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DESIGNATIONS
| CAS No.: | 50-29-3 |
| Registry name: | DDT |
| Chemical name: | 1,1,1-Trichloro-2,2-bis(4-chlorophenyl)ethane |
| Synonyms, Trade names: | p,p’-Dichlorodiphenyltrichloroethane, p,p’-DDT, 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane, Dicophane (GB); Chlorophenothane (USA); Anofex; Cezarex; Dinocide; Gesarol; Guesapon; Guesard; Guesarol; Gyron; Ixodex; Neocid; Neocidol; Zerdane |
| Chemical name (German): | DDT, 1,1,1-Trichlor-2,2-bis(4-chlorphenyl)ethan |
| Chemical name (French): | DDT |
| Appearance: | colourless crystals ranging from odourless to slightly aromatic |
BASIC CHEMICAL AND PHYSICAL DATA
| Empirical formula: | C14H9Cl5 |
| Rel. molecular mass: | 354.49 g |
| Density: | 1.55 g/cm3 |
| Melting point: | 109°C |
| Vapour pressure: | 25.3 x 10-6 Pa |
| Solvolysis/solubility: | in water: 3 x 10-6 g/l readily soluble in numerous organic solvents and in fats |
| Conversion factors: | 1 ppm = 14.7 mg/m3 1 mg/m3 = 0.07 ppm |
ORIGIN AND USE
Usage:
Contact poison and feed insecticide for combating a wide range of
insects (malaria and yellow-fever mosquito, plague flea, clothes
louse, tsetse fly etc.). The substance was used on a large scale
because of its broad-spectrum effectiveness, its low
phytotoxicity, its good long-term effect and its low acute
toxicity to warm-blooded animals. Whereas the use of DDT is
banned today in most industrial nations, it is still used in
numerous Third-World countries since the costs of substitute
materials are much higher.
Origin/derivation:
DDT is not found naturally. It was synthesised for the first time
in 1874 and has been commercially available by condensation of
chloral with chlorobenzene since 1945.
Production figures:
Recent data are not available. The estimated production
figures in 1974 (OECD) were about 60,000 t worldwide (WHO,
1979). DDT was originally manufactured in many countries, but by
1979 there were only 3 production facilities left, namely in
America, India and France (WHO, 1979). The DVGW, on the other
hand, quotes two companies in the EC alone (1988).
Emission figures:
Virtually all the DDT produced is released into the
environment. The quantities applied are usually between 1 and
3 kg DDT per hectare; the products used contain between 1
and 10 % active agent.
Toxicity
| Humans: | LD approx. 500 mg/kg, oral | acc. RIPPEN, 1989 |
| Mammals: | ||
| Rat | LD50 113 mg/kg, oral | acc. RIPPEN, 1989 |
| LD50 1900 mg/kg, dermal | acc. RIPPEN, 1989 | |
| Mouse | LD50 150-300 mg/kg, oral | acc. DVGW, 1988 |
| Dog | LD50 150-750 mg/kg, oral | acc. DVGW, 1988 |
| Cat | LD50 150-600 mg/kg, oral | acc. DVGW, 1988 |
| Insects: | ||
| House fly (musca domestica) | LD50 0.033 µg/animal (24 h) | acc. KORTE, 1980 |
| Aquatic organisms: | ||
| Fish | LC50 8-100 µg/l (96 h) | acc. RIPPEN, 1989 |
| Water flea (daphnia magna) | EC50 0.36-4.4 µg/l (24-48 h) | acc. RIPPEN, 1989 |
| Algae (skeletonema costatum) | EC50 100 µg/l (7 d) | acc. DVGW, 1988 |
Characteristic effects:
Humans/mammals: The exact mechanism of action still has to be completely clarified. DDT is a neurotoxin which mainly acts on the central nervous system. The external symptoms indicate a temporary easing of the transmission of stimuli followed by blockage. Various enzymes are inhibited by DDT. It thus also acts as a respiratory poison. It accumulates in fatty tissue. Damage to the liver in particular with high doses; sustained exposure (rats) led to liver, kidney and spleen damage. Mutagenity and carcinogenity are highly likely in humans; carcinogenity discovered in animal experiments.
Plants: DDT does not usually damage plants. Some sensitive plants show signs of impaired root growth in the event of DDT accumulation in the soil.
Synergism: Enhanced action (aquatic animals) due to lindane and alkylbenzene sulphonates.
ENVIRONMENTAL BEHAVIOUR
Water:
DDT exhibits a strong tendency towards adsorption on solid
particles in water. It thus accumulates in sediment and can be
transported in running water over long distances.
Air:
DDT is found in the atmosphere as a gas, as an aerosol and
adsorbed on dusts. It can still be detected 6 months after
application in the air over fields on which it has been used.
Adsorbed on dusts, it is sometimes transported over thousands of
kilometres and thus dispersed worldwide. DDT has been detected
not only in Antarctic snow, but also in precipitation over
Scotland and the Shetland Islands. The concentrations found in
rain permit to draw the conclusion that the distribution of DDT
throughout the world is relatively uniform.
Soil:
When DDT is applied, a considerable amount ends up in the soil.
Considerable accumulation has been discovered in the top few
centimetres, thus concluding that the mobility in soil is
relatively low.
Degradation, decomposition products:
Important metabolites of DDT are DDE
(1,1-bis-(4-chlorophenyl)-2,2-dichloroethene), DDA and DDD. DDE
is at least as toxic as DDT and would appear to be even more
resilient in the environment.
There is little information to date regarding the degradation of DDT in soil. The relationship between biological and chemical decomposition reactions remains to be explained. All in all, DDT and certain transformation products (see above) should be classed as very persistent.
There is also a lack of reliable data concerning the transformation and degradation processes of the substance in the atmosphere. HCl and CO2 were established as degradation products in laboratory experiments under simulated upper-atmosphere conditions. Rapid decomposition due to UV rays has been reported by various authors. There are no representative data regarding photomineralisation under natural conditions (WHO, 1979).
Food chain:
Considerable accumulation via food chains. It can be detected in
the circulation of warm-blooded animals soon after absorption, it
is however subsequently removed by organs containing lipids and
is stored in, for example, fatty tissue, the brain and the liver.
ENVIRONMENTAL STANDARDS
| Medium/ acceptor | Sector | Country/ organ. | Status |
Value | Cat. | Remarks | Source |
| Water: | Drinkw | A | (L) |
1 µg/l | DDT and isomers | acc. DVGW, 1988 | |
| Drinkw | CDN | (L) |
30 µg/l | MAC | DDT and isomers | acc. DVGW, 1988 | |
| Drinkw | D | L |
0.1 µg/l | single substance | acc. DVGW, 1988 | ||
| Drinkw | EC | G |
0.1 µg/l | acc. DVGW, 1988 | |||
| Drinkw | WHO | G |
1 µg/l | DDT and isomers | acc. DVGW, 1988 | ||
| Groundw | USA | G |
0.05 mg/l | State of Illinois | acc. WAITE, 1984 | ||
| Surface | IAWR | G |
0.1 µg/l | Drinking water1) | acc. DVGW, 1988 | ||
| Surface | IAWR | G |
0.5 µg/l | Drinking water2) | acc. DVGW, 1988 | ||
| Surface | D | G |
2 µg/l | Drinking water1) | acc. DVGW, 1988 | ||
| Surface | D | G |
10 µg/l | Drinking water2) | acc. DVGW, 1988 | ||
| Surface | USA | G |
0.05 mg/l | State of Illinois | acc. WAITE, 1984 | ||
| Air: | Workp | D | L |
1 mg/m3 | MAK | DFG, 1987 | |
| Workp | USA | (L) |
1 mg/m3 | TWA | acc. RIPPEN, 1989 | ||
| Foodstuffs: | |||||||
| Tea, spices | D | L |
1 mg/kg | acc. DVGW, 1988 | |||
| Fruit, vegetables | D | L |
0.1 mg/kg | acc. DVGW, 1988 | |||
| Other veg. foodstuffs | D | L |
0.05 mg/kg | acc. DVGW, 1988 | |||
| Fat in meat | D | L |
3 mg/kg | acc. DVGW, 1988 | |||
| Fat in fish | D | L |
2-5 mg/kg | acc. DVGW, 1988 | |||
| Fat in milk | D | L |
1 mg/kg | acc. DVGW, 1988 | |||
| Eggs | D | L |
0.5 mg/kg | acc. DVGW, 1988 | |||
Notes:
1) Drinking water treatment using natural methods
2) Drinking water treatment using chemophysical methods
The production and use of DDT has been banned in Germany since 1974. Usage is also banned in Sweden and the USA.
Comparison/reference values
| Water: | ||
| Surface water (1977-79) | USA | 0.1 ppb; (max. n=604) |
| Antarctic | 40 ppt | |
| Baltic | 0.2 ppt | |
| Groundwater (1977-79) | USA | 0.9 ppb; (max. n=1074) |
| Rainwater | GB | 104-229 ppt |
| Sediment: | ||
| Lakes and river (Berlin) | D | 0.01-136 ppb (n=8) |
| Lake | Libya | 0.02 ppb |
| Mediterranean (1981) | <0.01-19 ppb | |
| Air: | ||
| 'Clean air' | D | 0.2-0.6 ng/m3 |
| Persian Gulf | 0.05-0.58 ng/m3 (mean value: 0.08 ng/m3) | |
| Gulf of Mexico | 0.010-0.047 ng/m3 | |
| Humans: | ||
| Mother's milk | D | 1.5-1.8 mg/kg fat |
| Fatty tissue | 1.1-5.3 mg/kg (mean values) | |
| Animals: | ||
| Fish (Lake Michigan; 1969-78) | USA | 0.8-9.9 mg/kg |
| Fish (North Sea; 1972) | 2-73 µg/kg | |
| Pike-perch (Havel, Berlin; 1981) | D | 2-105 µg/kg |
| Plants: | ||
| Aquatic plants (Danube) | 2 µg/kg | |
Note: 1) If no other source is quoted, the data cited are from RIPPEN, 1989.
Assessment/comments
The ban of DDT in several countries in the early Seventies shows its hazardous nature which can primarily be attributed to its considerable persistence in all environmental media (a basic precondition of the worldwide distribution of DDT today). Apart from its acute toxicity, the decisive aspect for any assessment of DDT is its accumulation in organisms, soils, surface water and groundwater and thus its incalculable long-term effect. In view of the fact that substitute products already exist (although still expensive), the application of DDT and also its continued production are ecologically intolerable.