Measuring and monitoring persistent organic pollutants in the context of risk assessment Rudolf S.S. Wu a, * , Alice K.Y. Chan a , Bruce J. Richardson a , Doris W.T. Au a , James K.H. Fang a , Paul K.S. Lam a , John P. Giesy a,b,c a Department of Biology and Chemistry, Research Centre for Coastal Pollution and Conservation, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong b Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Canada c Zoology Department, Center for Integrative Toxicology, National Food Safety and Toxicology Center, Michigan State University, East Lansing, MI 48824, USA article info Keywords: POPs Guideline Risk assessment abstract Due to growing concerns regarding persistent organic pollutants (POPs) in the environment, extensive studies and monitoring programs have been carried out in the last two decades to determine their con- centrations in water, sediment, and more recently, in biota. An extensive review and analysis of the exist- ing literature shows that whilst the vast majority of these efforts either attempt to compare (a) spatial changes (to identify ‘‘hot spots”), or (b) temporal changes to detect deterioration/improvement occurring in the environment, most studies could not provide sufficient statistical power to estimate concentrations of POPs in the environment and detect spatial and temporal changes. Despite various national POPs stan- dards having been established, there has been a surprising paucity of emphasis in establishing accurate threshold concentrations that indicate potential significant threats to ecosystems and public health. Although most monitoring programs attempt to check compliance through reference to certain ‘‘environ- mental quality objectives”, it should be pointed out that many of these established standards are typically associated with a large degree of uncertainty and rely on a large number of assumptions, some of which may be arbitrary. Non-compliance should trigger concern, so that the problem can be tracked down and rectified, but non-compliance must not be interpreted in a simplistic and mechanical way. Contaminants occurring in the physical environment may not necessarily be biologically available, and even when they are bioavailable, they may not necessarily elicit adverse biological effects at the individual or population levels. As such, we here argue that routine monitoring and reporting of abiotic and biotic POPs concen- trations could be of limited use, unless such data can be related directly to the assessment of public health and ecological risks. Risk can be inferred from the ratio of predicted environmental concentration (PEC) and the predicted no effect concentration (PNEC). Currently, the paucity of data does not allow accurate estimation of PNEC, and future endeavors should therefore, be devoted to determine the thresh- old concentrations of POPs that can cause undesirable biological effects on sensitive receivers and impor- tant biological components in the receiving environment (e.g. keystone species, populations with high energy flow values, etc.), to enable derivation of PNECs based on solid scientific evidence and reduce uncertainty. Using the threshold body burden of POPs required to elicit damages of lysosomal integrity in the green mussel (Perna virvidis) as an example, we illustrate how measurement of POPs in body tissue could be used in predicting environmental risk in a meaningful way. Ó 2008 Published by Elsevier Ltd. 1. Introduction Since the publication of the book Silent Spring (Carson, 1962), an enormous number of surveys have been conducted in which local and regional contamination by a wide variety of xenobiotic sub- stances has been elucidated. Larger-scale surveys have also pro- vided a global and regional distribution picture for major contaminants (including metals, pesticides, industrial and con- sumer compounds) and, at least in some cases, attempts have also been made to correlate distribution patterns revealed with effects on living organisms (including humans). In recent years, particular attention has been paid to the occur- rence and role of various persistent organic pollutants (POPs) in marine environmental contamination. POPs include a wide variety of chemicals, from petroleum compounds and their derivatives (including the polycyclic aromatic hydrocarbons, PAHs) to organo- halogenated compounds, such as the chlorinated pesticides DDT, 0025-326X/$ - see front matter Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.marpolbul.2008.03.012 * Corresponding author. Tel.: +1 852 2194 2032; fax: +1 852 2194 2554. E-mail address: bh101dal@cityu.edu.hk (R.S.S. Wu). Marine Pollution Bulletin 57 (2008) 236–244 Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul