How manufacturing processes affect the level of pesticide residues in tea

Article (PDF Available)inJournal of the Science of Food and Agriculture 84(15):2123 - 2127 · December 2004with212 Reads
DOI: 10.1002/jsfa.1774
Abstract
Tea (both green and black) is consumed throughout the world, both for pleasure and therapeutic purposes. Most people will be unaware of their involuntary exposure to residues of pesticides lingering in processed tea and so possibly transferring into infusions of tea. The purpose of this work was to study the effect of green tea and orthodox black tea manufacturing processes on the fate of pesticides sprayed onto tea bushes (Camellia sinensis). The fates of residues of dimethoate, quinalphos, dicofol and deltamethrin in these two different types of tea manufacturing processes were compared. For black tea, the manufacturing process involves leaf harvesting, withering, rolling, fermentation and drying; and for green tea, leaf harvesting, microwave heating, rolling and drying. The two processes resulted in the same concentration factor of plant material into the dried commodity, while the decreases in residue levels were different for different pesticides. Initial microwave heating and dehydration in the green tea manufacturing process resulted in greater loss of pesticide residues than did withering and dehydration in black tea; no significant reduction in residue level resulted from the rolling and fermentation steps in black tea. Residue levels in both green and black teas were reduced during final drying. Copyright © 2004 Society of Chemical Industry
Journal of the Science of Food and Agriculture J Sci Food Agric 84:21232127 (online: 2004)
DOI: 10.1002/jsfa.1774
How manufacturing processes affect the level
of pesticide residues in tea
Chitra Sood, Shivani Jaggi, Vipin Kumar, SD Ravindranath and Adarsh Shanker
Hill Area Tea Science Division, Institute of Himalayan Bioresource Technology, Palampur-176061, Himachal Pradesh, India
Abstract: Tea (both green and black) is consumed throughout the world, both for pleasure and therapeutic
purposes. Most people will be unaware of their involuntary exposure to residues of pesticides lingering
in processed tea and so possibly transferring into infusions of tea. The purpose of this work was to
study the effect of green tea and orthodox black tea manufacturing processes on the fate of pesticides
sprayed onto tea bushes (Camellia sinensis). The fates of residues of dimethoate, quinalphos, dicofol
and deltamethrin in these two different types of tea manufacturing processes were compared. For black
tea, the manufacturing process involves leaf harvesting, withering, rolling, fermentation and drying; and
for green tea, leaf harvesting, microwave heating, rolling and drying. The two processes resulted in the
same concentration factor of plant material into the dried commodity, while the decreases in residue
levels were different for different pesticides. Initial microwave heating and dehydration in the green tea
manufacturing process resulted in greater loss of pesticide residues than did withering and dehydration
in black tea; no significant reduction in residue level resulted from the rolling and fermentation steps in
black tea. Residue levels in both green and black teas were reduced during final drying.
2004 Society of Chemical Industry
Keywords: pesticides; tea; processing
INTRODUCTION
Tea has long been consumed for its stimulating effect
and medicinal properties, but drinking a cup of tea
containing residues of pesticides used in growing and
maintaining the tea bushes is not desirable. Both green
tea and orthodox black tea are made from leaves of the
same plant (Camellia sinensis). Because tea producers
have striven to increase yields from their crops,
cultivation practices have become more intensive.
The tea industry uses integrated pest management
practices in which the use of pesticides is an essential
part. However, the pesticides, which are known toxic
compounds, are likely to leave residues in the final
product that is made into tea.
Tea cultivation in Kangra valley of Himachal
Pradesh (India) began in the mid-19th century.
1
Orthodox black and green teas produced from Kangra
tea plantation with their specific aroma and flavour are
some of the best quality teas in the world. This study
was undertaken to evaluate and compare the effect
of the two tea manufacturing processes, green tea
and orthodox black tea, on pesticides sprayed on tea
bushes. The main difference in the processing of green
tea and black tea is the prevention of fermentation of
the former by initial heat inactivation of the polyphenol
oxidase enzyme present in the tea shoots. Degradation
of pesticides in the green leaf takes place at the time
of manufacturing through evaporation and thermal
decomposition.
2
Tea is produced from young tender shoots, and
the surface area of leaves per unit weight in tea is
much higher than in other crops. Therefore, pesticide
deposition on tea leaves will also be higher than
that found on other crops when applied at the same
dosage.
3
However, the residue problem in the case of
tea may not be as severe, since pesticides applied on
tea bushes are lost during the manufacturing process
and also as a result of natural factors like rainfall,
dew, evaporation, photolysis, biodegradation, growth
dilution, etc,
4
and the time lapse between the spraying
of the pesticides and harvesting of the tea leaves.
5
Fresh green tea leaves (two and a bud), after plucking,
are subjected to a manufacturing process that involves
steps such as withering, rolling and drying. There
are chances for loss of pesticide in all the steps of
conventional manufacture. For black tea the leaves
are withered under a gentle hot air stream which
results in a major weight loss, and then subjected to
mechanical rolling, fermentation and drying.
Tea is finally dried at a temperature higher
than 100
C and, at this temperature, thermal
decomposition of some of the pesticides is significant.
Correspondence to: Adarsh Shanker, Hill Area Tea Science Division, Institute of Himalayan Bioresource Technology, Palampur-176 061,
Himachal Pradesh, India
E-mail: adarsh
shanker@yahoo.com
IHBT Communication number 2110
Contract/grant sponsor: Council of Scientific and Industrial Research, India
(Received 15 June 2001; revised version received 21 August 2003; accepted 1 March 2004)
Published online 1 September 2004
2004 Society of Chemical Industry. J Sci Food Agric 0022 5142/2004/$30.00 2123
C Sood et al
Furthermore, the drying process produces a concen-
tration factor of four in tea. Therefore, theoretically
the pesticide residues in tea shoots at harvest time
could increase by this same concentration factor in
made tea if they are not lost during the manufacturing
process. Chen and Wan
6
have reported 3060% pes-
ticide residue reduction in tea during manufacturing
processes, mainly during drying. A similar decrease
in pesticide residues in fresh fruits processing is also
cited in the literature.
7–9
The effect of cooking on
organophosphates has been reported by several groups
of workers.
2,10 12
In line with the above background, the objective
of this research was to investigate the loss/stability of
pesticide residues during the manufacturing of both
green and black teas. The pesticides approved for
use on tea are of three groups and representatives of
these were selected for study, on the basis of their
diverse properties and wide use in the tea industry:
quinalfos, dimethoate (organophosphates), dicofol (an
organochlorine) and deltamethrin (a pyrethroid).
EXPERIMENTAL
Stages involved in orthodox black and green tea
manufacturing
Orthodox black and green tea were manufactured in
the laboratory’s mini-manufacturing unit following the
standard manufacture procedure used in India.
Orthodox black tea
Green leaf Fresh green tea leaves (two and a
bud) were plucked by hand
and subjected to the further
processing stages.
Withering
(Step I)
The leaves (moisture free shoot)
were spread on withering
troughs and allowed to wither
artificially by means of
conditioned air at 30 35
C
for 1520 h to achieve
50 55% withering.
Rolling (Step II) Withered leaves were rolled to
twist and rupture the tissue to
express the juice. Rolling was
done using a piezy roller
(Punjab Engineering Ltd,
Jorhat Assam, India) for about
30 min with pressure.
Moisture content of the leaf
did not change after rolling
and remained more or less the
same as that of withered leaf.
Fermentation
(Step III)
For fermentation, the orthodox
‘dhool’ after roll breaking was
spread in thin layers and
allowed to undergo oxidation
for 12 h at 2530
Cand
95% RH.
Drying
(Step IV)
Fermented ‘dhool’ was then
dried in tea drier using hot air
at 100 ± 5
C to a final
moisture content of 23%.
Green tea
Green leaf Undamaged fresh green leaves (two
and a bud) were selected for
making green tea.
Microwave
heating
(Step I)
Green leaves were exposed to
microwave energy by using an
optimum super-high frequency of
2450 MHz (Model T-23 of
Kelvinator India Ltd, Mumbai,
India) for 3 min and then cooled
to room temperature. The leaves
remained green and appeared dry
without surface moisture
Dehydration
(Step II)
The leaves were dried in a current
of warm air at 6575
Cto
achieve 45% moisture.
Rolling
(Step III)
Rolling with a conventional piezy
roller for 20 min at different
pressures resulted in well-twisted
green leaves.
Drying
(Step IV)
The rolled leaves were then dried in
a drier using hot air at 95100
C
to a final moisture content of
5–6%.
Model system
A model experiment was used to evaluate the effect of
the drying process itself, ie the volatility and thermal
degradation of pesticides deposited onto the leaves.
Known amounts of standards of the pesticides under
study (dissolved in acetone), at concentrations similar
to those found in green tea shoots 24 h after spraying,
were placed into two screw-capped vials: one with
a hole in the cap and the other with a closed cap.
The vials were then subjected to the drying conditions
described above for leaf drying (Step IV).
Reagents and apparatus
The standards were obtained from Sigma Chemical
Co (St. Louis, USA) (purity >98%). All other solvents
and chemicals used were of analytical reagent grade
from E-Merck (Merck India, Mumbai, India).
The gas chromatograph was a Hewlett-Packard,
Wilmington, DE, USA 5890 series II with an
autosampler, nitrogen-phosphorus detector (NPD)
and electron-capture detector (ECD).
Quinalfos and dimethoate were detected with NPD
on a HP-1 fused silica gel capillary column (30 m
length × 0.25 mm id ×0.25
µm film thickness).
The operating conditions were: injector temperature,
220
C; detector temperature, 200
C; oven temper-
ature, held at 150
C for the initial 2 min and then
ramped at 10
Cmin
1
to 300
C and held for 5 min;
carrier gas, nitrogen with flow rate 20 ml min
1
; injec-
tion volume, 2
µl.
2124 J Sci Food Agric 84:2123 2127 (online: 2004)
Pesticide residues in tea
Dicofol and deltamethrin were detected with ECD
on a methyl silicone coated fused silica capillary
column (25 m length × 0.2 mm id, 0.25
µmfilm
thickness). The operating conditions were: injector
temperature, 250
C; detector temperature, 300
C;
oven temperature, held at 200
C for the initial
5minandthenrampedat4
Cmin
1
to 280
Cand
held for 10 min; carrier gas, nitrogen with flow rate
2.0 ml min
1
; injection volume, 2 µl.
Quantification of pesticides
Quantification of pesticides was accomplished using
standard curves prepared by diluting the stock
solutions in acetone to levels at which good linearities
were achieved in the range of 0.15 ppm with a
coefficient of correlation between 0.9991 to 0.9998.
Before laying of the experiments in the field, recovery
studies were performed at 1, 2 and 5 mg kg
1
of
fortification levels of active ingredient (five replicates)
of each tissue type (green leaves, rolled, fermented and
dried). These samples were prepared by adding known
amount of standard into tissues before extraction.
The extraction was carried out as described below
and duplicate injections of each extract were made
in the gas chromatograph. The performance of the
instrument was cross-checked by the injection of
standard (5mgkg
1
) before and after the end of the
sample runs. Recoveries were measured by comparing
average peak areas with external standards in acetone
and matrix matched controls which were prepared
from unfortified tea extracts. The recoveries obtained
for all tissue types were more than 90%.
Field trials
For field trials, a random block scheme was adopted
and each block contained 100 bushes (10 × 10).
Pesticides under study were sprayed (spray volume
400 l ha
1
) by a Knap-Sack sprayer. In normal tea
manufacturing, the leaves are harvested 710 days
after the application of pesticides. However, in the
present study, the sampling was done 24 h after
spraying to allow maximum possible assimilation of
pesticide by the plant; 2 kg of green tea shoots were
collected for analysis.
Sample preparation
After thoroughly mixing the sample, subsamples (five
replicates of 10 g each) were analysed for pesticide
residues and the remaining part was subjected to the
two different manufacturing processes of black and
green teas. At each step, the same quantity of the
sample was separated and analysed.
Extraction and clean-up procedure
The pesticides were extracted and cleaned up using
a modification of Luke’s method.
13
Pesticides were
extracted from tea leaves (10 g in five replicates) at
different manufacturing stages with 150 ml of acetone.
The extract was shaken mechanically with solvent
for 1 h. The extraction mixture was vacuum filtered
through Whatman No 1 filter paper, the cake was
washed twice with 20 ml solvent each time, and
the combined filtrate was transferred to a 250-ml
volumetric flask and made up to volume. A 20-ml
aliquot was then transferred to a 250-ml separatory
funnel containing saturated sodium sulfate solution.
The pesticides dimethoate and quinalfos were re-
extracted three times with 80 ml of dichloromethane,
and the extract was concentrated to near dryness at
40
C in a Flash evaporator. The residue was dissolved
in 5 ml of n-hexane and passed through a 4-cm layer
of activated (at 135
C) silica gel column (30 cm
length with 2.5 cm id) topped with 1 cm of anhydrous
sodium sulfate. The column was pre-conditioned with
50 ml of n-hexane before transferring the extract
to it and eluting with 50 ml of dichloromethane
and twice with 50 ml dichloromethane and n-hexane
(15 + 85 v/v). The combined eluate was evaporated to
dryness and reconstituted in 2 ml of acetone for gas
chromatography (GC) injections with autosampler.
Dicofol and deltamethrin were re-extracted three
times with 80 ml of n-hexane, concentrated to 5 ml
and the cleanup procedure was as used for the other
pesticides. The pesticides were eluted with 200 ml of
n-hexane, evaporated to dryness and reconstituted in
2 ml of acetone for GC injection.
RESULTS AND DISCUSSION
Tea shoots with deposited pesticides were submitted
to different steps during tea processing. Withering
in black tea production is replaced by heating
(microwave) in green tea. The effect of the latter
plays a very important role in reducing the pesticide
residues. Furthermore, due to loss of water during
processing, there is an increase in weight concentration
(four-fold) so that the amount of pesticide should
increase by a similar factor. However, during the
drying process the water contained in the tissue
could entrain pesticide molecules (codistillation) while
heat could cause evaporation and degradation. The
resulting decrease is mainly due to these three factors,
ie evaporation, degradation and codistillation.
9
The chances of the residue diminishing could be
greatest during drying as it might facilitate pesticide
distillation during water evaporation.
5
Each pesticide
could be distilled in different amounts in accordance
with their physico-chemical properties, such as vapour
pressure (Table 1). Compounds with high vapour
pressure degrade faster from sprayed plant tissue thus
leaving lower levels of residue during manufacture.
Furthermore, preliminary studies showed that the two
organophosphates used in the present study had some
degree of degradability, volatility,
9
pH stability
2
and
elevated temperature hydrolysis.
14
Mentioned above
are some of the basic principles that would help
in understanding the behaviour of pesticides during
manufacturing. Since the recommended dosages are
different for different pesticides on tea crop, the
data is presented on the basis of percentage loss of
J Sci Food Agric 84:2123 2127 (online: 2004) 2125
C Sood et al
Table 1. Properties of the pesticides under study
Pesticide
Water
solubility
(mg l
1
)
Vapour
pressure
(mbar)
Half-life
on tea
(days)
Melting point
(
C)
Boiling point
(
C)
Dimethoate 25 000 1 × 10
5
0.9 51 117
Quinalphos 22.0 4 × 10
6
1.2 3132 142
Dicofol 0.8 0.0 3.9 78.579.5 180
Deltamethrin 0.002 2 × 10
8
3.2 98109 Decomposes on distillation
Table 2. Percentage of pesticide residue left during orthodox black tea manufacture
Pesticides
Green tea
leaves
Step I
withering
Step II
rolling
Step III
fermentation
Step IV
drying
Dimethoate 100 52.0 ± 3.248.0 ± 1.648.0 ± 3.330.5 ± 2.4
Quinalphos 100 42.5 ± 2.641.6 ± 2.242.8 ± 5.036.0 ± 3.0
Dicofol 100 66.0 ± 6.064.0 ± 4.564.9 ± 6.248.0 ± 0.8
Deltamethrin 100 84.0 ± 4.084.2 ± 4.283.2 ± 4.868.0 ± 4.0
Table 3. Percentage of pesticide residue left during green tea manufacture
Pesticides
Green tea
leaves
Step I
microwave heating
Step II
dehydration
Step III
rolling
Step IV
drying
Dimethoate 100 45.0 ± 2.239.8 ± 2.440.6 ± 1.823.4 ± 0.8
Quinalphos 100 46.0 ± 4.636.6 ± 1.436.2 ± 1.028.6 ± 1.5
Dicofol 100 50.0 ± 5.547.0 ± 3.848.2 ± 3.036.6 ± 2.0
Deltamethrin 100 76.0 ± 7.070.5 ± 4.468.8 ± 4.556.2 ± 3.2
pesticides during manufacturing and take into account
the concentration factor.
Table 2 and 3 show the effect of different process-
ing conditions on the persistence of different pesticides
used in the present study. The residues of dimethoate,
the only systemic insecticide selected for the study,
showed the highest rate of disappearance. It decreased
to 30.5% in black tea and 23.4% during green tea
manufacture. It was observed that rolling and fermen-
tation (Steps II and III) in black tea manufacturing did
not contribute to any significant increase or decrease
in pesticide level. However, Step I resulted in 52.0%
(loss 48.0%) of dimethoate residue in black tea and
45.0% (loss 55.0%) in green tea, respectively. The loss
during withering (Step I of black tea) may be attributed
to the processing time and fugacity of dimethoate in
black tea and of heat treatment in the case of green
tea. Withering for 18 h in hot air (3040
C) may
result in codistillation of pesticide owing to its volatil-
ity and water solubility. Moreover, depending on the
distribution of the pesticides that are adhered to the
outside of the crop or translocated into the crop tissue
(systemically in case of dimethoate), the dissipation
rate of pesticides from the crop may not be same.
The higher decrease in pesticides during microwave
heating (Step I of green tea) is because most of the
pesticide would be released along with escaping water
as the microwave caused heating from the cores of
the particles. Dehydration (Step II) during green tea
processing reduced the residues further to 39.8%.
During final drying of rolled teas, a similar pattern of
degradation was obtained for both the processes as the
nature of treatment was same.
Quinalphos residues were reduced to 36.0 and
28.6% during black and green tea manufacturing,
respectively. However, during Step I (withering or
microwave heating), the fairly low vapour pressure
of quinalphos compared with dimethoate resulted
in residue deposits of 42.5% in withered leaves
under black tea processing. It remained at 46.0%
as residue deposit after initial heat treatment of green
tea processing and was further reduced to 36.6%
after dehydration (Step IIgreen tea). The overall
loss in the residues of the two pesticides may be
attributed to the coupled effect of thermal stability
and vapour pressure of the two pesticides, ie the
percentage loss of dimethoate due to evaporation
could be more than of quinalfos which is more liable to
thermal degradation, as is evident from their properties
(Tables 2,3).
In the case of dicofol, the different steps involved
in the manufacture of black or green tea resulted in
a product which had 48.0 and 36.6%, respectively,
of the initial deposited pesticide and, during Step
I, the residue was 66% in black tea and 50% in
green tea manufacture. The high vapour pressure
of dicofol resulted in greater thermal degradation
than evaporation. In the case of deltamethrin, the
decrease in residues observed was lowest, (32.0%)
and (43.8%) during black tea and green tea
manufacturing, respectively, compared with other
pesticides under study. Volatilization is the major
2126 J Sci Food Agric 84:2123 2127 (online: 2004)
Pesticide residues in tea
Table 4. Model system to study the effect of drying
Percentage left (loss)
Pesticides
Closed screw-cap vial
(thermal decomposition)
Open screw-cap vial
(evaporation)
Dimethoate 40.0 ± 4.0 (60.0) 32.8 ± 1.6 (67.2)
Quinalphos 36.6 ± 3.2 (63.4) 42.2 ± 2.4 (57.8)
Dicofol 55.4 ± 1.6 (44.6) 76.2 ± 3.8 (23.8)
Deltamethrin 86.2 ± 4.2 (13.8) 54.0 ± 5.2 (46.0)
pathway of dissipation for deltamethrin. The longer
half-lives and water insolubilities of these two
prevent them from faster degradation than the
organophosphates used.
Since maximum loss of pesticide occurred during
heating, the effect of drying was studied in a model
system to test the assumptions made on the behaviour
of pesticide loss. An experiment was carried out in
open and closed screw-cap vials to see the effect of
evaporation and thermal decomposition (Table 4).
For dimethoate and quinalphos, loss of pesticide
was observed in both the vials but the loss due
to evaporation in the former was higher (67.2%)
than the loss due to thermal decomposition (60.0%).
The reverse was true for quinalfos where thermal
decomposition and evaporation resulted in 63.4 and
57.8% loss, respectively, and the pesticide proved it to
be thermally weaker than dimethoate (Table 1). The
combined effect of the two factors described above,
must have resulted in relatively similar residue losses
in dimethoate and quinalfos despite the differences in
their nature.
Deltamethrin was thermally less degradable as the
pesticide loss was 13.8% while considerable loss
(46.0%) was observed during evaporation. However,
decrease in the dicofol residue due to its thermal
instability (44.6%) exceeded the loss observed due to
evaporation (23.8%) (Table 4).
If no losses occurred during manufacturing, the
residue levels of various pesticides were expected to
increase by a factor of four in both manufacturing
processes. The greater decrease in pesticide levels
during green tea manufacture in the present study may
be attributed to initial heat treatment and more water
loss (dehydration) due to higher temperature of air
(6075
C) than withering in black tea. The reduction
in the pesticide residues during manufacturing can
be attributed to the physico-chemical properties of
pesticides, ie evaporation, co-distillation and thermal
degradation as was confirmed with the model system.
This study should serve as a model for under-
standing the fate of pesticides during tea manufacture
processing even though, in normal practice, tea is
not manufactured from the leaves harvested before
7 10 days after pesticides spraying. The study helps
us in getting an insight into the residue levels.
ACKNOWLEDGEMENTS
We gratefully acknowledge sincere help and valuable
advice of our colleagues Ms Rita Bhandral, Indiver
Kaushik and Ajay Kumar and thank Ms Suman Lata
and Mr Suresh Kumar for their skillful technical
assistance. We are especially grateful to Director,
IHBT for providing necessary facilities and Council of
Scientific and Industrial Research, India for financial
assistance.
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J Sci Food Agric 84:2123 2127 (online: 2004) 2127
    • "September 25, 2015(8–13%) and imidacloprid (9–13%) were quite significant during drying among all steps in black tea manufacturing. The loss of residue would mainly attribute to factors of degradation, evaporation, and co-distillation [22]. PF ratio of dimethoate and dry matter concentration after withering (0.74–0.77) was much lower than spreading (0.90–0.92), indicating larger loss of dimethoate was occurred during withering than spreading. "
    [Show abstract] [Hide abstract] ABSTRACT: Residue levels of dimethoate and its oxon metabolite (omethoate) during tea planting, manufacturing, and brewing were investigated using a modified QuEChERS sample preparation and gas chromatography. Dissipation of dimethoate and its metabolite in tea plantation followed the first-order kinetic with a half-life of 1.08-1.27 d. Tea manufacturing has positive effects on dimethoate dissipation. Processing factors of dimethoate are in the range of 2.11-2.41 and 1.41-1.70 during green tea and black tea manufacturing, respectively. Omethoate underwent generation as well as dissipation during tea manufacturing. Sum of dimethoate and omethoate led to a large portion of 80.5-84.9% transferring into tea infusion. Results of safety evaluation indicated that omethoate could bring higher human health risk than dimethoate due to its higher hazard quotient by drinking tea. These results would provide information for the establishment of maximum residue limit and instruction for the application of dimethoate formulation on tea crop.
    Full-text · Article · Sep 2015
    • "In 2009, Canada alone had an annual per capita consumption of 77 l (Statistics Canada, 2009). Tea producers often use pesticides, such as insecticides and fungicides to protect crops from devastating insect and disease infestation (Sood et al., 2004). There is evidence that some teas contain detectable pesticide residues, including organochlorines (OC) and organophosphates (OP) (Canadian Food Inspection Agency (2010–2011; Wang et al., 2014 ).; Current Canadian prenatal nutrition guidelines (Public Canada, 2014) include caffeine content and medicinal properties that may lead to adverse health benefits but do not consider pesticide concentrations in the tea. "
    [Show abstract] [Hide abstract] ABSTRACT: Pesticide residues in tea may contribute to exposure during pregnancy; however, the impact on maternal and infant health is not well understood. The aim of this study was to determine whether tea intake in the first trimester was associated with elevated concentrations of various pesticides in maternal blood or urine. Further, we examined the relationship between tea consumption and adverse birth outcomes. Data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a pan-Canada pregnancy cohort, were used. All singleton, live births (n=1898) with available biomarkers were included in the analyses. Descriptive statistics were used to characterize the population. The geometric means (GM) of organochlorine (OC) pesticide constituents or metabolites in maternal plasma (lipid adjusted) and organophosphate (OP) pesticide metabolites (adjusted for specific gravity) in maternal urine were calculated for participants who drank regular, green or herbal tea in the first trimester and for those who did not. Differences between groups were examined using chi-square or t-tests. Associations between frequency of drinking tea and adverse birth outcomes were examined using logistic regression (preterm birth and small-for-gestational-age) or generalized linear models (birthweight decile and head circumference). The GM of the OC pesticide constituent trans-nonachlor was 2.74mg/g lipid, and for metabolites oxychlordane and p,p'-DDE this was 1.94ng/g lipid and 55.8ng/g lipid, respectively. OP pesticide metabolite concentrations adjusted for specific gravity, were dimethylphosphate (GM: 3.19µg/L), dimethylthiophosphate (GM: 3.29µg/L), dimethyldithiophosphate (GM: 0.48µg/L), diethlphosphate (GM: 2.46), and diethylthiophosphate (GM: 0.67µg/L). There was no significant difference in mean concentrations for these OC or OP pesticide constituents or metabolites between tea drinkers - of any type - and non-tea drinkers. Further, no association was found between tea intake and adverse birth outcomes. Pesticide concentrations did not differ by tea intake. Further, tea intake in the first trimester was not associated with adverse birth outcomes. In this study population, there was no evidence for concern about tea intake being a source of the OP or OC pesticide metabolites measured or adversely affecting birth outcomes; however, tea intake was lower than national Canadian data for women of reproductive age. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Jun 2015
    • "As tea is subjected to infusion prior to consumption, residues of pesticides in tea and its transfer in brew must be monitored prior to permitting the consumption by human beings. A few reports are available on the degradation of certain commonly used pesticides and their residues in tea (Rajukkannu et al., 1981; Singh & Agnihotri, 1984; Manikandan et al., 2001 Manikandan et al., , 2005 Manikandan et al., & 2006 Kumar et al., 2004; Sood et al., 2004; Tewary et al., 2005; Seenivasan and Muraleedharan, 2009). However, there is n o published information on the residues of bifenthrin in black tea, under the climatic conditions of south India. "
    Full-text · Article · Jan 2015
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