Chemical Risk Assessment in the Workplace: TLV, VLA, and Safety

**Chemical Risk Assessment in the Workplace**

Hygienic Evaluation

Methodology for detection and quantification of industrial pollutants and assessment of the risk for workers exposed to them.

• Environmental: Compare the actual exposure levels to theoretical allowable values.
• Biological: Determine the amount of pollutant or its metabolites in exposed workers.

Assessment Criteria

• Reference values
  • United States (ACGIH)
    • TLV (Threshold Limit Value)
    • BEI (Biological Exposure Indices)
  • Spain (INSHT)
    • VLA (Environmental Limit Values)
    • VLB (Biological Limit Values)
• Maximum values allowed
  • USA (OSHA)
    • PEL (Permissible Exposure Limit)
  • Spain (Current Legislation)
    • Regulation of Troublesome, Unhealthy, Harmful, and Dangerous Activities
    • Specific regulations (benzene, asbestos, lead, noise, vinyl chloride, radiation)

TLV - Threshold Limit Value

Values are proposed by the ACGIH for use by American industrial hygienists as guidelines for the control of hygiene risks.

TLV Definitions

• Average: 2ppm
• Ceiling
• Short periods

TLV-TWA: Concentration for a conventional 8-hour workday and 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.

TLV-C: Concentration that should not be exceeded during any part of the working exposure.

TLV-STEL: 15-minute time-weighted average exposure that should not be exceeded at any time during a workday.

VLA - Environmental Limit Values

Reference values for concentrations of pollutants proposed by the INSHT, equivalent to the TLV.

Types of VLA

• VLA-ED: Environmental value of daily exposure limit
• VLA-EC: Value of short-term exposure
• LD: Limits of deviation

Risk Assessment

% EMP = (Average Concentration / Limit Values) * (Exposure Time / 8) * 100

Chemical Risk

• There are more than 8 million chemicals.
• 100,000 are in common use (pharmaceuticals, pesticides, etc.).
• 1,000 new products enter the market every year.
• Between 300 and 400 million tons of hazardous waste are generated per year.