Table 3

Grading system for in vitro studies

StrongStudies that fulfill 5–6 out of 6 criteria.
  1. Appropriate study design.

  2. Use of human cell lines.

  3. Similar dosing to human applications.

  4. Similar exposure time to human applications.

  5. Significant dose response findings.

  6. Consistency of effect.

AverageStudies that fulfill 3–4 out of 6 criteria.
WeakStudies that fulfill 0–2 out of 6 criteria.