# NIOSH Pocket Guide to Chemical Hazards
Dimethyl sulfate | CAS 77-78-1
(CH3)2SO4 | RTECS WS8225000
Synonyms & Trade Names Dimethyl ester of sulfuric acid, Dimethylsulfate, Methyl sulfate | DOT ID & Guide 1595 156
Exposure Limits | NIOSH REL: Ca TWA 0.1 ppm (0.5 mg/m3) [skin] See Appendix A
OSHA PEL†: TWA 1 ppm (5 mg/m3) [skin]
IDLH Ca [7 ppm] | Conversion 1 ppm = 5.16 mg/m3
Physical Description Colorless, oily liquid with a faint, onion-like odor.
MW: 126.1 | BP: 370°F (Decomposes) | FRZ: -25°F | Sol(64°F): 3%
VP: 0.1 mmHg | IP: ? |  | Sp.Gr: 1.33
Fl.P: 182°F | UEL: ? | LEL: ? |
Class IIIA Combustible Liquid: Fl.P. at or above 140°F and below 200°F.
Incompatibilities & Reactivities Strong oxidizers, ammonia solutions [Note: Decomposes in water to sulfuric acid; corrosive to metals.]
Measurement Methods NIOSH 2524
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: No recommendation Provide: Eyewash, Quick drench | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration: (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/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, nose; headache; dizziness; conjunctivitis; photophobia (abnormal visual intolerance to light); periorbital (situated around the eye) edema; dysphonia, aphonia, dysphagia, productive cough; chest pain; dyspnea (breathing difficulty), cyanosis; vomiting, diarrhea; dysuria; analgesia; fever; proteinuria, hematuria (blood in the urine); eye, skin burns; delirium; [potential occupational carcinogen]
Target Organs Eyes, skin, respiratory system, liver, kidneys, central nervous system Cancer Site [in animals: nasal & lung cancer]
See also: INTRODUCTION