MF: C₁₂H₅Cl₅
MW: 326.433 g/mol
Density: 1.522 g/cm³ 
Flash Point: 183.6 °C
Index of Refraction: 1.619 
Enthalpy of Vaporization: 60.22 kJ/mol 
Boiling Point: 378.8 °C at 760 mmHg 
Vapour Pressure: 1.34E-05 mmHg at 25°C 
IUPAC Name: 1,2,3-Trichloro-4-(2,3-dichlorophenyl)benzene
Appearance: Colorless to pale-yellow, viscous liquid or solid (below 50F) with a mild, hydrocarbon odor.
Stability: Stable. Highly flammable. Incompatible with strong oxidizing agents. Attacks some forms of plastics and rubber.
Synonyms: Aroclor 1254, 1X1ML, ISO, 1000UG/ML ; [40cfr136(1986)]Pcb-1254 ; Chloriertebiphenyle,Chlorgehalt54% ; Chlorodiphenyl(54%chlorine) ; Chlorodiphenyl(54%cl) ; Clorodifenili,cloro54% ; Diphenylechlore,54%dechlore ; Diphenylechlore,54%dechlore(french)
Following is the molecular structure of polychlorinated biphenyl (aroclor 1254):

Consensus of polychlorinated biphenyl (aroclor 1254):
NTP 10th Report on Carcinogens. IARC Cancer Review: Group 2A IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1987,p. 322.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1974,p. 261.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Limited Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 18 ,1978,p. 43.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Human Limited Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 18 ,1978,p. 43.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . NCI Carcinogenesis Bioassay (feed); Some Evidence: rat NCITR*    National Cancer Institute Carcinogenesis Technical Report Series. (Bethesda, MD 20014) No. NCI-CG-TR-38 ,1978. . EPA Genetic Toxicology Program.

Confirmed carcinogen with experimental carcinogenic and neoplastigenic data. Poison by intravenous route. Moderately toxic by ingestion and intraperitoneal routes. Experimental teratogenic and reproductive effects. Mutation data reported. When heated to decomposition it emits toxic fumes of Cl⁻. Used in heat transfer, hydraulic fluids, lubricants, and insecticides.
Safety Information of polychlorinated biphenyl (aroclor 1254):
Hazard Codes  F,Xn,N,T
F  Highly Flammable N: Dangerous for the environment
Xn: Harmful     T:Toxic
Risk Statements  11-38-50/53-65-67-33-62-51/53-48/20-36/37/38-22-39/23/24/25-23/24/25-40-37/38-20/21/22
11: Highly Flammable 
38: Irritating to the skin
50/53: Very Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment
65: Harmful: May cause lung damage if swallowed
67: Vapors may cause drowsiness and dizziness 
33: Danger of cumulative effects 
62: Possible risk of impaired fertility
51/53: Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment
48/20: Harmful: danger of serious damage to health by prolonged exposure through inhalation
36/37/38: Irritating to eyes, respiratory system and skin
22: Harmful if swallowed
39/23/24/25: Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed
23/24/25: Toxic by inhalation, in contact with skin and if swallowed 
40: Limited evidence of a carcinogenic effect 
37/38:  Irritating to respiratory system and skin 
20/21/22:  Harmful by inhalation, in contact with skin and if swallowed 
Safety Statements: 9-16-29-33-60-61-62-35-36/37-36-26-45-7-23
9: Keep container in a well-ventilated place
16: Keep away from sources of ignition - No smoking
29: Do not empty into drains
33: Take precautionary measures against static discharges
60: This material and/or its container must be disposed of as hazardous waste
61: Avoid release to the environment. Refer to special instructions safety data sheet
62: If swallowed, do not induce vomiting: seek medical advice immediately and show this container or label 
35: This material and its container must be disposed of in a safe way 
36/37: Wear suitable protective clothing and gloves
36: Wear suitable protective clothing 
26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice 
45: In case of accident or if you feel unwell, seek medical advice immediately (show label where possible)
7: Keep container tightly closed 
23: Do not breathe gas/fumes/vapor/spray (appropriate wording to be specified by the manufacturer) 
RIDADR: 2315
RTECS: TQ1360000
HazardClass: 9
PackingGroup: II

OSHA PEL: TWA 0.5 mg/m³ (skin)
ACGIH TLV: TWA 0.5 mg/m³ (skin); Animal Carcinogen
DFG MAK: 0.05 ppm (0.70 mg/m³); Suspected Carcinogen
NIOSH REL: TWA (Polychlorinated Biphenyls) 0.001 mg/m³

For occupational chemical analysis use NIOSH: Polychlorobiphenyls, 5503; In Serum, 8004.