2,3,7,8-Tetrachlorodibenzo-p-dioxin plasma levels in Seveso 20 years after the accident.

Abstract

In 1976, near Seveso, Italy, an industrial accident caused the release of large quantities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) into the atmosphere, resulting in the highest levels of the toxicant ever recorded in humans. The contaminated area was divided into three zones (A, B, R) corresponding to decreasing TCDD levels in soil, and cohort including all residents was enumerated. The population of the surrounding noncontaminated area (non-ABR) was chosen as referent population. Two decades after the accident. plasma TCDD levels were measured in 62 subjects randomly sampled from the highest exposed zones (A and B) and 59 subjects from non-ABR, frequency matched for age, gender, and cigarette smoking status. Subjects living in the exposed areas have persistently elevated plasma TCDD levels (range = 1.2-89.9 ppt; geometric mean = 53.2 and 11.0 ppt for Zone A and Zone B, respectively). Levels significantly decrease by distance from the accident site (p = 0.0001), down to general population values (4.9 ppt) in non-ABR, thus validating the original zone classification based on environmental measurements. Women have higher TCDD levels than men in the entire study area (p = 0.0003 in Zone B; p = 0.007 in non-ABR). This gender difference persists after adjustment for location within the zone, consumption of meat derived from locally raised animals, age, body mass index, and smoking. There is no evidence for a gender difference in exposure, so variation in metabolism or elimination due to body fat or hormone-related factors may explain this finding. Elevated TCDD levels in women may contribute to adverse reproductive, developmental, and cancer outcomes.

Full text

Page 1

2,3,7,8-Tetrachlorodibenzo-p-Dioxin Plasma Levels in Seveso 20 Years after
the Accident
Maria Teresa Landi,1 2Dario Consonni,3 Donald G. Patterson, Jr.,4 Larry L. Needham,4 George Lucier,5 Paolo
Brambilla,6 Maria Angela Cazzaniga,6 Paolo MocarelliA6 Angela C. Pesatori,2'3 PierAlberto Bertazzi,Z3 and
Neil E. Caporaso1
1Genetic Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892 USA; 2EPOCA, Epidemiology Research Center, University of
Milan, Italy; 31nstitute of Occupational Health, Istituti Clinici di Perfezionamento, Milan, Italy; 4Centers for Disease Control and Prevention,
Atlanta, GA 30341 USA; 5National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 USA; 6Desio Hospital,
University of Milan, Milan Italy
In 1976, near Seveso, Italy, an industrial accident caused the release oflarge quantities of2,3,7,8-
terchlorodibenzo-pdi
(TCDD) nto the atmosphere, resulting in the highest levels of the
toxicant ever recorded in humans. The contminated area was divided into three zones (A, B, R)
corresponding
decreasing TCDD levels in soil, and a cohort incuding all residents was enu-
merated. The population of the surrounding noncontaminated area (notn-ABR) was chosen as
referent population. Two decade after the accident, plasmaTCDD level were measured in 62
subjects randomly sampled from the highest exposed zones (A and B) and 59 subjects from non-
ABR, frequency matched for age, gender, and cigarette smoking status. Subjects fliing in the
*exoed areas have persistently .elevated.plama TCDD levels (ran
mean _ 53.2 and 11.0 ppt for ZoneA anid Zone B,
distance from the accident site (p= 0.0001), down to general population values (4.9 ppt) in non-
ABR, thus vaidating the original zone classification based on.environmental measurements.
Womein have higherTCDD levels than men in the entirestudy area (p-0.0003 in Zone B;p -
0.007 in non-ABR). This gender difference persist after adjustment for location within the zone,
consumption of meat ived from loally raisdam, age, body mass index, and smoing.
There is no evidence for a gender di&rence in exposure, so variation in metabolism or elimina-
tion due to body fat or hormone-related factors mxiay exli
in women may contribute to adverse reproductive, developmental, and cancer outcomes. Key
work accident, dioxin, fat, gender, hormones, TCDD. Environ Health Penpec 106:273-277
(1998). [Online 31 March 1998]
hap://ehpne1.niehs.nib.gv/docs119981106p273-277landiJabsaracthsml
1.2I89.9 ppt; geometc
ivel). Levels significantyd
by
this finding.Eleted TCDD levels
The Seveso accident occurred on 10 July
1976 when a reaction vessel in a local facto-
ry went exothermically out of control and
sent kilogram quantities of 2,3,7,8 tetra-
chlorodibenzo-p-dioxin (TCDD) into the
atmosphere. The doud of material was car-
ried southeast in a fan-shaped plume of fall-
out. Based on soil TCDD measurements,
the contaminated area was divided in three
zones (A,B,R) with progressively lower but
distinct contamination. Over the next few
weeks, chloracne developed in almost 200
local residents, and over the next several
weeks, the entire population of Zone A
(about 730 persons) was evacuated. To
investigate the possibility of long-term
health effects ofTCDD, a cohort, including
all the subjects ever living from the time of
the accident onward in Zone A (currently
around 800), Zone B (around 5,900), and
Zone R (around 38,000), was enumerated
and periodically updated. Approximately
232,000 subjects from the surrounding non-
contaminated area (non-ABR) were fol-
lowed to serve as a reference population for
mortality and cancer incidence studies (1).
TCDD is important because of its
broad toxicity in experimental animals and
humans (2, which includes teratogenic (3),
carcinogenic (4-7), hormonal (8,9),
immunologic (10), and possibly sex ratio
(11) effects. In addition, its persistence in
the environment and long half-life in
humans [estimated at 7 or more years
(12,13), and precisely at 8.2 years in the
Seveso population (14)], create an oppor-
tunity for chronic disease in humans and
long-term environmental consequences.
Seveso offers a unique opportunity to elu-
cidate these effects because the exposure
was relatively specific and substantial and
occurred over a wide dose range and in a
large and stable human population that
includes both genders and various age
groups.
A 15-year mortality study of the Seveso
population showed an increase in gastroin-
testinal cancer (particularly in females),
lymphatic and hematopoietic neoplasms,
and possibly soft tissue sarcoma (15). A 10-
year morbidity study showed similar find-
ings (in particular an increase of hepatobil-
iary cancer among females) and also
showed a slight decrease of breast and uter-
ine cancer incidence (16). Several studies
have detected a positive association of a
variety of cancers in other TCDD-exposed
populations (17-23), but other studies,
generally involving low exposures, have not
(24-28). However, most studies derive from
occupationally exposed groups, which
include mostly men, have potential exposure
to multiple occupational toxicants, and
involve chronic rather than acute exposure.
In addition, most of them lack a registry to
provide a framework for study. A compre-
hensive review of these studies can be found
in the recent IARC (International Agency
for Research on Cancer) Monograph on
polychlorodibenzo-para-dioxins and poly-
chlorinated dibenzofurans (29) in which
TCDD is defined as carcinogenic to
humans.
In this paper we present the distribution
of TCDD in the Seveso area, almost two
decades following the event.
Methods
Sixty-two subjects from the most TCDD-
contaminated zones (A and B) and 59 from
the noncontaminated area (non-ABR) were
studied. Subjects were randomly sampled
from the cohort and frequency matched by
gender, age, and cigarette smoking status.
Residence in the specific zone (A, B, or non-
ABR) was established by determining
address and verified by establishing actual
domicile (i.e., did the subject actually live at
the address corresponding to the legal
address?) and presence in the specified area at
the time ofthe accident. Subjects with severe
medical illness (liver, kidney, cardiac,
immune, neoplastic, or major psychiatric dis-
ease) were excluded through telephone calls
assisted by a physician. Exclusion rates were
low and similar across the zones (precisely,
five from non-ABR and four from zone B).
Informed consent was obtained from partici-
pants, and the study was reviewed and
approved by the local Institutional Review
Address correspondence to M.T. Landi, Genetic
Epidemiology Branch, EPN 400A, NCI/NIH, 6130
Executive Boulevard, Bethesda, MD 20892-7360
USA.
The authors are grateful for support from the
Region of Lombardy and Fondazione Lombardia
per l'Ambiente. We thank colleagues who reviewed
this work, including Bob Hoover, Patricia Hartge,
Margaret Tucker, and Carlo Zocchetti.
Received 17 September 1997; accepted 8 January
1998.
Environmental Health Perspectives
* Volume 106, Number 5, May 1998
273

Page 2

Articles * Landi et al.
Board. A questionnaire including data on
demographics, lifestyle, foods consumed at
the time of the accident, residential history,
occupation, and reproductive and medical
history was administered by trained inter-
viewers. The dioxin assay was performed at
the Centers for Disease Control and
Prevention (CDC) using a high-resolution
gas chromatography/high resolution mass
spectrometric analysis performed on human
plasma, as described by Patterson et al. (30).
Specifically, we assayed for TCDD, other
dioxins, dibenzofuran congeners, and copla-
nar polychlorinated biphenyls (PCBs), with
results reported in parts per trillion (ppt),
lipid adjusted. Of 121 subjects, 11 samples
(4 from zone B and 7 from non-ABR) were
inadequate for analysis and were exduded.
Another 23 samples (9 from zone B and 14
from non-ABR) with valid but nonde-
tectable results had levels estimated by divid-
ing the lipid-adjusted detection limit by the
square root oftwo (31). Excluding or assign-
ing zero values for these samples did not
substantially change the reported findings.
Nonparametric tests (Wilcoxon rank-sum
and Kruskal-Wallis) for medians, and t- and
F-tests for geometric means were used in
univariate comparisons and in multiple
regression analyses. Geometric mean (GM)
and standard deviation (SD) values are
shown, unless otherwise specified.
Table 1. Characteristics of the study population by
zone and gender
Zone A Zone B Non-ABR Total
Gender (n)
F
M
Smoking8 (n)
F
M
Mean age (years)
F
M
Mean weight (kg)
F
M
Mean height (cm)
F
M
Mean BMI
F
M
Mean PBFC
F
M
Mean years living in
the zone
F
M
Abbreviatons: Non-ABR, noncontaminated area; BMI, body
mass index; PBF, percentage bodyfat F, female; M, male.
&Ever smoked cigarettes.
bM and F combined.
cDerived from BMI and normed for gender(39).
dThe Zone A population was evacuated and some people never
went back.
Variable
2
5
28
27
32
27
0
3
6
10
18
19
62
59
16
40
48.7
57.9
48.8
46.1
45.5
46.9
79.0
80.2
161
171
58.7
77.6
161
172
61.0
72.9
163
172
30.5
27.4
22.7
26.3
23.1
24.8
39.0
21.3
28.8
20.0
29.5
18.0
0.07d
13.3d
15.3
16.1
16.4
16.9
Results
Characteristics of the study population are
shown in Table 1. There were 7 subjects
from Zone A (2 females, 5 males), 55 from
Zone B (28 females, 27 males), and 59
from non-ABR (32 females, 27 males).
The current mean TCDD levels in
individuals from Zone A, Zone B, and
non-ABR were 53.2 ppt, 11.0 ppt, and 4.9
ppt, respectively (p= 0.0001) (Table 2). If
we assume an 8.2-year half-life (14), the
extrapolated mean levels at the time of the
accident are 230.0 ppt for subjects from
Zone A and 47.5 ppt for residents of Zone
B (extrapolation is not relevant to the non-
ABR area, which was unaffected by the
accident). The absolute and extrapolated
median levels show a similar difference
across zones. All samples in Zone A had
detectable TCDD levels; when nine sam-
ples from Zone B with nondetectable
TCDD levels were excluded, the difference
across the zones persisted (extrapolated
mean in Zone B became 66 ppt).
Females from Zone B had significantly
higher plasma TCDD levels than did
males; 26 females had a mean of 17.6 ppt
compared to 25 males who had a mean of
6.7 ppt (p=0.0003). In non-ABR, females
also exhibited higher TCDD levels than
did males (means, 6.1 ppt and 3.7, respec-
tively; p=0.007) (Table 3). The highly sig-
nificant elevation in females was similarly
present when median levels were compared
using a ranking statistic (Zone B, p =
0.0003; non-ABR, p = 0.005). The small
numbers of subjects in Zone A precluded a
reasonable gender comparison. Besides
gender, no other variables were associated
with TCDD levels in non-ABR.
Based on analysis of a separate group of
Seveso subjects, a longerTCDD half-life has
been suggested in females (9.0 years, n= 15)
than men (7.1 years; n= 12) (L. Needham,
personal communication). When we extrap-
olated TCDD levels back to 1976, taking
into account the gender-specific half-lives,
the gender difference remained significant
(females, GM=66.8 ppt; males, GM=36.4
ppt; p=0.02, Zone B).
An increase in TCDD levels was found
in older subjects in Zone B (F-test, GM, p
= 0.03), most evident in individuals over
the age of 60 years. (Fig. 1). With fluctua-
tions due to small numbers, females had
higher levels than males in each age class
except for subjects over 70 years ofage.
As expected, the weight, height, and
body mass index (BMI) were higher in
males, while percentage body fat (PBF) was
higher in females (Table 1). Within gender
categories, TCDD levels were unrelated to
PBF, BMI, height, or weight. Reported
weight loss (Table 4) was weakly related to
TCDD levels in females only [no weight
loss (n=21;TCDD GM= 16.3; SD=2.1);
Table 2. Current and extrapolated TCDD levels (ppt) by zone
TCDD levelsa
Zone
A
Current
Extrapolated
B
Current
Extrapolated
Non-ABR
No.
GM
GSD
Median
Range
7
53.2
230.0
2.2
2.2
73.3
325.9
9.8-89.9
41.2-399.7
51
11.0
47.5
4.9
2.7
2.7
1.9
12.4
52.5
5.5
1.2-62.6
5.3-273.0
1.0-18.1
52
(p= 0.0001)b
(p=0.0001)c
Abbreviations: Non-ABR, noncontaminated area; GM, geometric mean; GSD, geometric standard deviation.
fHalf-life,8.2 years (14).
bFTest for mean In(TCDO) difference among zones (current values).
CKruskal-Wallis test for median difference among zones (current values).
Table 3. TCDD Levels (ppt) by zone and gender
Gender
A
F
M
Zone
No.
2
5
GM
60.5
50.5
GSD
1.5
2.5
Median
63.0
73.3
(p=0o99)b
16.8
6.5
(p = 0.0003)b
6.6
4.4
(p= 0.005)b
Range
45.3-80.7
9.8-89.9
(p=0.81)8
17.6
6.7
(p=0.0003)8
6.1
3.7
(p=0.007)8
B
F
26
25
2.1
2.7
1.3-62.6
3.5-44.7
M
Non-ABR
F
M
28
24
1.7
2.0
1.8-18.1
1.0-13.8
Abbreviations: Non-ABR, noncontaminated area; F, female; M, male; GM, geometric mean; GSD, geometric standard
deviation.
at-Test for mean ln(TCDD) difference between males and females.
bWilcoxon rank-sum test for median difference between males and females.
Volume 106, Number 5, May 1998
* Environmental Health Perspectives
24.4b
24.4b
274

Page 3

Articles * Seveso, 20 years after
weight loss reported (n = 5; TCDD GM =
24.2; SD = 2.5; p = 0.30)]. There was no
association between amount of weight loss
andTCDD levels, after controlling for other
covariates (e.g., distance from the accident,
meat consumption, etc.). None ofthese fac-
tors, that is, higher BMI in men, explains
away the gender difference when using a
multivariate model including gender and
other covariates (Table 5).
When other variables were evaluated
(Table 4), only consumption of locally
raised meat at the time of the accident
retained an association with higher TCDD
levels, both in females (no meat, n = 15,
TCDD GM = 16.4 ppt, SD = 1.7; ate
meat, n = 11, GM = 19.3 ppt, SD = 2.8)
and in males (no meat, n = 16, GM = 4.8
ppt, SD = 2.3; ate meat, n = 9, GM = 12.1
ppt, SD = 1.0).
In a multivariate analysis of subjects in
Zone B (subjects from Zone A were exclud-
ed because of small numbers), we consid-
ered several variables and interaction terms
(e.g., gender and BMI, age and BMI).
None of these interactions significantly
contributed to TCDD variance. The final
model, based on factors plausible in our
study or reported in other TCDD-exposed
groups, included gender, distance from the
source within the zone (also taking into
account the course ofthe toxic doud imme-
diately after the accident), consumption of
locally produced meat, age, cigarette smok-
ing, and BMI (as an estimate ofPBF). Only
the first three variables were significantly
associated with measured TCDD levels
(Table 5). In a similar model, which also
included the gender-specific half-lives, the
gender difference remained statistically sig-
nificant (p<0.01).
Among women in Zone B, oral contra-
ceptive users (n = 13; TCDD GM = 13.2
ppt; SD = 2.4) had lower levels than
nonusers (n = 13; GM = 23.4; SD = 1.7; p
= 0.05). In a multivariate model that also
included distance from the accident site,
age, BMI, and meat consumption, oral con-
traceptive use was significantly inversely
associated with TCDD levels (p = 0.04).
Adding parity to the model did not sub-
stantially change the result. When added to
the model, advanced age at menarche
exhibited a borderline association with
higher TCDD levels (p =0.07). This differ-
ence was unrelated to whether women
experienced menarche before or after the
accident. Other reproductive factors, e.g.,
age at menopause, were not associated.
Parity was not significantly associated with
TCDD levels, although the tendency was in
accord with expectations (parous, n = 20,
GM = 16.7 ppt, SD = 2.3 vs. nulliparous, n
=6, GM = 20.8 ppt, SD = 1.8).
We also measured current levels ofsome
PCBs, polychlorinated dibenzodioxins
(PCDDs), and polychlorinated dibenzofu-
rans (PCDFs) in the entire study area.
None of them varied across the zones, but
most of them (PCB126; 1,2,3,7,8-
pentaPCDD; 1,2,3,7,8,9-hectaCDD;
1,2,3,4,6,7,8-heptaCDD; octaCDD;
2,3,4,7,8-pentaCDF; 1,2,3,4,7,8-hecta-
CDF; 1,2,3,6,7,8-hectaCDF; 2,3,4,6,7,8-
hectaCDF) had significantly higher levels in
women and exhibited an age effect stronger
than forTCDD (data not shown).
30
25
20
,.
CL
ta
15
10
5
20-29
30-39 40-49
50-59
6069
70+
Age (years)
Figure 1. Median TCDD levels (ppt) by gender and age in Zone B.
The numbers over each column indicate the number ofsubjectsin eachageandgender category.
Discussion
This is the first study to confirm that ele-
vated TCDD levels persist in people from
the exposed areas almost 20 years after the
accident. Furthermore, mean TCDD levels
correspond to zone categorization based on
soil TCDD measurements determined in
1976 (1). Typical population values are
present in the surrounding non-ABR area.
Exceptionally high levels of TCDD have
been previously measured in serum speci-
mens drawn in 1976 from people who
were living in Seveso, particularly those
with chloracne (32, 33). These studies were
Table 4. TCDD levels (ppt) by zone, gender, and
selected variables,
Females
No.
Males
Variables
Pack-yearsb
Zone B
0
0.1-9
9.1 +
Non-ABR
0
0.1-9
9.1 +
Alcohol
Zone B
No
Yes
Non-ABR
No
Yes
Coffeec
Zone B
0-2
3+
Non-ABR
0-2
3+
Weight loss
Zone B
No
Yes
Non-ABR
No
Yes
Employed in 1976d
No
Yes
Knowledge of accidentd
No
Yes
Consumed locally grown vegetablesd
No
Yes
Consumed locally raised animalsd
No
Yes
Abbreviations: GM, geometric mean; Non-ABR, noncont-
aminated area.
&Subjects responding 'don't know or don't remember were not
included when totals fell short of 26 females and 25 males in Zone
B and 28 females and 24 males in non-ABR.
bPacks of cigarettes per year.
COnlytwosubjects drank no coffee.
dZone B only.
GM
No. GM
21
4
1
16.9
19.9
23.0
7
8
10
5.9
11.2
4.9
19
6
3
6.2
6.4
4.8
8
7
9
4.4
2.8
4.1
18
8
18.3
15.9
5
5.4
7.1
20
19
9
5.8
6.6
8
16
4.1
3.6
13
13
15.3
20.2
12
13
5.8
7.7
17
11
7.0
4.9
14
10
4.2
3.2
21
5
16.3
24.2
21
4
7.2
4.7
23
5
6.3
5.2
19
5
3.6
4.3
20
6
17.8
19.6
12
13
6.7
11.6
15
10
19.6
15.2
18
6
5.6
11.3
6
17
14.8
18.4
11
14
7.3
6.3
15
11
16.4
19.3
16
9
4.8
12.1
Environmental Health Perspectives * Volume 106, Number 5, May 1998
275

Page 4

Articles * Landi et al.
Table 5. Multivariate model8 considering the relationship of measured TCDD doseb(ppt) to predictor vari-
ables in Zone B
Independent variables
Gender
Specification
F
M
No.
25
24
Fvalue
16.30
GM
26.70
8.40
25.80
10.10
12.80
12.00
18.50
1.06d
12.50
22.20
11.90
1.01d
p-Value
0.0002
Distancec
1
2
3
7
4.59
0.02
27
15
30
19
49
27
12
10
49
Consumed locally
raised animals
BMI
Smoking (pack-years)
No
Yes
3.91
0.05
Continuous
0
0.1-9
9+
Continuous
3.24
2.72
0.08
0.08
Age
Abbreviations: GM, geometric mean; F, female; M, male; BMI, body mass index.
'Each variable was adjusted forthe others in the model. Ofthe 51subjectsofZone B, 49 are included in the model because information on
distance from the accident sie within the zone was missing for 2subjects.
bDependent variable is measured ln(TCDD).
cZone B was divided into three areas according to the distance from the accident site and direction of the toxic cloud; 1 is the closest to the
accident
dValues shown are ,.
0Currentlever/never smoking and smoking in 1976 (the time ofthe accident)were not associated with TCDD in other models.
3.11
0.09
focused on the potentially most highly
exposed residents. On the contrary, we
selected subjects randomly in order to have
a more representative sample of the general
population ofthe area. In this study group,
subjects with severe medical illness and pre-
vious chloracne were excluded.
We observed higher TCDD levels in
women in both univariate analysis and after
adjustment for other variables potentially
associated with TCDD. We consider expo-
sure to be an unlikely source for the gender
effect. First, presence in the area at the time
of the accident, number ofyears spent in the
zone, occupation, and distance from the acci-
dent site within the zone, did not explain the
gender difference. Second, if the difference
was solely due to some factor that favored
women being exposed to TCDD during the
accident, the effect should not be present in
the non-ABR area, which was unaffected by
the accident. We observed a significant gen-
der difference in the unexposed area, suggest-
ing that the effect does not specifically
depend upon the Seveso accident. We also
found higher levels of most dioxins, furans,
and PCBs in women of the entire area, sug-
gesting that the gender effect may be relevant
for a wider array of related compounds and
exposure settings. Finally, studies performed
on a separate group of exposed individuals
showed no hint of a gender difference at the
time ofthe accident (33).
A gender difference in TCDD metabo-
lism has been shown in rats (34), but the
mechanism underlining this difference is not
dear.
There is evidence that TCDD influ-
ences both male (8) and female (9) hor-
mones, but we are unaware of a hormonal
mechanism that can explain TCDD gender
differences. Evaluation of hormone-related
differences in TCDD metabolism is very
difficult because of the slow rate of metab-
olism. Oral contraceptive use was associat-
ed with lower TCDD levels. Oral contra-
ceptive use is known to reduce activity of
CYP1A2 (35), an enzyme that is involved
in estrogen metabolism (36) and is also
induced by TCDD. Neither of these estab-
lished effects of CYP1A2 provides a clear
mechanistic rationale for the oral contra-
ceptive/TCDD relationship.
Lactation is one of the few known
means of eliminating the highly lipophilic
dioxin from the body (37). Using parity as
a surrogate of lactation (the great majority
of women in the local region nurse their
children), we only observed a weak nega-
tive association of childbearing with
TCDD levels.
One mechanism that might contribute
to a gender difference is excretion of
TCDD via semen emission in men. Such a
mechanism might potentially account for
the lack ofa gender difference at older ages
in our study. However, in the only study
reported, to date, where TCDD levels were
determined in pooled semen from Vietnam
veterans (38), levels were relatively low [<5
parts per quadrillion (ppq), wet-weight],
suggesting that this mechanism is unlikely
to account for the difference observed in
this study. Given the relatively low serum
TCDD levels in the veterans study, an
investigation in subjects with higher expo-
sures would be more appropriate for assess-
ingTCDD excretion via semen.
Covariates that might influence the
half-life, based on literature reports
(12,13), include age and body fat. We
observed a weak effect of age on TCDD
levels, possibly due to declining steroid
hormones, TCDD excretion via semen, or
changes in body fat distribution or
amount. The reduction in the age effect
between the univariate (p = 0.03) and mul-
tivariate (p = 0.08) models suggests that
other factors are likely to contribute to the
association of age with TCDD. Body fat is
a plausible determinant ofthe gender effect
because higher TCDD levels in women
might be due to enhanced retention of the
lipid-soluble compound due to a greater
proportion of body weight as fat in
women. Women had higher PBF than
men; however, within each gender, PBF
was unrelated to TCDD levels. It was not
possible to include PBF and gender in the
same multivariate model because PBF is
gender normed (39). Including BMI alone
in the model does not influence the gender
effect. Ott and Zober (40) observed a rela-
tionship of PBF to half-life, with estimates
of 5.1 years in those with 20% body fat
and 8.9 years for 30% body fat. The failure
to observe a strong relationship between
PBF and TCDD levels in our study may
derive from the fact that in contrast to Ott,
we considered body fat at the time of the
study (i.e., 1993-1995) rather than at the
time of the original exposure (1976), even
though we controlled for weight loss.
Diet is likely to be a major route for
dioxin exposure in the general population
(41). Authorities prohibited consumption
of animals and vegetables from the conta-
minated area shortly after the accident, but
some residents may have been unaware of
or ignored these restrictions. In fact, we
found an association with meat consump-
tion, but it did not account for the gender
difference.
Smoking might influence the TCDD
level by CYP450 induction with a resultant
alteration in metabolism or as a marker for
hand-to-mouth activity, increased alcohol
intake, or changes in peripheral body fat. A
shorter TCDD half-life in smokers has
been suggested (13), but we found only a
weak relationship of pack-year history of
smoking to TCDD levels in females of
Zone B.
To our knowledge, a gender difference
has not been previously observed in
TCDD-exposed populations, perhaps
because most groups have consisted largely
ofmen exposed due to occupation or mili-
tary service, but at least one study that
induded a fewwomen has observed consis-
tent findings (42).
TCDD causes a dose-dependent
increase in hepatocellular carcinoma in
female but not male rats (43), and gender
differences in cancer occurrence have been
observed in Seveso (e.g., a significant
increase in hepatobiliary cancer in women
in Zone B) (16).
Volume 106, Number 5, May 1998 * Environmental Health Perspectives
276

Page 5

Articles * Seveso, 20years after
The observed gender difference in
TCDD levels must be considered not only
in light of possible adverse effects in
women but also for developmental effects
in the offspring (44) exposed in utero as
well as via breast feeding. Given the myriad
biological effects of this environmental
contaminant, further research is needed to
determine whether a gender effect is pre-
sent in other groups exposed to TCDD or
related xenobiotics and to better under-
stand its basis.
REFERENCES
1.
Bertazzi PA, di Domenico A. Chemical, environmen-
tal, and health aspects of the Seveso, Italy accident.
In: Dioxins and Health, (Schecter A, ed). New
York:Plenum Press, 1994;587-632.
De Vito M, Birnbaum LS. Toxicology of dioxins and
related chemicals. In: Dioxins and Health (Schecter
A, ed). New York:Plenum Press, 1994;139-155.
Theobald HM, Peterson RE. Developmental and
reproductive toxicity of dioxins and other Ah receptor
agonists. In: Dioxins and Health (Schecter A, ed) New
York:Plenum Press, 1994;309-335.
Poland A, Palen D, Glover E. Tumor promotion by
TCDD in skin of HRS-J hairless mice. Nature
300:271-273 (1982).
Holder JW, Menzel HM. Analysis of 2,3,7,8-TCDD
tumor promotion activity and its relationship to can-
cer. Chemosphere 19:861-868 (1989).
Rao MS, Subbarao V, Prasad JD, Scarpelli DG.
Carcinogenicity of 2,3,7,8, tetrachlorodibenzo-p-diox-
in in the Syrian golden hamster. Carcinogenesis
9:1677-1679 (1988).
Huff J. Dioxins and mammalian carcinogenesis. In:
Dioxins and Health (Schecter A, ed). New York:
Plenum Press, 1994;389-402.
Egeland GM, Sweeney MH, Fingerhut MA. Total
serum testosterone and gonadotropins in workers
exposed to dioxin. Am J Epidemiol 139:272-281 (1994).
Kharat I, Soatcioglu F. Anti-estrogenic effects of
2,3,7,8-terachlorodibenzo-p-dioxin are mediated by
direct transcriptional interference with the liganded
estrogen receptor. Cross talk between aryl-hydrocar-
bon- and estrogen-mediated signaling. J Biol Chem
271 (18):10533-10537 (1996).
10. Kerkviiet NI. Immunotoxicology of dioxins and related
chemicals. In: Dioxins and Health (Schecter A, ed).
New York:Plenum Press, 1994;199-225.
11. Mocarelli P, Brambilla P, Gerthoux PM, Patterson DG
Jr, Needham LL. Change in sex ratio with exposure to
dioxin. Lancet 348 (9024):409 (1996).
12. Michalek JE, Pirkle JL, Caudill SP, Tripathi RC,
Patterson DG Jr, Needham LL. Pharmacokinetics of
TCDD in Veterans of Operation Ranch Hand: 10 year
follow-up. J Toxicol Environ Health 47:209-220 (1996).
13. Flesch-Janys D, Becher H, Gurn P, Konietzko J, Jung
D, Manz A, Papke 0. Elimination of polychlorinated
dibenzo-p-dioxins and dibenzofurans in occupation-
ally exposed persons. J Toxicol Environ Health
47:363-378 (1996).
14. Needham LL, Gerthoux PM, Patterson DG Jr,
Brambilla P, Pirkle JL, Tramacere PI, Turner WE,
Beretta C, Sampson EJ, Mocarelli P. Half-life of
2,3,7,8-tetrachloro-dibenzo-p-dioxin in serum of
2.
3.
4.
5.
6.
7.
8.
9.
Seveso adults: interim report. Organohalogen
Compounds 21:81-85 (1994).
15. Bertazzi PA, Zocchetti C, Guercilena S, Consonni D,
Tironi A, Landi MT, Pesatori AC. Dioxin exposure and
cancer risk. A 15-year mortality study after the
`Seveso accident". Epidemiology 8:646-652 (1997).
16. Bertazzi PA, Pesatori AC, Consonni D, Tironi A, Landi
MT, Zocchetti C. Cancer Incidence in a population
accidently exposed to 2,3,7,8-tetrachlorodibenzo-
para-dioxin. Epidemiology 4:398-406 (1993).
17. Manz A, Berger J, Dweyer JH, Flesch-Janys D, Nagel
S, Waltsgott H. Cancer mortality among workers in
chemical plant contaminated with dioxin. Lancet 338
(87731:959-96411991).
18. Saracci R, Kogevinas M, Bertazzi PA, Bueno de
Mesquita BH, Coggon D, Green LM, Kauppinen T,
L'Abbe' KA, Littorin M, Lynge E. Cancer mortality in
workers exposed to chlorophenoxy herbicides and
chlorophenols. Lancet 338 (8774):1027-1032 (1991).
19. Ott MG, Olson RA, Cook RR, Bond GG. Cohort mortali-
ty study of chemical workers with potential exposure
to the higher chlorinated dioxins. J Occup Med
29:422-429 (1987).
20. Becher H, Flesch-Janys D, Kauppinen T, Kogevinas
M, Steindorf K, Manz A, Wahrendorf J. Cancer mor-
tality in German male workers exposed to phenoxy
herbicides and dioxins. Cancer Causes Control
7:312-321 (1996).
21. Fingerhut M, Halperin VTE, Marlow DA, Piacitelli DA,
Honchar LA, Sweeney MH, Griefe AL, Dill PA,
Steenland NK, Suruda AJ. Cancer mortality in work-
ers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
New EngI J Med 324:212-218 (1991).
22. The Selected Cancers Cooperative Study Group. The
association of selected cancers with service in the
US Military in Vietnam. Ill. Hodgkin's disease, nasal
cancer, nasopharyngeal cancer, and primary liver
cancer. Arch Intern Med 150:2495-2505 (1990).
23. Zober A, Messserer T, Huber P. Thirty-four year mor-
tality follow-up of BASF employees exposed to 2,3,7,8
TCDD after the 1953 accident. Int Arch Occup Environ
Health 62:139-157 (1990).
24. Smith AH, Pearce NE. Update on soft-tissue sarcoma
and phenoxyherbicides in New Zealand. Chemosphere
9-12:1795-1798 (1986).
25. Bond GG, McLaren EA, Lipps TE, Cook RR. Update of
mortality among chemical workers with potential
exposure to the higher chlorinated dioxins. J Occup
Med 31:121-123 (1989).
26. The Selected Cancers Cooperative Study Group. The
association of selected cancers with service in the
US Military in Vietnam. II. Soft-tissue and other sar-
comas. Arch Intern Med 150:2485-2492 (1990).
27. Kang H, Enziger F, Breslin P, Feli M, LeeY, Shepard B.
Soft tissue sarcoma and military service in Vietnam: a
case-control study. J NatI Cancer Inst 79:693-699
(1987).
28. Wiklund K, Holm L-E. Soft tissue sarcoma risk in
Swedish agricultural and forestry workers. J NatI
Cancer Inst 76:229-234 (1986).
29. IARC. IARC Monographs on the Evaluation of
Carcinogenic Risks to Humans. Vol. 69: Polychlorinated
Dibenzo-para-Dioxins and Polychlorinated Dibenzo-
furans. Lyon:lnternational Agency for Research on
Cancer, 1997.
30. Patterson DG Jr, Hampton L, Lapeza CR Jr, Belser
Wr, Green V, Alexander L, Needham L. High-resolu-
tion gas chromatography/high-resolution mass spec-
trometric analysis of human serum on a whole-
weight and lipid basis for 2,3,7,8-tetrachlorodibenzo-
p-dioxin. Anal Chem 59:2000-2005 (19871.
31. Hornung RW, Reed LD. Estimation of average con-
centration in the presence of non-detectable values.
AppI Occup Environ Hyg 5(l):48-51 (1990).
32. Mocarelli P, Needham LL, Marocchi A, Patterson DG
Jr, Brambilla P, Gerthoux PM, Meazza L, Carreri V.
Serum concentrations of 2,3,7,8-tetrachlorodibenzo-
p-dioxin and tests results from selected residents of
Seveso, Italy. J Toxicol Environ Health 32:357-366
(1991).
33. Needham LL, Gerthoux PM, Patterson DG Jr,
Brambilla P, Turner WE, Beretta C, Pirkle JR,
Colombo L, Sampson EJ, Tramacere PL, et al. Serum
dioxin levels in Seveso, Italy population in 1976.
Teratog Carcinog Mutagen 17(4/5):225 (1997/1998).
34. Jackson JJ, Diliberto JJ, Birnbaum LS. Modulation of
cytochrome p-450 isozymes in male F344 rats does
not alter the biliary excretion of 2,3,7,8-tetra-
chlorodibenzo-p-dioxin (TCDD). In: Proceedings of
the 33rd Annual Meeting of the Toxicology Society,
13-17 March 1994, Dallas TX. Toxicologist 14:273
(1994).
35. Horn EP, Tucker MA, Lambert G, Silverman D,
Zametkin D, Sinha R, Hartge T, Landi MT, Caporaso
NE. A study of gender-based cytochrome P4501A2
variability: a possible mechanism for the male excess
for bladder cancer. Cancer Epidemiol Biomarkers
Prev 4:529-533 (1995).
36. Eugster HP, Probst M, Wurgler FE, Sengstag C.
Caffeine, estradiol, and progesterone interact with
human CYPIAI and CYPIA2. Evidence from cDNA-
directed expression in Saccharomyces cervisiae.
Drug Metab Dispos 21:43-49 (1993).
37. Yakushiji TR. Levels of PCBs and organochlorine pes-
ticides in human milk and blood. Int Arch Occup
Environ Health 43:1-15 (1979).
38. Schecter A, McGee H, Stanley JS, Boggess K,
Brandt-Rauf P. Dioxins and dioxin-like chemicals in
blood and semen of American Vietnam Veterans,
State of Michigan. Am J Ind Med 30:647-654 (1996).
39. Knapik JJ, Burse RL, Vogel JA. Height, weight, per-
centage fat and indices of adiposity for young men
and women entering the US Army. Aviat Space
Environ Med 223-231 (1983).
40. Ott GM, Zober A. Cause specific mortality and cancer
incidence among employees exposed to 2,3,7,8-TCDD
after a 1953 reactor accident. Occup Environ Med
53:606-612 (1996).
41. Skene SA, Dewhurst IC, Greenberg M. Polychlor-
inated dibenzo-p-dioxins and polychlorinated diben-
zofurans: the risks to human health. Hum Toxicol
8:173-203 (1989).
42. Patterson DG Jr, Hoffmann RA, Needham LL, Roberts
DW, Bagby JR, Pirkle JL, Falk H, Sampson EJ, Houk
VN. 2,3,7,8-tetrachlorodibenzo-p-dioxin in adipose tis-
sue of exposed and control persons in Missouri: an
interim report. J Am Med Assoc 256:2683-2686 (1986).
43. Lucier GW, Tritscher A, Goldsworthy T, Foley J, Clark
G, Goldstein J, Maronpot R. Ovarian hormones
enhance 2,3,7,8 tetrachlordibenzo-p-dioxin-mediated
increases in cell proliferation in preneoplastic foci in
a two-stage model for rat hepatocarcinogenesis.
Cancer Res 51:1391-1397 (1991).
44. Brouwer A, Ahlborg UG, Van den Berg M, Birnbaum
LS, Boersni ER, Bosweld B, Gray LE, Hagnor L,
Holene E, Bentson MS. Functional aspects of devel-
opmental toxicity of polyhalogenated aromatic hydro-
carbon in experimental animals and human infants.
Eur J Pharmacol 293:1-40 (1995).
Environmental Health Perspectives * Volume 106, Number 5, May 1998
277