In the early to mid-1990s, nurse practitioners for the California Childhood Lead Poisoning
Prevention Program identified Mexican candy products that appeared to be associated with
excessive childhood lead exposures. At that time, the primary issue appeared to be the presence
of lead in candy wrappers [1]. Since that time there have been numerous analytically significant
results where the lead content is apparently unrelated to the wrapper. In April 2004, a series of
articles in the Organic County Register in California reported high levels of lead in imported
Mexican candy products and potentially toxic levels of lead in a number of chili-based products
[2-7]. Earlier FDA analyses of these products were plagued by an inability to obtain
reproducible results from separate portions of a particular sample. Although these results were
in part due to the extreme variability of lead in the products, this variability “restrained” potential
regulatory actions. Clearly, development of appropriate methods for this application that can
achieve both good precision and accuracy is a priority for FDA.
Definitive information on the specific source(s) of lead contamination in these products is not
available at this time. The major ingredient in lollipops, sucrose, does not appear to be
contaminated. Past and present findings suggest that the origin of the lead contamination is
largely associated with at least two common ingredients in many Mexican candies (i.e., chili and
alt). Lead contamination has been found in other types of candies including tamarind-based and
tejocote-based candy in lead-glazed ceramic jars, and some tamarind, tejocote, and chocolatebased
candy with and without chili. Several Mexican candy manufacturers have concluded that
the chili additives were being contaminated during the open-air drying process. Other potential
sources of this contamination might be the grinding process involved in preparation of chili
powder, or the possible use of lead arsenate as a pesticide agent.
At the present time, a variety of Mexican candy and salt-based products appear to contain
analytically significant but highly variable amounts of lead. We suspect that the lead
contamination is caused by small particles that have relatively high levels of lead. This
variability is not only between lots of the same product but within individual items from the same
lot. In general, these types of products are very difficult to grind or blend in a fashion that will
yield a suitably homogenous composite sample. Although the use of grinding large quantities of
these products was attempted as a means for sample homogenization, this was unsuccessful in
producing a homogeneous sample from which a smaller subsample (0.5-1.0 g) could be removed
for subsequent analysis to yield acceptable levels of precision.
The scope of this work was the development of a suitable sample workup procedure for
determination of lead in a variety of hard and soft candy, powdered candy products, and fruit
candy products, especially those containing chili and salt as major ingredients. The primary goal
of this procedure was to produce a homogeneous composite and therefore an analytical portion
that can be sampled repetitively with the expectation of accurate and precise analytical results.