The determination of TLVs is a complex process that involves a comprehensive review of scientific literature, including toxicological, epidemiological, and medical data. ACGIH relies on expert committees to evaluate this information and recommend exposure limits. These committees consider various factors such as the toxicity of the substance, the duration and frequency of exposure, and the potential for cumulative effects. Their recommendations are subject to rigorous scrutiny and are periodically updated to reflect new scientific findings.