NIOSH Pocket Guide to Chemical Hazards

1,3-Dichloro-5,5-dimethylhydantoin CAS 118-52-5
C5H6Cl2N2O2 RTECS MU0700000
Synonyms & Trade Names
Dactin, DDH, Halane
DOT ID & Guide
NIOSH REL: TWA 0.2 mg/m3 ST 0.4 mg/m3
OSHA PEL†: TWA 0.2 mg/m3
IDLH 5 mg/m3 Conversion
Physical Description
White powder with a chlorine-like odor.
MW: 197.0
BP: ?
MLT: 270°F
Sol: 0.2%
VP: ?
IP: ?

Sp.Gr: 1.5
Fl.P: 346°F
UEL: ?
LEL: ?

Combustible Solid
Incompatibilities & Reactivities
Water, strong acids, easily oxidized materials such as ammonia salts & sulfides
Measurement Methods
None available
Personal Protection & Sanitation
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash
First Aid (See procedures)
Eye: Irrigate immediately
Skin: Soap wash promptly
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA
Up to 2 mg/m3: (APF = 10) Any supplied-air respirator
Up to 5 mg/m3: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece
Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
Escape: (APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern and having a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, mucous membrane, respiratory system
Target Organs Eyes, respiratory system