Di-chlorobenzene

Sommer C, H Gorisch (1997) Enzymology of the degradation of (di)chlorobenzenes by Xanthobacter flavus 14pl. Arch Microbiol 167 384-391. 

TRINITROBENZENE m-DIBROMOBENZENE m-CHLORONITROBENZENE o-CHLORONITROBENZENE p-CHLORONITROBENZENE tn-D I CHLOROBENZENE o-DICHLOROBENZENE p-DI CHLOROBENZENE m-DIFLUOROBENZENE o-DIFLUOROBENZENE p-DIFLUOROBENZENE m-DI NITROBENZENE o-DINITROBENZENE p-DINITROBENZENE BROMOBENZENE MONOCHLOROBENZENE m-CHLOROPHENOL o-CHLOROPHENOL p-CHLOROPHENOL... 

Biological. Under aerobic conditions, biodegradation products may include 1,2-di-chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and carbon dioxide (Kobayashi and Rittman, 1982). A mixed culture of soil bacteria or a Pseudomonas sp. transformed 1,2,4-tri-chlorobenzene to 2,4,5- and 2,4,6-trichlorophenol (Ballschiter and Scholz, 1980). When 1,2,4-trichlorobenzene was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, significant biodegradation occurred, with gradual acclimation followed by a deadaptive process in subsequent subcultures. At a concentration of 5 mg/L, 54, 70, 59, and 24% losses were observed after 7, 14, 21, and 28-d incubation periods, respectively. At a concentration of 10 mg/L, only 43, 54, 14, and 0% were observed after 7, 14, 21, and 28-d incubation periods, respectively (Tabak et al., 1981). In activated sludge, <0.1% mineralized to carbon dioxide after 5 d (Freitag et al., 1985). 

If you are exposed to 1,4-di chlorobenzene, many factors determine whether you ll be harmed. These factors include the dose (how much), the duration (how long), and how you come in contact with it. You must also consider the other chemicals you re exposed to and your age, sex, diet, family traits, lifestyle, and state of health. 

The chemical 1,4-di chlorobenzene is usually called para-DCB or p-DCB, but there are about 20 additional names for it, including para crystals and paracide. It is also called paramoth because it is one of two chemicals commonly used to make mothballs. 1,4-Dichlorobenzene is used to make deodorant blocks used in garbage cans and restrooms, as well as to help control odors in animal-hoi ding facilities. 1,4-Dichlorobenzene has also been used as an insecticide on... 

At room temperature, 1,4-dichlorobenzene is a white solid with a strong odor that you would probably recognize as the smell of mothballs. When a package of 1,4-di chlorobenzene is opened, it slowly changes from a solid into a vapor and is released into the atmosphere. The released vapor acts as a deodorizer and insect killer. Most of the 1,4-di chlorobenzene that is released to the general environment is present as a vapor. 1,4-Dichlorobenzene can burn, but does not burn easily. Most people begin to smell 1,4-di chlorobenzene when it is present in the air at a concentration of 0.18 parts per million (ppm) and in water at a concentration of 0.011 ppm. 

Dichlorobenzene does not occur naturally, but is produced by chemical companies to make products for home use and other chemicals such as resins. More information on the properties and uses of 1,4-di chlorobenzene may be found in Chapters 3 and 4. 

Most of the 1,4-di chlorobenzene enters the environment as a result of its uses in moth-repellant products and in toilet-deodorizer blocks. Because it changes from a solid to a gas easily, almost all of what is produced is released into the air. Some 1,4-di chlorobenzene is released to the air by factories that make or use it, and minor amounts are released to soil and water. Very little 1,4-dichlorobenzene enters the environment from hazardous waste sites. 

Because 1,4-dichlorobenzene does not dissolve easily in water, the small amounts that enter bodies of water quickly evaporate into the air. If it is released to groundwater, it may be transported to surface water. Depending on conditions, some 1,4-di chlorobenzene may bind to soil and sediment. 1,4-Dichlorobenzene in soil is not usually easily broken down by soil organisms. There is evidence that plants and fish absorb 1,4-di chlorobenzene. It has been detected at concentrations up to 400 ppb in fish. 

Humans are exposed to 1,4-dichlorobenzene mainly by breathing vapors from 1,4-dichlorobenzene products used in the home, such as mothballs and toilet-deodorizer blocks. Reported levels of 1,4-dichlorobenzene in some homes and public restrooms have ranged from 0.29 to 272 parts of 1,4-di chlorobenzene per billion parts (ppb) of air. Outdoor levels of 1,4-dichlorobenzene are much lower, and reported levels in cities range from 0.02 to 20 ppb. Even levels in the air around hazardous waste sites are low reported levels range from 0.03 to 4.25 ppb. 

Dichlorobenzene has also been detected in foods such as beef, pork, chicken, and eggs. This is because 1,4-di chlorobenzene is sometimes used as an odor-control product around animal stalls. 1,4-Dichlorobenzene has been found in fish levels of 1-4 ppb were measured in trout caught in the Great Lakes. 

The average daily adult intake of this chemical is estimated to be about 35 micrograms ( g), which comes mainly from breathing vapors of 1,4-di chlorobenzene that are released from products in the home. These levels are not expected to result in harmful effects. 

More information on how you might be exposed to 1,4-di chlorobenzene is given in Chapter 5. 

The main way 1,4-di chlorobenzene enters your body is through the lungs when you breathe in... 

Dichlorobenzene can also get into your body if you drink water that contains this chemical or if you eat certain foods that contain 1,4-di chlorobenzene, such as meat, chicken, eggs, or fish. Most of the 1,4-di chlorobenzene that enters your body from food and water will get into your bloodstream. It is not known if 1,4-di chlorobenzene can enter your body through the skin if you touch products that contain it. 

There is also a possibility that 1,4-di chlorobenzene used in the home can be accidentally swallowed, especially by young children. When 1,4-di chlorobenzene is used in mothballs or deodorant blocks, these products may be freely available in closets or bathrooms. 

Of the 1,4-di chlorobenzene that enters your body, most of it (perhaps more than 95%) leaves through the urine in less than a week. Another 1-2% leaves in the feces, and about 1-2% leaves in the air that you breathe out. Tiny amounts remain in your fat and may stay there for a long time. 

In your body, most 1,4-di chlorobenzene is changed to the chemical 2,5-dichlorophenol. It is not known if this breakdown product is more or less harmful than 1,4-di chlorobenzene itself... 

In laboratory animals, breathing or eating 1,4-dichlorobenzene can cause harmful effects in the liver, kidneys, and blood. Rats and mice given oral doses of 1,4-dichlorobenzene in lifetime studies had increased rates of liver cancer when compared with animals that did not receive 1,4-di chlorobenzene. 

We do not definitely know if 1,4-dichlorobenzene plays a role in the development of cancer. The Department of Health and Human Services (DHHS) has determined that 1,4-di chlorobenzene may reasonably be anticipated to be a carcinogen in humans. The International Agency for Research on Cancer (lARC) has determined that 1,4-dichlorobenzene is possibly carcinogenic to humans. The EPA has determined that 1,4-di chlorobenzene is a possible human carcinogen. 

There is no reliable evidence that suggests that 1,4-di chlorobenzene affects reproduction in humans. More information on how 1,4-di chlorobenzene can affect your health is given in Chapter 2. 

Children are exposed to 1,4-di chlorobenzene in many of the same ways that adults are. There is a possibility that 1,4-di chlorobenzene used in the home can be accidentally swallowed, especially by young children. When 1,4-di chlorobenzene is used in mothballs or toilet bowl deodorant blocks, these products may be freely available in closets or bathrooms. Although most of the exposure pathways for children are the same as those for adults, children may be at a higher risk of exposure because of their lack of consistent hygiene practices and their curiosity about unknown powders and liquids. 

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