Health Risk from ConsumingPOC-Contaminated Fish:

Part II. Risk Analysis and Prevention Strategies

Michael H. Dong, MPH, DrPA, PhD

October, 2007

Readings

taken at the Epcot Center, Orlando, Florida, USA

Lecture Objectives

Appreciate the POC residue levels in fish observed in various countries.

Compare these real-time residue levels to their respective screening values that have been adopted as threshold levels.

Revisit the basic strategies used for preventing health risk from consuming fish contaminated with POCs.

Performance Objectives

Students are expected to know that worldwide levels of some POCs are still far exceeding their screening values.

. . to know what the methodological issues and associated uncertainties are in the risk analysis conducted here.

. . to know that the prevention strategies so discussed can be costly, yet crucial.

Table 2. POC residues in fish from selected localities, as published after the year 2000a

Country (Location)b PCDDs/Fs PCBs DDT Aldrin/ Dieldrin

Screening Valuec 0.03 ppt 2.5 ppb 14.4 ppb 0.3 ppb

China (Pearl River Delta) (a) - - 1.5 - 62 -

China (Taihu Lake) (b) 0.5 - 3.8 1.5 - 27.6 - -

India (River Ganges) (c) - - 13.6 - 1,666 3.1 - 86.1

Korea (coastal waters) (d) - 3.0 - 96.6 0.8 - 27.0 -

Spain (Atlantic sw coast) (e) 0.04 - 0.19 0.9 - 23.8 - -

Sweden (Baltic sea) (f) 0.5 - 33.4 - - -

USA (salmon worldwide) (g) 65 73 28 6.3 a all tissue residue concentrations of POCs are in ppb (g/g) wet weight, except for PCDDs/PCDFs for which the levels are in TEQ-based ppt (g/g) wet weight.

b from the following studies: (a) Kong et al. (2005); (b) Zhang and Jiang (2005); (c) Kumari et al. (2001); (d) Yim et al. (2005); (e) Bordajandi et al. (2006); (f) SNFA (2004); (g) Hites et al. (2004).

c levels exceeding the screening values (as derived by U.S. EPA, 2000a) are considered to be of potential public health concern.

Advisory for High Risk Groups

A considerable number of monitoring sites were noted to have POC levels > the screening values by 30-fold+.

For these areas, no more than 1 or 2 fish meals/month should be recommended.

Fish advisories of this kind may not be all that practical to residents who rely on fish as their main diet.

Issues Inherent in the Analysis

Risk analysis of the type conducted here is far from flawless.

High consumption observed may not correlated well with high residue level detected even in the same vicinity.

Nor are all fish species in the same vicinity necessarily contaminated by the same chemical or to the same extent.

Other Related Issues (I)

The characteristics, the transport, and the fate of POCs present in the aquatic environment all can play a crucial role.

Current trends may not be indicative of the POC levels in fish in the future.

For example, some POCs have been transported to remote sites where the chemicals have never been used.

Other Related Issues (II)

There are also uncertainties with the empirical data used in the analysis.

All tolerance limits or screening values are based on the toxicity data on hand, which are ever lacking or indirect.

Residue data are vulnerable to technical errors inherent in sample collection and in the analytical procedures used.

Implications of Analysis Data

While both the tolerance levels and the POC residue data must be applied with caution, some level of conservatism could/should still be exercised to err on the side of health protection.

Certain prevention strategies are thus warranted here for fish contamination with POCs in many localities.

Concerns with Bioaccumulation

Bioaccumulation refers to cumulative and aggregate exposures during the same time interval.

Its occurrence in humans can lead to further alarming health consequences.

The main concern here is that fish and shellfish are not a person’s only source of exposure to the same/a similar POC.

Issues with Bioaccumulation

Once a lipophilic chemical (e.g., POC) is inside the human body, it will not go away any time soon.

A large enough single dose (exposure) can induce an acute adverse effect.

The ADI or RfD used might not have taken into account the extra amount of a POC coming from other sources.

A Case of Bioaccumulation A pregnant woman was exposed to a

POC daily at a constant dose of 10 units from fish consumption, and 5 units through other sources (e.g., milk, water).

Then on day 10, this woman would have as her body burden a total of 150 (not 100) units of this chemical, which would exceed the threshold of 100 units.

Risk Prevention Strategies Certain risk prevention strategies hence

should be in place to cope with the potential hazard from consuming fish contaminated with POCs.

These would involve: environmental health policy; regulatory/research activities; residue monitoring programs; and self awareness/prevention.

Environmental Health Policy Programs/policies should be

developed, with a focus on better use of POCs and on better handling of waste removal.

FQPA-like laws should be adopted to focus on children’s higher sensitivity.

Governments should have available more, as well as more effective, POC-related illness surveillance programs.

Regulatory/Research Activities

Activities should be in place to enrich risk communication resources for fish contamination with POCs.

Research is needed to refine the works done on risk assessment methodology, on toxicity studies, and on relevant exposure parameters including fish consumption pattern.

Residue Monitoring Programs

More monitoring programs for POCs in fish need to be developed around the ‘hot spot’ areas (which should be more aggressively identified).

These programs should be effective with a special focus on sampling, on the analytical technique used, and on uniform reporting of monitoring data.

Self Awareness/Prevention (I) Awareness/prevention at the individual

level is the most effective approach to minimizing the human health risk from consumption of POC-contaminated fish.

This assertion is based upon the notion that risk prevention at the individual level is much more tangible, more controllable, and thus more attainable.

Self Awareness/Prevention (II)

A fish consumer should make every effort to choose younger fish to eat.

The person should remove the fish’s guts as these are the organs where some POCs also tend to concentrate in.

The person should also trim the fish’s fat, remove the skin, and cut away the fatty dark meat.

Self Awareness/Prevention (III)

Lastly, the consumer should cook fish in a way that would allow the fat to drip away or drain off.

This can be accomplished effectively with most cooking methods.

Up to 60% or more of the POCs could be reduced by the way in which the fat is dripped or drained away.

Self Prevention with a Price

In closing, it is fair to forewarn that the type of self risk prevention measures suggested here is not without a price, unless fish can swim in or be cultivated in a cleaner aquatic environment.

Otherwise, the individual consumers would end up getting less intake of the good (i.e., the essential) fats in fish.