Two names for the same substance

Tetrachloroethylene and perchloroethylene describe the same substance, also abbreviated PERC. It must not be confused with trichloroethylene or dichloromethane. Correct product identification enables selection of toxicological information and the measurement method. The inventory must include equipment, containers, waste and materials that may retain solvent after the main operation.

Relevant effects

NIOSH describes irritation, dizziness, drowsiness, impaired coordination and other effects. ILO/WHO notes effects on the central nervous system, liver and kidneys and identifies it as probably carcinogenic to humans. Prolonged exposure needs attention even without acute poisoning. Risk assessment uses actual concentration and duration without turning hazard classification into an individual prediction.

Closed systems need verification

Closed equipment can reduce emissions during operation, but loading, unloading, cleaning and maintenance create different scenarios. Seals, pipework, waste and every opening point must be reviewed. Nearby people can be exposed without handling the product. Measurements with the machine closed do not automatically represent interventions that change containment.

Substitution and maintenance

Process alternatives and solvent substitution are analysed by comparing the full risks. If use continues, containment and extraction must be verified and maintained. Protective materials are chosen for compatibility and permeation, not similarity to those used for another solvent. Waste containers are part of emission control.

Heat and incident response

Process safety must consider decomposition conditions and incompatible materials listed in the current information sheet. Contaminated equipment is not taken into operations involving heat without first reviewing the procedure. A leak triggers access control and the planned response. A dizzy person must not stay to carry out checks and locate the problem.

Occupational hygiene review example

In a hypothetical example, routine measurements are favourable, but an emission is detected when waste is removed from the equipment. That stage is assessed separately, and extraction and the removal system are changed. Subsequent verification reproduces representative intervention conditions. The report distinguishes improvement in the normal cycle from improvement in maintenance, so unmeasured exposures are not treated as resolved.