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EC number: 203-458-1
CAS number: 107-06-2
None of the studies described fulfilled completely the requirements from
internationally accepted guidelines or were documented with
deficiencies. Thus, in a weight of evidence approach from out of 5
studies with conclusive results the lowest LD50 of 413 mg/kg bw
determined in mice (Munson, 1982) was chosen for
classification/labelling and risk assessment.
For inhalation toxicity, a 4-h LC50 of 1886 ppm (approx. 7758 mg/m³) in
albino rats was derived from a dose-response graph (Spencer, 1951).
Additional information, Hotchkiss study (2010), clearly suggest that the
4-h LC50 is higher that 2000 ppm (approx. 10000 mg/ m³). A
new study was conducted to determine the acute inhalation toxicological
properties of 1,2-dichloroethane (EDC) vapors by Hotchkiss et al
(2017). Groups of five rats/sex were exposed for four hours, using a
whole-body inhalation exposure system, to a mean chamber concentration
of 2520 ppm EDC vapor (10.2 mg EDC/L air). Based on the data generated
in this study, the 4-hour LC50of inhaled 1,2-dichloroethane
vapors is > 2520 ppm (10.2 mg/L) for male and < 2520 ppm (10.2 mg/L) for
female F344/DuCrl rats.
Previous studies reported no mortality in any male and female
F344/DuCrl rats whole-body exposed for 4 hours to vapor concentrations
of 196, 678, 1904, or 2029 ppm 1,2-dichloroethane. Taking into account
all of these data, calculated LC50values of > 2520 ppm (10.2
mg/L) for male and 2273 ppm (9.2 mg/L) for female F344/DuCrl rats were
determined and the combined LC50for both sexes was 2404 ppm
The dermal route was waived since more reliable data were available for
exposure routes with higher relevance, i.e. oral and inhalation route.
However, the mean LD50-value for acute dermal toxicity after application
of 1,2-dichloroethane under occluded conditions to rabbits was 4890
mg/kg bw with a 95 % confidence interval of 4270–5600 mg/kg bw based on
a study by Mellon Inst. Industr. Research (1948).
In an acute oral toxicity study, groups of fasted (18
hours), 6 -week-old CD-1 mice were given a single oral dose of 1,2
-dichloroethane and observed for 14 days.
The mice died over a 48 -hour period. Those surviving 48
hours recovered and appeared normal at the end of the 14 -days
observation period. Macroscopically, target organs appeared to be liver
and lungs. The calculated LD50 values using log probit analysis were 489
mg/kg bw (95% C.I. 424 -552 mg/kg bw) and 413 mg/kg bw (95% C.I. 337-499
mg/kg bw) for male and female mice, respectively.
1,2 -dichloroethane is of low acute oral toxicity based
on the LD50 in male and female CD-1 mice.
The 4-h LC50 corresponded to approx. 1886 ppm (approx.
7758.5 mg/m³) and was derived from the data by Standard Probit analysis
(please refer to "Seuils de Toxicité aiguë 1,2-Dichloroéthane from
Groupe d’Experts Toxicologues du Ministère de l’Ecologie, de l’Energie,
du Développement Durable et de l’Aménagement du Territoire" dated
With 22000 ppm (approx. 90420 mg/m³), death occurred
within 24 min after deep anaesthesia by depression of the central
nervous system. At 12000 ppm and lower concentrations this depressant
action resulted in varying degrees of "drunkenness".
In special groups of animals (exposure causing 99.9, 50
or 0.01 % death), reported signs of exposure mediated toxicity were
decreased body weights, increased liver and kidney weights and slight
parenchymatous degeneration to severe haemorrhagic necrosis (kidney,
liver, adrenals), congestion (kidney, liver, adrenals, lungs) and oedema
(kidney, lungs), increase in blood urea nitrogen concentration, plasma
prothrombin clotting time, liver lipids, decrease in serum phospatase
The following concentrations and exposure times were not
300 ppm (approx. 1200 mg/m³) after 7 h (20 animals)
600 ppm (approx. 2400 mg/m³) after 5 h (20 animals)
1500 ppm (approx. 6100 mg/m³) after 2 h (10 animals)
3000 ppm (approx. 12100 mg/m³) after 0.5 h (22 animals)
20000 ppm (approx. 81000 mg/m³) after 0.1 h (10 animals)
The following concentrations were void of adverse
200 ppm (approx. 800 mg/m³) for 7 h
300 ppm (approx. 1200 mg/m³) for 3 h (but effects at 5.5
1000 ppm (approx 4000 mg/m³) for 1.5 h (but effects at 3
In an acute inhalation toxicity study,
groups of young adult albino rats (10-54/dose, approximately equal
numbers of males and females) were whole body exposed to 1,2
-dichloroethane for 0.1 to 8 hours at concentrations of 200, 300, 600,
800, 1000, 1500, 3000, 12000 or 20000 ppm (corresponding to 823, 1234,
2468, 3290, 4113, 6169, 12339, 49354 and 82256 mg/m³). Animals then were
observed for 2 to 3 weeks. At 20000 ppm, death occurred within 24 min
after deep anaesthesia by depression of the central nervous system. At
12000 ppm and lower concentrations this depressant action resulted in
varying degrees of "drunkenness". According to authors, deaths tended to
occur at three different time intervals and in such a manner as to
suggest three separate toxic actions of fatal degree:
1. At very high concentrations (e.g. 20000
ppm), deaths occurred due to depression and paralysis of CNS functions.
2. At all vapour concentrations causing
death, a large proportion died rather suddenly and quietly a few hours
after termination of exposure, showing marked cyanosis, reduced body
temperature, stupor or coma and failing respiration. The character and
sudden development of this response suggested "shock" or cardiovascular
3. All other deaths occurred delayed over a
period of 2 to 7 days with progressive loss of body weight and other
evidence of toxic effects, suggesting organ failure, probably due to
The 4 -h LC50 derived by Standard Probit
analysis in this acute inhalation study in rats was 1886 ppm (approx.
1,2 -dichloroethane is of low acute oral
toxicity based on the LC50 (4 hours) in male and female albino rats.
In an acute dermal toxicity study, groups of
male rabbits (6 -11 animals/dose level) were dermally exposed to 1,2
-dichloroethane at doses of 3972, 5000, 5594 or 6285 mg/kg bw and
observed for 14 days. Mortality was observed in 2/6 at 3972 mg/kg bw
within 5 -10 days, 3/11 at 5000 mg/kg bw within 1 -5 days, 8/9 at 5594
mg/kg bw within 1 -11 days and 5/6 at 6285 mg/kg bw within 1 day. Weight
loss was reported in most survivors. Gross necropsy evaluation revealed
no adverse effects. The calculated LD50 by the method of probits was
3.89 mL/kg bw (3.40 -4.46 mL/kg bw) or 4890 mg/kg bw (4270–5600 mg/kg
The acute toxicity of 1,2-dichloroethane was investigated
by the oral, dermal and inhalation routes of administration. By the oral
or inhalation route the test substance proved to be moderately toxic and
virtually non-toxic after dermal application to the animals tested.
After oral administration to rats, LD50-values determined
were in the range of 770-967 mg/kg bw. Signs of toxicity were
characterised by lung congestion, pale kidneys and livers as well as
congestion of intestinal blood vessels (Mellon Inst. Industr. Research,
1948; Smyth et al., 1969). A single maximum tolerated dose (MTD) of 625
mg/kg (oral, gavage) in SD rats was reported to produce liver effects: a
slight decrease in hepatic porphyrin and cytochrome-P450 content and a
more pronounced in the activity of hepatic aminolaevulinic acid
dehydratase activity and the level of glutathione (Moody and Smuckler,
1986). In mice, LD50-values determined were in the range of 413–911
mg/kg bw. LD50-value of about 910 mg/kg bw and >2500 mg/kg bw were
reported for rabbits and dogs, respectively (Barsoum and Saad, 1934;
Heppel et al., 1945; Mellon Inst. Industr Research, 1948; Munson et al.
1982). The solvent was reported to act as a cardiac depressant in dogs,
but deaths occurred through respiratory arrest prior to cardiac failure
(Barsoum and Saad, 1934). None of the studies described fullfilled
completely the requirements from internationally accepted guidelines or
were documented with deficiencies. Thus, in a weight of evidence
approach out of 5 studies with conclusive results the lowest LD50 of 413
mg/kg bw in mice (Munson, 1982) was chosen for classification/labelling
and risk assessment.
After acute inhalation exposure to 1,2-dichloroethane,
LC50-values obtained in rats ranged from 4100 mg/m³/7.2 h to 49400
mg/m³/0.5 h (Spencer et al., 1951). In compliance with these results,
another 6-h LC50 was found at about 1650 ppm (= 6670 mg/m³) (Bonnet et
al., 1980). A 4 -h LC50 in rats of about 7800 mg/m³ (= 1900 ppm) was
derived from a concentration-response graph (Spencer et al., 1951). In
mice, the LC50 after a 6 -h exposure was 272 ppm (= 1080 mg/m³)
(Gradiski et al., 1978), and in guinea pigs an LC50 of 6400 mg/m³/7 h
was reported (Heppel et al., 1945). In principal, results from other
acute studies in rats, mice and rabbits lacking a sufficient data base
to establish a defined LC50 (Heppel et al., 1945; Frankovitch et al.,
1986) were consistent with those findings. The comprehensive study by
Spencer et al. (1951) provided the following non-lethal
concentration-time exposures in female rats (post-exposure observation
for 2 to 3 weeks):
Determinations of LC0:
- 300 ppm (approx. 1200 mg/m³) [7 h] ,
- 500 ppm (approx. 6200 mg/m³) [2 h],
- 3000 ppm (approx. 12400 mg/m³) [0.5 h]
Determinations of NOAELs (based on blood parameters and
- 200 ppm (approx. 800 mg/m³) [7 h];
- 300 ppm (approx. 1200 mg/m³) [3 h] (but effects at 5.5
- 1000 ppm (approx. 4000 mg/m³) [1.5 h] (but effects at 3
The 4-h LC50 of 1886 ppm (7758 mg/m³) was
derived from the dose-response graph provided in the report. In
addition, in a very recent study by Hotchkiss et al. (2010), rats were
exposed to 1,2-dichloroethane vapor at 0, 50, 200, 600 or 2000 ppm for 4
h in order to assess neurobehavioral and neuropathologic effects. The
animals were observed for 14 days for neurobehavioral signs and
mortality. No mortality occurred during the observation period (10 rats
were used). Although these results demonstrated that the LC50 (4 h) is
probably higher than 2000 ppm, the Spencer study (1951) was chosen as
The mean LD50-value for acute dermal toxicity of
1,2-dichloroethane after application under occluded conditions to
rabbits was 4890 mg/kg bw with a 95 % confidence interval of 4270–5600
mg/kg bw (Mellon Inst. Industr. Research, 1948).
In particular after inhalation exposure, a steep
concentration-response relationship associated with sudden, often
unexpected mortality was characteristic for 1,2-dichloroethane toxicity
(see Bonnet et al., 1986; Gradiski et al., 1978; Spencer et al., 1951;
Mellon Inst. Industr. Research, 1948). For example, among dose groups of
SD rats covering just an increment of 400 ppm 1,2-dichloroethane
(1300-1700 ppm), mortality increased steeply from about 17 to 75 %
(Bonnet et al., 1986), and the incidences of mortality observed in male
albino rats were 0/10 animals at 500 mg/kg, 3/10 at 630 mg/kg bw after 1
to 5 days, 5/10 at 795 mg/kg after 1 day and 8/10 at 1000 mg/kg bw after
2 to 3 days. Similar results were seen with rabbits and mice (Mellon
Inst. Industr. Research, 1948).
Regardless of the route of administration chosen, signs
of toxicity in rats, mice, guinea pigs and rabbits after administration
of high doses were characterized by liver damage (fatty degeneration and
haemorrhagic necrosis, increased hepatic enzyme activities and reduction
of glutathione levels), kidney damage (congestion, haemorrhage,
necrosis, interstitial oedema, dilatation of renal tubules, fatty
degeneration of the tubular epithelium and hypertrophy of tubular cells)
and damage to the lungs (congestion, haemorrhage, oedema, fluid in the
pleural and peritoneal space).
Justification for selection of acute toxicity – oral endpoint
In a weight of evidence approach out of 5 studies with conclusive
results, the lowest LD50 of 413 mg/kg in mice (Munson, 1982) was chosen
for classification/labelling and risk assessment.
According to the lethal doses determined in rodents after
oral administration or inhalation exposure, 1,2-dichloroethane has to be
classified as follows:
- Oral route:
Xn, R22 (harmful if swallowed) according to Directive
67/548/EEC and acute tox. oral cat. 4 (H302: harmful if swallowed)
according to CLP (Regulation 1272/2008/EC)
In a weight of evidence approach out of 5 studies with
conclusive results, the lowest LD50 of 413 mg/kg in mice (Munson, 1982)
was chosen for classification/labelling and risk assessment.
- Inhalation route:
Xn, R20 (harmful by inhalation) according to Directive
67/548/EEC, and acute tox. inhal. cat. 3 (H331: toxic if inhaled)
according to CLP (Regulation 1272/2008/EC).
- Dermal route:
1,2-dichloroethane was uncritical after dermal
application, and based on this result the substance is not subject to
classification and labelling for acute dermal toxicity according to
Directive 67/548/EEC and Regulation 1272/2008/EC.
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