The association between razor clam consumption and memory in the CoASTAL cohort

Abstract

This study represents a preliminary effort to examine the possible impacts of chronic, low level Domoic Acid (DA) exposure on memory in the CoASTAL cohort. Five hundred thirteen men and women representing three Native American Tribes were studied with standard measures of cognition and razor clam consumption (a known vector of DA exposure) over a four year period. In addition, a pilot metric of DA concentration exposure was used which took into consideration average DA concentration levels in source beaches as well as consumption. Based upon GEE analysis, controlling for age, sex, race, year, education level, tribe, and employment status, findings indicated that high razor clam consumers (15 or more per month) had isolated decrements on some measures of memory (p=.02 to .03), with other cognitive functions unaffected. The relatively lower memory scores were still within normal limits, thus not clinically significant. The pilot DA exposure metric had no association with any aspect of cognition or behavior. There is a possible association between long term, low level exposure to DA through heavy razor clam consumption and memory. The availability of a reliable biological marker for human exposure to DA is needed.

Harmful algal blooms and public health

“…The extent to which chronic low level exposure impacts human health remains to be determined. Preliminary findings from Grattan et al, (in press) in this issue raise the possibility that milder memory problems may be associated with lower level, chronic exposures in adults who are heavy consumers of razor clams. Thus, domoic acid neurotoxicity may potentially be associated with a non-amnesic syndrome.…”

Perception of risk for domoic acid related health problems: A cross-cultural study

“…A final limitation is that limited “actual knowledge” is available for the risk of low level, chronic exposure to DA through razor clam consumption. Although studies are underway (Tracy et al, in press; Grattan et al, in press), at this time perceived risk is being assessed to an ambiguous hazard. Meanwhile, it is anticipated that knowledge from cross cultural studies such as this one, can contribute to more effective risk communication, outreach, and education efforts to HAB communities in distress.…”

Dietary assessment of domoic acid exposure: What can be learned from traditional methods and new applications for a technology assisted device

“…The cohort was assembled for the purpose of studying the impacts of repeated exposure to low levels of DA over time (Grattan et al, this issue, a, b; Tracy et al, this issue). In the absence of a human biomarker, robust dietary assessment is essential to studying the impact of long term exposure.…”

“…When these toxic species proliferate, they may cause massive kills of fish and shellfish; wildlife mortality due to consumption at higher trophic levels; and human illness or death. One algal toxin, domoic acid (DA) is a known neurotoxin that has been associated with amnesic shellfish poisoning in humans (see Grattan et al a,b, this issue). In the United States, P seudo-nitzschia -producing blooms responsible for DA neurotoxins have been intermittently found in the coastal waters of the Pacific Northwest for nearly three decades (c.f.…”