The article below provides an excellent (and fascinating) discussion of
organic food safety issues.

Organic Food: Buying More Safety or Just Peace of Mind? A Critical Review
of the Literature.
Authors: Magkos, Faidon, Arvaniti, Fotini, Zampelas, Antonis

Critical Reviews in Food Science & Nutrition
Jan 2006, Vol. 46 Issue 1, p23-56.

Abstract:
Consumer concern over the quality and safety of conventional food has
intensified in recent years, and primarily drives the increasing demand for
organically grown food, which is perceived as healthier and safer. Relevant
scientific evidence, however, is scarce, while anecdotal reports abound.
Although there is an urgent need for information related to health benefits
and/or hazards of food products of both origins, generalized conclusions
remain tentative in the absence of adequate comparative data. Organic
fruits and vegetables can be expected to contain fewer agrochemical
residues than conventionally grown alternatives; yet, the significance of
this difference is questionable, inasmuch as actual levels of contamination
in both types of food are generally well below acceptable limits. Also,
some leafy, root, and tuber organic vegetables appear to have lower nitrate
content compared with conventional ones, but whether or not dietary nitrate
indeed constitutes a threat to human health is a
matter of debate. On the other hand, no differences can be identified for
environmental contaminants (e.g. cadmium and other heavy metals), which are
likely to be present in food from both origins. With respect to other food
hazards, such as endogenous plant toxins, biological pesticides and
pathogenic microorganisms, available evidence is extremely limited
preventing generalized statements. Also, results for mycotoxin
contamination in cereal crops are variable and inconclusive; hence, no
clear picture emerges. It is difficult, therefore, to weigh the risks, but
what should be made clear is that 'organic' does not automatically equal
'safe.' Additional studies in this area of research are warranted. At our
present state of knowledge, other factors rather than safety aspects seem
to speak in favor of organic food. [ABSTRACT FROM AUTHOR]

Tom Billings