confidentiality. The informed consent form was duly
approved by the Ethics Review Board of the University of
the Philippines-National Institutes of Health and
accompanied each interview schedule.
There were more males than females in both groups. The
full-time farmers (N = 398) had lower mean age than the
part-time farmers (N = 192): 46.67 ± 11.978 years and
48.44 ± 12.97 years, respectively. The full-time farmers
had an age range of 15–78 years, with the majority
belonging to the 36–50 years age range. The part-time
farmers had an age range of 21–78 years, with an almost
equal distribution of respondents belonging to the
36–50 years and 51–65 years age groups. Most of the
respondents for both groups were married (79.3% and
Household sizes ranged from farmers living alone to
families as large as 22 members for full-time farmers, and
12 for part-time farmers. Most had lived in their current
residence for more than 5 years (95.2% and 92.5%) with
the majority of full-time farmers living less than or equal to
about 50 m away from the plantation (44.3% and 35.8%).
Most of the respondents from both groups lived in homes
less than 50 m away from the highway. The demographic
profile of the two groups was similar, except for the age
distribution (P = 0.029), educational attainment (P =
0.001), number of household members (P = 0.039), and
distance from plantation (P = 0.001).
The majority of the respondents from both groups were
mainly agricultural workers (85–87%). The remaining 13–
15% were purely housewives, pesticide applicators, growers,
pesticide distributors, students or government employees.
There were a total of 831 and 266 pregnancies among
the female full-time and part-time farmers, respectively;
the majority of outcomes for both groups were full term
(92.06% and 98.12%). There were five preterm outcomes
among full-time female farmers compared with none
among part-time female farmers. Some congenital
abnormalities and pregnancy disorders reported among full-time
female farmers were microcephaly, mental retardation,
clubfoot, hydatiform mole, and ectopic pregnancy. There
were about 10 times more spontaneous abortions among
full-time female farmers than among part-time female
farmers. However, these differences were not statistically
significant (P = 0.99).
Pesticide use and exposure
Of full-time and part-time farmers, 96.5% and 95%,
respectively, were pesticide users. About 58.7% of
fulltime farmers and 46.8% of part-time farmers had family
members working with pesticides. For the full-time
farmers, 18.27% were under the age of 15 years, and for the
part-time farmers this value was 44.44%.
The majority of the farmers in both groups used
pyrethroids (71.1%, 73%). For full-time farmers, this was
followed by organophosphates (67.8%) and carbamates
(57%). For part-time farmers, carbamate (48%) was the
second most commonly used. Organophosphate was the
least used pesticide (31%). Other pesticides used by both
groups included organochlorides and nitrites (Table 2).
The two groups were similar in terms of pyrethroid,
carbamate, and other pesticide use. However, their use of
organophosphate was significantly different (P = 0.001),
such that about 2/3 of the full-time farmers used
organophosphate, while only 1/3 of the part-time farmers used it.
In terms of the specific active ingredients for each pesticide
type, Table 3 shows the usage by the two groups.
Both groups were similar in terms of pesticide use,
pyrethroid, carbamate, and other pesticide use, but differed
significantly in terms of organophosphate use (P = 0.001).
Organophosphate was used more frequently by the
fulltime farmers compared to the part-time farmers.
Full-time farmers spent a longer mean time of
110.33 min spraying per load of pesticide compared with
85.43 min for part-time farmers, this difference being
Farmers from both groups were involved in mixing,
applying or loading pesticides or combination of the
three. For full-time farmers, there were more farmers
involved in mixing (93.9%), while 88.6% of part-time
farmers were involved in either mixing or loading.
Practices were similar in the two groups except for
mixing (P = 0.045), which was more prevalent among
Most of the farmers from both groups used a knapsack
or backpack sprayer (88.2%, 88.98%). Of full-time
farmers, 11.8% used power sprayer, hand spray (0.5%), or
mechanical, tank or compressor sprayer (0.25% each).
Of the full-time and part-time farmers, 91% and 87.8%,
respectively, reported that they wore protective clothing
but, when itemized, the majority did not wear coveralls,
goggles, face shield or mask, or use respirators. Slightly
more than half (50.3%) of the full-time farmers and 1/3 of
the part-time framers used gloves. Of the full-time and
part-time farmers, 95% and 75%, respectively, used boots.
Both groups differed significantly in their use of face mask,
gloves, and boots.
Farmers from both groups used makeshift protective
clothing in the form of a handkerchief around the face, hats
or bonnets, jackets or pants used as arm covers, shirts used
alone or wrapped in plastic, or raincoats or plastics.
There are also practices that should be done after
pesticide use to minimize risk of intoxication or poisoning.
Such practices include washing of hands, keeping a
distance from recently sprayed areas (especially if the area is
poorly ventilated), and avoiding spraying against the wind
N = 376
Slightly more than half (53%) of the full-time farmers,
and approximately 2/3 (64.22%) of the part-time farmers
used contaminated cloth to wipe sweat from their faces.
This difference between the two groups was significant
(P = 0.031). Of the high- and low-exposure groups, 31.7%
and 36.3%, respectively, reentered recently sprayed areas.
Used pesticide containers were either buried (34.8%),
thrown away (31.4%), sold (20.2%) or burned (6.9%). The
majority of the farmers from both groups buried the used
pesticide containers, followed by destroying or throwing
the container away. Of full-time farmers, 20.2% sold the
pesticide container, while 12.8% of the part-time farmers
burned it. Other respondents from both groups kept their
pesticides in storage areas, while the remaining left them
either beside or inside the house; in the backyards, garden
or fields; or stored the used containers inside their
storehouses. The two groups differed significantly in terms of
disposal method for used pesticide containers. More
fulltime farmers sold or destroyed their used pesticide
containers than did part-time farmers. In contrast, there was a
higher percentage of part-time farmers who burned or
buried their used pesticide containers.
Pesticide exposure and illness
The difference between the full-time and part-time farmers
is shown in Table 5. There were more full-time farmers
who complained of falling ill because of work. This
difference was statistically significant (P = 0.05). However,
only about 31% of the full-time farmers, and 17% of the
part-time farmers reported receiving or seeking medical
attention for their illness and/or exposure; this behavior
Statistically significant difference at P = 0.05
Statistically significant difference at P = 0.01
Statistically significant difference at P = 0.01
Statistically significant difference at P = 0.05
Statistically significant difference at P = 0.01
was significantly different between the two groups
(P = 0.01).
Exposure commonly occurred in the farm or field (65%
for high-exposure, 55% for low-exposure groups). The
majority of the farmers from both groups were exposed to
insecticides, and the two groups were significantly different
in this regard.
Muscle pain was the most common general symptom felt
by both groups of farmers. This was followed by weakness
and easy fatiguability. Paresthesia and localized
fasciculation were the top motor symptoms experienced by the
full-time farmers, with 9.8% affected by each symptom,
followed by tremors (7.8%) and convulsion (5.6%). For the
part-time farmers, localized fasciculation was the top
motor symptom, followed by paresthesia and tremors.
Physical and neurologic examination
Two hundred and seventy-nine (69.8%) of the full-time
farmers, and 100 (71.94%) of the part-time farmers had
at least one abnormal physical examination finding.
However, only 42.6% of the full-time farmers, and 35.8%
of the part-time farmers had an abnormal clinical
diagnosis. Both groups were similar in all physical
examination findings except for the nose, throat, chest, and
lungs (P = 0.05).
A neurologic examination was conducted. Of the
fulltime and part-time farmers, 22 and 2, respectively, had
abnormal neurologic diagnosis.
In assessing the individual components of the neurologic
examination, 5.22% of the full-time farmers, and 8.63% of
the part-time farmers had abnormal cranial nerve function.
Of the full-time and part-time farmers, 22 (5.7%) and 9
(6.47%), respectively, had abnormal motor strength. All
individuals tested for reflexes, meningeals, and autonomics
from both groups were normal. Three out of 139 part-time
farmers had cerebellar dysfunction characterized by
dysmetria, inability to walk with feet in tandem, and difficulty
Similar to the results in health symptoms, most of the
farmers had normal physical examination findings. A
physical examination at any one point in time is a
crosssection of a person’s physiological make-up at that
particular time. Most of the symptoms that the respondents
reported had occurred in the past. Likely, any abnormalities
associated with acute pesticide exposure had resolved prior
to the physical examination.
The hematologic examination revealed that the full-time
farmers had higher mean values for creatinine (89.6 vs.
86.4 lmol/L), white blood cell (7.4 vs. 7.0 G/L), red blood
cell (5.2 vs. 4.7 T/L), hemoglobin (148.4 vs. 147.7 g/L),
hematocrit (0.429 vs. 0.415 L/L), MCH (31.2 vs. 31.1 pg),
MCHC (351.5 vs. 350.4 g/L), and platelets (278 vs. 263 G/
L). MCV was slightly higher for part-time farmers (88.7 fl)
than for full-time farmers (88.2 fL) (Table 6).
About 20 full-time farmers (mean reading 148.43 g/L)
and 7 part-time farmers (mean reading of 146.68 g/L) had
low hemoglobin. About 65% and 57.14%, respectively, had
microcytic anemia, as evidenced by corresponding low
MCV and low MCH values. Around 15% and 14.29%,
respectively, had normocytic anemia, with low hemoglobin
but normal MCV and MCH values.
Among the farmers, however, most of those with anemia
at the time of extraction did not exhibit pancytopenia,
making aplastic anemia an unlikely diagnosis.
Increases in hemoglobin, hematocrit, and RBC may
reflect polycythemia secondary to high altitude. Benguet
province is 2000 m above sea level at its highest peak. As
altitude increases, atmospheric pressure decreases. This
means that the oxygen pressure in air also decreases, which
in turn leads to a decrease in the capacity of red blood cells
to bind oxygen. The human body adapts to this by
increasing the volume of erythrocytes or red blood cells.
This in turn increases hemoglobin and hematocrit as well.
Creatinine is a byproduct of the metabolism of muscles
and is produced in a constant amount in the body. As such
it is often used as a marker for renal function, wherein its
clearance is used to estimate the glomerular filtration rate
of the kidneys. Some pesticides adversely affect renal
function by producing acute tubular necrosis. Creatinine
clearance ranged from 6.6 to 957 mL/min with mean of
89.6 mL/min for the full-time farmers, and it ranged from
27 to 171 mL/min with mean of 86.4 mL/min for the
Of the 232 blood cholinesterase results, 94 (40%) were
abnormal (Table 7). The normal value for cholinesterase
reference used is D 0.75–1.0 ph/h.
Worldwide there are numerous studies documenting the
relationship between farming practices, pesticide use and
exposure, and its effect on farmers’ health. The health and
environmental impacts of pesticide exposure to Filipino
farmers have been correlated both here and abroad [
The full-time and part-time farmers groups were similar
in demographics, with the majority of respondents in both
groups falling between the ages of 36–50 years, and being
married. Most from both groups lived in households with
Abortive outcomes among pregnant women are affected
by a variety of factors. These factors may include poor
prenatal care, inaccessible health facilities, infectious
diseases, and chromosomal and genetic abnormalities. Direct
and indirect exposure to pesticides by both pregnant
women and their husbands have been implicated in a wide
variety of adverse reproductive effects including
disturbances in the menstrual cycle, reduced fertility,
spontaneous abortion, developmental defects, and stillbirths [
In this study, there were 10 times more abortions among
full-time farmers compared with among part-time farmers.
Among women exposed to pesticides, the risk for
spontaneous abortion increases with exposure anytime before or
after conception [
Pesticides have adverse effects and their effects may be
potentiated in children. It is disturbing that there are still
9% of children below the age of 15 years who work with
and therefore are directly exposed to pesticide in this study.
Guillette et al. [
] conducted a study on effects of pesticide
exposure on preschool children in Mexico. Children who
were exposed had less generalized physical endurance,
decrease in ability to catch a ball, lesser fine eye–hand
coordination, and difficulty grasping the concept of
repeating numbers, of 30 min recall, and of ability to draw
About 95% from both groups used pesticides. While
more than 3/4 from both groups received instruction on
pesticide use, understanding and practice seemed to be a
different matter. Both groups were different in terms of
organophosphate exposure. In the study of Clarke et al. [
in Ghana, organophosphates were the most commonly used
pesticides, followed by carbamates and organochlorides.
The same trend was seen among farmers in Sri Lanka and
The use of personal protective equipment (PPE) is
encouraged by the Department of Agriculture, but the
practice is not strictly enforced. Of the PPEs, the groups
differed significantly in their use of face mask, gloves, and
boots. Proper protective clothing was replaced by
makeshift items such as handkerchiefs, hats or bonnets to cover
the face, old shirts, and jackets or pants used as arm covers,
which may not actually protect the farmers. Different
studies have already been published to investigate the use
of PPE during pesticide use. Most often, gloves are the
most commonly used PPE because hands are the most
exposed areas, often associated with poor hand-washing
practices after pesticide activities [
farmers still failed to employ protective equipment
themselves. Cheng and Bersamina  conducted a previous
study of the hazardous effects of pesticides in the farming
community of Benguet. In their study with 2000
respondents, 5% wore boots and no respondents wore the other
PPEs. Reasons cited by the farmers included that these
protective gears are more of a hindrance than a help.
Other practices that increased the risk for possible
pesticide exposure were spraying against the wind (as less than
a half of them do) and reentering recently sprayed areas.
Spillage of pesticides, from either a defective backpack
sprayer while spraying the pesticide or while mixing it, was
also a risk factor for exposure. However the two groups
were similar in this regard.
Although there are no significant differences in exposure
of family members to pesticide, it remains alarming that
family members, even the young, were exposed to or in
contact with chemicals.
In terms of symptoms, muscle pain was the most
common symptom experienced by the farmers from both
groups, followed by muscle pain. For full-time farmers,
weakness (62.4%) and easy fatiguability (53.96%)
followed next. This is consistent with existing data on
selfreported symptoms of farmers exposed to pesticides.
Dizziness, headache, skin irritation, and burning sensation
on the face are common self-reported symptoms by farmers
in Malaysia, Ghana, the Gaza Strip, and Tanzania [
Among the farmers, tears or eye redness are also common,
as well as nausea and salivation for gastrointestinal
symptoms. Farm workers exposed to pesticide usually
complained of wheezing and breathlessness . Some
respiratory problems such as chronic bronchitis and asthma
have also been associated with pesticide use [
Pesticide poisoning in agricultural areas may be more
chronic than acute and the symptoms of chronic
intoxication may be so nonspecific as to be nonattributable by the
farmer to pesticide exposure.
However, both groups in this study were significantly
different in neurologic diagnosis such that full-time
farmers had significantly more abnormal cases than part-time
farmers. If this is related to pesticides, it may because
fulltime farmers used organophosphates more than part-time
farmers, as these pesticides are known neurotoxic agents.
Of full-time and part-time farmers, 20 and 7,
respectively, had anemia (low hemoglobin). In Thailand,
pesticide use has been correlated with occurrence of aplastic
anemia. Aplastic anemia is defined as total reduction in
blood cells with corresponding hypocellular marrow. There
is an estimated relative risk of 2.1 for organophosphates
and 6.4 for DDT and 7.4 for carbamates [
The study also showed that 40% had abnormal red blood
cell cholinesterase reading. The activity of cholinesterase
enzymes in the blood can be utilized as a biomarker for the
effect of organophosphates. An exposed person will show
abnormally low levels of activity of cholinesterase
enzymes measured in the serum or in red blood cells (as
RBC cholinesterase). The latter is more closely correlated
with cholinesterase activity in the nervous system [
This study has shown differences in pesticide use, farming
practices, and health conditions between full-time and
parttime farmers. Full-time farmers manifested more abnormal
health findings compared with part-time farmers.
There were more full-time farmers who complained of
falling ill because of work. This difference was statistically
significant (P = 0.05). The level of seeking medical
attention was also significantly different between the two
groups (P = 0.01).
Based on hematologic examination, full-time farmers
had higher mean values for creatinine, white blood cell, red
blood cell, hemoglobin, and hematocrit. Of full-time and
part-time farmers, 20 and 7, respectively, had anemia (low
hemoglobin). Of 232 blood cholinesterase results, 94
(40%) were abnormal.
Further studies are needed to elucidate the differences in
symptomatology and neurophysical examination findings
between full-time and part-time farmers. Although both
groups showed a high percentage who had received
instructions on proper pesticide use and application, there
still exist discrepancies in practices among farmers.
Important among these are the use of makeshift PPEs,
which the farmers utilize in the belief that they are
adequate protection when in fact they may promote further
exposure to pesticides.
Acknowledgments This project was funded by the Department of
Science and Technology through the Philippine Council for Health
Research and Development.
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