1,4-Dichlorobenzene

 

Profile Summary

Most commonly referred to as paradichlorobenzene (para-DCB or p-DCB), 1,4-Dichlorobenzene is a chemical used to control moths, mildew, and mold. It does not occur naturally in the environment. There are approximately 20 additional terms used for this chemical, a few of which are: Paramoth, para crystals, and paracide, reflecting its widespread use as a moth killer. It is also used to make deodorant blocks used in deodorizing restrooms and waste containers. At least 70 million pounds of p-DCB are used each year in the manufacture of these 2 types of products.

The three major uses of 1,4-dichlorobenzene account for over 90 percent of its use in the United States: in space deodorizers (20 million pounds); in moth balls or blocks (8 million pounds); and in the production of polyphenylene sulfide resins (22 million pounds). Approximately 95 percent of the environmental releases of 1,4-dichlorobenzene occurs during its use, rather than during its manufacture or processing. 1,4-dichlorobenzene has been found in at least 244 of 1,300 National Priorities List (Superfund) sites identified by the Environmental Protection Agency.

Most people recognize the odor of 1,4-dichlorobenzene as the smell of mothballs, and can smell p-DCB in the air at very low levels. Most p-DCB in our environment comes from its use in moth repellent products and in toilet deodorizer blocks. When exposed to air, it is slowly transformed from its solid state into a vapor. The released vapor then acts as a deodorizer and insect killer.

1,4'-Dichlorobenzene is a registered insecticide, used for the control of ticks and lice in and around bird cages, as well as in museums for the protection of insect, plant and stuffed animal collections. 1,4-Dichlorobenzidene is also used in the manufacture of certain resins, in the pharmaceutical industry, and as a general insecticide in farming.

 

Physical Properties

Molecular formula: C6H4Cl2
Molecular weight: 147.02 g/mol
Chemical family:
Image:
Characteristics: white, colorless crystalline solid; penetrating odor; insoluble in water
Vapor Pressure: 0.923 mm Hg at 25 oC
Water Solubility:
Soil Sorption:
Synonyms: PDB

 

Sources, Pathways, and Environmental Effects

The major source of 1,4-dichlorobenzene emission to the atmosphere is volatization from use in toilet bowl deodorants, garbage deodorants and moth flakes. If released to soil, 1,4-dichlorobenzene can be moderately to tightly absorbed. Leaching from hazardous waste disposal areas has occurred and the detection of 1,4-dichlorobenzene in various groundwaters indicates that leaching can occur. It is possible that it will be slowly biodigraded in soil under aerobic conditions. If released into the air, it will exist predominantly in the vapor-phase and will react with photochemically produced hydroxyl radicals at an estimated half-life rate of 31 days in typical atmosphere.

The three major production plants for 1,4-dichlorobenzene in the United States are in Delaware, Illinois, and West Virginia. Of the total U.S. annual production of 75 million pounds, about 25 million pounds are exported. Since 1980, virtually no 1,4-dichlorobenzene has been imported into the United States.

P-dichlorobenzene is released into the environment during both its manufacture and its use. Heavily populated and/or industrialized areas tend to have the highest concentrations of p-DCB in air and in water, including surface water, groundwater, and drinking water; whereas some areas, especially rural areas, may have lower or undetectable levels.

Chemical waste dump leachates and direct manufacturing effluents are reported to be the major source of pollution of the chlorobenzenes (including dichlorobenzenes) to Lake Ontario. The major source of emission to the atmosphere is volatization from use in toilet bowl deodorants, garbage deodorants and moth flakes.

From 1987 to 1993, according to the TRI, p-DCB releases to water totaled almost 34,000 lbs. Releases to land totaled nearly 4,500 lbs. These releases were primarily from a single chemical manufacturing plant in West Virginia.

In air, 1,4-dichlorobenzene can break down to harmless products in about a month. It does not dissolve easily in water. It evaporates easily from water and soil, so most is found in the air. It is not easily broken down by soil organisms. It is taken up and retained by plants and fish.

People are exposed to this chemical when breathing indoor air in public restrooms and homes that use p-DCB as a deodorizer; breathing air around some mothballs; and when breathing workplace air where p-DCB is manufactured. Exposure also occurs through drinking contaminated water around hazardous waste sites; eating foods such as pork, chicken, and eggs that are contaminated with p-DCB from its use as an odor control product in animal stalls; and eating fish from contaminated waters. Infants can be exposed by drinking human breast mill from mothers exposed to p-DCB.

1,4-dichlorobenzene will exist in the gas phase in the atmosphere, and has a half-life of 1 month and a lifetime of 1.5 months.

 

Health Effects

Exposure to 1,4-dichlorobenzene happens mostly from breathing high levels of indoor air or workplace air. Extremely high exposures can cause dizziness, headaches, and liver problems. Other means of exposure are ingesting contaminated food (e.g. fish) and water. Exposure can also occur through the skin if we touch products containing it, such as mothballs and toilet deodorizer blocks.

There is no evidence that moderate use of common household products that contain p-DCB will result in harmful effects to your health. Harmful effects, however, may occur from high exposures. There is no direct evidence that p-DCB can cause birth defects or affect reproduction in humans. Animal studies indicate that breathing or eating p-DCB can harm the liver, kidney and blood. The Department of Health and Human Services (DHHS) has determined that p-DCB may reasonably be anticipated to be a carcinogen. EPA has classified 1,4-dichlorobenzene as a Group C, possible human carcinogen of low carcinogenic hazard. California State has also determined, under Proposition 65, that this chemical is a carcinogen.

Analysis of 1993 National Toxics Inventory Version 9801

 

Largest state emissions : CA, TX, NY, WV, IL, MA, FL, DE, OH, PA

Largest county emissions: New Castle, DE; Harris, TX; Marshall, WV; Los Angeles, CA; Worcester, MA; Cook, IL; Wetzel, WV; St. Clair, IL; Orange, CA; Sand Diego, CA

 

Largest source categories (top 10) based on total national emissions, as listed in the 1993 NTI Version 9801:

NTI Source Category Description

Total National Emissions (tons/year)

% Contribution of Total Emissions

Total National Number of Emitting Counties

Total National Number of Emitting States

NTI SCC

Consumer Products Usage

4.4E+03

 

3141

51

10445

Chemical Manufacturing: p-Dichlorobenzene (1,4-)

2.9E+02

 

4

4

10340

Abrasive Grain (Media) Manufacturing

1.8E+02

 

4

4

3291

Chlorine Production

1.7E+02

 

1

1

12047

Chemical Manufacturing: Alkalies and Chlorine

1.7E+02

 

38

21

2812

Consumer & Commercial Product Solvent Use

1.5E+02

 

2

2

49

MON - Continuous Processes

7.1E+01

 

1425

51

10056

Chemical Manufacturing: Cyclic Crude and Inferred

4.4E+01

 

3

3

2865

Sewage Sludge Incineration

3.5E+01

 

3141

51

21

Chemical Manufacturing: p-Dichlorobenzene (Storage)

1.8E+01

 

4

4

10348

 

Revisions to 1990 112(k) Inventory as of May 1999 (to be listed in 1996 NTI) - largest source categories (top 10) based on total national emissions have changed

NTI Source Category Description

Total National Emissions (tons/year)

% Contribution of Total Emissions

Consumer Products Usage

4.4E+03

85.0

Chemical Manufacturing: p-Dichlorobenzene (1,4-)

2.9E+02

5.7

Paper and Other Webs (Surface Coating) - [Abrasive Products] *

1.8E+02

3.6

Hydrochloric Acid Production *

1.7E+02

3.4

MON - Continuous Processes

7.1E+01

1.4

Chemical Manufacturing: p-Dichlorobenzene (Storage Emissions)

1.8E+01

0.34

Publicly Owned Treatment Works (POTW) Emissions *

1.4E+01

0.26

Tire Production *

6.6E+00

0.13

Polishes and Sanitation Goods Manufacturing

4.2E+00

0.08

Industrial Organic Chemicals Manufacturing

3.4E+00

0.07

* indicates MACT standards in place or planned

For complete May 1999 update to 1990 112(k) Inventory for 1,4-Dichlorobenzene, see page ______.

 

1993 National Toxics Inventory State Emissions Data for 1,4-Dichlorobenzene

 

 

1993 National Toxics Inventory County Emissions Data for 1,4-Dichlorobenzene

Top 20 1,4-Dichlorobenzene Emitting Counties in the United States


1993 National Toxics Inventory State Emissions Data for 1,4-Dichlorobenzene

State Emissions (tons/year) % Total
1. California (CA) 5.5E+002 10.0%
2. Texas (TX) 5.1E+002 9.2%
3. New York (NY) 3.4E+002 6.2%
4. West Virginia (WV) 2.8E+002 5.1%
5. Illinois (IL) 2.8E+002 5.0%
6. Massachusetts (MA) 2.5E+002 4.6%
7. Florida (FL) 2.3E+002 4.1%
8. Delaware (DE) 2.2E+002 4.0%
9. Ohio (OH) 2.2E+002 4.0%
10. Pennsylvania (PA) 2.2E+002 3.9%
11. Michigan (MI) 1.7E+002 3.1%
12. New Jersey (NJ) 1.4E+002 2.6%
13. Louisiana (LA) 1.4E+002 2.5%
14. Georgia (GA) 1.2E+002 2.2%
15. North Carolina (NC) 1.2E+002 2.2%
16. Indiana (IN) 1.2E+002 2.1%
17. Virginia (VA) 1.1E+002 2.0%
18. Washington (WA) 9.4E+001 1.7%
19. Tennessee (TN) 9.4E+001 1.7%
20. Missouri (MO) 9.2E+001 1.7%
21. Wisconsin (WI) 8.9E+001 1.6%
22. Maryland (MD) 8.5E+001 1.5%
23. Alabama (AL) 8.3E+001 1.5%
24. Minnesota (MN) 7.8E+001 1.4%
25. Kentucky (KY) 6.8E+001 1.2%
26. Arizona (AZ) 6.5E+001 1.2%
27. South Carolina (SC) 6.5E+001 1.2%
28. Connecticut (CT) 6.1E+001 1.1%
29. Colorado (CO) 5.9E+001 1.1%
30. Oklahoma (OK) 5.6E+001 1.0%
31. Oregon (OR) 5.3E+001 1.0%
32. Iowa (IA) 5.0E+001 0.9%
33. Kansas (KS) 4.7E+001 0.8%
34. Mississippi (MS) 4.7E+001 0.8%
35. Arkansas (AR) 4.2E+001 0.8%
36. Utah (UT) 3.1E+001 0.6%
37. Nebraska (NE) 2.8E+001 0.5%
38. New Mexico (NM) 2.7E+001 0.5%
39. Nevada (NV) 2.3E+001 0.4%
40. Maine (ME) 2.3E+001 0.4%
41. Hawaii (HI) 2.0E+001 0.4%
42. New Hampshire (NH) 2.0E+001 0.4%
43. Rhode Island (RI) 1.8E+001 0.3%
44. Idaho (ID) 1.8E+001 0.3%
45. Montana (MT) 1.4E+001 0.3%
46. South Dakota (SD) 1.2E+001 0.2%
47. North Dakota (ND) 1.1E+001 0.2%
48. Washington, D.C. (DC) 1.1E+001 0.2%
49. Alaska (AK) 1.0E+001 0.2%
50. Vermont (VT) 9.9E+000 0.2%
51. Wyoming (WY) 8.0E+000 0.1%
Total 5.6E+003

 

1993 National Toxics Inventory County Emissions Data for 1,4-Dichlorobenzene

 

Top 20 1,4-Dichlorobenzene Emitting Counties in the United States

 

Top 20 1,4-Dichlorobenzene Emitting Counties in the U.S. Ranking Total Source Categories

County Name Source Category
Emissions (tons/year)
% Total
1. New Castle County, DE
All Sources (total)
2.2E+002
100.0%
Chemical Manufacturing: p-Dichlorobenzene (1,4-)
1.7E+002
75.3%
Chemical Manufacturing: Cyclic Crude and Intermediate Production
3.4E+001
15.7%
Chemical Manufacturing: p-Dichlorobenzene (Storage Emissions)
9.9E+000
4.5%
Consumer Products Usage
7.8E+000
3.5%
Chemical Manufacturing: Alkalies and Chlorine
2.0E+000
0.9%
Other
1.7E-001
0.1%
2. Harris County, TX
All Sources (total)
2.1E+002
100.0%
Consumer & Commercial Product Solvent Use
1.5E+002
69.4%
Consumer Products Usage
5.0E+001
23.2%
Chemical Manufacturing: Alkalies and Chlorine
1.4E+001
6.5%
MON - Continuous Processes
2.0E+000
1.0%
Other
1.1E-002
0.0%
3. Marshall County, WV
All Sources (total)
1.7E+002
100.0%
Chlorine Production
1.7E+002
98.9%
Chemical Manufacturing: Alkalies and Chlorine
1.2E+000
0.7%
Other
6.9E-001
0.4%
4. Los Angeles County, CA
All Sources (total)
1.7E+002
100.0%
Consumer Products Usage
1.6E+002
93.8%
Chemical Manufacturing: p-Dichlorobenzene (1,4-)
4.4E+000
2.7%
MON - Continuous Processes
1.9E+000
1.2%
Chemical Manufacturing: Cyclic Crude and Intermediate Production
1.7E+000
1.0%
Other
2.2E+000
1.3%
5. Worcester County, MA
All Sources (total)
1.5E+002
100.0%
Abrasive Grain (Media) Manufacturing
1.4E+002
91.7%
Consumer Products Usage
1.2E+001
8.1%
Other
3.0E-001
0.2%
6. Cook County, IL
All Sources (total)
9.5E+001
100.0%
Consumer Products Usage
9.0E+001
94.2%
Abrasive Grain (Media) Manufacturing
3.3E+000
3.5%
MON - Continuous Processes
2.1E+000
2.2%
Other
1.3E-001
0.1%
7. Wetzel County, WV
All Sources (total)
7.5E+001
100.0%
Chemical Manufacturing: p-Dichlorobenzene (1,4-)
6.6E+001
87.7%
Chemical Manufacturing: Alkalies and Chlorine
4.8E+000
6.3%
Chemical Manufacturing: p-Dichlorobenzene (Storage Emissions)
4.0E+000
5.3%
Other
5.2E-001
0.7%
8. St. Clair County, IL
All Sources (total)
7.4E+001
100.0%
Chemical Manufacturing: p-Dichlorobenzene (1,4-)
5.8E+001
78.3%
Chemical Manufacturing: Cyclic Crude and Intermediate Production
7.9E+000
10.7%
Consumer Products Usage
4.6E+000
6.2%
Chemical Manufacturing: p-Dichlorobenzene (Storage Emissions)
3.5E+000
4.7%
Other
9.5E-002
0.1%
9. Orange County, CA
All Sources (total)
5.2E+001
100.0%
Consumer Products Usage
4.2E+001
81.2%
Chromium Plating: Chromic Anodizing
7.8E+000
14.9%
Sewerage Systems
1.4E+000
2.7%
Other
6.6E-001
1.3%
10. San Diego, CA
All Sources (total)
4.4E+001
100.0%
Consumer Products Usage
4.4E+001
99.0%
Other
4.4E-001
1.0%
11. Kings County, NY
All Sources (total)
4.2E+001
100.0%
Consumer Products Usage
4.0E+001
97.3%
Other
1.1E+000
2.7%
12. Wayne County, MI
All Sources (total)
3.9E+001
100.0%
Consumer Products Usage
3.7E+001
96.2%
Other
1.5E+000
3.8%
13. Maricopa County, AZ
All Sources (total)
3.8E+001
100.0%
Consumer Products Usage
3.7E+001
98.2%
Other
6.9E-001
1.8%
14. Queens County, NY
All Sources (total)
3.5E+001
100.0%
Consumer Products Usage
3.4E+001
97.4%
Other
9.0E-001
2.6%
15. Brazoria County, TX
All Sources (total)
3.5E+001
100.0%
Chemical Manufacturing: Alkalies and Chlorine
3.1E+001
87.2%
Consumer Products Usage
3.4E+000
9.6%
MON - Continuous Processes
1.1E+000
3.2%
Other
1.1E-003
0.0%
16. Dade County, FL
All Sources (total)
3.4E+001
100.0%
Consumer Products Usage
3.4E+001
99.5%
Other
1.8E-001
0.5%
17. Dallas County, TX
All Sources (total)
3.3E+001
100.0%
Consumer Products Usage
3.3E+001
98.5%
Other
5.0E-001
1.5%
18. Philadelphia County, PA
All Sources (total)
2.9E+001
100.0%
Consumer Products Usage
2.8E+001
96.7%
Other
9.4E-001
3.3%
19. King County, WA
All Sources (total)
2.7E+001
100.0%
Consumer Products Usage
2.7E+001
98.7%
Other
3.5E-001
1.3%
20. New York County, NY
All Sources (total)
2.7E+001
100.0%
Consumer Products Usage
2.6E+001
97.5%
Other
6.7E-001
2.5%

 

Controls

The following section identifies regulations currently in place to control emissions for 1,4'-dichlorobenzene at the international, federal, state, regional and local levels. Current voluntary initiatives and strategies aimed at managing such emissions are also listed. Any future plans for controls at all levels are described. The following table summarizes findings for major source categories listed in the May 1999 update to the 1990 112(k) Inventory. There are many changes which have been made to the total national emissions for specific source categories for 1,4-dichlorobenzene, which can be compared to past percentage totals.

 

1,4-Dichlorobenzene Sources and Controls (May 1999 update to 1990 112(k) Inventory

Largest Source Categories

Current Control

Future Control

Total National Emissions (tons/year)

Current% Total

Past % Total

Consumer Products Usage

   

4.4E+03

85.0

 

Chemical Manufacturing: p-Dichlorobenzene (1,4-)

HON Rule

 

2.9E+02

5.7

35.2

Paper and Other Webs (Surface Coating) [Abrasive Products]

   

1.9E+02

3.5

21.8

Hydrochloric Acid Production

   

1.7E+02

3.4

 

MON - Continuous Processes

   

7.1E+01

1.4

 

Chemical Manufacturing: p-Dichlorobenzene (Storage Emissions)

HON Rule

 

1.8E+01

0.3

2.1

Publicly Owned Treatment Works (POTW) Emissions

   

1.4E+01

0.3

 

Tire Production

 

Rubber Tire Production MACT (expected 12/99)

6.6E+00

0.1

0.8

Polishes and Sanitation Goods Manufacturing

   

4.2E+00

0.1

 

Industrial Organic Chemicals Manufacturing

   

3.4E+00

0.1

 

Soaps, Cleaners, and Toilet Goods

   

3.2E+00

0.1

0.9

Sewage Sludge Incineration

   

7.4E-01

0.01

 

Soap and Other Detergents Manufacturing

   

3.6E-01

0.01

 

Clay Products Manufacturing

   

2.3E-01

<0.01

 

Cement, Hydraulic (not subject to Portland Cement MACT)

   

1.8E-02

<0.01

 

Chemicals and Allied Products Manufacturing

   

5.0E-03

<0.01

 

Agricultural Chemicals and Pesticides

   

2.5E-03

<0.01

 

TOTAL

   

5.1E+03

   

 

Also previously listed were source categories such as: alkalies and chlorine manufacturing (20.7%); miscellaneous organic chemical processes (8.46%); petroleum refining: cyclic crude and intermediate production (5.07%); and sewage sludge incineration (2.11). All of these source categories are not listed in the May 1999 update to the 1990 112(k) inventory. The source category for soap and other detergents manufacturing was previously referred to as cleaning products.

 

Current Regulations, Initiatives and Strategies to Manage or Control 1,4-Dichlorobenzene

 

International

Federal (under construction)

 

Current Federal Regulations for 1,4-Dichlorobenzene

CURRENT FEDERAL REGULATIONS AND PROGRAMS

 

CAA

CWA

CERCLA

RCRA

SDWA

SARA/EPCRA

TSCA

Current Federal Regulations and Standards

             

Policy and Programs

· Great Lakes Binational Toxics Strategy (BNS): Level II Substance

· International Joint Commission (IJC): Critical Pollutant

Acronyms:
CAA: Clean Air Act
CWA: Clean Water Act
CERCLA: Comprehensive Environmental Response, Compensation, and Liability Act
RCRA: Resource Conservation and Recovery Act
SDWA: Safe Drinking Water Act
SARA/EPCRA: Superfund Amendment Reauthorization Act / Emergency Planning and Community Right-to-Know Act
TSCA: Toxic Substances Control Act

 

U.S. States

California

Regional (Multi-State)

Industrial Voluntary Activities and U.S. Partnerships

Planned Regulations, Initiatives, and Strategies to Manage or Control 1,4-Dichlorobenzene

International

Federal

 

U.S. States

 

Regional (Multi-State)

 

Industrial Voluntary Activities and U.S. Partnerships

 

Evaluation

In California, emissions of 1,4-dichlorobenzene have been reported by the following primary stationary sources: coating and engraving metal manufacturing, crude petroleum and natural gas extraction, and sanitary services. Approximately 37 pounds were used in 1993. Total emissions from stationary sources are estimated to be at least 28,000 pounds per year, based on data from the state’s Air Toxics "Hot Spots" Program.

Chemical waste dump leachates and direct manufacturing effluents are reported to be the major source of pollution of the chlorobenzenes (including the dichlorobenzenes) to Lake Ontario. Analysis of Lake Ontario sediment cores has indicated the presence and persistence of 1,4-dichlorobenzene since before 1940.

Release of the 1996 NTI may show emissions of 1,4-dichlorobenzene from the manufacturing of 1,4-dichlorobenzene (the largest source category, accounting for over 35 percent of the 112(k) inventory) to have decreased as a result of implementation of the HON Rule. Likewise, emissions from the miscellaneous organic chemical manufacturing sector may have decreased because of the HON Rule. There do not appear to be any regulatory or voluntary controls in place to reduce emissions of 1,4-dichlorobenzene from the abrasive grain (media) manufacturing sector, which accounts for over 21 percent of the 112(k) inventory. Likewise, emissions from the alkalies and chlorine manufacturing sector appear to be uncontrolled until after the year 2000 when the Chlorine Production MACT is promulgated. Some of the smaller source categories have current controls in place or are scheduled to be controlled under future MACTs expected by the year 2000.

1,4-dichlorobenzene is also listed for inclusion under several EPA regulatory and voluntary programs, including the 112(k) Integrated Air Toxics Strategy and a new Chemical Right-To-Know initiative to test high-production volume chemicals. Projects to reduce equipment leaks in the CSI Petroleum Refining Sector may also result in reduced emissions of 1,4-dichlorobenzene.

 

Additional Sources of Information

 

Endnotes

1 . Agency for Toxic Substances and Disease Registry (ATSDR). 1989. Public Health Statement: p-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

2 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

3 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

4 . Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

5 . Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/ToxProfiles/phs8814.html

6 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

7 . EDF. Chemical Scorecard. Chemical Profiles. 1,4-Dichlorobenzene. Http://www.scorecard.org/chemical-profiles/html/14dichlorobenzene.html

8 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

9 . Spectrum Laboratories: Chemical Fact Sheet - Cas #106467, 1,4-Dichlorobenzene. Http://www.speclab.com/compound/c106467.htm

10 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

11 . Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/ToxProfiles/phs8814.html

12 . USEPA, Office of Water - Office of Ground Water and Drinking Water. Drinking Water and Health. National Primary Drinking Water Regulations. Technical Fact sheet on p-Dichlorobenzene. Http://www epa.gov/OGWDW/dwh/t-voc/p-dichlo.html

13 .Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

14 . EDF. Chemical Scorecard. Chemical Profiles. 1,4-Dichlorobenzene. Http://www.scorecard.org/chemical-profiles/html/14dichlorobenzene.html

15 . Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

16 . USEPA, OAQPS, TTN Web. 1,4-Dichlorobenzene, 106-46-7. Http://www.epa.gov/ttnuatw1/hlthef/dich-ben.html

17 . EDF. Chemical Scorecard. Chemical Profiles. 1,4-Dichlorobenzene. Http://www.scorecard.org/chemical-profiles/html/14dichlorobenzene.html

18 .Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

19 .Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

20 .Agency for Toxic Substances and Disease Registry (ATSDR). 1993. Toxicological profile for 1,4-dichlorobenzene. Atlanta: U.S. Department of Health and Human Services, Public Health Service. Http://www.atsdr.cdc.gov/tfacts10.html

21 . Environmental Writer, 1,4-Dichlorobenzene (C6H4C12) Chemical Backgrounder. Environmental Health Center. Http://www.nsc.org/EHC/ew/chems/dibenzen.htm

22 . Occupational Safety & Health Administration (OSHA), U.S. Department of Labor. Occupational Safety and Health Guideline for P-Dichlorobenzene. Http://www.osha-slc.gov/SLTC/healthguidelines/p-dichlorobenzene/recognition.html

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24 . EDF. Chemical Scorecard. Chemical Profiles. 1,4-Dichlorobenzene. Http://www