Reviews of Environmental Contamination and Toxicology Vol 203 (eBook)

Foreword 4
Preface 6
Contents 8
Contributors 9
Bioavailability of Xenobiotics in the Soil Environment 12
1 Introduction 13
1.1 What is ''Bioavailability''? 13
1.2 Relation to Biodegradation, Bioaccumulation, Ecotoxicity, and Risk Assessment 14
1.3 Purpose and Scope 15
2 Transport Mechanisms of Molecules Through Membranes 16
2.1 Passive Diffusion 16
2.2 Facilitated Transport 17
2.3 Energy-Dependent (Active) Transport 18
2.4 Phagocytosis (Endocytosis) 18
3 Uptake Mechanisms of Chemicals by Organisms and Their Kinetics 18
3.1 Kinetics of Chemical Transport Through Membranes by Passive Diffusion 18
3.2 Uptake by Microorganisms 19
3.3 Uptake by Plant Roots 20
3.4 Uptake by Soil Fauna 23
3.5 Passive Diffusion: A Common but Variable Mechanism Among Organisms 25
4 Properties of Xenobiotics and Soils, and Their Interactions 26
4.1 Sorption Isotherms 26
4.2 Properties of Xenobiotics That Affect Their Sorption to Soil 28
4.3 Soil Properties That Affect Sorption of Xenobiotics to Soil 28
4.4 Desorption and Dissolution 30
4.5 Effects of Dissolved Organic Matter and Surfactants 31
4.6 Effects of Aging and ''Bound Residue'' 36
4.7 Environmental and Management Factors 38
5 Bioassays to Measure Bioavailability 39
5.1 Microorganisms 40
5.2 Higher Plants 45
5.3 Earthworms and Other Soil Fauna 46
6 Chemical Methods to Measure Bioavailability 52
6.1 Chemical Extraction Methods 52
6.2 Estimations Based on K p or K oc 56
7 Simulation Modeling to Estimate Bioavailability 57
7.1 Degradation Models: Bioavailability to Microorganisms 58
7.2 Uptake Models: Bioavailability to Plants 62
7.3 Uptake Models: Bioavailability to Soil Fauna 68
8 Recommendations for Further Research 71
9 Summary 74
10 Appendix: A Description of Equation Symbols, and the Units They Use 75
References 80
Effects of Pesticides on Freshwater Diatoms 98
1 Introduction 98
2 Effects on Cytology and Cell Ultrastructure 99
2.1 The Cytoskeleton 100
2.2 The Nucleus and DNA 100
2.3 The Siliceous Cell Wall 101
3 Effects on Cell Metabolism 102
3.1 Photosynthesis 102
3.2 Synthesis of Protein, Lipids, and Carbohydrates 103
3.3 Nutrient Absorption 103
4 Effects on Diatom Growth 104
4.1 Algal Biomass 104
4.2 Diatom Cell Density 105
5 Effects on Species Composition 105
5.1 Diatom Species 105
5.2 Algal Community 107
6 Interferences in the Response of Diatoms to Pesticide Exposure 107
7 Summary 108
References 109
The Toxic Effects of Formaldehyde on the Nervous System 115
1 Introduction 115
1.1 Physical and Chemical Features 115
1.2 Sources and Uses 116
1.3 Harmful Effects 117
2 Formaldehyde Neurotoxicity 118
2.1 The Effect on Various Biochemical Parameters 118
2.2 The Effect on Neuronal Morphology 120
2.3 The Effect on Behavior 121
3 Conclusion 122
4 Summary 123
References 124
Dermal Toxicity and Environmental Contamination: Electron Transfer, Reactive Oxygen Species, Oxidative Stress, Cell Signaling, and Protection by Antioxidants 129
1 Introduction 130
2 Mechanisms of ET and ROS Formation 131
3 Atmospheric Contaminants and Toxicants 132
3.1 Radiation 133
3.2 Metals and Metal Compounds 133
3.3 Phenols 134
3.4 Quinones 134
3.5 Polycyclic Aromatic Hydrocarbons (PAHs) 135
3.6 Mustard Gas 136
3.7 Acrylamide 136
3.8 Dioxin 136
3.9 Naphthalenes 137
3.10 2,4,6-Trinitro-1-Chlorobenzene (TNCB) 137
3.11 Nitric Oxide (NO) 137
3.12 Carvoxime 137
3.13 Trichloroethylene (TCE) and Perchloroethylene (PERC) 138
3.14 Methyl Bromide 138
3.15 Reactive Carbonyl Species (RCS) 138
3.16 Geraniol 138
3.17 Linalool 139
3.18 Sunscreens 139
3.19 Fullerenes 139
4 Therapeutic Drugs 139
4.1 Doxorubicin 139
4.2 Methyl Salicylate 140
4.3 Methotrexate 140
5 Occupational Sources and Other Dermal Toxins 140
6 Cell Signaling 141
7 Antioxidants 141
8 Summary 142
References 142
Heavy Metals Alter the Potency of Medicinal Plants 149
1 Introduction 149
2 Effects on Growth and Metabolic Status 150
3 Effects on Secondary Metabolite Production 151
4 Heavy Metals: Actions and Mechanisms 152
5 Summary 155
References 156
Index 160