series: [Analysis of Pesticides in Food and Environmental Samples, edited by Jose L. Tadeo]

Pesticides #

A pesticide is any substance or mixture of substances, natural or synthetic, formulated to control or repel any pest that competes with humans for food, destroys property, and spreads disease. The term pest includes insects, weeds, mammals, and microbes, among others.
There are different classes of pesticides according to their type of use. The main pesticide groups are herbicides, used to kill weeds and other plants growing in places where they are unwanted; insecticides, employed to kill insects and other arthropods; and fungicides, used to kill fungi. Other types of pesticides are acaricides, molluscicides, nematicides, pheromones, plant growth regulators, repellents, and rodenticides. ¹

Pesticides are defined by the United States Federal Insecticide Fungicide Rodenticide Act (FIFRA) as ‘‘any substance or mixture of substances intended for preventing, destroying or repelling any pest,’’ where pests are defined as organisms that may be deleterious to human or the environment, including vertebrates other than human, invertebrates, plants, fungi, and microorganisms. This gives rise to specific terms such as insecticides, acaricides, herbicides, fungicides, nematicides, and rodenticides. ²

Three important molecular properties that determine if the pesticide will or will not be recovered and detected are polarity, volatility, and thermal lability.

Volatility and thermal lability are important because they determine whether the pesticide can be determined by GC or not.

Pesticides are one of the most important tools in the protection of agricultural crops against weeds, pests, and diseases. ³

Mycotoxins #

Mycotoxins – from the Greek μύκης (mykes, mukos) “fungus” and the Latin toxicum “poison” – are a large and growing family of secondary metabolites and hence natural products produced by fungi, in particular by molds.

The most important classes of fungi responsible for these compounds are Alternaria, Aspergillus (multiple forms), Penicillium, and Stachybotrys. The biological activity of mycotoxins ranges from weak and/or sometimes positive effects such as antibacterial activity (e.g. penicillin derivatives derived from Penicillium strains) to strong mutagenic (e.g. aflatoxins, patulin), carcinogenic (e.g. aflatoxins), teratogenic, neurotoxic (e.g. ochratoxins), nephrotoxic (e.g. fumonisins, citrinin), hepatotoxic, and immunotoxic (e.g. ochratoxins, diketopiperazines) activities. ⁴

Molds and fungi can produce carcinogenic mycotoxins, including ochratoxin A and aflatoxins.