Environ. Sci. Technol. 2004, 38, 1062-1065
scale incinerators under well-controlled conditions. Public
Formation of Dioxins from
Incineration of Foods Found in
Domestic Garbage
concerns in developed countries, including the United States
and Japan, however have focused on the formation of toxic
dioxins during incineration of this garbage. Dioxin contami-
nation in the environment occurs from the combustion of
waste materials as well as from many other high-temperature
processes commonly used in industrial settings (2, 3). Dioxins,
in particular 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-
TCDD), are the most potent man-made carcinogen.
There are some reports on dioxin formation from domestic
wastes incinerated under less-controlled systems (4) and from
waste plastic combusted at various temperatures (5). How-
ever, there are no reports on dioxin formation from food
wastes incinerated under well-controlled conditions.
We have reported the formation of dioxins (PCDDs,
PCDFs, and coplanar PCBs) from various woods with the
presence of chloride combusted in a small-scale incinerator
under well-controlled conditions (6). In the present study,
dioxin formations from mixtures of various food items
combusted under well-controlled conditions in a small-scale
incinerator was investigated.
T A K E O K A T A M I
Gifu Prefectural Institute for Bio-industrial Technology,
3481-2, Hachiya-cho, Minokamo-shi, Gifu 504-0838, Japan
A K I O YA S U H A R A
Research Center for Material Cycles and Waste Management,
National Institute for Environmental Studies, 16-2, Onogawa,
Tukuba, Ibaraki 305-0061, Japan
T A K A YU K I S H I B A M O T O *
Department of Environmental Toxicology, University of
California, Davis, California 95616
There has been great concern about the large amounts
of garbage produced by domestic households in the modern
world. One of the major sources of dioxins (PCDDs,
PCDFs, and coplanar PCBs) in the environment is the
combustion of domestic waste materials. Exhaust gases
from an incinerator, in which mixtures of 67 food itemss
including fruits, vegetables, pasta, seafoods, meats,
and processed foods and seasoned foodsswere analyzed
for dioxins. Gases collected at the chimney port (9.15 ng/
g) contained less total dioxins than those collected at the
chamber port (29.1 ng/g). The levels of Cl1-Cl6-PCDDs
and Cl1-Cl5-PCDFs were much lower in the gas collected
at the chimney port than in the gas collected at the
chamber port. The levels of Cl7-Cl8-PCDDs and Cl6-Cl8-
PCDFs were higher in the gas collected at the chimney port
than in the gas collected at the chamber port. A total of
Cl4-Cl8-PCDDs (1.84-3.04 ng/g) comprised over 80% of
the total PCDDs formed (2.24-4.00 ng/g). Total PCDFs
(16.2-22.6 ng/g) comprised 78-86% of the total dioxins
formed (18.9-29.1 ng/g). The PCDFs formed in the greatest
amounts were M1CDFs (9.68-10.7 ng/g). Mixtures of
commonly consumed food items produced ppb levels of
total dioxins in exhaust gases upon combustion, suggesting
that incineration of domestic food wastes is one of the
sources of dioxins in the environment. A mixture containing
some seasoned foods, such as mayonnaise spread on
bread, produced more dioxins (29.1 ng/g) than a mixture
without seasoned foods did (18.9 ng/g).
Experimental Section
Chem icals. Isotope-labeled PCDDs, PCDFs, and coplanar
PCBs (nonortho-PCBs and mono-PCBs) for internal standards
(10 ng/ mL n-nonane) were purchased from Cambridge
Isotope Laboratories, Inc. (Andover, MA). For the solution
of the sampling spike recovery test, a 1 mLn-nonane solution
containing 0.0005 ng/ µL each of
13
C -1,2,3,4-T4CDD;
12
1,2,3,4,7,8-H6CDF; and 1,2,3,4,6,7,8-H7CDF solution was
prepared. For the solution of the cleanup spike recovery test,
a 100 µL n-nonane solution containing 0.005 ng/ µL each of
13
C -2,7-D2CDD; 2,3,7-T3CDD; 2,3,7,8-T4CDD; 1,2,3,7,8-
12
P5CDD; 1,2,3,6,7,8-H6CDD; 1,2,3,4,6,7,8-H7CDD; 1,2,3,4,6,7,8,9-
13
O8CDD; C12-2,3,7,8-T4CDF; 1,2,3,7,8-P5CDF; 1,2,3,4,7,8-
13
H6CDF; 1,2,3,4,7,8,9-H7CDF; 1,2,3,4,6,7,8,9-O8CDF; C12-
3,3′,4,4′-T4CB; 3,4,4′,5-T4CB; 3,3′,4,4′,5-P5CB; 2′,3,4,4′,5-P5CB;
3,3′,4,4′,5,5′-H6CB; 2,3′,4,4′,5,5′-H6CB; and 2,3,3′,4,4′,5,5′-
H7CB was prepared. For the solution of the internal stand-
ards, a 2 µL n-nonane solution containing 0.25 ng/ µL each
of 13C-121,3,6,8-T4CDD; 1,2,3,7,8,9-H6CDD; and 2,2′,3,4,4′,5,5′-
H7CB was prepared. n-Nonane was bought from Kanto
Chemical Co., Inc. (Tokyo, Japan).
Food Sam ples. Table 1 shows the food samples used for
the experiments, along with the chlorine content of each
dried sample. Food sample A was a mixture of food scraps
produced during food preparation. Food sample B was a
mixture of waste produced after eating. The some food itemss
soy sauce spread on bread, mayonnaise spread on bread,
tomato ketchup spread on bread, pork with salt, and pork
with brothsin Table 1 were seasoned with the seasoning as
described. Methods of seasonings were adapted from general
home practices. Food samples were dried using a vacuum
oven (Advantec model VR-320, Tokyo, Japan) equipped with
a vacuum pump (Hitachi VR16G, Tokyo, Japan). The samples
were placed on aluminum foil spread over a shelf in the
oven. Drying was performed at 60 °C and 0.0133 Pa for over
24 h. Dried samples were put into a plastic bag with an airtight
fastener and kept in a freezer at -20 °C until used for
combustion. Only dried samples were used for combustion
experiments. Chlorine contents in the food samples were
analyzed by a total organic halogen analyzer TOX 100 (Dia
Instruments Co., Ltd., Tokyo, Japan).
Introduction
There has been great concern about the large amounts of
garbage produced by domestic households in the modern
world. The composition of this garbage is very complicated.
For example, domestic wastesas wet weight basessin six
cities in Japan consisted of 38.3% food waste, 29.4% paper,
13.2% plastic, 3.9% glass, 3.5% metal, and 2.4% textiles in
1999 (1). This domestic waste has been combusted in large-
Com bustion of Sam ples. Samples were combusted using
a small-scale incinerator as previously reported (7). The inlet
for combustion samples was 0.35 m (height) ×0.40 m (width).
* Corresponding author phone: (530)752-4523; fax: (530)752-3394;
e-mail: tshibamoto@ucdavis.edu.
9
1 0 6 2 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 38, NO. 4, 2004
10.1021/es030606y CCC: $27.50
2004 Am erican Chem ical Society
Published on Web 01/16/2004