DDT Environmental Persistence from Its Use in a ... - Science Direct

Environmental Research Section A 86, 174}182 (2001) doi:10.1006/enrs.2001.4258, available online at http://www.idealibrary.com on

DDT Environmental Persistence from Its Use in a Vector Control Program: A Case Study Elisa D. R. Vieira, Joa o P. M. Torres,1 and Olaf Malm LaboratoH rio de RadioisoH topos Eduardo Penna Franca, Instituto de BiofnH sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21949-900 Rio de Janeiro, Brazil Received September 29, 2000

whose insecticide properties were discovered in 1939. Since then, around 1.8 million tons of DDT have been produced all over the world (Dejonckheere, 1990). About 80% of this amount has been used in agriculture. DDT use was banned in the 1970’s in almost all developed countries, due to its toxicity, persistence in the environment, potential bioaccumulation, and insect resistance. Its persistence in the environment and in biota is of particular concern. In developing countries DDT is mainly used in vector control programs for diseases, such as malaria, yellow fever, and leishmaniasis. In these cases, DDT is sprayed as water-dispersible powder at 2 g.m\2 (Singh et al., 1992). In Brazil, DDT was banned for agricultural use in 1985; however, it still can be used in malaria and leishmaniasis vector control programs. DDT is highly stable under most environmental conditions. It is also very fat soluble (K : 9.6;105 ), favoring its bioaccumulation along the food chain (Morrison and Newell, 1999). After the 1960’s, symptoms of toxicity in wildlife were associated with DDT. Examples include avian eggshell thinning (Blus et al., 1997) and feminization of birds and reptiles (Anderson et al., 1982; Fry, 1995). The persistence of DDT permits many interactions between the pesticide and the soil, which are in8uenced by the physical, chemical, and biological characteristics of the soil (Racke et al., 1997). Usually, volatilization is high, mainly in tropical countries, where it may exceed 50% of the active compound applied (Hassett and Banwart, 1992). The high DDT lipophilicity favors its sorption by soil particles rich in organic matter. This sorption removes DDT from solution, reducing leaching through soil and increasing their persistence. Half-lives up to 7 years have been observed in temperate regions (WHO, 1989; Morrison and Newell, 1999).

DDT contamination was investigated in soil, sediment, and chicken eggs from an endemic leishmaniasis area located in Rio de Janeiro City, Brazil. The last DDT application in this area was in 1990, for sand-By vector control. Sampling campaigns were conducted in 1997 and 1999. DDT was extracted by use of a modiAed soxhlet apparatus and analysis was performed by gas chromatography with electron capture detector. The results show that, in 1997, soil samples contained up to 351 lg.kgⴚ1 d.w. of DDT near the insecticide-sprayed sites. In 1999, the soil concentration decreased to 112 lg.kgⴚ1 d.w. of DDT. Sediments from small creeks also showed low concentrations (up to 32.9 lg.kgⴚ1 d.w. of DDT). Chicken eggs had, on average, 1.98 mg.kgⴚ1 DDT (twice FAO’s maximum residue limit), comprising 82% of p,p-DDE. Taking into account the egg results, DDT bioaccumulation is a question of concern. Considering just the egg consumption, it was estimated that DDT intake in the study area is 0.38ⴛ10ⴚ4 mg.kgⴚ1 body weight.dayⴚ1 whereas the reference maximum dose (US EPA) is 5ⴛ10ⴚ4 mg.kgⴚ1 body weight.dayⴚ1. This approach can be used to estimate DDT exposure in other places where DDT contamination may be of concern, especially in places where locally produced animals and eggs are a signiAcant portion of the diet.  2001 Academic Press Key Words: DDT; persistence; soil; bioaccumulation; human exposure.

INTRODUCTION

Organochlorine pesticides have been used worldwide since the 1940’s. Dichlorodiphenyltrichloroethane (DDT) is a synthetic organochlorine, 1

To whom correspondence should be addressed. Fax: 55212808193. E-mail: [email protected] or [email protected]. 174 0013-9351/01 $35.00 Copyright  2001 by Academic Press All rights of reproduction in any form reserved.

DDT ENVIRONMENTAL PERSISTENCE

DDT may be degraded by UV radiation or by microorganisms, but its main metabolites, dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), are also persistent and toxic. DDT and its metabolites are also considered endocrine disrupters. DDE inhibits androgen binding to the androgen receptor, whereas DDT has a potent estrogenic activity in mammals and birds (Kelce et al., 1995; Fry, 1995). DDD has insecticide properties and affects the adrenals (WHO, 1979). DDT and its metabolites are considered probable carcinogenics, according to IARC and US EPA. Thus, DDT degradation to DDD or DDE in the environment or in biological tissues cannot be considered a detoxi7cation step. In contaminated soils, photochemical reactions and DDT dechlorination by bacteria and invertebrates degrade DDT to DDE (StroK mpl and Thiele, 1997; Aislabie et al., 1997). Mechanisms for the breakdown of DDE have not yet been identi7ed. Degradation to DDD is mediated by bacteria and fungi under reducing conditions, as found in anaerobic sediments, present in swamps, ponds, or soils in the wet season (Parr and Smith, 1974; Ramesh et al., 1989). Stimulation of DDD mineralization may occur by use of ligninolytic fungi in vitro experiments but, in situ, degradation rates are very slow (Aislabie et al., 1997). In tropical countries, due to a higher solar radiation and microorganism diversity in soils, degradation is supposed to be higher. Usually, DDT half-life (14C-DDT dissipation) is about 340 days (Khan, 1994). In acid soil (pH 4.5), overall half-life of 14CDDT dissipation was about 1400 days (AndreH a et al., 1994). The purpose of this study was to develop a model of approach for the evaluation of DDT and its metabolites contamination in tropical areas where DDT was used for disease vector control. A leishmaniasis endemic rural area;where DDT was used in recent past;located within the boundaries of Rio de Janeiro Municipality, close to a tropical forest area and on the outskirts of the urban area, was chosen for this study. American cutaneous leishmaniasis (ACL) is considered the sixth priority infectious parasitic disease in the world, with 1 to 1.5 million annual cases in 88 endemic countries. In Brazil, 28,000 ACL cases were reported annually, from 1987 to 1997 (FUNASA, 1999). The most affected regions are the central-west, north, and northeast. In the Amazon region, ACL can be considered an occupational illness, due to mineral extractive actions and deforestation.

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In Rio de Janeiro State, there are several endemic regions of ACL, with 302 autochthonous cases reported in 1997 (FUNASA, 1999). In the city of Rio de Janeiro, JacarepaguaH neighborhood is the main ACL endemic region, speci7cally in the Camorim, Maciio da Pedra Branca, and Pedra Grande areas. The study area chosen for our model is located at Estrada do Pau da Fome, near Maciio da Pedra Branca (Fig. 1). One house and its surroundings were chosen to be used in our model. The last public health DDT spraying program was conducted in this area by the National Health Foundation (FUNASA) in 1990. For leishmaniasis vector control, the insecticide is sprayed indoors and outside of house walls, hen houses, barns, and kennels. The pesticide use is implemented in communities where two or more ACL cases have occurred (Gomes and Neves, 1998). Nowadays (since 1993), the Brazilian government recommends the replacement of DDT with pyrethroid deltametrin. MATERIALS AND METHODS

The super7cial soil in the surroundings of the DDT-sprayed house chosen and sediment from small creeks nearby were collected manually, with a metallic spoon (for soil) or a scoop (for sediment). The samples were collected in April 1997 (n"14) and in March 1999 (n"9). In addition, samples from outside (n"3) and inside (n"1) the house walls were collected with a metallic cylinder. To study the possible DDT bioaccumulation in domestic animals, eggs of chickens which live free around the house were collected in May 1999 (n"9). To compare these values with background values, a soil sample from our University campus and eggs bought in a Rio de Janeiro market (n"5) were also analyzed. All soil/sediment samples were stored in acetonerinsed glass jars covered with aluminum foil and all samples (including eggs) were kept at 4@C until analysis. Between the sampling points all of the metallic devices used were rinsed three times with pesticidegrade acetone. Analytical Methods The soil/sediment extraction procedure comprised the mixing of 2 g of wet sample with 4 g of silica gel 60 (70}230 Mesh). This mixture underwent a continuous soxhlet extraction with 20 mL of hexane:ciclohexane (3:1) and 2 mL of isooctane as solvents in a water bath for 2 h (Torres et al., 1999; Japenga et al., 1987). Cleanup was performed on a

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FIG. 1. Map of Rio de Janeiro City. Estrada do Pau da Fome (*), located in the JacarepaguaH neighborhood, is an endemic area of American cutaneous leishmaniasis.

chromatographic glass column 7lled with an Al2O3 , NaOH, and Na2SO3 mixture (7 g), with 20 mL of hexane as solvent. An internal standard (octachloronaphtalene}OCN) was added (0.5 mL at 200 lg.L\1 ) for quanti7cation and the whole solution was evaporated to 1.0 mL. Since DDT and its metabolites are highly lipophilic, only the egg yolks were analyzed. The yolks were separated and mixed with silica (1:3), and the same soxhlet extraction was performed. The solvents were completely evaporated (with N2 ) for extractable lipid measurement. The cleanup was done with the addition of 4 mL of concentrated H2SO4 and 0.5 mL of isooctane (method adapted from FAO/SIDA, 1983). The internal standard OCN (0.5 mL) was also added for quanti7cation. Analysis was performed by gas chromatography with electron capture detector (ECD-GC) (Shimadzu GC-14B with autosampler AOC-17) with two different capillary columns (Shimadzu CBP1 and CBP5). The carrier gas was high-purity hydrogen (99.999%), and nitrogen (99.999%) was used as the ECD makeup gas. The injector and detector

temperatures were 300 and 310@C, respectively. The oven program temperature started at 110@C (for 1 min), rising to 170@C (at 20@C per min) and subsequently to 290@C (at 7.5@C per min), where it remained for 12 min. The isomers o,p-DDE, p,p-DDE, p,p-DDD, o,p-DDT, and p,p-DDT were detected ( DDT is the sum of all isomers). Analyses were done in triplicate. Blank correction was applied to the results. The physical and chemical characteristics of the soil, such as pH, potential acidity, cation exchange capacity (CEC), organic matter content, and granulometry, were analyzed. These parameters were analyzed by EMBRAPA (Brazilian Agricultural Research Institution), following the methods of Claessen et al. (1997) (Table 1). Analytical Quality Some soil samples were also analyzed by gas chromatography coupled to a mass spectrometer (GC/MS) to con7rm the identity of each compound. The con7rmatory results of the GC/MS analysis

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TABLE 1 Physical and Chemical Characteristics of Soils at the Study Area, Estrada do Pau da Fome, JacarepaguaH , Rio de Janeiro (Samples Collected in 1999) Granulometry (%)

Sampling sites

pH

Potential aciditya (cmolc.kg\1 )

Near house walls1 Near house walls2 At hen house3 12 m from house4

6.9 7.0 6.6 6.6

0.7 0.5 1.8 1.0

CECb (cmolc.kg\1 )

Organic matter (g.kg\1 )

Coarse sand

Fine sand

Silt

Clay

134.3 161.9 1201.6 134.2

3.79 9.65 18.79 10.17

52.6 44.2 64.0 84.2

14.8 14.2 9.0 5.2

6.6 14.6 11.8 6.6

18.0 30.0 10.0 4.0

[H>]#[Al3>]. [H>]#[Al3>]#[Ca2>]#[Mg2>]#[K>]#[Na>]. 1,2,3,4 see Fig. 2 for locations. a b

were performed at a Brazilian Reference Laboratory at CESTEH/FIOCRUZ (Ministry of Health, Brazil) with the SIM method. The second capillary column (CBPS), with 5% of phenyl, was also used at the Radioisotopes Laboratory for con7rmatory purposes. A certi7ed reference material from an intercomparison exercise of the International Atomic Energy Agency (IAEA) was analyzed (IAEA 408). According to IAEA, our laboratory performance was acceptable for all organochlorinated compounds measured (Villeneuve et al., 1999). The minimum detectable concentrations (2;SD of analytical blanks) for soils were 0.71, 1.79, 0.21, 1.74, and 5.06 lg.kg\1 for o,pDDE, p,p-DDE, p,p-DDD, o,p-DDT, and p,p-DDT, respectively. The minimum detectable concentrations for the eggs are given in Table 2. RESULTS

In 1997, soil samples obtained closer to DDTsprayed sites (house walls and hen house) showed

higher DDT and DDE concentrations (up to 208.6$28.2 and 135.2$28.2 lg.kg\1 d.w., respectively) (Fig. 2a). These data show that, despite the 10 years since this place had been sprayed with DDT, the soil still presents DDT contamination. DDT levels in more distant sampled points from application places were lower, showing a decreasing concentration gradient. DDE levels also followed the same gradient. The DDT lowest value observed was 4.74$0.67 lg.kg\1 d.w. at a point 12 m from the sprayed house (the farthest sampled point). DDD showed a different decreasing gradient, since only the hen house contained the highest DDD concentration (13.8$8.62 lg.kg\1 d.w.). In 1999 (Fig. 2b), DDT concentration in soils decreased to 40.3$7.01 lg.kg\1 d.w. near house walls. DDE concentration was up to 66.7#6.11 lg.kg\1 d.w. DDT and DDE decreasing gradients from the sprayed house were still observed, but values were lower than in 1997. DDD decreasing gradient followed the same 1997 pattern,

TABLE 2 DDT and Its Metabolite Concentrations in Eggs (10ⴚ3mg.kgⴚ1 Extractable Lipids, the Yolks Had Approx 20% fat) at the Studied Area, at a Close Locality (Both at Estrada do Pau da Fome, JacarepaguaH ), and at a Market in Rio de Janeiro City Studied area (n"3) Compound

10\3 mg.kg\1

o,p-DDE p,p-DDE p,p-DDD o,p-DDT p,p-DDT DDT

1.4$1.25 1630$958 23.4$13.1 4.30$0.1 324$149 1983

a

2;SD of blanks. Below minimum detectable quantity.

b

Close locality (n"6) %

10\3 mg.kg\1

%

Market (n"5) 10\3 mg.kg\1

0.07 82.19 1.18 0.22 16.35 100

0.94$0.88 599$129 4.40$1.55 1.60$1.23 124$18 730

0.13 82.06 0.60 0.22 16.99 100

(MDb (MD (MD (MD (MD ;

Minimum detectablea 10\3 mg.kg\1 0.77 1.57 1.40 0.85 2.61

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FIG. 2. DDT, DDE, and DDD concentration (lg.kg\1 dry wt.) in soil at Estrada do Pau da Fome, JacarepaguaH , Rio de Janeiro in 1997 (a) and in 1999 (b). The last DDT application was in 1990 for leishmaniasis vector control at house walls and hen house. n, sampling points. 1}4, see Table 1.

with the highest concentration at the hen house (6.47$1.75 lg.kg\1 d.w.). The extracted samples from outside and inside house walls showed average concentration of 1062$1517 and 449$121 lg.kg\1 of DDT, with 50 and 83.7% of p,p-DDT, respectively, indicating

a high persistence of DDT at the sprayed house and a high variability in wall samples. Those compartments are still a DDT source, despite the fact that the soil contamination is decreasing over time. In 1997, in the sediments from two nearby streams located at around 300 m from the studied

DDT ENVIRONMENTAL PERSISTENCE

area, DDT concentrations were relatively low (8.68 and 32.9 lg.kg\1 d.w.), probably because of the high soil retention capacity. A higher DDD concentration percentage was found in the streams (26.24 and 63.92%) compared with soil samples that were around the studied house. The stream that receives the water runoff of this house presents the highest DDT value (32.9 lg.kg\1 d.w.). In the stream sediments analyzed in 1999, the DDT residues veri7ed were below the minimum detectable quantity. The soil ratio p,p-DDD/p,p-DDE was low: 0.06 in 1997 and 0.09 in 1999 (median). This was expected due to soil aerobic characteristics, where DDT tends to be degraded to DDE (Aislabie et al., 1997). In anaerobic conditions, DDT is degraded to DDD (Parr and Smith, 1974; Ramesh et al., 1989), which is observed in the stream sediments analyzed (p,pDDD/p,p-DDE 2.36). DDT dispersion from soil to river basin does not seem to be signi7cant in this study. Animal manure cause high organic matter contents in soil (from 3.79 g.kg\1 in places far from the chicken coop to 18.79 g.kg\1 at the chicken coop) (Table 1). CEC also

FIG. 3.

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increases from 134.3 to 1201.6 cmol .kg\1  ("meq.100g\1 ). Organic matter, CEC, and soil acidity increase the pesticide retention in soil (AndreH a et al., 1994; Morrison and Newell, 1999), mainly in places such as a chicken coop, as was here observed. On the other hand, 61.25% of soil particles are coarse sand, where leaching is more signi7cant, but behind the studied house (point 2 in Fig. 2b), there are more 7ne grains as silt and clay which increase DDT retention. The p,p-DDT/p,p-DDE ratio (T/E) may provide an estimate of DDT inputs over time. In the commercial product, the T/E ratio is 19.27 (WHO, 1979). In this study, in 1997, T/E was 1.91 in soil (median). In 1999, this ratio diminished to 1.19. In the United States, where DDT use stopped in 1973, Aigner et al. (1998) analyzed soils from the corn belt in 1986 and found concentrations varying from :0.5 to 11,846 lg.kg\1 DDT (average, 9.63 lg.kg\1 ). The T/E ratio found ranged from 0.5 to 6.6. According to Fig. 3, it can be observed that, in front of the house, there is a trend of low degradation to DDE (higher T/E: 2.8 in 1997 to 1.56 in 1999 at 1 m

Persistence of DDT according to p,p-DDT/p,p-DDE ratio in soil in 1997 (a) and in 1999 (b).

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from the house), which may be related to low organic matter contents and CEC. Oppositely, at the hen house, DDT degradation is higher; T/E diminished from 2.18 to 0.59 over the period studied. A similar pattern is observed behind the house, with small T/E (1.35 in 1997, 0.54 in 1999). It is dif7cult to con7rm the real exact year of the last DDT application (we know only the last of7cial application year). DDT half-life values should help to estimate the last application year. Studies on tropical soils (Khan, 1994) measured the overall half-life 14C-DDT dissipation under laboratory conditions (340 days, on average, and a range of 35 to 1400 days). But our study did not occur under laboratory conditions and there are some parameters still unknown that in8uence the concentrations found in 1997 and 1999, such as initial metabolite quantities in soil (DDT, DDE, and DDD) and loss rates during the studied period. In addition, it is known that DDT degradation is not constant over time, being faster in the beginning (when volatilization is the main process) and slower afterward (through leaching, sorption, and enzymatic degradation) (Khan, 1994). The soil used as a control sample (at the University campus) showed no detectable concentrations of DDT or its metabolites. Chicken eggs collected at this area showed high DDT average concentration: 1.98 mg DDT.kg\1 of extractable lipids (average value), with 82% of p,pDDE (Table 2). The standard deviations of DDT residues are very high, probably because of a heterogeneous chicken population and/or a low sampling number. To have a better representation of this region, chicken eggs from a nearby locality, also endemic of leishmaniasis (Monte Alegre, at Estrada do Pau da Fome), were analyzed, showing 0.73 mg DDT.kg\1 of extractable lipids, with 82% of p,pDDE. It is interesting to note the same percentage of all DDT residues in the eggs from both areas. The eggs bought in the Rio de Janeiro market showed concentrations below the minimum detectable concentration (Table 2). Extractable lipid contents in yolks were on average 20%, yolk weights were 20 g and egg weights were 41 g (average, 4 g of extractable lipid per egg"9.75% lipid). DISCUSSION

In the super7cial soils collected, a high percentage of DDE was observed. This was expected since aerobic environments promote a signi7cant DDT degradation to DDE, instead of DDD, which is more likely to occur under reducing conditions (Aislabie et al., 1997). On the other hand, in the streams nearby,

a higher percentage of DDD was observed, even in places with low DDT concentration. The soil of this area does not present high DDT contamination. Souza et al. (1988) studied organochlorine contamination in agricultural soils in southern Brazil in 1986 and found 268 mg.kg\1 of DDT in soil of soy and wheat crops;at that time, DDT use in agriculture had been recently banned. In addition to the low concentration found in this study, DDT contamination is diminishing, as indicated by the decreasing T/E ratio from 1997 to 1999. Due to the high DDT lipophilicity, bioaccumulation in eggs is a risk to the local human population. The major source of DDT intake for the general population is food. The DDT extraneous maximum residue limit (EMRL) in eggs recommended by FAO/Codex Alimentarius is 0.1 mg.kg\1. The egg concentrations (per kg of egg instead of extractable lipid) in this study area were twice the recommended EMRL (0.198 mg.kg\1 ; Table 2). In another study conducted at Sa o Paulo City, eggs from a market showed 0.04 mg.kg\1 of DDT (Barreto et al., 1991). Compared with eggs from a Rio de Janeiro market, DDE concentration in the eggs from the studied region were, at least, 1000 times higher. Considering a daily egg consumption of 11.8 g per person per day (data for Latin American consumers; GEMS/Food, 1999) and 9.75% lipids in eggs (lipid from egg consumption"11.8;9.75), the DDT daily intake from eggs from this area is 2.27;10\3 mg.person\1.day\1, from the quantity: Egg Consumption (1.15 g of lipids. day\1 ); [DDT]egg (1.98 mg.kg\1 extractable lipids). Around 1965, when DDT use was at its peak, the intake from food in the United States was estimated to be 0.04 mg.person\1.day\1 (WHO, 1989). In India, DDT intake among vegetarian adults, through feeding, is 0.02 mg DDT.person\1.day\1 (Kashyap et al., 1994). Considering 60 kg of body weight (world average), DDT daily intake from eggs in our study is 0.378;10\4 mg.kg\1 body weight.day\1. The risk value of DDT (reference dose) for chronic toxicity is 5;10\4 mg.kg\1 body weight.day\1 (US EPA, 1997). It is important to note that this estimate for this area considers only the egg consumption, therefore underestimating the DDT total daily intake for the local population. At least, milk and meat consumption (also rich in lipid) should be considered in further studies. Despite no adverse effects having been described for repeated dosages of 1.5 mg.kg\1.day\1 in 1-year volunteers (WHO, 1979), other studies should be considered. Recently, DDT, especially its o,p metabolites, has been considered an endocrine disrupter,

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even in very low concentrations. Studies with human fertility and environmental exposure to p,pDDE showed reduction in human sperm counts (Cocco, 1997) and a decreasing breastfeeding period (Wolff and Weston, 1997). Cocco et al. (2000) observed a signi7cant correlation between liver cancer mortality and adipose DDE levels. DDT is also suspected of causing spontaneous abortion and premature delivery (US EPA, 1997). Biomagni7cation of DDT in human milk has been observed (US EPA, 1997). Levels of p,p-DDT above the limit (0.02 mg.kg\1 ) recommended by WHO for cow’s milk were observed in human milk from an agricultural area of Sa o Paulo State, 0.149 mg.kg\1 DDT (Matuo et al., 1992), and in the capital of Rio Grande do Sul State, 2.98 mg.kg\1 DDT (Beretta and Dick, 1994). In both studies, DDT levels were high, despite DDT prohibition in 1986 for agricultural use. There are few studies on the fate of DDT from its use in public health programs to compare with our values. Here, DDT concentrations in soil and bottom sediment are low, compared to agriculture soil concentration. Still, bioaccumulation occurs and it is of concern. In view of DDE concentrations found in eggs, the population of this region, speci7cally pregnant women and breastfeeding infants, may be at risk due to their increased exposure. DDT is still one of the main insecticides used for malaria control in Africa and Asia, due to its low cost and good residual effectiveness (Curtis and Lines, 2000). Its acute toxicity to mammals is low, but chronic effects from DDT exposure are considerable, including hormonal effects. Concentration in edible domestic birds, such as chickens and ducks, should be studied to better estimate DDT intake in contaminated areas, particularly in speci7c organs, such as liver and heart. Furthermore, research on alternative insect and disease control methods should be stimulated.

ACKNOWLEDGMENTS The authors are grateful to CESTEH/FIOCRUZ for GC-MS analysis and to Luz Claudio from Mount Sinai School of Medicine for her comments on the manuscript. This study was supported by CAPES (Coordenaia o de Aperfeiioamento de Pessoal de NmH vel Superior) and PRONEX/CNPq (Conselho Nacional de Pesquisas). The chromatographic laboratory was built during a Joint Research Project funded by the Commission of the European Community (Project number: C11*-CT93-0055). Dr. Joa o Torres is a Selikof Fellow at the Mount Sinai School of Medicine and Queens College in New York and is supported in part by Grant 1 D43 TW00640 from the Fogarty International Center of the National Institutes of Health.

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