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Adverse Effects and Perchlorate

This symposium discusses the adverse effects of perchlorate, focusing on its impact on thyroid function, including the relationship between subnormal circulating T3 and TSH levels and developmental delays. The presentations explore iodide uptake inhibition, increased perchlorate excretion, and definitional ambiguity surrounding adverse effects. Various perspectives on adverse effects, including definitions from TERA and the EPA, emphasize the complexities of determining what constitutes an adverse effect. This event contributes valuable insights into regulatory and health implications for communities affected by perchlorate exposure.

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Adverse Effects and Perchlorate

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  1. Adverse Effects and Perchlorate

  2. UNMC SoS Symposium

  3. UNMC SoS Symposium Subnormal circulating T3 Adverse Developmental delays Hypothyroxinema Subnormal circulating TSH Pre-adaptive or Adaptive Iodide uptake inhibition Increased perchlorate excretion

  4. Alternative Definitions of Adversity

  5. Definitional Ambiguity 1 • TERA (‘adverse effect or precursor’) • “first adverse effect, or its known precursor, that occurs as dose rate or exposure level increases” (2002 RfD) • “known and immediate precursor” [citing Barnes and Dourson 1988, p. 473] (2005 EHP letter) • p. 473 is not revealing • ‘precursor’ appears out of context; ‘immediate’ does not appear’ • ‘there may be sound professional differences of opinion in judging whether or not a particular response is adverse’ (p. 480)

  6. Definitional Ambiguity 2 • EPA • ‘Adverse Effect’: ‘A biochemical change, functional impairment, or pathologic lesion that affects the performance of the whole organism or reduces an organism's ability to respond to an additional environmental challenge’ (EPA 2002, p. G-1) • ‘Key Event’: ‘an empirically observable precursor step that is a necessary element of the mode of action or is a marker for such an element’ (2002 ClO4 RA, p. 7-4).

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