Docket No. 99N-1075
Dockets Management Branch (HFA-305)
Food and Drug Administration
5630 Fishers Lane, Room 1061
Rockville, Maryland 20852

Re:     Draft Risk Assessment on the Public Health Impact of Vibrio parahaemolyticus in Raw Molluscan Shellfish; Docket No. 99N-1075

Dear Sir or Madam,

     The Food Marketing Institute is pleased to respond to the Food and Drug Administration's (FDA's) request for comments on the document entitled, "Draft Risk Assessment on the Public Health Impact of Vibrio parahaemolyticus in Raw Molluscan Shellfish" (hereinafter "Risk Assessment"). As discussed more fully below, FMI commends FDA for undertaking a comprehensive risk assessment on V. parahaemolyticus in raw molluscan shellfish and for seeking comments from the public on the draft document. Once finalized, we hope that the Risk Assessment will serve as a sound scientific basis upon which to further enhance the safety of the food supply.

     Briefly by way of background, FMI is a non-profit association that conducts programs in research, education, industry relations and public affairs on behalf of its 1,500 members and their subsidiaries. Our membership includes food retailers and wholesalers, as well as their customers, in the United States and around the world. FMI's domestic member companies operate approximately 21,000 retail food stores with a combined annual sales volume of $300 billion, which accounts for more than three-quarters of all grocery sales in the United States. FMI's retail membership is composed of large multi-store chains, small regional firms, and independent supermarkets. Our international membership includes 200 members from 60 countries.

     FMI and its members have a longstanding commitment to improving food safety and consumer education efforts. We value the opportunity to work closely with FDA on important food safety programs, such as the Partnership for Food Safety Education and the consumer brochure on irradiation. FMI has also undertaken a variety consumer education activities independently, including the development of a series of pamphlets for consumers with safe handling practices for a variety of foods, such as dairy, produce, and meat. In this regard, we have enclosed FMI's pamphlet entitled, "A Consumer Guide to Food Quality and Safe Handling: Seafood," which many of our members offer to consumers.

     A.     Background

     Vibrio parahaemolyticus is a marine bacterium that occurs naturally in filter-feeding molluscan shellfish, such as oysters. Some strains or types of V. parahaemolyticus are pathogenic, and can cause food poisoning in people who eat shellfish containing them. The Centers for Disease Control (CDC) estimates that the total numbers of foodborne V. parahaemolyticus cases in the United States for the years 1996 through 1998 were 2730, 8596, and 5525, respectively.1   

     Vibrio parahaemolyticus is destroyed by thorough cooking; therefore, the disease is generally associated with eating raw shellfish. Food intake surveys cited in the draft Risk Assessment indicate that raw shellfish is consumed by about ten to twenty percent of the population at least once per year.

     In response to outbreaks of V. parahaemolyticus in 1997 and 1998, FDA prepared a risk assessment to characterize the public health impact associated with the consumption of raw oysters harboring pathogenic V. parahaemolyticus. The objectives of the risk assessment were to determine the risk of illness resulting from ingestion of pathogenic V. parahaemolyticus in raw oysters, and to provide FDA with the information that it needs to evaluate the efficacy of V. parahaemolyticus-related public health programs.

     The draft Risk Assessment demonstrates that the single most important factor related to the risk of illness caused by V. parahaemolyticus is the level of the bacterium in oysters at the time of harvest. Interpretive Summary at 11. The draft Risk Assessment identified several possible interventions that might be used to control or reduce the level of V. parahaemolyticus in shellfish, including reducing time to refrigeration, mild heat treatment, freezing, hydrostatic pressure, depuration, irradiation, and relaying. Draft Risk Assessment at 24. However, only three of these mitigation strategies were actually evaluated in the Risk Assessment. See Draft Risk Assessment at 36. The report concludes that cooling oysters immediately after harvest and quick freezing oysters both reduced V. parahaemolyticus counts and illness estimates; mild heat treatment "practically eliminated" the likelihood of illness. Interpretive Summary at 11.

     B.     Comments

     FMI applauds FDA's recognition of the need to prepare a risk assessment to support interventions to control V. parahaemolyticus in raw molluscan shellfish. However, beyond ensuring that raw molluscan shellfish are received from approved harvesting waters and protected from cross-contamination, food retailers may have little ability to eliminate or reduce bacterial or viral hazards associated with the sale of raw molluscan shellfish. As discussed more fully below, none of the three interventions on which the draft Risk Assessment focuses are appropriate for use by retailers to enhance the safety of raw molluscan shellfish.

     One intervention considered by FDA is the use of a mild heat treatment. A study reviewed by the Agency concluded that heating shucked oysters for 5 minutes at 50oC caused a 6-log reduction of V. vulnificus. Assuming that V. parahaemolyticus would respond similarly to heat as V. vulnificus did, the draft Risk Assessment states that a 4.5- to 6-log reduction of V. parahaemolyticus densities could be expected by treating oysters for 5 minutes at 50oC.

However, the study apparently addressed treatment of shucked oysters rather than live oysters. Although the mild heat treatment identified by the Agency appears to be a viable option for controlling V. parahaemolyticus, rapid cooling recommendations after mild heat treatment must be provided or the same treatment will allow other pathogens to grow. Listeria monocytogenes, a known problem for raw molluscan shellfish, Vibrio cholera, and Staphylloccus aureus all grow at 50oC. Therefore, the FDA Food Code - and, thus, those state and local jurisdictions that have adopted the Food Code - prohibit storage of raw molluscan shellfish at 50oC. Accordingly, the mild heat treatment evaluated in the draft Risk Assessment may increase the overall level of pathogenic organisms in shellfish, even though it would reduce V. parahaemolyticus, and may also violate state and local food safety laws and regulations.

     The draft Risk Assessment also considers freezing as a possible intervention. Freezing combined with frozen storage is expected to produce an approximate 2-log reduction of pathogenic V. parahaemolyticus. However, freezing the shellfish will also kill them, thereby preventing the retailer from offering fresh, live molluscan shellfish to consumers.

     The third intervention evaluated in the draft Risk Assessment is immediate post-harvest cooling or refrigeration of oysters. According to the Agency, oysters are generally stored unrefrigerated on the oyster boat for some period of time after harvesting, ranging from a few hours to more than a half day. Interpretive Summary at 6. The draft Risk Assessment uses a quantitative model to describe the growth of V. parahaemolyticus in oysters during this unrefrigerated period. Refrigeration, however, not only slows the growth of V. parahaemolyticus, but it also destroys some V. parahaemolyticus cells. Therefore, immediate refrigeration can serve as an immediate brake on the ability of V. parahaemolyticus to multiply after the shellfish are harvested.

     As FDA finalizes the draft Risk Assessment and considers moving forward with regulatory action, we urge the Agency to adopt interventions that will be most effective in ensuring that raw molluscan shellfish has the lowest possible levels of V. parahaemolyticus before it reaches food retailers because, beyond sound sourcing and sanitation practices, retailers have little ability to eliminate or reduce bacterial hazards associated with the sale of raw molluscan shellfish. The draft Risk Assessment suggests that the adoption of an immediate chilling or refrigeration requirement would assist greatly in minimizing bacterial loads in raw oysters. As discussed above, neither mild heat treatment nor freezing is appropriate for retailers to use when providing raw molluscan shellfish to consumers.

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     We commend FDA for undertaking a risk assessment on V. parahaemolyticus and appreciate your consideration of our comments. If we may elaborate further on our comments or provide assistance in any other way, please do not hesitate to call on us.

Sincerely,

Jill Hollingsworth, DVM
Vice President, Food Safety Programs

Enclosure


1   CDC included a projection in these numbers to account for underdiagnosis and underreporting; the actual number of cases reported is twenty times lower than the figures given by CDC. Interpretive Summary at 4.