Food quality - Organic Agriculture: A Global Perspective - page 313

Consumers find this risk unacceptable, since the presence of organic products show that these
production aids are unnecessary (Torjusen et al 2004), so they are seen as indicators that the
conventional producers are more concerned with profits than with food quality. The authori-
ties consistently find detectable synthetic pesticide residues in a substantial proportion of
samples analysed from conventional farms. Some samples contain more than one residue. Few
conventional samples exceed tolerances and most residues are well below tolerance levels.
Residues are commonly not present on organic produce and, where present, residue levels are
significantly lower in organic products than in corresponding conventional ones (Weber et al .
2001, Baker et al . 2002). However, all pesticides, food additives and so forth used by conven-
tional food producers are thoroughly tested to determine whether they pose any health risk. If
such indications are found, they are prohibited, so the occurrence of residues in present day
conventional food is not considered a significant health risk (Diehl 2002). However, history
has taught us that chemicals considered harmless today might be labelled 'poisonous' in the
future, and little is known about how combinations of low levels of pesticides affect human
health. For example, a study on the effect of the growth regulator chlorocholine chloride indi-
cated significant reductions in semen quality among rats fed wheat grown with this substance,
compared with untreated wheat (Torner et al . 1999). This study is being followed up with a
study on pigs in the QLIF project (M.T. Sørensen, pers. comm., 2005).
In addition, preservative substances and food colourings used in conventional food have
been implicated as health risks (Dengate and Ruben 2002, Bateman et al . 2004), but here also,
the effects are difficult to measure, and there is no consensus in the scientific community on
safe levels. The recent increased acceptance of the concept of hormesis (i.e. that effects at low
concentrations can be opposite, normally beneficial, than the normally toxic effects at high
doses) is likely to lead to a complete re-evaluation of the existing framework for safety evalua-
tion (Calabrese 2004), but the outcome of hormesis is impossible to predict. Some authors
argue that hormesis means that all synthetic pesticides are generally much safer than previ-
ously thought (Trewavas 2004). On the contrary, others caution that when the possibility of
hormesis is ignored, poorly devised dose-response curves could lead to either underestimating
or overestimating the risk at the actual exposure levels (Calabrese 2004).
So although there is no doubt that the presence of pesticide residues and food additives is
significantly different between organic and conventional foods, there are no generally accepted
volumes of data showing that the difference in composition makes a difference to the health of
consumers. However, a more precise estimate of the magnitude of risk from pesticide residues
or food additives may not make much difference to the view of many consumers, who do not
want to take any risk, no matter how small, when not associated with clear benefits for them-
selves (Torjusen et al . 2004).
There may be some effect on consumer views if clear health benefits are proven. However,
ensuring a defined level of residues in food will be even more difficult than keeping the levels
below a certain limit. As described below (see Indirect measurements of effects on health) , if pes-
ticide residues are good for health, organic foods will be better still because of their high
content of natural pesticides.
Synthetic toxins unintentionally occurring in food (pollutants)
Although most pollutants would be considered equally likely to occur in organic and conven-
tional foods, Harnly et al . (2000) found the level of dioxins was seven times higher in eggs
from free-ranging private f flocks with unlimited access to soil in a strongly polluted area in the
USA than f flocks kept in a confined soil area in the same region, and that the high levels con-
tained in many eggs constituted a definitive human health danger. Since organic egg produc-
tion must include access to outdoor runs, this finding caused great concern for organic egg
producers. A recent Belgian study, while confirming high dioxin levels in eggs from small