Development of a Seaweed Consumption Survey Tool for Dietary Exposure Assessment to Heavy Metals

Abstract

Seaweed products are widely consumed due to their perceived health benefits. Nonetheless, they can serve as sources of toxic contaminants, particularly heavy metals such as lead and cadmium, which may accumulate from their aquatic environments. To accurately assess dietary exposure to these contaminants, it is essential to obtain detailed information on seaweed consumption patterns, including type and quantity consumed. However, existing data often lack such specificity, as prior studies did not differentiate between seaweed types, thereby complicating the classification of sources, particularly in distinguishing between freshwater and marine varieties. This study focused on the development and validation of a semi-quantitative food frequency questionnaire (SQ-FFQ) for evaluating seaweed consumption patterns. To fill the gap, the four steps were performed: (1) conducting a market survey (2) compiling a detailed list of seaweed types, seaweed-based products, and commonly consumed menus, (3) developing an online SQ-FFQ via google form, and (4) evaluating the tool’s content validity through expert review using the Index of Item-Objective Congruence (IOC), as well as assessing internal consistency reliability with Cronbach’s alpha coefficient (α-coefficient). The market survey identified 103 nori items, 5 zi-cai items, and 29 wakame items. Based on this, a total of 16 seaweed-based menu items were selected and incorporated into the questionnaire, comprising 10 nori-based menus, 1 zi-cai-based menu, and 5 wakame-based menus. The SQ-FFQ showed acceptable content validity (IOC = 0.6-1.0) and high reliability (α = 0.954), confirming its suitability for assessing seaweed consumption in dietary exposure to heavy metals.