|Chemical Abstract Number (CAS #)||
||EPA Method 553||EPA Method 605
||EPA Method 625
||EPA Method 8270
Link to the National Library of Medicine's Hazardous Substances
Database for more details
on this compound.
|Use|| MANUFACTURE OF DYES; AS REAGENT FOR HYDROGEN PEROXIDE IN
ORG SYNTHESIS; STAIN IN MICROSCOPY; STIFFENING AGENT IN RUBBER
MFR OF PLASTIC FILMS; IT REACTS WITH INK ERASERS TO GIVE COLORED
PRODUCTS & THEREFORE HAS BEEN USED IN SECURITY PRINTING; LAB AGENT
FOR DETECTION OF HYDROGEN CYANIDE & SULFATE, FOR QUANTITATIVE
DETERMINATION OF NICOTINE & AS SPRAY REAGENT FOR SUGARS
Benzidine is a chemical intermediate in the synthesis of direct black 4, 8; direct blue 2, 6; direct
brown 1A, 2, 6, 31, 59, 74, 95, 154; direct green 1, 6, 8; direct orange 8; direct red 1, 28, 37;
direct violet 1, 22; and acid red 85.
ALCOHOLIC BENZIDINE & HYDROGEN PEROXIDE WERE FORMERLY USED TO
VERIFY TLC BANDS ATTRIBUTED TO BLOOD.
|Apparent Color|| WHITE OR SLIGHTLY-REDDISH, CRYSTALLINE POWDER ; NEEDLES SRP:
WHEN CRYSTALIZED FROM WATER ; GRAYISH, YELLOW CRYSTALLINE POWDER;
POWDERS, OR LEAVES
|Boiling Point|| ABOUT 400 DEG C
|Melting Point|| 115-120 DEG C
|Molecular Weight|| 184.23
|Density|| 1.250 @ 20 DEG C/4 DEG C
|Sensitivity Data|| Contact dermatitis to primary irritation or sensitization has been reported.
|Environmental Impact|| Benzidine may be released as emissions and in wastewater during its production and use
in the manufacture of azo dyes or may be formed during the degradation of benzidine-based dyes
which have been discharged in waste water. If spilled on soil, it will adsorb to it, especially if the
soil is acidic, form complexes with clay particles and be oxidized by metal cations. The rate of
degradation in soil in the few studies reported in the literature were 79% degradation in 4 weeks
and 10% mineralization in 1 yr. If released in water, it will rapidly adsorb to suspended clay
particles, and be oxidized by naturally occurring metal cations such as Fe(III). It will also be lost
by reaction with radicals and photolysis. Its half-life in water is approximately 1 day. It will adsorb
to sediments and bioconcentrate only moderately in fish. In the atmosphere, it would primarily
exist in aerosols, be bound to particulate matter and be subject to gravitational settling and
wash-out. It may photolyze and would be readily oxidized by reactive species in the atmosphere
such as hydroxyl radicals. Human exposure to benzidine would be primarily occupational.
|Environmental Fate|| TERRESTRIAL FATE: If released on land benzidine will both sorb and react with cations
such as Fe(III) in the soil. Benzidine adsorbs more strongly at lower pH's when larger fractions of
the compound are ionized. Its reaction with clay minerals is particularly striking since a blue
complex is formed. Only a few determinations of its persistence in soil could be found, 79%
degradation in 4 weeks in a silty clay loam and 10% mineralization in 1 yr.
AQUATIC FATE: When released into water benzidine will completely degrade in approximately
one day due to reaction with radicals, redox reactions with naturally occurring cations, and
perhaps photodegradation. Degradation should occur more rapidly in humic waters because of the
presence of reactive radicals, cations and molecules; however, measurements of degradation rates
in different water types are lacking.
ATMOSPHERIC FATE: Should benzidine be released into the atmosphere, it will most likely be
in the form of aerosols or adsorbed to particulate matter and be subject to wash-out by rain and
gravitational settling. Although there are no experimental data on persistence in the atmosphere, it
may photolyze and would react with reactive atmospheric species such as hydroxyl radicals and
ozone. It is estimated to have a half-life of approximately 1 day in the atmosphere.
|Drinking Water Impact|| Surface Water: Buffalo River, Buffalo, NY - upstream and downstream of Allied
Chemical plant where benzidine was believed to have been discharged (42 samples from 7 sites)
-not detected . Niagra River near intake of Tonawanda water treatment plant -not detected .
Sumida River, Japan-site of several dye and pigment plants -concentration of aromatic amines
including benzidine 0.21-0.56 ppm . Rhine River-detected, not quantified . Benzidine was
specifically looked for but not found in Lake Erie or Lake Michigan . Of the 879 stations
reporting benzidine in ambient water in EPA's STORET database, 0.1% contained detectable
levels of the chemical .
EFFL: Maximum concentration in wastewater from foundries 10 ppb; Wastewater from
nonferrous metals manufacture 1.2 ppb avg, 6.0 ppb max . Detected in oil refinery, municiple
and industrial effluents . Effluents from textile factories using benzidine-based dyes 3.5 ppb avg;
leather factory 0.25 ppb; manufacturing plant using benzidine dyes 3.5 ppb . In a comprehensive
survey of wastewater from 4000 industrial and publicly owned treatment works (POTWs)
sponsored by the Effluent Guidelines Division of the USEPA, benzidine was identified in 1
discharge of the auto and other laundries industry, 70.0 ppb, and two discharges from an
unidentified industry, 215.1 ppb mean . Of the 1235 stations reporting benzidine in effluents in
EPA's STORET database, 1.1% contained detectable levels of the chemical .
The author analyzed the water of the Sumida River in Tokyo during 1964. Colorimetric
analysis revealed that total aromatic amine content of the water (including benzidine) reached
levels up to 0.562 mg/l.
High levels of benzidine (up to 2.5 mg/l) were found after analysis of purge wells and seepage
water near a waste disposal lagoon receiving DCB-manufacture wastes.