Dioxin-contaminated farmed salmon: Foran et al. respond.

Middaugh et al. suggest that relying strictly on risk assessment to develop fish consumption advice has many shortcomings. We agree. They also argue that risk assessment is only part of the risk management process. Although we separate risk assessment and risk management, we agree conceptually that risk management decisions often must be based on more than just the results of a quantitative risk assessment.

What Middaugh et al. fail to recognize is that our report on dioxins in salmon (Foran et al. 2005) was not intended to serve as a fish consumption advisory. Such advisories should be left to appropriate state, federal, and international organizations charged with protection of public health. Rather, we reported risk-based consumption advice that would be triggered by dioxin-like compounds (DLCs) in farmed Atlantic and wild Pacific salmon using two different approaches; the World Health Organization (WHO) tolerable daily intake (TDI) for DLCs and a margin-of-exposure approach advocated by the U.S. Environmental Protection Agency (EPA 2002). We also reported cancer risks, based on the proposed U.S. EPA cancer slope factor for DLCs (U.S. EPA 2002) that would be generated at particular salmon consumption levels. Our results demonstrate clearly that consumption of some farmed Atlantic salmon, even at relatively modest levels, raises human exposure to DLCs above the lower end of the WHO TDI and considerably above background DLC intake for adults in the United States. Further, consumption at these levels poses elevated cancer and noncancer health risks.

Middaugh et al. suggest that human biomonitoring should be used rather than relying on calculated estimates of exposure, presumably to generate fish consumption advice. We strongly disagree, particularly in the case where the exposure source (farmed Atlantic salmon) is not localized. This is a global problem that would require human biomonitoring on immense temporal and spatial scales, in this case, quantitative risk assessment, which includes an assessment of chemical fate, transport, exposure, and effects, is an appropriate surrogate for human biomonitoring. Further, given our vast knowledge of the toxicokinetic behavior and toxicologic effects of dioxin and other bioaccumulative compounds in farmed Atlantic salmon, requiring human biomonitoring before issuing consumption advice is akin to continuing a clinical trial of a drug where unacceptable adverse effects have already been demonstrated. Clearly, responsible public health professionals should strenuously object to such an approach.

Middaugh et al. suggest that two aspects of our study are problematic. First, they argue that measuring contaminants in skinon fillets may overestimate contaminant concentrations in edible fish tissue and, ultimately, human exposure. We addressed this issue in our article (Foran et al. 2005). We encourage Middaugh et al. to reexamine our conclusion that most studies of the effects of preparation (including removal of skin) and cooking on contaminant concentrations in fish tissue

   suffer from small sample sizes, questionable data
   analyses, inconsistent analytical techniques, inconsistent
   data presentation, and variability in initial
   and postintervention contaminant concentrations
   within and among species, preparation techniques,
   and cooking techniques. Deficiencies in study
   design and variability in contaminant reductions
   preclude development of a useful quantitative correction
   factor for the effects of preparation and
   cooking on contaminant burden. As a result,
   reductions in exposure and risk associated with
   reduction in contaminant concentrations from
   preparation and cooking cannot be evaluated
   quantitatively; thus, we have not incorporated the
   effects of cooking and preparation in our risk
   assessments.

Second, Middaugh et al. are correct in stating that we did not adjust for the existing background concentration that incorporates DLC exposure via fish consumption. However, we did assess such exposures and concluded that they were so low, compared with exposure to DLC through consumption of farmed Atlantic salmon, as to be inconsequential in our risk assessment calculations.

Finally, we regret that Middaugh et al. ignored two critically important conclusions of our work. First, in all of our articles (Hites et ah 2004a, 2004b; Foran et al. 2004, 2005) that address contamination of salmon sold commercially, we provided information that will allow and encourage consumers to choose other fish, including wild Pacific salmon, as well as other sources of beneficial n-3 fatty acids. Second, our work has exposed serious deficiencies and inconsistencies in national and international approaches to the management of contaminants in commercially sold fish. These deficiencies and inconsistencies must be resolved so that consumers can confidently choose and consume fish with lower contaminant concentrations while continuing to accrue the health benefits of fish consumption.

The authors declare they have no competing financial interests.

REFERENCES

Foran JA, Carpenter DO, Hamilton MC, Knuth BA, Schwager SJ. 2005. Risk-based consumption advice for farmed Atlantic and wild Pacific salmon contaminated with dioxins and dioxin-like compounds. Environ Health Perspect 113:552-556.

Foran JA, Hites RA, Carpenter DO, Hamilton MC, MathewsAmos A, Schwager SJ. 2004. A survey of metals in farmed Atlantic and wild Pacific salmon. Environ Toxicol Chem 23(9):2108 2110.

Hites RA, Foran JA, Carpenter DO, Hamilton MC, Knuth BA, Schwager, SJ. 2004a. Global assessment of organic contaminants in farmed salmon. Science 303:226-229.

Hites RA, Foran JA, Schwager S J, Knuth BA, Hamilton MC, Carpenter DO. 2004b. Global assessment of polybrominated diphenyl ethers in farmed and wild salmon. Environ Sci Technol 38(19):4945-4949.

U.S. EPA. 2002. Draft Dioxin Reassessment. Washington, DC:U.S. Environmental Protection Agency. Available: http://cfpub.epa.gov/ncea/cfm/part3.cfm?ActType=default [accessed 18 January 2005].

Jeffery A. Foran

Midwest Center for Environmental Science and Public Policy

Milwaukee, Wisconsin

E-mail: [e-mail]

David O. Carpenter

Institute for Health and the Environment University at Albany

Rensselaer, New York

M. Coreen Hamilton

AXYS Analytical Services Ltd.

Sidney, British Columbia, Canada

Barbara A. Knuth

Steven J. Schwager

Cornell University

Ithaca, New York