Levels of exposure to organochlorine pesticides in open-air dump dwellers



Eladio Santos FilhoI; Rebeca de Souza e SilvaII; Heloisa H C BarrettoIII; Odete N K InomataIII; Vera R R LemesIII; Tereza Atsuko KussumiIII; Sônia O B RochaIII

IHospital Guilherme Álvaro da Secretaria de Estado da Saúde. Santos, SP, Brazil
IIDepartamento de Medicina Preventiva da Universidade Federal de São Paulo. São Paulo, SP, Brazil
IIIInstituto Adolfo Lutz. São Paulo, SP, Brazil





OBJECTIVE: To estimate the degree of internal exposure to organochlorine pesticides (persistent organic pollutants, POP) among inhabitants of an open-air dump.
METHODS: This was an observational study with simultaneous measurement and control, in which the criterion for subjects was that they dwelled in an area contaminated by POP and the effect of such contamination was the concentration of such substances into the blood. The study population consisted of 238 people living on an open-air dump in Pilões, in the municipality of Cubatão, SP, Brazil, and the control population was formed by 258 people, also resident in that municipality, in the Cota 200 district. The following pesticides were analyzed: hexachlorobenzene (HCB), p-p’DDT, p-p’DDE, p-p’DDD, o-p’DDT, a HCH (hexachlorocyclohexane); b HCH; g HCH; aldrin; dieldrin; endrin; heptachlor; heptachlor-epoxy and mirex.
RESULTS: The average blood level of HCB in Pilões was 4.66 µg/l, which was 155 times higher than the average for Cota 200 (0.03 µg/l). In Pilões the average blood concentration of total DDT was 3.71 µg/l, which was twice the level found in Cota 200 (1.85 µg/l). Total HCH presented blood concentrations that were six times greater in Pilões (0.84 µg/l versus 0.13 µg/l).
CONCLUSIONS: A positive association was shown between dwelling in Pilões and the presence of POP in the blood, with much higher risks than in localities without the presence of these contaminants.

Keywords: Environmental exposure. Insecticides, organochlorine. Sanitary landfill. Hazardous waste disposal. Environmental pollution. Risk factors.




According to a study carried out by the Departamento de Águas e Energia Elétrica do Estado de São Paulo ( Department of Water and Electric Energy of the State of São Paulo (DAEE) and the Companhia de Tecnologia e Saneamento Ambiental (CETESB) (Environmental Sanitation and Technology Company)3 in 1978. five industrial plants located in the municipality of Cubatão presented inadequate final disposal of hazardous waste,* discarding such waste into the open-air dump in Pilões, a locality used by the Cubatão authorities for dumping the municipality’s solid waste until the year 1983. The results from that study revealed that 1000 tons of hazardous waste per year were being dumped in the Pilões area.

At the start of the 1990s, CETESB performed analyses on soil, water and sediments from the Pilões region and detected the presence of the organochlorine compounds hexachlorobenzene and pentachlorophenol, in all three sample types. The majority of sediment samples were contaminated by these compounds and one of the samples revealed the presence of another organochlorine that is found widely in the environment: DDT.

Like most garbage dumps around the country, the Pilões dump was an open-air one and there were families there who made a living from scavenging recyclable products. With the implementation of the Program for Pollution Reduction Targets in 1984, the open-air dump was deactivated and covered with inert material. However, the garbage scavengers who lived at that place continued to do so, on the site of the dump.

On the basis of these data, the hypothesis was put forward that the population dwelling on the open-air dump in Pilões might have been exposed to organochlorine compounds present in the region. Thus, the present study was made with the objective of estimating the degree of internal exposure of the population of Pilões to organochlorine pesticides and assessing the possible effects of this exposure on the population’s health.



The original work was characterized as an observational study with simultaneous non-directional measurement and control, in which the criterion for subjects was external exposure to organochlorine pesticides through dwelling in an area contaminated by persistent organic pollutants (POP). Internal exposure (concentration of POP in the body) was the possible effect considered. The biological indicators of such internal exposure, i.e. the response of the body to POP, had to be capable of demonstration through the alterations seen in clinical and/or laboratory tests (enzymatic and hematological alterations, and others). The present article has been limited to showing the relationship between external and internal exposure, or in other words, determining the risk of dwelling in locations with the presence of POP.

The study population was defined as the 252 inhabitants of the Pilões housing area. However, 14 people (5.6%) belonging to three families refused to participate, such that the study population consisted of 238 people that were living in direct contact with POP. The locality chosen for selecting the control population was the district within the municipality of Cubatão known as Cota 200, for the following reasons:

a) It presents the same socioeconomic characteristics (Cubatão municipal authority – CDE/APLAN, 1993**).8

b) It is in the same air basin, which would eliminate differences in atmospheric exposure to the pollutants studied.

c) It is the same distance from the municipality’s industrial area and presents access difficulties for vehicles, which would rule it out as a place for industrial waste disposal.

d) It was not mentioned as a location used for industrial waste disposal in the DAEE/CETESB survey of 1978.3

e) It is supplied with untreated water, as is the population in Pilões.

The control population was selected by matching with the study population according to the characteristics of age, sex, income and length of residence. Following accessibility criteria, two specially trained healthcare agents from the local healthcare unit searched through an extensive area of the district in order to obtain the most uniform representation possible of that population. The criteria adopted for inclusion in the control group were income (individuals with incomes of up to three minimum salaries, matched according to number of minimum salaries), sex, age group (in 5-year intervals) and length of residence (in years) equal to that person’s pair in the study population. Individuals who said they had previously lived in Pilões were not included in the control group. The final size determined for the control population was 258 individuals. All those who participated in the research underwent clinical and laboratory tests performed by the author.

The toxicological laboratory analyses were performed by the Instituto Adolfo Lutz, in São Paulo (IAL). The organochlorine pesticides investigated in blood samples were: hexachlorobenzene (HCB); p-p’DDT; p-p’DDE; p-p’DDD; o-p’DDT; a HCH (hexachlorocyclohexane); b HCH; g HCH; aldrin; dieldrin; endrin; heptachlor; heptachlor-epoxy and mirex. The method employed for the determinations of organochlorine pesticide levels in blood serum was that of Thompson14 (1982). Chromatography was utilized with the following specifications: HP5890 gas chromatography with an electron capture detector and nickel source, equipped with a column of methylsilicone HP1 (30mx0,53mmx2,65um), column temperature of 200ºC, injector temperature of 220ºC, detector temperature of 260ºC.

The detection limit for blood serum samples was 0.2 µg/l for HCB and heptachlor, 0.8 µg/l for DDT and 0.4 µg/l for the remaining compounds.

The collection locations were different for the two populations. For the study population, the collection was done in the mornings, at the collection unit of the Coordination Office for Healthcare Surveillance, and was done by personnel trained and qualified for this type of task. Vacuum tubes were utilized, employing the technique recommended by Siqueira10 (1994). For the control population, the individuals were sent straight to the municipal laboratory in the mornings, where the collection was then done, following the same rules described above. The blood was collected via peripheral vein puncture, and the quantity collected was a minimum of 10 ml to a maximum of 20 ml per person. Absenteeism was greater in the control group, probably because these individuals did not have the same motivation for the test as did the exposed group.

The Epi-Info 6 software was utilized for performing the statistical analyses. Bivariate analysis was used for verifying the differences between the groups studied, via the Pearson c2 method. Parametric statistical tests of ANOVA type were performed to assess average differences between the groups and subgroups. The significance level of a=0.05 was established. Values below the detection limit were included in the calculations by assuming a value of zero, in a similar way as done in the population studies of Stehr-Green13 (1989), which were based on the Second National Health and Nutrition Examination Survey (NHANES II), conducted by the National Center for Health Statistics of the United States of America.



The attributes of sex and age presented similar distributions between the study and control populations. In Pilões, the median age was 17 years, versus 18.5 years in Cota 200 (p=0.66).

Of the 238 persons in the study population, 96 were female (40.3%) and 142 male (59.7%). The control population of 258 persons was made up of 111 females (43.0%) and 147 males (57.0%), thus presenting a slightly lower proportion of men.

In environmental exposure studies, the length of residence is equivalent to the length of exposure. This is a variable of great importance when the aim is to measure the effects of such exposure, especially when dealing with substances that accumulate in the human body, as is characteristic of organochlorine compounds. What is expected is that the concentrations of toxins in the body will increase in direct relationship with the length of exposure.

The length of residence is shown in Table 1. It can be seen that the control population (Cota 200) presented greater length of residence (median of 6.3 years) than the study population (median of 4.2 years), a statistically significant difference (p<0.01).

Control populations are considered not to have been exposed and for this reason it would be expected to find lower serum levels of POP than in exposed (study) populations. Thus, shorter length of residence (or exposure) in a control group could represent a bias in the data.

From the point of view of family income, the two groups presented the same characteristics, with income of up to three minimum salaries (MS). In Pilões, 10.5% of those surveyed presented incomes of up to one MS, versus 8.5% in Cota 200. In Pilões, 52.9% said their income was between one and two MS, in comparison with 54.3% in Cota 200, and 36.6% in Pilões had income of up to three MS, versus 37.2% in Cota 200.

The education levels attained were also similar between the two groups. In Pilões, 10.5% of the individuals were classified as illiterate, in comparison with 8.9% in Cota 200. In Pilões, 15.5% declared that they had completed their fundamental education (primary school; grades 1-4), versus 14.3% in Cota 200. Only 2.5% of those interviewed in Pilões and 1.9% in Cota 200 said that they had completed their middle school education (up to grade 8). The average length of education completed was 3.1 years in Pilões and 3.2 in Cota 200.

To analyze the occupational activities performed in the two groups (Table 2), these activities were classified according to criteria utilized by the Brazilian Institute of Geography and Statistics (IBGE,6 1980), which characterize individuals of more than ten years old as economically active or inactive. Pilões presented a slightly greater proportion of economically active persons (40.5%) in comparison with Cota 200 (35.4%), partly due to a type of activity that does not exist in Cota 200, namely sand extraction from the Cubatão River.

The unemployment rate, considering only those who were economically active, was 20.6% in Pilões and 25% in Cota 200. The proportion of persons employed in manufacturing industry was a little greater in Cota 200 (5%) than in Pilões (3%). When asked if they had ever worked or were working in industrial plants, 47 persons (28%) in Pilões responded affirmatively, versus 38 in Cota 200 (21%), a difference that was not statistically significant (p=0.08).

Another important variable is the place that the individuals come from or where they lived previously, because of the possibility that environmental exposure may have occurred in places other than the study location. In Pilões, around 15% of the population were native to that location, 73.5% came from other districts of Cubatão and 10.5% came from other municipalities in the Santos lowlands. Cota 200, in contrast, housed immigrants from other regions, probably because it has better urban infrastructure and is an older center for housing. It also presented a large percentage of native residents (41.5%), in comparison with Pilões (15%), a significant difference (p<0.01).

It was ascertained that the average length of residence for the natives of Cota 200 was 11.1 years and for the non-natives 10.7 years (p=0.90), thus without statistical significance. On the other hand, in Pilões the average length of residence for natives was 2.5 years and for non-natives 6.0 years, a significant difference (p<0.01). In Cota 200, the fact that an individual was born in that locality or not did not interfere in the length of exposure. Nor was there any association between place of birth and presentation of residues of hexachlorobenzene (HCB), total DDT and total hexachlorocyclohexane (HCH) in the blood.

In Pilões, the individuals who went to live at that location presented greater lengths of exposure than those who were born there. It would be reasonable to think that this group could present worse conditions of internal exposure to POP, but no association was found between being a native or not and displaying serum residues of HCB and total HCH, although this association was positive in relation to DDT.

It is therefore deduced that the difference in place of birth between the groups studied did not interfere in the position regarding internal exposure to HCB and HCH, but may have interfered in the exposure to DDT.

Comparing the individuals who were born in Pilões (36 children aged zero to ten years) with the natives of Cota 200 (107 persons aged zero to 41 years), it can be seen that the average levels of POP found in the natives of Pilões (HCB=1.28±3.22 mg/l, total DDT=5.21±12.23 mg/l and total HCH=0.78±1.22 mg/l) were significantly higher (p<0.01) than those found among the natives of Cota 200 (HCB=0.01±0.05 mg/l, total DDT=1.98±6.26 mg/l and total HCH=0.13±0.78 mg/l), which demonstrates the seriousness of the exposure in Pilões.

Comparing the persons with less than one year of residence (exposure) in the two groups, it can be seen that, independent of the age group, almost all those in Pilões (ten out of 12 individuals) presented residues of HCB (X=1.01±1.62 mg/l) and total DDT (X=4.15±7.41 mg/l) and five out of these 12 individuals presented total HCH in their blood (X=0.65±1.27 mg/l), whereas none of those in Cota 200 (total of 13 persons) presented residues of HCB and only one person presented b HCH in the blood (0.26 mg/l), thereby demonstrating the risk of exposure to these pesticides among inhabitants of Pilões. In Cota 200, DDT was found in five of the 13 individuals (X=0.39±0.67 mg/l).

In Pilões, there were seven breast-feeding infants of less than one year of age. Toxicological analyses were performed on five of them, which demonstrated that four were already presenting exposure to HCB (X=0.90±0.79 mg/l). Total DDT (X=1.32±1.26 mg/l) was found in three babies and one presented b HCH of 2.1 mg/l in the blood. In the control group, out of the seven breast-feeding infants examined, only one presented any organochlorine pesticide in the blood (p-p’DDE=1.00 mg/l).

It was possible to identify persons who said they had come from regions with environmental pollution problems. In Pilões, 9.9% of the inhabitants declared that they had previously lived in places with environmental pollution, versus 6.5% of the control population, without a statistical difference (p=0.70) between the groups. No association was found between declaring an origin in a polluted region and internal exposure to the POP investigated. Nor was any difference found in the average blood levels of the POP investigated between those who said they had or had not come from places with environmental pollution.

Investigation of social habits such as tobacco and alcohol use is very important, because this could interfere in the internal exposure results (Cabras & Angioni,1 2000). Smoking, just like alcohol use, produces appreciable damage to health and moreover may at least theoretically be a source of exposure to pesticides used in tobacco cultivation. In Brazil, while the use of POP in agriculture has been prohibited, the smoking industry has utilized organophosphate and carbamate pesticides. There was a distinct preponderance of smokers in Pilões (p=0.013), in comparison with Cota 200. However, the length of time for which individuals had smoked was similar in the two groups: 20 years in Pilões and 23.1 years in Cota 200 (p=0.23). Pilões also presented a greater proportion of alcohol users (p<0.01), but with the same duration of such usage, 19.8 years versus 19.7 years in Cota 200. There was generally no association between smoking and presenting POP residues in the blood, with the exception of total DDT, which was found more among the smokers of Cota 200 (p=0.03). No relationship was seen between drinking habits and presenting POP residues in the blood.

The use of barbiturates may interfere in the blood concentration of POP (Rea et al,8 2001), because this stimulates hepatic metabolism. However, only two individuals in Pilões were regularly using such medication, and three in Cota 200, such that there was no interference in average blood levels of POP. No difference was found in the use of medications in general between the two locations (p=0.86).

A few years ago, medications based on lindane (g HCH) could be found on the market, for the treatment of pediculosis and scabies. Such medications could possibly become important sources of exposure to this agent. For this reason, it was necessary to quantify the use of such products in the groups studied. It was seen that a significantly greater number of persons (p<0.01) in Pilões said that they had utilized such products, in comparison with Cota 200. Nevertheless, no relationship was observed between using these products and presenting POP residues in the blood.

Table 3 shows the average concentrations of POP in the blood that were found in the two populations. It was seen that the study group presented higher levels of internal exposure in comparison with the control group. A positive association was found between dwelling in Pilões and presenting blood residues of organochlorine pesticides.

Among the presentations of HCH, the a HCH isomeric form was found most in the study population, followed by the b HCH and g HCH isomers. In terms of chronic toxicity, it is known that the b HCH isomer is the most toxic, followed by a HCH and g HCH. The exposure to the various isomers of HCH is due to the commercialization of technical HCH, a compound formed by a mixture of these isomers.

a HCH is the predominant form in this type of presentation and has been shown to be the main HCH residue found in certain populations (Fernandez et al,5 1987). However, other studies (Santos Filho et al,9 1993; Stehr-Green,13 1989) have recorded b HCH as the most common isomer, because this has greater potential for and duration of storage in the human body, in comparison with the other HCH isomers (Smith,11 1991). It is probable that the predominance of a HCH in Pilões reflects recent exposure to HCH.

The relationship between b HCH and g HCH can be utilized for diagnosing the length of exposure to this pesticide. The lower this relationship is, the more recent the exposure to HCH is. The relationship between the average concentrations of the b and g isomers of HCH was 4.4 in Pilões and 0.86 in Cota 200, which demonstrates recent exposure to the pesticide.

Also in Table 3, it can be seen that p-p’DDE was the most commonly found DDT isomer in the two populations, with more than half of the examinations in Cota 200 positive for this pesticide and around 90% positive in Pilões. This confirms the importance of DDT as a ubiquitous toxin as a result of its indiscriminate use in the past. The technical DDT commercialized is a mixture of various isomers, with p-p’DDT the dominant form (77.1%). Many animals, including man, metabolize p-p’DDT into p-p’DDE, and this latter form is stored and thus is the isomer most commonly found in general populations.

The relationship between the blood levels of p-p’DDE and p-p’DDT can be utilized for estimating the length of exposure to DDT. The average levels in Cota 200 were 1.84 mg/l for p-p’DDE and 0.01 mg/l for p-p’DDT, thus giving a ratio of 184. In Pilões, the average levels were 3.65 mg/l for p-p’DDE and 0.07 mg/l for p-p’DDT, giving a ratio of 52, or in other words, 3.5 times less than in Cota 200. This demonstrates more recent exposure to this pesticide in Pilões. Carvalho et al2 (1988), when studying a population in the State of Bahia without occupational exposure, found a p-p’DDE/ p-p’DDT ratio of 49, thereby showing an exposure situation similar to that of Pilões.

The finding of more recent exposure to HCH and DDT in Pilões may be reflecting the high degree of environmental contamination of that area, thus demonstrating the frequent exposure risk among that community.

The number of individuals in Pilões who presented some POP residue in the blood was 212 persons, or in other words, 95.5% of all those who underwent this examination. In Cota 200, the number of positive examinations for POP was 141, i.e. 57.3% of all examinations.

The differences increase when we analyze POP separately: for HCB, 87.4% of the examinations positive in Pilões, versus 5.7% in Cota 200; total DDT, 88.3% versus 52.4%; and total HCH, 59.9% versus 4.5%.

Table 3 shows that the average blood levels of HCB, p-p’DDE, a HCH and b HCH were all significantly higher in Pilões than in the control group (p<0.01). No statistical difference was found in the average levels of p-p’DDT (p=0.24) and g HCH (p=0.77) between the groups studied. The inhabitants of Pilões not only presented a greater number of persons with POP residues, but also higher concentrations than in the control group.

A positive association was found between dwelling in Pilões and presenting blood residues of POP, with a 115-fold greater chance of this in relation to HCB, sevenfold in relation to p-p’DDE, 20-fold in relation to b HCH and fourfold in relation to g HCH.

Table 4 shows the blood concentrations of POP by sex and age group. Some studies (Stehr-Green,13 1989; Lommel et al,7 1985; Delgado et al,4 2002) have demonstrated a positive correlation between blood levels of POP and age. In the present study, no correlation was verified between blood levels of HCB (r=0.10), total DDT (r=0.13) and total HCH (r=0.13), and age. This characteristic was maintained, with only those individuals who presented blood levels of POP above the detection limit kept in the calculation. This signifies that the blood concentrations of POP were presumably expressing a state of equilibrium that did not depend on the individual’s age, but rather the degree of external exposure. Stehr-Green et al12 (1988) found slightly greater levels of POP among males. There was generally no difference between the sexes in the different age groups, with the exception of women from 20 to 39 years of age, dwelling in Pilões, who presented higher levels of total HCH than the men of the same age.

The data presented demonstrate the excess risk of exposure to all the organochlorine pesticides to be found in Pilões, for the population of that region.

From the public health point of view, such conditions are in themselves sufficient to justify sanitary measures such as the cleanup of the area, with the removal of the hazardous waste or, if this is not viable, the removal of the people from the place of risk. There is no need to wait until the toxic effects appear before taking the measures necessary for preserving the health of this population.



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Correspondence to
Eladio Santos Filho
Av. Washington Luís, 522 apto102 Gonzaga
11055-000 Santos, SP, Brasil
E-mail: elladiosto@aol.com

Received on 8/10/2002.
Reviewed on 28/2/2003.
Approved on 28/3/2003.



Based on thesis presented to the Department of Epidemiology of the Faculdade de Saúde Pública of Universdade de São Paulo, in 1998.
* Hazardous waste: The Environmental Protection Agency of the USA defines hazardous waste as “materials that, because of their quantity, concentration, or physical, chemical or infectious characteristics, may cause an increase in mortality or an increase in serious irreversible or reversible illness that produces invalidity or contributes significantly to this, and also pose a substantial real or potential risk to human health and the environment when they are improperly treated, stored, transported, disposed of or handled” (USEPA,15 1986).
** Demographic and socioeconomic survey of the Pilões locality. Unpublished data.

Faculdade de Saúde Pública da Universidade de São Paulo São Paulo - SP - Brazil
E-mail: revsp@org.usp.br