Page 401 - Environment: The Science Behind the Stories

easily quantified, and of a discrete and stable amount, Philosophical and Policy
whereas health risks are hard-to-measure probabilities,
often involving a small percentage of people likely to suf- Approaches
fer greatly and a large majority likely to experience little
effect. When a government agency bans a pesticide, it may Because we cannot know a substance’s toxicity until we meas-
mean considerable economic loss for the manufacturer and ure and test it, and because there are so many untested chemi-
potential economic loss for the farmer, whereas the benefits cals and combinations, science will never eliminate the many
accrue less predictably over the long term to some percent- uncertainties that accompany risk assessment. In such a world
age of factory workers, farmers, and the general public. of uncertainty, there are two basic philosophical approaches
Because of the lack of equivalence in the way costs and to categorizing substances as safe or dangerous (Figure 14.19).
benefits are measured, risk management frequently tends to
stir up debate.
In the case of bisphenol A, eliminating plastic linings Two approaches exist for
in our food and drink cans could do more harm than good, determining safety
because the linings help prevent metal corrosion and the con-
tamination of food by pathogens. Alternative substances exist One approach is to assume that substances are harmless until
for most of BPA’s uses, but replacing BPA with alternatives shown to be harmful. We might nickname this the “innocent-
will entail economic costs to industry, and these costs are until-proven-guilty” approach. Because thoroughly testing
passed on to consumers in the prices of products. Such com- every existing substance (and combination of substances) for
plex considerations can make risk management decisions dif- its effects is a hopelessly long, complicated, and expensive
ficult even if the science of risk assessment is fairly clear. This pursuit, the innocent-until-proven-guilty approach has the
difficulty may help account for the hesitancy of U.S. regula- virtue of facilitating technological innovation and economic
tory agencies to issue restrictions on BPA so far. As of 2013, activity. However, it has the disadvantage of putting into wide
both the FDA and the EPA were continuing to review options use some substances that may later turn out to be dangerous,
for managing risk from BPA. such as happened with the pesticide DDT.

“Innocent until proven Precautionary
Sequence of events guilty” approach principle approach

Industrial research and
development

Pre-market testing by
industry, government,
and academic
scientists Limited testing; most Rigorous testing; only the safest
products brought to market products brought to market

Figure 14.19 Two main
Consumer use of approaches can be taken to
products introduce new substances to
Some products harm Minimal impact on the market. In one approach,
human health human health
substances are “innocent until
proven guilty”; they are brought to
Post-market testing by market relatively quickly after limited
industry, government, testing. Products reach consum-
and academic scientists ers more quickly, but some fraction
Rigorous testing demanded Limited testing required
of them (blue bottle in diagram)
may cause harm to some fraction
of people. The other approach is to
Regulations and bans adopt the precautionary principle,
of unsafe products bringing substances to market cau-
tiously, only after extensive testing.
Unsafe products recalled
Products that reach the market
should be safe, but many perfectly
Consumer use of safe safe products (purple bottle in
products diagram) will be delayed in reaching
400 consumers.

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