2,7-Dichlorodibenzo-p-dioxin

253.08084

253.08

3KMT7J3HEQ

3077

DTXSID1020435

COLORLESS CRYSTALS

2932999060

18.5

5.82

2,7-dichlorodibenzo-p-dioxin appears as colorless crystals or a white powder. (NTP, 1992)

1.5±0.1 g/cm3

209-210 °C

328.83°C (rough estimate)

140.2±28.0 °C

1.643

Water solubility of roughly 0.19 ppm (estimated)

1.125X10-6 mm Hg at 25 deg C

Insoluble in water.

Ethers

9

3077

Stable. Combustible. Incompatible with strong oxidizing agents.

WHO; Environ Health Criteria 88: Polychlorinated Dibenzo-para-dioxins and Dibenzofurans p.262 (1989)|Skene SA et al; Hum Toxicol 8 (3): 173-204 (1989). Polychlorinated Dibenzo-P-Dioxins and Polychlorinated Dibenzofurans; The Risk to Human Health A review.|DHEW/NCI; Bioassay of 2,7-Dichlorodibenzo-p-dioxin (DCDD) for Possible Carcinogenicity p.vii (1979) Technical Rpt Series No. 123 DHEW Pub No. (NIH) 79-1378

Flash point data are not available for this chemical. It is probably combustible. (NTP, 1992)

Fires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. (NTP, 1992)

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]: As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase, in the downwind direction, as necessary, the isolation distance shown above. FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2016)

SMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then dampen the solid spill material with toluene, then transfer the dampened material to a suitable container. Use absorbent paper dampened with toluene to pick up any remaining material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent-wash all contaminated surfaces with toluene followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned. STORAGE PRECAUTIONS: You should store this material under ambient temperatures. (NTP, 1992)

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

The concn of dichlorodibenzo-p-dioxin occurring in fly ash from various Canadian municipal incinerators has been reported to range from 1-21 ppb(1). Dichlorodibenzodioxin has been detected in emissions from coal-fired utility boilers(1).

The average 2,7-dichlorodibenzo-p-dioxin level occurring in various formulations of the pesticide 2,4-dichlorophenoxy prior to 1982 has been reported to range from 45 to 2400 ug/kg(1); an avg concn of 0.02 ppm 2,7-dichlorodibenzo-p-dioxin has been reported to occur in the pesticide dicamba(1).

DICHLORODIBENZODIOXIN APPEARED TO PROMOTE SKIN CARCINOGENESIS INDUCED IN MICE BY DIMETHYLBENZANTHRACENE. /DICHLORODIBENZODIOXIN/

A bioassay of 2,7-dichlorodibenzo-p-dioxin for possible carcinogenicity was conducted by administering the test chemical in feed to Osborne-Mendel rats and B6C3F1 mice. Groups of 35 rats of each sex were administered 2,7-dichlorodibenzo-p-dioxin at one of two doses, either 5,000 or 10,000 ppm, for 110 weeks. Groups of 50 mice of each sex were administered these same doses for 90 weeks. Controls consisted of 35 untreated rats of each sex and 50 untreated mice of each sex. All surviving male rats were killed at 110 to 112 weeks, all surviving female rats at 110 to 117 weeks, all surviving male mice at 92 to 101 weeks, and all surviving female mice at 91 to 98 weeks. Mean body weights of most of the dosed groups of rats and mice were lower than those of corresponding controls of both when placed on study and for much of the study period; however, survival of any group was not significantly affected by administration of the test chemical. Sufficient numbers of dosed and control rats and mice of each sex were at risk for the development of late-appearing tumors. No tumors were induced in male or female rats or female mice at incidences that were significantly higher in the dosed groups than in the corresponding control groups. Both low- and high-dose rats had toxic hepatic lesions characterized by centrilobular fatty metamorphosis and/or necrosis. In the male mice, hepatocellular adenomas or carcinomas occurred at incidences that were dose related (p= 0.008), and in direct comparisons, were higher in the low-dose group (p= 0.008) and the higher-dose group (p= 0.010) than in control group (controls 8/49, low-dose 20/50, high-dose 17/42). However, the historical incidence of this lesion in control male B6C3F1 mice at this laboratory does not permit a clear association of the lesion with the administration of the test cmpd. There were also significant increases in the incidence of combinations of leukemias and lymphomas and of hemangiosarcomas and hemangiomas in the low-dose male mice, but these findings were not supported by the high-dose animals. It is concluded that under the conditions of this bioassay, 2,7-dichlorodibenzo-p-dioxin was not carcinogenic for Osborne-Mendel rats of either sex or female B6C3F1 mice. The marginal increased incidences of combinations of leukemias and lymphomas, of hemangiosarcomas and hemangiomas, and of hepatocellular carcinomas and adenomas in male B6C3F1 mice are, however, considered as suggestive of a carcinogenic effect of 2,7-dichlorodibenzo-p-dioxin in these animals.

2,7-Dichlorodibenzo-p-dioxin is released to the environment in fly ash emissions from municipal waste incineration and in stack emissions from coal-fired boilers(1). 2,7-Dichlorodibenzo-p-dioxin has been reported to occur as a minor contaminant in the pesticides 2,4-dichlorophenoxyacetic acid and dicamba(1); therefore, direct environmental release may occur from environmental applications of these pesticides(SRC). A wide spectrum of chlorinated dibenzo-p-dioxins is found in both municipal incineration emissions and automobile exhausts(2); therefore, it is possible that 2,7-dichlorodibenzo-p-dioxin is also found in leaded automobile exhausts(SRC).

TERRESTRIAL FATE: Based on a soil TLC study using five different soils types, 2,7-dichlorodibenzo-p-dioxin is expected to be immobile in soil(1). If applied indirectly to soils, it is not expected to move any further into the soil profile, although it may be subject to runoff or wind erosion transport(1). A single biodegradation study using two soil types has shown that about 5% of initial concns of 2,7-dichlorodibenzo-p-dioxin are metabolized to CO2 over a ten week incubation period(2). No data are currently available to suggest that dichlorodibenzo-p-dioxin is abiotically degraded within soil systems. Photodecomposition on soil surfaces is not important(3).|AQUATIC FATE: 2,7-Dichlorodibenzo-p-dioxin has been found to be immobile in soil mobility studies(1) which suggests that partitioning from the water column to sediment and suspended material may be significant. In the presence of significant adsorption, volatilization may not be important. The volatilization half-life from a model environmental pond, which considers the effect of adsorption, can be estimated to be about 30 years(2,SRC); if parameters are introduced into the pond model to exclude adsorption effects, the volatilization half-life is reduced to 15.2 days(SRC). Photodegradation may have some importance in surface waters exposed to sunlight; 2,7-dichlorodibenzo-p-dioxin in methanol solution has been shown to decompose within several hours when exposed to sunlight(3). Based upon a predicted log Kow of 5.75(4), significant bioconcentration in aquatic organisms may occur. Aquatic hydrolysis is not expected to be important. Insufficient data are available to predict the importance of biodegradation in water. (SRC)|ATMOSPHERIC FATE: Based upon a predicted vapor pressure of 1.125X10-6 mm Hg at 25 °C(1), 2,7-dichlorodibenzo-p-dioxin may exist in both the vapor and particulate phases in the ambient atmosphere(2,SRC). When associated with fly ash releases, dichlorodibenzodioxin can be expected to be very tightly adsorbed to particulates based on experimental examination of monochloro and other chlorinated dibenzo-p-dioxins(3). Vapor-phase 2,7-dichlorodibenzo-p-dioxin is degraded relatively rapidly in the atmosphere by reaction with photochemically produced hydroxyl radicals; the half-life for this reaction has been estimated to be about 1.6 days in average air(4). The vapor phase may also be susceptible to direct photolysis. Particulate phase dibenzo-p-dioxin is susceptible to physical removal from air by both wet and dry deposition processes. (SRC)

2,7-Dichlorodibenzo-p-dioxin has strong absorption maxima at 298 nm in acetonitrile, 302 nm in chloroform, and 298 nm in methanol(1,2) which suggest a potential for direct photolysis in the environment(SRC). Concns of 5 ppm 2,7-dichlorodibenzo-p-dioxin in methanol solution have been observed to photodecompose when exposed to either sunlight or simulated sunlight for several hours(3). Simulated solar irradiation of aqueous suspensions of semiconductors (such as TiO2) and 2,7-dichlorodibenzo-p-dioxin has been shown to result in nearly complete photocatalytic degradation of the dioxin within one day(4); however, concns of the semiconductors used (such as 4 g/L TiO2) is greatly in excess of concns of similar materials which may occur in the environment(SRC). Based upon sunlight exposures of unsubstituted dibenzo-p-dioxin in water, it has been suggested that photolysis of the 2,7-dichloro isomer in water may be significantly catalyzed by the presence of nitrate ions(1).|The rate constant for the vapor-phase reaction of 2,7-dichlorodibenzo-p-dioxin with photochemically produced hydroxyl radicals can be estimated to be 9.93X10-12 cu cm/molecule-sec at 25 °C which corresponds to an atmospheric half-life of about 1.6 days at an atmospheric concn of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Polycyclic and halogenated aromatic hydrocarbons are generally resistant to environmental hydrolysis(2); therefore, 2,7-dichlorodibenzo-p-dioxin is not expected to hydrolyze in water(SRC). Photodecomposition of 2,7-dichlorodibenzo-p-dioxin is insignificant on dry soil surfaces(3).

346.74|UPTAKE OF (14)C LABELLED ... 2,7-DICHLORODIBENZO-P-DIOXIN ... FROM NUTRIENT SOLN OR SOIL WAS MEASURED IN OATS & SOY BEANS. SOLN CONTAINED ... 0.26 MG/L 2,7-DICHLORODIBENZO-P-DIOXIN ... SOIL SAMPLES CONTAINED ... 0.1 MG/KG ... AFTER 14 DAYS, SEEDLING OATS & SOY BEANS CONTAINED (MINUS CONTROL) ... 0.16 & 0.01 MG/KG ... AT MATURITY... 0.02 & LESS THAN 0.001 MG/KG 2,7-DICHLORODIBENZO-P-DIOXIN ... NO TRANSLOCATION ... WAS OBSERVED AFTER ... APPLICATION TO FOLIAGE.|Based on a predicted log Kow of 5.75(1) and an estimated water solubility of roughly 0.19 ppm(2), the BCF of 2,7-dichlorodibenzo-p-dioxin can be estimated to range from 1580 to 13800 from various recommended regression-derived equations(3,SRC). These BCF estimations indicate that bioconcentration in aquatic organisms may be important(SRC).

Using soil thin layer chromatography, 2,7-dichlorodibenzo-p-dioxin was found to be immobile (Rf values of 0.0) in five different types of soil(1); if applied to soils, it is not expected to move any farther into the soil profile, although it may be subject to runoff or wind erosion transport(1).

The Henry's Law Constant for 2,7-dichlorodibenzo-p-dioxin can be estimated to be 4.88X10-5 atm cu m/mole at 25 °C using a chemical group estimation method(1,SRC). This value of Henry's Law constant indicates that some volatilization from environmental waters will occur, but the rate is not rapid(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep flowing 1 m/sec with a wind velocity of 3 m/sec) can be estimated to be about 1.4 days(2,SRC); however, this estimation neglects the potentially significant effect of adsorption(SRC). The volatilization half-life from an environmental pond, which considers the effect of adsorption, can be estimated to be about 30 years(3,SRC); if parameters are introduced into the pond model to exclude adsorption effects, the volatilization half-life is reduced to 15.2 days(SRC).

The general population may be exposed to 2,7-dichlorodibenzo-p-dioxin through inhalation of fly ash particulates and emissions from municipal waste incinerators and, perhaps, through inhalation of automobile exhaust. Occupational exposure may be possible through inhalation or dermal contact to workers handling the pesticides 2,4-D and dicamba in which 2,7-dichlorodibenzo-p-dioxin may occur as a minor impurity. (SRC)

The polychlorinated dibenzo-p-dioxins and the polychlorinated dibenzofurans are predominantly stored in fat, but they are also excreted in milk and pass the placenta. They also appear in the blood and vital organs at lower concentrations. /Polychlorinated dibenzo-p-dioxins/

IN RATS, 2,7-DICHLORODIBENZO-P-DIOXIN IS METABOLIZED TO MONO- & DIHYDROXY DERIVATIVES. PRIMARY HYDROXYLATION OF DIBENZO-P-DIOXINS TAKES PLACE EXCLUSIVELY AT 2, 3, 7, OR 8 POSITION.|Dioxins were administered to rats. Urine and feces were collected and analyzed. ... 2,7-Dichlorodibenzo-p-dioxin yielded two monohydroxy, one monochloro-dihydroxy and one dihydroxy metabolite.

1.70 Days

SYMPTOMS: Symptoms of exposure to this chemical may include chloracne, porphyria and irreversible liver damage. ACUTE/CHRONIC HAZARDS: When heated to decomposition this compound emits toxic fumes of chloride ion. (NTP, 1992)

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment. INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing. INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. (NTP, 1992)

Persons with recent exposure to polychlorodibenzodioxins ... should have the chemicals removed from their skin as quickly as possible to prevent additional absorption of the compounds. Exposed person should be asked for an exposure history, including onset of exposure, duration of exposure, and type of exposure. Physical examinations, including a thorough examination of the skin, should be given. Routine blood and liver laboratory tests should be carried out. In most situations, however, evidence of exposure and disease relatable to the exposure will be lacking. Because chloracne is the only human effect documented thus far, no other specific abnormality can be considered pathognomonic for exposure. /Polychlorodibenzodioxins/

The most prominent acute manifestation of toxicity that has been shown in humans is chloracne, an acne-like condition that takes months or years to disappear. Clinically, this skin lesion is characterized by hyperplasia and hyperkeratosis of the interfollicular epidermis, hyperkeratosis of the sebaceous follicles, and the squamous metaplasia of the sebaceous glands that form cysts and keratinaceous comedones in a typical distribution. Data are not yet available to determine the amount, route, or duration of exposure that is necessary to cause chloracne. /Polychlorodibenzodioxins/|Other less consistency reported effects from dioxin exposure in humans include aesthenia, headaches, and pain in the extremities, peripheral neuropathy, ulcers, altered liver function, enzyme induction, altered lipid metabolism, and abnormal urinary porphyrin patterns. Immune system dysfunction and altered T-cell subsets have been reported by some investigators but have not been found by others. /Polychlorodibenzodioxins/

2,7-dichlorodibenzo-4-dioxin

Thermal or chemical degradation of chlorophenols can produce ... /Polychlorodibenzoparadioxins/

All aspects of the use of mass spectrometry for identification & quantitation of chlorodibenzo-p-dioxins (incl TCDD) are critically reviewed.|EPA Method 8280. Matrix-specific Extraction, Analyte Specific Clean-up, and High Resolution Capillary Column Gas Chromatography/Low-Resolution Mass Spectrometry (HRGC/LRMS) techniques. These techniques are appropriate for the determination of polychlorinated dibenzodioxins and dibenzofurans including 2,3,7,8-tetrachloro-dibenzo-p-dioxin chemical wastes. For (13)C 12-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin the method detection limit is 0.13 parts per trillion in fuel oil/sandust. The method performance results included the following: for 2,3,7,8-tetrachlorodibenzo-p-dioxin in sludge the RSD is 4.4 at a spiked analyte level of 5.0 ng/g and the mean percent recovery is 61.7 at a spiked analyte level of 5.0 ng/g.