Regulatory science on dioxin reversed course twice over two decades.

Evidence

The chemical dioxin, which is a shorthand reference to many related chemical compounds, provides a good example. During the early 1980s, concerns about dioxin prompted widespread, costly environmental cleanups and the imposition of stringent nationwide regulation of emissions into air and water. Entire towns were evacuated and literally shut down. A decade later, however, in the early 1990s, both government and industry officials raised questions, based on the results of further scientific research, concerning the validity of those earlier concerns. Many condemned the dioxin scare of the 1980s as a classic overreaction to unjustified public fears and, accordingly, as a prime example of what was wrong with environmental law. With the passage of yet another decade, however, we seem to be coming full circle. The latest scientific evidence suggests yet again that dioxin does in fact present the kinds of serious hazards to human health that were feared in the 1980s. — Richard J. Lazarus, The Making of Environmental Law, 120

Categorization

• CANDY: The dioxin scare-condemn-vindication swing is a striking, self-contained regulatory-history anecdote — whole towns evacuated, then declared a false panic, then confirmed again.
• SHARE: Send to anyone who teaches risk regulation or science-policy swings — a textbook oscillation of precautionary panic and backlash.
• XREF: connects to: Bright-line environmental rules would over-regulate harmless acts while missing real harms. — Richard J. Lazarus, The Making of Environmental Law, 105