Vulnerability as a function of individual and group resources in cumulative risk assessment.

BACKGROUND: The field of risk assessment has focused on protecting the health of individual people or populations of wildlife from single risks, mostly from chemical exposure. The U.S. Environmental Protection Agency recently began to address multiple risks to communities in the "Framework for Cumulative Risk Assessment" [EPA/630/P02/001F. Washington DC:Risk Assessment Forum, U.S. Environmental Protection Agency (2003)]. Simultaneously, several reports concluded that some individuals and groups are more vulnerable to environmental risks than the general population. However, vulnerability has received little specific attention in the risk assessment literature. OBJECTIVE: Our objective is to examine the issue of vulnerability in cumulative risk assessment and present a conceptual framework rather than a comprehensive review of the literature. In this article we consider similarities between ecologic and human communities and the factors that make communities vulnerable to environmental risks. DISCUSSION: The literature provides substantial evidence on single environmental factors and simple conditions that increase vulnerability or reduce resilience for humans and ecologic systems. This observation is especially true for individual people and populations of wildlife. Little research directly addresses the topic of vulnerability in cumulative risk situations, especially at the community level. The community level of organization has not been adequately considered as an end point in either human or ecologic risk assessment. Furthermore, current information on human risk does not completely explain the level of response in cumulative risk conditions. Ecologic risk situations are similarly more complex and unpredictable for cases of cumulative risk. CONCLUSIONS: Psychosocial conditions and responses are the principal missing element for humans. We propose a model for including psychologic and social factors as an integral component of cumulative risk assessment.

Use and role of invertebrate models in endocrine disruptor research and testing.

Historically, invertebrates have been excellent models for studying endocrine systems and for testing toxic chemicals. Some invertebrate endocrine systems are well suited for testing chemicals and environmental media because of the ease of using certain species, their sensitivity to toxic chemicals, and the broad choice of models from which to choose. Such assays will be useful in identifying endocrine disruptors to protect invertebrate populations and as screening systems for vertebrates. Hormone systems are found in all animal phyla, although the most simple animals may have only rudimentary endocrine systems. Invertebrate endocrine systems use a variety of types of hormones, including steroids, peptides, simple amides, and terpenes. The most well-studied hormone systems are the molting and juvenile hormones in insects, the molting hormones in crustaceans, and several of the neurohormones in molluscs and arthropods. These groups offer several options for assays that may be useful for predicting endocrine disruption in invertebrates. A few invertebrate phyla offer predictive capabilities for understanding vertebrate endocrine-disrupting chemicals. The echinoderms, and to a lesser extent molluscs, have closer evolutionary relationships with the vertebrates than the arthropods and these phyla. The recently identified estrogen receptor structure within the genome of the marine gastropod, Aplysia, indicates that the estrogens, and probably the basic steroid receptor, are quite old evolutionarily. This review of the recent literature confirms the effects of some endocrine-disrupting chemicals on invertebrates--tributyltin on snails, pesticides on insects and crustaceans, and industrial compounds on marine animals.

Implementing the precautionary principle.

The precautionary principle can be found in international treaties that protect human health and the environment from a variety of pollutants and perturbations. One of the earliest forms of the precautionary principle was used in the 1980s in Europe to protect the North Sea. In 1992, the Rio Declaration specifically included the precautionary principle in calling on nations to protect the environment. The US articulation that best embodies this approach to environment and human health protection is the Wingspread statement: 'When an activity raises threats of harm to human health or the environment, precautionary measures should be taken, even if some cause and effect relationships are not fully established scientifically.' The key element is the matter of acting in the face of uncertainty. Applications of the precautionary principle are not, however, new to US environmental policy and management. The present paper uses case studies to examine the application of the precautionary principle to environmental decisions. These cases range from ecosystem protection on the Charles River, Massachusetts, to the effort to prevent computer crashes at the end of the year 2000. These cases deal with the problem of uncertainty, whether concerning the cause, effect, systemic condition or multiple factors. Uncertainty represents one of the features that provoke controversy over these issues and the precautionary principle.

ANALYSIS OF HEMOLYMPH OXYGEN LEVELS AND ACID-BASE STATUS DURING EMERSION 'IN SITU' IN THE RED ROCK CRAB, CANCER PRODUCTUS.

Hemolymph samples were taken from small (< 100 g) individuals of Cancer productus following ca. 3 h air exposure (emersion) on the beach, `in situ', at Friday Harbor, Washington. Compared with crabs of similar size in sea water in the laboratory, these crabs emersed `in situ' had lower Pao2, and Pvo2, but no significant change in pH and a small, not significant, internal hypercapnia. Total CO2 (Cco2) content of the hemolymph was elevated by 70% (15.2 versus 9.0 mM), possibly as compensation for input of acid into the hemolymph. These responses are qualitatively similar to those resulting from similar treatment in the laboratory, but differ in the reduced magnitude of the internal hypercapnia and acidosis of the hemolymph. It is suggested that the particular conditions of emersion `in situ' permit some gas exchange with interstitial sea water. Interstitial sea water was found to be hypoxic (Po2 = 20-40 torr), which would limit oxygen supply yet permit CO2 excretion to continue, in agreement with the data.