Mercury and methylmercury bioaccessibility in swordfish

Area of Science:

• Food Safety
• Environmental Toxicology
• Marine Biology

Background:

• Mercury (Hg) contamination in swordfish (Xiphias gladius) is a significant global food safety concern.
• Regulatory limits for mercury in fish are established to protect public health.
• Understanding mercury bioaccessibility is crucial for accurate risk assessment.

Purpose of the Study:

• To analyze total mercury (t-Hg) and methylmercury (MeHg) concentrations in Spanish swordfish.
• To determine the bioaccessible fractions of mercury after in vitro digestion.
• To assess the dietary intake risks for Spanish consumers, particularly children and adults.

Main Methods:

• Analysis of 27 swordfish samples marketed in Spain (2005).
• In vitro digestion method to simulate gastrointestinal conditions.
• Determination of total mercury (t-Hg) and methylmercury (MeHg) in fish tissue and bioaccessible fractions.

Main Results:

• 37% of swordfish samples exceeded the Spanish legal limit for Hg (1.0 mg kg(-1) wet weight).
• Bioaccessible t-Hg represented 64% of total mercury, with MeHg comprising 94% of bioaccessible t-Hg.
• Estimated Hg and MeHg intakes exceeded tolerable daily intake (TDI) limits for regular consumers, especially children.

Conclusions:

• Swordfish consumption in Spain presents a risk of exceeding safe mercury intake levels.
• Recommendations are needed for specific population groups regarding swordfish consumption.
• Further monitoring and regulatory review of mercury levels in swordfish are warranted.