Yu SJ. The Toxicology and Biochemistry of Insecticides. London,England: CRC Press,Llc;2008.

Wait, don’t run away! If you are a toxicologist that does not make human health risk assessments from pesticide exposures or addresses, in some form, toxicity testing of economic poisons, you might be inclined to blow past this review. Read on. On the other hand, you may be a pesticide toxicologist, drooling in anticipation of reading this review as you scramble to round up your shekels so you can run out and purchase this book. Not so fast! The moral of the admonishments to both groups is that “things may not be what they appear at first glance.” The book addresses the toxicity of insecticides to the intended targets—insects—not collateral, unintended and unwanted toxicities to humans and other noninsect species such as food-producing animals. Perhaps a more precise title could have been chosen, but at times, one has to play the hand that is dealt.

The author’s intent was to create a textbook for students of entomology, crop protection, plant medicine, and related agricultural disciplines. The author achieved his objective and in so doing, updated the agronomic community with salient information about how insecticides work and exert their affects on insects. However, biology is biology and the molecular choreography that occurs when insecticides exert their affects in insects, can, may, might, perhaps, etc occur in nontargeted mammals. There is the requirement for a thoughtful extrapolation from the targeted insect to the nontargeted animal. Toxicologists are familiar with the extrapolation process from their experience in using surrogate animal testing to make human health-risk assessments. Indeed, certain insect species have been used by biologists to understand various physiological systems in animals. One can appreciate the value of the book by understanding what it contains and what it does not contain.

The textbook consists of 11 chapters with 250 pages of text and 25 pages of index materials. From a toxicologist’s perspective, the first 3 chapters with 24 pages, are introduction material, covering all types of agricultural economic poisons. This introduction covers the need and use patterns of pesticides, formulation of pesticides and the regulatory framework for pesticide registration and use. Chapter 4 entitled “The Classification of Insecticides” makes up 25% of the book and is the transition from pesticides to insecticides. These first 4 chapters (85 pages) have marginal value to the toxicologist, possibly serving as reference material on occasion.

“Chapter 5 Evaluation of Toxicity” describes in 17 pages, the various testing procedures that are used for assessing insecticide activity. Essentially, the variation in testing procedures occurs in the way in which an insecticide is administered to the test insects. The end-point of the tests and the data analysis is the same—lethality. Consequently, insecticide development is a suitable home for the LD50.

Chapters 6 through 10 represent the core of the material that is of interest to the practicing mammalian toxicologist. Collectively, these 5 chapters constitute 50% of the book. “Chapter 6 The Uptake of Insecticides” is the mammalian equivalent of absorption – the “A” in ADME. “Chapter 7 The Mode of Action of Insecticides” is the “D” in ADME but with a large dose (pun intended) of biochemistry, physiology, and pharmacology, for both insects and mammals. “Chapter 8 Principles of pesticide Metabolism” addresses the “M” in ADME. There is no chapter for “E” in ADME and for those with a penchant for symmetry and perfect analogies, Section 5.1 discusses the LD50. In Section 5.1 the author makes a convincing case that the LD50 and the ED50 are one in the same and lethality is efficacy for insecticides. Consequently, the elimination or excretion of an insecticide in insects is moot.

While “E” is a nonissue for toxicity of insecticides to insects, “M” discussed in Chapter 8 is important because it is an opportunity for insects to develop resistance, which is discussed in “Chapter 10 Insecticide Resistance.”

Rounding out the core of the book is “Chapter 9 Species Differences and Other Phenomena Associated with the Metabolism of Xenobiotics.” Chapter 9 along with Chapter 10 comprise the genetic module of insecticide action. Chapter 9 also has a strong tie to “Chapter 8 Principles of Pesticide Metabolism.” The author extends his discussion of the various detoxification enzymes in Chapter 8 to include insect species variability and inducibility of detoxifying enzymes as the basis of insecticide effectiveness.

The final chapter of the book, “Chapter 11 Pesticides in the Environment” should be entitled “Insecticides in the Environment” because the chapter addresses only insecticides and not other pesticides such as nematocides, rodenticides, herbicides, and fungicides. Chapter 11 is not part of the core of the book that would be of interest to the practicing mammalian toxicologist. Yet, the chapter is not a political statement nor does it take an advocacy position. Rather, Chapter 11 documents facts that an informed scientist should know about the environmental consequences of using insecticides.

The author achieved his objective of preparing a text book for agricultural students explaining how insecticides work on the intended target organisms. Will practicing toxicologists use the book as an important reference for practicing toxicology? Probably not. Should toxicologists purchase the book for their personal library? No. Should toxicologists be aware of the text if they have close associations with agricultural schools? Yes.

The book provides interesting and informative reading for toxicologists about intended and desired effects, which are different foci than unintended adverse effects, and the risks associated with those unintended effects. These shifts in foci allow the convergence of lethality and effectiveness. While the perspective is different, biology is biology and after reading the book, the agronomist and the toxicologist might experience a thought convergence and collectively recall the words of the famous poet, philosopher, dramatist, and literary critic, T.S. Eliot from his poem, “Little Gidding” ¹ :

We shall not cease from exploration

And the end of all our exploring

Will be to arrive where we started

And know the place for the first time.