Abstract |
The present study was designed to investigate the degree of environmental
deterioration through the detection of pesticides residues in agricultural products and
biological samples (human hair and urine), in order to explain the negative effects on
human health by chronic and widespread use of pesticides in the primary agricultural
sector, especially in the area of Ierapetra. The increase in health problems and in
particular the increasing trend in several types of cancer in the region and in other
European countries that follow intensive agricultural practices show an urgent need to
investigate the deterioration in public health.
This study tries to answers questions such as: the degree of contamination of human
population affected by the chronic and intensive use of pesticides (by detecting
organophosphate metabolites in biological samples, hair and urine) and the
consumption of agricultural products (by detecting common pesticides used in
agriculture). Also, the possible correlation between the detected levels in biological
samples of hair and urine was examined.
The main steps of this thesis was a)the detection of non-specific metabolites of
organophosphorus pesticides in hair and urine samples of rural and professionally
exposed population of Crete and b) the investigation of residual levels of pesticides in
fresh agricultural products. The results were analyzed and a total assessment of the
hazard exposure, on the population of Crete and especially in the area of Ierapetra,
was estimated. The detection of pesticides in agricultural products was focused
mainly on plant protection substances that are widely used in the area.
For the implementation of this study, hair and urine samples of sprayers and residents
of Ierapetra were collected. The sprayers involved in this study were employed in
greenhouse cultivations but they also involved themselves in sprays throughout the
year (n=34). The residents of the area of Ierapetra were people who lived in the area,
but not involved in agricultural activities (n=86). Because of the high rate of
organophosphates pesticides in the area of Ierapetra, the samples that were collected,
were analyzed by the technique of gas chromatography – mass spectrometry for the
detection of non-specific metabolites of organophosphates (dialkylofosfines,
dialkylphosphates DAPs). For the isolation of analytes from biological samples of
hair, the technique of solid-liquid extraction with methanol in an ultrasonic bath was
followed, while for the isolation of analytes from biological samples of urine the technique of liquid-liquid extraction with a mixture of diethylether:acetonitrile was
followed. The combined organic solvent from each sample was collected and
evaporated to dryness under a nitrogen blander after added 15mg K2CO3. The
resulting precipitate was followed by the derivatization procedure with 2, 3,4,5,6
pentafluorobenzyl bromide (PFBBr). To control methods for both hair and urine
samples various analytical parameters were calculated and found satisfactory.
Differences were observed between the detected concentration of metabolites and the
percentages of positive samples for both hair and urine samples between the two
studies groups (sprayers and residents of the rural area of Ierapetra).
As far as it concerns the results of the detected levels of non-specific
organophosphates pesticides differences were observed between the samples of
sprayers and the residents of the rural area of Ierapetra. Statistically significant
difference was observed for the metabolite DMP (p<0,001) and DETP (p=0,007).
This could be the result of the extensive past use of application of plant protection
substances of sprayers. The levels of metabolites DEP & DEDTP were higher for the
sprayers than that of the residents of the area but the differences were not statistically
significant (p>0, 05). The frequency of detection for the metabolites DMP, DEP and
DETP was quite high for both sprayers (91-100%) and the residents (93-100%). In
contrast, the frequency of detection for DEDTP was lower for both studies groups.
For all the detected metabolites, hair samples of sprayers gave significantly higher
levels than that of the residents (p<0,001).
Mean detected concentration of DAPs metabolites of urine samples of sprayers were
higher than that of the residents (p<0,001). A statistically significant difference was
observed between the two studied groups for DEP (p=0,005) and DETP (p=0,001).
The difference between the 2 groups for DMP & DEDTP was not statistically
significant (p=0,244 & p=0,193 respectively). The major difference shown in the first
dialkylfosfines in urine samples of sprayers can be attributed to the fact that the urine
of the participants were taken during spraying period. These facts makes them more
exposed at that time. This is confirmed by the analysis of the urine. The detection
rates of positive samples ranged from 90% to 100% for sprayers while for the
residents ranged from 83% to 100%.
Furthermore, representative samples of fresh agricultural products grown in the area
of Ierapetra were collected in order to analyze for the determination of residual
quantities of pesticides. Specifically, 45 tomatoes, 50 cucumbers, 60 peppers and 45 aubergines were collected and analyzed. For extraction, the samples followed the
QuEChERs method. The analysis was obtained by the technique of gas
chromatography – mass spectrometry GC-MS. None of the samples analyzed
exceeded the maximum residue levels (MRLs). Pesticide detection ranged from
11.1% (Carbendazim και Benomyl) to 22.2% (Oxamyl και Oxamyl-Oxine) for
tomatoes, from 6% (Tolyfluanid) to 24.0% (Spinosad A + D) for cucumbers, from
3.3% (Endosulfan a, Endosulfan b, Endosulfan sulfate) to 18.3% (Thiacloprid) for
peppers and from 8.9% (Cyprodinil και Thiacloprid) to 24.4% (Carbendazim και
Benomyl) for aubergines.
In summary, the management and control of the application of plant protection
substances is a necessary step by the actors as well as the producers. The
biomonitoring of sprayers, residents and consumers in general is a useful tool for
estimating the cost of using such products. The compliance with regulations is
necessary as well as with the basic safety standards but is not enough. Information
and awareness of all inputs is necessary and required by today’s society through
control, specialization and continuing education of those involved in agriculture.
|