# 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
Exposure Limits | 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
See also: INTRODUCTION