TIME-WEIGHTED AVERAGE (TLV-TWA): 50 ppm - Carcinogenicity Designation A3

TLV BASIS - CRITICAL EFFECT(S) : CNS (central nervous system); Anoxia (oxygen deficiency)

BIOLOGICAL EXPOSURE INDICES (BEIs): The ACGIH has adopted a BEI for this chemical. BEIs provide an indication of worker exposure by measuring the chemical or its breakdown products in the body or by measuring biochemical changes resulting from exposure to the chemical. Consult the BEI documentation for further information.

CARCINOGENICITY DESIGNATION A3 - Animal Carcinogen: Substance is carcinogenic in laboratory animals under conditions that are not considered relevant to worker exposure. Available human studies and evidence suggest that the substance is not likely to cause cancer in humans except under unusual or unlikely routes or levels of exposure. Worker exposure to an A3 carcinogen should be controlled to levels as low as reasonably achievable below the TLV.

NOTE: This is a substance for which the TLV is higher than the OSHA Permissible Exposure Limit (PEL) and/or the NIOSH Recommended Exposure Limit (REL).

NOTE: This substance has been identified by other sources as a suspect or confirmed human carcinogen.

NOTE: In many Canadian jurisdictions, exposure limits are similar to the ACGIH TLVs. Since the manner in which exposure limits are established, interpreted and implemented can vary, obtain detailed information from the appropriate government agency in each jurisdiction.

Methylene chloride is essentially non-flammable under most conditions of use. However, it becomes flammable at 102 deg C. During a fire, irritating/toxic hydrogen chloride and phosgene gases may be generated.

Normally stable. On prolonged contact with water, slowly decomposes forming hydrochloric acid.

Temperatures above 100 deg C

A wide range of values are reported (1.2 to 440 ppm), but detection occurs around 150 ppm and recognition around 230 ppm.

Poor/unreliable - odour threshold is above the TLV, olfactory fatigue may occur (smell may not be noticed after short exposures).

This material is VERY TOXIC (SUSPECTED CANCER HAZARD). Before handling, it is extremely important that engineering controls are operating and that protective equipment requirements and personal hygiene measures are being followed.

Only authorized personnel should have access to this material. They should be properly trained regarding its hazards and its safe use. Maintenance and emergency personnel should be advised of potential hazards.

If methylene chloride is released, immediately put on a suitable respirator and leave the area until the severity of the release is determined. Attach appropriate warning signs to storage area and to containment devices. Closed handling systems for processes involving this material are recommended. Immediately report leaks, spills or ventilation failures. Be aware of typical signs and symptoms of poisoning and first aid procedures. Any signs of illness should be reported immediately to supervisory personnel. Do not use with incompatible materials such as strong oxidizers, caustics, aluminum powder, amines, azide forms of quaternary ion exchange resins, dimethyl sulfoxide and perchloric acid, reactive materials (e.g. lithium, sodium, potassium), nitric acid, N-methyl-nitrosourea and potassium tert-butoxide. All these may lead to exothermic reaction and/or explosion. Do not use near welding operations, flames or hot surfaces because of the risk of formation of toxic hydrogen chloride or phosgene. Do not perform any welding, cutting, soldering, drilling or other hot work on an empty vessel, container or piping until all liquid and vapours have been cleared.

Avoid generating mists. Prevent the release of vapours/mists into workplace air. Use in smallest possible amounts in appropriate, labelled containment devices (fume hood, glove box, biological safety cabinets, isolation cabinets). Containment devices should be made of smooth, unbreakable, compatible material. Maintain containment devices at appropriate air flow and negative pressure. Check regularly. Use in clearly labelled, designated areas. Control access to designated area. Inspect containers for leaks before handling. Cautiously, transfer material from storage to work area in a sealed, unbreakable container (primary container) and place primary container inside sealed, unbreakable outer container (secondary container). Place sufficient packing between primary and secondary containers to minimize disturbing the material. Prevent damage to containers. Label containers. Open containers carefully on a stable surface. Keep containers closed when not in use. Assume that empty containers contain residues which are hazardous. Keep a record of acquisition date, opening date and quantity used. Cover work surfaces with compatible, chemical resistant and/or disposable material for easier containment and clean-up of spills.

Never return contaminated material to its original container. Good housekeeping is very important. Keeping work areas clean is essential. Use work surfaces that can be easily decontaminated. Do not contaminate air or water systems with this material when used in conjunction with vacuum devices. Protect vacuum lines. Use separate vacuum pump inside or vented into appropriate chemical fume hood. If possible, air flow should move from area of lower contamination potential to area of higher contamination potential.

Follow handling precautions on Material Safety Data Sheet. Have suitable emergency equipment for fires, spills and leaks readily available. Maintain handling equipment. Comply with applicable regulations.

Provide properly designed and maintained mechanical ventilation systems, including local exhaust and dilution (general) ventilation to reduce levels of the airborne contaminant, as indicated by a hazard assessment. Administrative controls and personal protective equipment may also be required. Local exhaust ventilation and/or process enclosure is usually necessary to control airborne mist and vapour. Supply sufficient replacement air to make up for air removed by exhaust systems. Treatment of exhaust emissions to prevent environmental contamination may be required.