Can living in the surroundings of a petrochemical complex be a risk factor for autoimmune thyroid disease? Environ Res

Epidemiological Surveillance Center-CVE/SES/SP, Arnaldo, 351, 6(o) Andar, São Paulo/SP-CEP:01246-000, Brasil.
Environmental Research (Impact Factor: 4.37). 11/2009; 110(1):112-7. DOI: 10.1016/j.envres.2009.10.009
Source: PubMed
Based on a suspicion raised by a health professional and due to a subsequent legal request, a cross-sectional study was made with a comparison group to investigate a possible excess of Hashimoto's thyroiditis-HT and antibodies-ATA in the surroundings of a Petrochemical Complex.
People of both sexes aged over 20 years were investigated in a random sample of residents in the area surrounding the Petrochemical Complex. Controls were investigated in an area with steel industries. In the areas searched, participants were chosen randomly and stratified a priori by sex and age group. As a result, 90.5% of the expected sample was obtained, totaling 1533 individuals. HT and ATA prevalences were compared by the chi-square test. Logistic regression was used to control the possible confounding factors for HT and ATA.
Both TH (9.3%) and ATA (17.6%) prevalences were higher in the Petrochemical Complex area than in the control area (3.9% and 10.3%, respectively). After controlling the possible confounding factors, the POR for living in the surroundings of the Complex and presenting HT was 2.39 (CI95%: 1.42-4.03). According to the ATA criterion, the POR for living in the surroundings of the Complex was 1.78 (CI95%: 1.23-2.60).
The authors have found higher prevalence and risk of developing thyroiditis and anti-thyroid antibodies among residents of areas surrounding the Petrochemical Complex and think these findings need to be further studied in similar areas.


Available from: William Waissmann, Oct 11, 2014
Can living in the surroundings of a petrochemical complex be a risk factor for
autoimmune thyroid disease?
$, $$
Clarice Umbelino de Freitas
, Rosa
ria A. Grimaldi Campos
, Mirta Alcira F. Rodrigues Silva
Maria Rosana I. Panach
, Jose Ca
ssio de Moraes
, William Waissmann
, Ant
onio Roberto Chacra
Marina Y.S. Maeda
, Regina S. Minazzi Rodrigues
, James Gonc- alves Belchor
, Sonia Oliveira Barbosa
Raimunda Telma M. Santos
Epidemiological Surveillance Center–CVE/SES/SP, Arnaldo, 351, 6
Andar, S
ao Paulo/SP–CEP:01246-000, Brasil
Department of Social Medicine–Santa Casa de Miserico
rdia Hospital/SP, Brazil
Oswaldo Cruz Foundation–FIOCRUZ/MS, Brazil
Department of Endocrinology–UNIFESP, Brazil
Adolfo Lutz Institute–IAL/SES/SP, Brazil
City Department of Health - S
ao Paulo, Brazil
Santo Andre
City Department of Health - S
ao Paulo, Brazil
article info
Article history:
Received 3 May 2009
Received in revised form
12 October 2009
Accepted 20 October 2009
Available online 12 November 2009
Hashimoto’s thyroiditis
Anti-thyroid antibodies
Petrochemical plant
Background: Based on a suspicion raised by a health professional and due to a subsequent legal request,
a cross-sectional study was made with a comparison group to investigate a possible excess of
Hashimoto’s thyroiditisHT and antibodiesATA in the surroundings of a Petrochemical Complex.
Methods: People of both sexes aged over 20 years were investigated in a random sample of residents in
the area surrounding the Petrochemical Complex. Controls were investigated in an area with steel
industries. In the areas searched, participants were chosen randomly and stratified a priori by sex and
age group. As a result, 90.5% of the expected sample was obtained, totaling 1533 individuals. HT and ATA
prevalences were compared by the chi-square test. Logistic regression was used to control the possible
confounding factors for HT and ATA.
Results: Both TH (9.3%) and ATA (17.6%) prevalences were higher in the Petrochemical Complex area
than in the control area (3.9% and 10.3%, respectively). After controlling th e possible confounding
factors, the POR for living in the surroundings of the Complex and presenting HT was 2.39 (CI95%: 1.42–
4.03). According to the ATA criterion, the POR for living in the surroundings of the Complex was 1.78
(CI95%: 1.23–2.60).
Conclusions: The authors have found higher prevalence and risk of developing thyroiditis and anti-
thyroid antibodies among residents of areas surrounding the Petrochemical Complex and think these
findings need to be further studied in similar areas.
& 2009 Elsevier Inc. All rights reserved.
1. Introduction
In mid-2002, the Epidemiological Surveillance Center of the
ao Paulo State Department of Health (Brazil) was notified by an
endocrinologist that in her private medical office, in the
municipality of Santo Andre
, an excessive number of Hashimoto’s
thyroiditis (HT) was observed. According to the doctor, the disease
also affected male individuals of younger age groups residing in
the surroundings of the Petrochemical Complex of Capuava, in the
municipalities of Maua
, Santo Andre
and S
ao Paulo. The press
announced the possible association between what had been
observed and the influence of the above-mentioned Complex.
The Petrochemical Complex of Capuava is located in the
municipality of Santo Andre
, state of S
ao Paulo, Brazil, in an area
of approximately 125 ha, between the municipalities of Maua
ao Paulo. It is composed of 9 industries producing polyethylene
and polypropylene from naphtha distillation, as well as various
intermediate substances used as raw material for manufacturing
other composites or for marketing. The area surrounding the
Complex is densely populated and the state environmental
Contents lists available at ScienceDirect
journal homepage:
Environmental Research
0013-9351/$ - see front matter & 2009 Elsevier Inc. All rights reserved.
doi:10.1016/j.envres.2009.10.0 09
This project was conducted by the Centro de Vigil
ancia Epidemiolo
gica CVE
da Secretaria de Estado da Sau
de de S
ao Paulo. Avenida Doutor Arnaldo, 351, 6
andar, S
ao Paulo/SP Brasil. CEP:01246-000 and funded by the Coordenac-
ao de
Controle de Doenc- as (CCD).
The authors declare they have no competing financial interests
Corresponding author. Fax: +55 11 30668304.
E-mail address: (C.U. Freitas).
Environmental Research 110 (2010) 112–117
Page 1
agency, CETESB, has a continuous air quality monitoring station in
the neighborhood of Capuava, where the levels of particulate
matter, PM10 and ozone O3, are measured. According to CETESB,
PM10 levels at the monitoring station are within legal limits (an
annual mean of 50
PM10) although ozone levels are above
the standard 160
/h, especially in summer.
HT is a disease caused by specific self-destruction resulting
from abnormal immune response, both in the field of humoral
immunity and cellular immunity. As a result, individuals start
producing antibodies against their own thyroid. This may cause
insufficient hormone production. The disease appears in many
forms, ranging from a subclinical form to frank hypothyroidism
(Akamizu et al., 2008).
Scientific production concerning health damages in areas
surrounding petrochemical industries has focused mainly on
cancer and undesirable effects during pregnancy (Belli et al.,
2004; Liu et al., 2008; Neuberger et al., 2003; Yang et al., 2002; Yu
et al., 20 06). The authors have only found studies relating
substances that may be present in Petrochemical Complexes and
the development of immunotoxicity (Fournier et al., 20 00). One
study analyzing the population surrounding these industries has
been previously reported and is quoted in the discussion
conducted here.
Based on the notification by the endocrinologist in the region,
the local Public Ministry requested the S
ao Paulo State Depart-
ment of Health to clarify the finding. The present study was
developed with the purpose of comparing the prevalence of
thyroid autoimmunity and HT development within the area of
influence of the Petrochemical Complex of Capuava with an
industrialized area that is not under the influence of the Complex.
2. Methodology
2.1. Sampling
A cross-sectional study with a comparison group was made
with individuals over 20 years of both sexes. The size of the
sample was calculated based on a 6.5% prevalence rate, the mean
reported in literature for thyroid changes (3–10%) (Canaris et al.,
2000; Hollowell et al., 2002; Tunbridge et al., 1977), with a 5%
significance level and an 80% power. After adding a 10% loss
estimate, the sample included 847 individuals per extract:
residents in the vicinity of the Complex and individuals living
far from it. The choice of the sites for selecting residents in the
vicinity of the Complex was based on the prevailing wind
direction, informed by CETESB, and the existence of an infra-
structure for systematic data registration of inhabitantsthe
Family Health Program (PSF). Another industrialized area in the
Metropolitan Region of S
ao Paulo also having an industrial
complex with prevailing steel industries and a similar social and
economic situation was chosen for population control. It will be
called control area here. This area is located in the neighborhood
of Serraria, in the municipality of Diadema, 11.8 miles away from
the Petrochemical Complex of Capuava. PM10 and ozone are also
monitored by CETESB in Diadema. Both municipalities present a
similar situation regarding the atmospheric concentration of
these regulated pollutants.
Based on the population census of 2000, conducted by the
agency in charge of Brazilian demographic statisticsthe Brazi-
lian Institute of Geography and Statistics (IBGE)the sample was
proportionally stratified by sex and age in the following age
groups: 20–39, 40–59, 60 years and over.
The PSF obtained a list with the residents of the municipalities
of Santo Andre
ao Paulo and Maua
. This list contained
information on the age and sex of the population of the selected
locations and made it possible to update the data from the
Brazilian 2000 census. There was no family health care structure
in the control area. Therefore, a preliminary listing of its residents
was made before the random sample. All residences in the
neighborhood of Serraria were visited and the census of all of its
residents was made. Taking into consideration all the information
obtained, individuals were selected in both areas using the
random sampling method before fieldwork began.
Until 2003, regulatory iodine levels to be added to salt in Brazil
ed from 40 to 100 mg/kg. In 2003, the regulatory level of
iodine addition to salt was changed to 20–60 mg/kg. There is
presently a discussion on whether the incipient quality control of
manufacturers guarantees that the iodine added to salt complies
with these rules. In order to check whether there was any
difference between iodine levels in table salt and iodine excretion
in urine among the populations studied, a 10% subsample for
urine iodine measurement and table salt iodine measurement at
the residences was drawn at random among the participants of
each area. The choice for a small sample was due to the small
capacity of the laboratory.
The visits occurred on all days, including during weekends, in
order to guarantee the greatest participation possible of men and
women. In case the residence chosen was closed or the chosen
individual was absent on the day of the visit, the interviewer
should try again twice.
Losses were observed during the preliminary evaluation phase
of participation in the study, especially among young men,
because they either refused to participate or did not attend the
medical consultation. As young men were less willing to
participate, these individuals were visited more than twice. In
case they did not agree to participate in the study, their
replacement by another person of the same sex and age group
residing next door was allowed. In case this second individual did
not agree to participate, it was considered a loss.
Trained interviewers applied the questionnaire to all partici-
pants in the investigation. The questionnaire contained identifica-
tion data, profession and exposure to chemical substances in the
work, family history of thyroid pathology, and frequency of
consumption of algae and fish. A list of medications containing
iodine was included in the questionnaire and people were asked
whether they used medicine containing hormones. As Brazilian
endocrinologists have observed that people who eat much food
containing high concentrations of salt are more exposed to iodine,
with possible damage to the thyroid (Duarte et al., 2004),
questions regarding the habit and frequency of eating salty snacks
were asked. When people were visited, interviewers collected
table salt used in the residences of the individuals chosen for this
subsample and instructed them to collect the urine sample in the
container provided for that purpose and to take it on the day
scheduled for consultation. The medical consultation was sched-
uled according to the resident’s available dates and always took
place on weekends, so as to ensure the participation of as many
working men as possible. The consultation was performed in
neighboring health care units or within each chosen area of study.
On the occasion, blood was also collected to perform the
prescribed exams and thyroid ultrasonography by professionals
contracted and trained to this purpose. As for thyroid diagnosis,
endocrinologists were trained to fill in the questionnaire about
the existence of a family history of autoimmune diseases as well
as use of medicine that may damage thyroid function.
Laboratory exams were processed by the Adolfo Lutz Institute
(IAL). Urine iodine measurement was performed according to the
guidelines of the International Council for the Control of Iodine
Deficiency (ICCIDD) and the World Health Organization (WHO),
which recommend the use of methods based on the Sandell
and Kolthoff (1937) preceded by a digestion stage modified by
C.U. Freitas et al. / Environmental Research 110 (2010) 112–117 113
Page 2
Pino et al. (1996) in order to eliminate oxidizing and reducing
substances that may interfere with the reaction (Pino et al., 1996;
Sandell and Kolthoff, 1937). The colorimetric technique was used
and iodine concentration was measured by a spectrophotometer
connected to a software program.
The analyses of thyroid function markers were performed
using Electrochemiluminescence Immunoassay (ECLIA) with the
Elecsys 2010–Roche analyzer. Anti-thyroid peroxidase (anti-TPO)
reference values ranged from 0.00 to 34.0 UI/mL and anti-
thyroglobulin (anti-TG) reference values ranged from 0.00 to
115.0 0 UI/mL. In thyroid-stimulating hormone (TSH) analyses,
reference values ranged from 0.270 to 4.20
UI/mL. TSH levels
were also measured for ethical reasons and all individuals with
values out of the reference range were referred to medical
The reference values defined by Dunn et al. (1993) for normal
and deficient urine iodine concentration were considered. The
methodology used for measuring iodine concentration in table
salt was titration according to the 383/IV technique (IAL, 2005)).
The present work was approved by the Ethics Committee of
Adolfo Lutz Institute (Process Nr. CCD/PA 001/2004). All partici-
pants have signed the Free and Informed Consent Term and those
diagnosed for thyroid pathology were sent for medical treatment.
2.2. Case definition
For the purposes of this study, thyroid diagnosis criteria have
been standardized based on laboratory and ultrasonography
results. After fieldwork was concluded, all diagnoses were
reviewed; the criteria established during the research prevailed.
2.2.1. Individuals older than 20 years of both sexes presenting
auto anti-thyroid antibodies above reference values and ultra-
sound thyroid changes presenting echogenic modification were
defined as cases of Hashimoto’s thyroiditis (HT).
2.2.2. Considering that anti-thyroid antibodies participate in
the physiopathological process of the genesis of Hashimoto’s
thyroiditis and that their rise above reference values may precede
the existence of alterations detectable by ultrasonography, the
category ‘presence of antibodies–ATA’ was also defined: cases
presenting either anti-thyroid peroxidase (anti-TPO) or anti-
thyroglobulin (anti-TG) antibodies above reference values. (Larsen
et al., 1998 )
2.3. Data analysis
In view of the losses observed when compared to the sample
proposed, the data were stratified by sex and age with the purpose
of assessing whether these losses would influence the initially
established distribution.
To analyze the cases according to the proposed criteria,
pathologies classified as other thyroidopathies were excluded
and homogeneity of the distribution by sex and age was assessed.
HT and ATA prevalence was calculated for the Complex area
and for the control area. The chi-square test for proportions was
performed. Data were stratified by sex, age group, and skin color.
Prevalence was calculated based on these variables.
Various residence time classifications were tested to perform
linear trend tests both among the residents of the Complex and
those of the control area. Ten-year categories were chosen. The
purpose of this analysis was merely to check whether residence
time was a factor to be considered in the area studied. It was not
considered as a cause leading to a conclusion.
As a second approach, the Prevalence Odds Ratio (POR) for
living in the Complex area and having HT or ATA was calculated.
The POR for various risk factors described in the literature and
those related to consumption of food naturally rich in iodine were
also calculated. In order to do so, variables were transformed into
dichotomic variables, except for the residence time, which was
classified into 6 categories of 10 years of residence in the site. In
the case of consumption of food containing much salt as well as
salty snacks, the affirmative response was combined with
frequency. Non-consumption or consumption only once a week
were considered as a baseline. When treating the variable use of
medicine interfering with thyroid function, all affirmative re-
sponses for the various products inquired were added to a single
dichotomic variable for using or not using these substances.
A multivariate logistic regression analysis was performed to test
all factors having po 0.20. Model adequacy was checked by the
maximum likelihood method. Interactions were always tested
when a variable included in the model changed the value of the
previous ones by 10% or more. Variables entered the multivariate
model following either its level of significance observed in
univariate analysis or POR value. After building the final model,
variables presenting po 0.20 in univariate regression were
reintroduced one by one. Those which were neither statistically
significant nor presented interaction were excluded from the final
When analyzing iodine levels, the correlation between iodine
concentration in table salt and urine was assessed by the Pearson
correlation test after testing distribution normality. Iodine means
in table salt and urine were compared according to residence area.
In the last stage of the analysis, only the data of interviewees
supplying both salt and urine samples for assessing iodine levels
were considered, as not all of those who supplied table salt
attended the medical consultation. A univariate regression
analysis between ATA and iodine levels in table salt and urine
as dichotomic variables was performed. Mean iodine concentra-
tion was taken as a parameter for the analysis.
The analyses were performed with the statistical packages
Epi-Info and SPSS version 14. A 5% probability rate or po 0.05 was
considered significant.
3. Results
Table 1 pr
esents the distribution of the sample proposed and
effectively obtained. It may be observed that losses were greater
in the control area (11.2%) than in the Complex area (7.8%), with a
significant difference. Although losses were homogeneous,
women participated in the study more than men in both areas.
After excluding other thyroidopathies (443 cases) having no
HT, 1090 registers were left for analysis. According to the chi-
square test, the distribution of these participants was homo-
geneous among the areas of study concerning sex (p=0.84) and
age group (p=0.15). Among these 1090 individuals, 71 (6.5%) were
found to have HT. A lesser proportion of thyroiditis was observed
Table 1
Sample distribution proposed and obtained according to sex and age group.
Sex Age Complex Area Control Area
Proposed Obtained Proposed Obtained
Feminine 20–39 234 212 234 202
40–59 146 153 146 146
60 and + 55 54 55 52
Masculine 20–39 227 171 227 184
40–59 139 143 139 124
60 and + 46 48 46 44
Total 847 781 847 752
C.U. Freitas et al. / Environmental Research 110 (2010) 112–117114
Page 3
among men (1.8% of 542 men) than among women (11.3% of 477
women). Considering the self-assigned skin color variable (999
people), most cases occurred among whites (7.3%). There was a
4.0% prevalence rate among those who declared themselves black
(75 people) and a 5.2% prevalence rate among pardo (i.e. mulatto)
(252 people). No cases were found among those who declared
themselves of Asian descent (6 people). When analyzing age
group and presence of the disease, a similar proportion was
observed in the brackets from 40 to 59 years old (9.3%) and 60 and
over (9.2%), with 397 and 98 people, respectively. There was a 4.2%
proportion (595 people) in the group from 20 to 39 years old.
HT prevalence among the residents of the Complex was 9.3%
(49 cases), being greater (po 0.01) than in the control area, with
3.9%. Crude POR for living in the Complex area and presenting HT
was 2.53 (CI: 1.51–4.25).
After having used the presence of antibodies criterion and
excluded individuals not fitting into the ATA criterion (512 cases),
1021 registers were left to be analyzed. Of those, 142 (13.9%) were
classified as ATA. A lesser proportion of ATA was observed among
men (6.6% of 515 men) than among women (21.3% of women).
Considering the self-assigned skin color variable (972 people),
cases were predominant among whites (8.0% of 646 people).
There was a 4.1% prevalence rate among those who declared
themselves black and a 5.7% prevalence rate among pardos.No
cases were found among those who declared themselves of Asian
descent. A growing trend with greater proportion between the
elderly (24.7% of 93 people aged 60 and over) was observed in the
analysis of age groups and ATA. The proportion of the group from
20 to 39 years old was 8.6% and 19.3% of the group from 40 to 59
years old in a population of 560 and 368 people, respectively. The
proportion of anti-TPO above the values considered acceptable
(132 people) was greater in the Complex area (62.1%) than in the
control area (37.9%).
ATA prevalence among the residents of the Complex was
significantly greater than in the control area: 17.6% (89 cases) and
10.3% (53 cases), respectively. Crude POR for living in the Complex
area and fitting into the ATA criterion was 1.87 (CI: 1.30–2.69).
Table 2 presents the POR of the univariate regression analysis
for both diagnosis criteria. It may be observed that the following
variables were statistically significant for HT: use of medicine
containing iodine and family history of thyroid disease. For the
ATA criterion, significant variables were consumption of
appetizers (as a protection factor), family history of thyroid
diseases, use of medicine containing iodine or hormones, reported
skin color having white as the baseline, and residence time in the
Tables 3 and 4 present POR values in the final model for the HT
and ATA criteria, respectively. They show that residing in the
complex was a risk factor for both classifications, having greater
magnitude of association for the HT criterion. Only reference to
the use of medicine containing iodine or hormones remained an
independent risk factor in this criterion. The variable consumption
of appetizers was considered a protection factor for the ATA
criterion. Besides use of medicine, the existence of a family history
of thyroid disease and residence time were also risk factors for
this criterion.
The chi-square test for linear trend among residents of the
Complex was significant only for the ATA criterion (p=0.02).
Considering that the individuals who have lived in the location for
a long time are probably the oldest, the linear trend test for
residents in the control area was performed with the same
classification. No statistical significance was found (p=0.93). The
collection and analysis of 139 samples for iodine in table salt and
141 samples for iodine in the urine were conducted. General
means were 30.4 mg/kg and 27.1
g/dL, respectively. These iodine
levels are within the acceptable limits of 20–60 mg/kg of salt
(Brasil, 2003) and 10–30
g/dL of urine iodine, according to the
method chosen. No significant differences were found when
comparing the means of iodine among the residents of the
Table 2
Prevalence ODDS RATIO and 95% Confidence Interval for residing in the Petrochemical Complex and exploratory variables according to the Hashimoto’s thyroiditis (HT) and
anti-thyroid antibodies (ATA) criteria.
Variables HT Criterion ATA Criterion
Living in the Petrochemical Complex 2.53 1.51–4.25 0.00 1.87 1.30–2.69 0.00
Use of medicine with iodine or hormone 3.83 2.31–6.36 0.00 2.37 1.56–3.59 0.00
Family history of thyroid diseases 1.76 1.03–3.00 0.03 1.91 1.28–2.86 0.00
Consumption of appetizers 0.59 0.25–1.38 0.23 0.46 0.23–0.89 0.02
Skin color (white as reference) 0.67 0.39–1.15 0.15 0.62 0.42–0.93 0.02
Residence time 1.14 0.95–1.35 0.15 1.16 1.02–1.33 0.02
Consumption of salty food 0.40 0.96–1.66 0.21 0.58 0.25–1.37 0.21
Working with chemical products 0.75 0.44–1.28 0.29 0.83 0.56–1.21 0.33
Smoking 0.68 0.34–1.36 0.28 0.46 0.53–1.34 0.46
Consumption of fish 0.95 0.37–2.44 0.92 1.26 0.66–2.41 0.48
Reporting autoimmune disease 0.43 0.06–3.17 0.40 1.20 0.45–3.17 0.72
Consumption of algae 0.00 0.00–??? 0.99 0.00 0.00–??? 0.99
Table 3
Prevalence ODDS RATIO and 95% Confidence Interval of the multivariate logistic
regression model for living in the Petrochemical Complex based on the
Hashimoto’s thyroiditis (HT) criterion.
Variables POR CI p
Living in the petrochemical complex 2.39 1.42–4.03 0.00
Use of medicine with iodine or hormone 3.65 2.18–6.08 0.00
Table 4
Prevalence ODDS RATIO and 95% Confidence Interval of the multivariate logistic
regression model for living in the Petrochemical Complex based on the anti-
thyroid antibodies (ATA) criterion.
Variables POR CI p
Living in the petrochemical complex 1.78 1.23–2.60 0.00
Use of medicine with iodine or hormone 2.48 1.61–3.48 0.00
Family history of thyroid diseases 1.65 1.09–2.51 0.02
Consumption of appetizers 0.40 0.20–0.82 0.01
Residence time 1.20 1.05–1.37 0.01
C.U. Freitas et al. / Environmental Research 110 (2010) 112–117 115
Page 4
Complex and those of the residents of the control area. The means
for urine iodine was 26.5
g/dL in the Complex area and
g/dL in the control area (p=0.69). Regarding iodine
concentration in table salt, a 31.9 mg/kg means was found in the
Complex area and a 29.2 mg/kg means was found in the control
area (p=0.09). Only two of the salt samples analyzed were above
legal limits. They were both in the Complex area.
The Pearson correlation test between table salt and urine
iodine levels ( 0.07) was not significant (p=0.93).
Regression analysis chose only the 139 participants who
supplied table salt and urine samples. Other thyroidopathies
were observed in 51 of them. After excluding these other
thyroidopathies, only 88 were left for analysis. No statistical
significance was found by transforming table salt and urine iodine
measurements into dichotomic variables and testing them for ATA
(p=0.06 for table salt iodine levels and p=0.22 for urine iodine
levels). No p value was significant for the HT criterion in the same
analysis (p=0.67 for urine iodine and p=0.23 for salt iodine).
4. Discussion
Considering the areas studied in the Petrochemical Complex of
Capuava and in the neighborhood of Serraria in Diadema, higher
prevalence of Hashimoto’s thyroiditis and greater risk of having
the disease were found in the Complex area. The risk was also
greater for the ATA criterion. The greater risk of presence of TH
and ATA in the Complex area remains even after controlling
possible confounding factors.
Various measures were taken when elaborating and conduct-
ing the study in order to avoid losses in the proposed sampling.
However, losses have been observed especially among men. There
are no mechanisms available in order to assess the health
condition of those who were not persuaded to take part in the
investigation. The lesser participation of men may reflect the
smaller proportion of adult males who attend health services in
general in Brazil (Travassos et al., 2002 ). This limitation of the
study is supposed to have led to the overestimation of HT and ATA
prevalence in both populations, as HT and ATA prevalence is
greater for women.
In agreement with the literature consulted, Hashimoto’s
thyroiditis and ATA prevalence is higher in women and increases
with age (Vanderpump et al., 1995). The skin color variable was
collected based on the self-evaluation of participants. Higher
prevalence was found among those who classed themselves as
white, followed by pardo and black. The literature consulted
indicates higher risk of developing HT among Caucasians (Ban
et al., 2007). Similarly, Hollowell et al. (2002) found higher TSH
levels among the white, followed by Mexican Americans and
blacks, in a population free from hypothyroidism.
Based on the ATA criterion, the linear trend chi-square test
presented statistical significance for time of residence in the
Complex. However, it is important to notice that increase in the
percentage of the population presenting positive anti-thyroid
antibodies was associated with increase in age (Okayasu et al.,
1994). It applies to 1/3 of the population.
Comparison of the findings of this study with those of other
studies assessing the prevalence of Hashimoto’s thyroiditis is a
difficult task. As described by Dayan and Daniels (1996),HT
prevalence varies depending on the criteria used for its diagnosis,
on the region where it is studied, on the period of investigation, and
on the age group of the individuals investigated. Only the presence
of serum antibodies against the thyroid, only TSH elevation and
also both criteria have already been used. Associating these criteria
with the use of image exams is rare. There have been studies
using autopsies, the purpose of which was the histopathological
detection of gland lymphocytic infiltration. The high prevalence
found in these last studies is surprising (Okayasu et al., 1994;
Williams and Doniach, 1962), reaching 45% for women and 20%
for men. Autoantibodies titles may amount to 13% in women
and 3% in men in surveys (Tunbridge et al., 1 977). They are
strongly associated with hypothyroidism evolution within 25 years
nderpump et al., 1995), especially when TSH was already above
the prescribed level at the beginning of the cohort. A population-
based prevalence study performed by Tunbridge et al. (1977) found
high TSH levels (4 6 mU/L) more frequently in women (7.5%) than
in men (2.8%). Global prevalence was 3.6%, approximately the same
found in the control area of the present study (3.9%) based on the
HT criterion. The prevalence found by Tunbridge for the presence of
anti-thyroid antibodies was 8.8%, the closest to the ATA criterion
(10.3%). In the United States, Hollowell and collaborators (2002)
found that 4.6% of the population had hypothyroidism and 13.0%
had anti-TPO autoantibodies.
In studies of populations that look for endocrinology services
the prevalence has been higher. A study performed with patients
who resorted to the Department of Endocrinology in Tunisia
found a 22.8% prevalence of cases of Hashimoto’s thyroiditis,
which is clearly much higher than that found in the study
performed in the Complex of Capuava because it assessed an
oriented demand (Chabchoub et al., 2006). Only one investigation
has assessed compared HT prevalence between the Petrochemical
Complex of Capuava and the control area (S
ao Bernardo do
Campo). The findings of this investigation were opposite to those
found in the present study. In the study performed by Camargo
et al. (2006), HT prevalence in the Complex was 14.6% and that of
the control area was 19.5% (p=0.16). The present investigation has
found a prevalence of 9.3% and 3.9% (po 0.01), respectively, in the
Complex area and in the control area, based on the HT criterion.
A 17.6% rate was found in the Complex and a 10.3% rate in the
control area (Diadema) for the ATA criterion (po 0.01).
It may be argued that divergence between these findings is due
to different diagnosis criteria. In order to verify this hypothesis,
the data of the present survey were subsequently classified
according to the criterion used by Camargo et al. (2006) to
calculate prevalence per area. Prevalence remained significantly
higher in the Complex than in the control area (31.3% and 19.7%).
One of the hypotheses that may be considered for explaining
these differences concerns how individuals were selected by that
study. In the study conducted by Camargo et al. (2006), volunteers
who were at home on the day of the interview were selected.
Interviews took place on workdays, according to the author,
‘‘when most men (blue-collar workers) were away from their
respective homes’’.
Both iodine deficiency and excess of iodine are described as
causes of thyroidopathies (Nagata et al.,1998; Pedersen et al., 2007;
Vanderpump and Tunbridge, 2002). In Brazil, the limits set by
ANVISA (Health Control Agency) for table salt iodine concentra-
tions are questioned as too high for consumption (Camargo et al.,
2006; Duarte et al., 2004). As a consequence, there would be higher
intake of this component and harm to the thyroid. In this study,
table salt iodine levels were high in two of the samples. No
correlation between iodine concentrations in table salt and urine
were found. On the other hand, PORs for food consumption that
may naturally contain high iodine concentration were not found to
be significant when compared with the presence or absence of HT
among the participants. Only the consumption of appetizers
containing high levels of salt was presented as a protection factor
for developing the disease based on the ATA criterion. However,
high iodine concentration in the urine of both groups should
be carefully considered. They were above prescribed values
g/dL) in 44% of the 141 individuals investigated, and a
similar proportion was found in both areas (44.3% in the control
C.U. Freitas et al. / Environmental Research 110 (2010) 112–117116
Page 5
area and 43.5% in the Complex). In spite of the use of medicine
containing iodine or hormone having been considered a risk factor
for the development of HT or ATA, the small proportion of users
does not explain the magnitude of the findings. Other factors are to
be further investigated in order to improve understanding of urine
levels, as they may indicate high iodine intake.
The presence of autoimmune disease in the individual or his/
her relatives is indicated as a risk factor for the development of
thyroid autoimmune diseases (Biro
et al., 2006; Brix et al., 2000 ;
Fu et al., 2005; Prahalad et al., 2002; Rodrigues et al., 2008;
Villanueva et al., 2003). In this study, the presence of an
autoimmune disease among the participants was not found to
be significant for HT and ATA, although this may not have been
significant to the analysis due to the small number of cases. On
the other hand, the existence of a family history of thyroid
diseases was a significant independent variable in the multi-
variate regression using the ATA criterion.
Anti-TPO levels above acceptable limits is not a pathognomo-
nic of Hashimoto’s thyroiditis. Although low anti-TPO levels are
common and correlated with lymphocyte infiltration in people
with no thyroid pathology, they are a clear risk factor for
hypothyroidism when above acceptable parameters according to
Prummel and Wiersinga (2005). Anti-TPO levels may be used in
the follow-up of the development of hypothyroidism in healthy
individuals and in individuals prone to developing the pathology
(Prahalad et al., 2002; Prummel and Wiersinga, 2005).
Some compounds (polycyclic aromatic h ydrocarbons, furans,
dioxins, toluene and others) that may be found in petrochemical
plants can be related to immunot o xicity. They can affect the cellular
mechanisms of signaling, mediate apoptosis of immune cells, induce
autoimmunity or depress immune function (Fournier et al., 2000).
According to the authors, only very limited epidemiologic data
invol ving these chemicals and immunotoxicity exist.
In view of the limited epidemiological data and the complexity
of the subject of this study, the authors conclude that it is
necessary to investigate the residents of other areas located in the
surroundings of Petrochemical Complexes.
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  • Source
    • "However, the mechanisms by which petrochemical industrialisation affects residents' health were not fully understood, it is possible that the residents of the industrialized county suffered from air pollutants, possibly due to the local petrochemical facility, which resulted in more chronic illness and therefore smaller increases in life expectancy rates than in the reference county. Most of the previous literature reported negative effects of petrochemical emissions on neighboring residents' health, which might explain the smaller increase in life expectancies in the industrialized county345678924,25]. "
    [Show abstract] [Hide abstract] ABSTRACT: Petrochemical industries have been identified as important sources of emissions of chemical substances, and adverse health outcomes have been reported for residents who live nearby. The purpose of the current study was to examine the adverse effects of petrochemical industrialization in Taiwan on the life expectancy and personal income of people living in nearby communities. This study compared life expectancies and personal income between one industrial county (Yunlin County) and one reference county (Yilan County), which had no significant industrial activity that might emit pollutants, in Taiwan through analysis of 11 year long and publicly available data. Data from before and after the petrochemical company in the industrial county started (year 1999) operating were compared. Residents of the industrialized county had lesser increases in life expectancy over time than did residents of a similar but less-industrialized county, with difference means ranging from 0.89 years (p < 0.05) to 1.62 years (p < 0.001) at different stages. Male residents were more vulnerable to the effects of industrialization. There were no significant differences in individual income between the two counties. Countries, including Taiwan and the U.S., embracing petrochemical industries now face the challenge of environmental injustice. Our findings suggested that life expectancy lengthening was slowed and income growth was stalled for residents living in the industrial communities.
    Full-text · Article · Mar 2014 · BMC Public Health
  • Source
    • "Thus, recent studies have shown the close relationship between either excessive iodine levels (Camargo et al., 2006; Doğan et al., 2011; Teng et al., 2011) or Selenium deficiency (Toulis et al., 2010) and HT. High levels of several chemical agents have also been implicated in the incidence of goiter and autoimmune thyroiditis (de Freitas et al., 2010). Moreover, the components of several viruses (hepatitis C, human parvovirus B19, coxsackie and herpes viruses) were detected in the thyroid of Hashimoto's thyroiditis patients (Mori & Yoshida 2010). "
    Full-text · Article · Feb 2012
  • No preview · Article · Feb 2002 · Methods in Enzymology
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