Why the Dose Matters: Assessing the Health Risk of Exposure to Toxicants

253 Pages·2023·7.674 MB·English

by  Urs A. Boelsterli

Why the Dose Matters
Each day we are exposed to a myriad of natural and human-made chemicals
in our food, drinking water, air, soil, at home or at the workplace—pesticide
residues, food additives, drugs, household products—but how can we gauge
the human health risk posed by these chemicals? Should we believe the som-
ber headlines that depict a serious threat to humans and the environment, or
should we follow the reassuring voices of others who claim that the angst is
totally unfounded?
Why the Dose Matters: Assessing the Health Risk of Exposure to Toxicants uses a
rational, science-based approach to explain in plain language that a quantita-
tive view is key for understanding and predicting potentially toxic effects of
chemicals.
Key Features:
• Explains the basics of toxicology in easily understandable terms.
• Includes numerous examples.
• Clears up common misconceptions and dispels myths.
• Provides take-home messages for each chapter.
This book is aimed at interested laypeople. It uses numerous examples to illus-
trate the basic concepts and ensure that the reader will get a better understand-
ing of why not only the hazard but also the overall exposure will determine
whether some chemicals pose a serious risk while others are of little or negli-
gible concern.

Why the Dose Matters
Assessing the Health Risk
of Exposure to Toxicants
Urs A. Boelsterli
Designed cover image: Shutterstock | Danusya.
First edition published 2023
by CRC Press
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ISBN: 978-1-032-38765-9 (hbk)
ISBN: 978-1-032-38764-2 (pbk)
ISBN: 978-1-003-34666-1 (ebk)
DOI: 10.1201/9781003346661
Typeset in Caslon
by KnowledgeWorks Global Ltd.
To the late Gerhard Zbinden, who taught me
the difference between hazard and risk.
To Carmen, who taught me that life is full of hazards and risks,
but that managing the risk is better than worrying about it.
Disclaimer
It is important to note that the readers should not base any personal
decision about dosage of chemicals including pharmaceuticals,
choice of consumer products, handling of household chemicals, or
exposing themselves to foreign chemicals solely on the numbers
given in this book; instead, the latest original sources should be
consulted, for two major reasons. First, as science advances and
new knowledge is being gained, dosage or exposure limits can
change, and second, even though the author has put maximum
effort in providing accuracy, errors are not inevitable.
Contents
List of figures and tabLes xi
Preface xiii
about the author xv
chaPter 1 introduction 1
Part I the concePts: hazard and exPosure
chaPter 2 What does “toxic” Mean? 7
Pegging a Chemical a Priori as Bad? 7
Of Industrial Toxicants, Plant Toxins, Magic Poisons,
and Snake Venoms 8
Potency 10
Is It Safe? On Hazard and Risk 12
chaPter 3 ParaceLsus reLoaded: the dose concePt 15
From Master of Alchemy to Founder of Toxicology 15
A Novel Approach 17
The Dose Makes the Poison 17
The Dose-Response 18
The Dose Does Not Always Reach Its Target 19
chaPter 4 exPosure: the Key deterMinant in risK
assessMent 23
What Does “Exposure” Mean? 23
Different Ports of Entry 23
Checkpoint Liver 24
vii
viii Contents
How Much, How Often, for How Long? 25
Exposure Determines the Risk 27
A Ubiquitous Metal 28
chaPter 5 naturaL and synthetic cheMicaLs 33
Why That Chemophobia? 33
Natural Versus Synthetic 34
Natural Medicines 35
Of Natural and Organic Pesticides 37
High-Hazard Natural Toxins 39
chaPter 6 What our body does to a cheMicaL 43
Toxicokinetics 43
Cellular Transport Systems for Chemicals 44
Paraquat—A Hazardous Pesticide That Hijacks
a Carrier in the Lung 46
The Liver as the Major Metabolic Organ 47
Gut Bacteria—More Than Just Quiet Coresidents 49
The Kidney as the Major Excretory Organ 51
Hard-to-Get-Rid-of Chemicals 52
chaPter 7 What a cheMicaL does to our body 55
Toxicodynamics 55
Targeting Nerve Cell Function 56
Disrupting the Endocrine System 59
Cell Death—By Accident or Suicide 61
Cancer 62
chaPter 8 defense shieLds 69
Standing Troops, Reserves, and Help from Outside 69
Trapping Chemicals Before They Hit 70
Oxidant Stress, Radicals, and Antioxidants 71
Stress Is Not Always Bad 73
Refusing Unwanted Chemicals Admittance to Cells 75
Antidotes 76
chaPter 9 correLation and causaLity 79
Does Drinking from a Plastic Bottle Cause
Cardiovascular Disease? 79
Is a Correlation Enough to Make a Strong Case? 80
Do Storks Deliver Babies? 81
Plasticizers and Sex Hormones 82
The Search for Causality 84
Can Phthalates Cause Cells to Store Fat? 85
Part II the cheMicaLs
chaPter 10 Pesticides: KiLLers With a License 91
Insidious Threat or Benefit for Humankind? 91
Pesticide Basics 92
Glyphosate: The Commotion 94
Contents ix
Glyphosate: The Facts 95
Glyphosate: The Cancer Controversy 97
Does Glyphosate End Up on Our Food? 99
chaPter 11 toxic food 101
Ingredients, Additives, and Contaminants 101
Toxic Fries? 104
Just My Cup of Tea 107
Invisible and Unavoidable: A Mold Toxin 108
Trans Fat 110
chaPter 12 dietary suPPLeMents: the More
the better? 113
Boosting Health with Vitamin Supplements? 113
Green Tea, Red Wine, and Dark Chocolate 114
Herbal Supplements 115
chaPter 13 significant cheMicaL risKs: Persistent
and WidesPread 119
Chemicals That Don’t Make the Headlines (Anymore) 119
Arsenic 120
Mercury 121
Cadmium 122
Lead 124
Benzene 124
Wood Smoke and Air Pollution 125
Dioxins 126
Hazardous Pesticides Revisited 128
chaPter 14 drugs 131
Adverse Drug Reactions 131
The Opioid Crisis 134
People Are Different—Individual Susceptibility 136
Part III the risK
chaPter 15 safety assessMent 145
Can We Predict and Prevent a Toxic Response? 145
Drug Development 146
Translation from Mice to Humans? 148
Non-Clinical Studies 149
Clinical Trials 152
First Exposure 153
Testing of Agrochemicals 155
Computer Simulations, Omics, and Organs-on-a-Chip 155
chaPter 16 accePtabLe LiMits, toLerance, and red Lines 159
Crossing the Line 159
How Much Is Considered Safe? 159
Detection Limits for Chemicals 162