ABSTRACT
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 Invertebrate Immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366
The Invertebrate Phyla. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366 Origins of Adaptive Immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
Overview of Invertebrate Immune Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 Evidence for Immunotoxicity in Invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Immunotoxic Chemicals and Their Effects . . . . . . . . . . . . . . . . . . . . . . . . . . 371 Mechanisms of Immunotoxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Immunotoxicity and Its Environmental Impact . . . . . . . . . . . . . . . . . . . . . . . 375
Biomarkers and Emerging Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
It has been hypothesized that many compounds released into the environment as a consequence of human activity may be capable of altering immune function in exposed human and wildlife populations, leading to permanent alterations in the structure and regulation of the immune system and to increases in disease incidence. This hypothesis is supported by a growing body of evidence from laboratory studies in which it has been shown that individual chemicals, including aromatic hydrocarbons, heavy metals, organotins, oxidant air pollutants, organophosphates, organohalogens, solvents, and particulates, may adversely affect different components of the immune system.1,2 In humans, a number of studies have examined links between accidental or environmental exposure to immunotoxic contaminants and apparent increases in disease incidence, and similar links have been suggested for certain wildlife populations. Recent attention has focused on marine mammals inhabiting the heavily polluted coastal waters of NorthWestern Europe.3 An outbreak of phocid distemper virus-1 that occurred in the late 1980s in Harbor seals (Phoca vitulina) was instrumental in suggesting human activity as a factor in the dynamics of the disease, as high levels of organochlorine compounds were found in the tissues of seals that had died. Subsequent studies have confi rmed and extended these fi ndings, providing evidence for potential mechanisms of toxicity4
(chapter 24 of this volume) and highlighting the extremely high body burdens of persistent organic pollutants that can accumulate in meat eating species such as Orcinus orca, the Pacifi c killer whale.
