Dr. Mahmoud Amr, Professor of Environmental Medicine at Cairo University who has supervised research on the health effects of agricultural pesticides in Egypt, expressed growing concern amongst scientists: "Our recent studies confirm our fears about the effect on workers, particularly of organophosphates (OPs), which attack the nervous system. OPs are widely used in Egypt, as are other insecticide groups-carbamates, pyrethroids and small quantities of organochlorines." As a result of their research, the faculty has advised the government on pesticide policy, and their work has contributed to raising awareness of pesticide hazards, and to reducing the amounts of pesticides imported and used in the country. Their studies indicate the extent of the problem.
Cotton
spraying
In a cotton growing
region, the health of 114 farmers who spray
cotton in the village of Tanan, Kalubia
Governorate was compared with a control group
from the same village. The farmers spray a range
of pesticides, predominantly OPs (malathion,
monocrotophos, profenofos, methamidophos,
chlormephos, chlorpyrifos, dimethoate, dicofol;
but also carbamates (methomyl, thiodicarb) and
pyrethroids (deltamethrin and cypermethrin).
Among the exposed group, 61% showed symptoms of
chronic pesticide poisoning in the form of
blurring of vision (experienced by 16.6%),
dizziness (14%), parasthesia (12%), numbness
(16.6%), headache (16.6%), asthenia (weakness)
(9.5%), arthralgia (joint pain) (12%), low back
pain (16.6%). Less than half (40%) reported no
symptoms.
Neurological
andpsychiatric effects
Furthermore 50% of
workers showed signs of neurological effects such
as superficial or deep sensory loss and decrease
or lost reflexes in their ankle or ankle and
knee(1). The longer the applicator had been
exposed to pesticides, the higher the incidence.
Superficial sensory loss was experienced by 36%
of farmers, compared to only 7% of the control
group.
A further study(2) of 175
pesticide applicators working on cotton confirmed
a far higher incidence of psychiatric
disorders-31% and 24% compared with 17% and 14.6%
in the control group. Many workers suffered from
a chronic depressive state, associated with at
least two of a number of symptoms: poor appetite,
insomnia, low energy or fatigue, low self-esteem,
poor concentration and feelings of hopelessness.
A general health questionnaire showed
significantly higher problems in the exposed
group, with 65% affected compared with 35% in the
control. The symptoms mirrored those in a study
of formulation workers (see below) by the same
authors.
Exposure in
formulation
In spite of significant
formulation in Egypt, safety levels in plants are
poor, and workers lack proper knowledge or
training in safe handling. Poor practices
observed include little attention to: ventilation
and air-conditioning facilities; regular and safe
disposal of pesticide formulation waste products;
protective clothing and daily showers. Workers
were shifted from one department to another
haphazardly, sometimes on a daily basis.
A study of psychiatric
disorders of 208 employees took place in two
formulation plants, one in the Nile Delta, about
100 km from Cairo (120 subjects) and an urban
plant 5 km. from Cairo (88 subjects). The rural
plant is well established and large, with 1200
employees formulating organochlorines, OPs,
carbamates and pyrethroids. The urban plant, with
600 employees, formulates OPs, carbamates,
pyrethroids and non-pesticide products. The study
revealed a high frequency of psychiatric
disorders and symptoms, particularly depressive
neurosis. Significant symptoms were irritability
and erectile dysfunction. Differences were more
pronounced in those exposed for 20 years or more.
A study of 300 workers for
neurological disorders in the same two plants
found significantly higher incidence of
polyneuropathy compared with matched control
groups(4). The most frequent symptoms were
sensory parasthesia (30%) (control group 14%) and
impotence (56%) (control group 4.7%). About
one-fifth of the workers displayed optic
neuropathy and diminution of visual acuity.
Workers complained of tremors and muscular
twitches. As with spray workers exposed,
neurological disorders were significantly higher
in those exposed for more than 20 years-52.6%
compared with 27.7%.
Cholinesterase
puzzle
Low cholinesterase
enzyme activity, an indicator of OP exposure,
affected nearly 37% of applicators in Tanan,
compared with 10.5% of the control group. However
there was no strong correlation between this low
activity and those with neurological symptoms,
suggesting that the enzyme is only an indicator
of exposure. Chronic inhibition of the enzyme may
result in tolerance to some of the acute
neurological symptoms, but may still result in
clinical illness. According to these studies,
long-term exposure to OPs does induce more severe
symptoms.
The work of the Faculty raises
questions about how much evidence is needed
before stronger action is taken to use
alternatives. (BD)
References
1. Amr, .M. et. al., Neurological effects of pesticides, study by the Industrial Medicine and Occupational Diseases Faculty of Medicine-Cairo University.
2. Amr, M.M., et. al., Screening for psychiatric morbidity in Egyptian pesticide applicators, Department of Occupational Medicine and Department of Psychiatry, Cairo University, Egypt.
3. Amr, M.M. et. al., Psychiatric disorders in Egyptian pesticide formulators, Department of Occupational Medicine and Department of Psychiatry, Cairo University, Egypt.
4. Amr, M.M., et. al., Neurological disorders among workers involved in pesticide formulation-Egypt, from Departments of Occupational Medicine, Neurology and Psychiatry, Faculty of Medicine, Cairo University.
These papers were presented at the 5th International Symposium of Neurobehavioural Methods and Effects in Occupational and Environmental Health., Cairo, 1994.
The International Development Research Centre (IDRC) of Canada has supported the Kasr El Aini Faculty of Medicine at the University of Cairo in its research into the effects of pesticides on human health in industry and agriculture and has awarded the Faculty a Citation in recognition of the major impact of their research on the health and economic well being in the region. The research has been supervised by Prof. M.M. Amr.
[This
article first appeared in Pesticides News No. 30,
December 1995, page 10]