Can build up inside mussels
Are not destroyed by cooking
Can cause serious illness
Without modern monitoring, avoiding shellfish during hot months was a practical safety rule.
What Modern Science Says Today
The good news? The old “R-month” rule is no longer a universal requirement.
✔️ Modern Farming & Refrigeration
Most mussels sold commercially today are:
Farmed under strict regulations
Harvested from monitored waters
Kept continuously refrigerated
This dramatically reduces spoilage and contamination risks.
✔️ Ongoing Water Quality Monitoring
In many countries, health authorities routinely test for:
Harmful algal toxins
Bacteria such as Vibrio
Overall water safety
If toxin levels rise, harvesting areas are temporarily closed. Mussels only enter the market when they meet safety standards.
✔️ Safety Depends on Handling — Not the Calendar
Today, safety comes down to:
Buying from reputable suppliers
Keeping mussels properly chilled
