I am suspicious that the repeated comparison to standards for water here aren't really fair. Heavy metals are a natural occurrence in pretty much all foods that we eat, regardless of environmental pollution (though pollution does have a notable impact).
For instance, it's incredibly common for even the highest-quality 'organic' produce to contain levels of heavy metals such as lead in amounts that drastically exceed California's prop 65 standards. Things like avocados and watermelons often have close to 10x more lead than what prop 65 considers acceptable. Spinach, wines, cruciferous vegetables and nuts tend to be even worse. Even when grown in relatively unpolluted soils with 'natural' lead levels (50-400 ppm range), many such produce items STILL drastically exceed prop 65 standards.
That said, I'm not a food safety expert or toxicologist, so I might have an incredibly bad take on this.
For instance, it's incredibly common for even the highest-quality 'organic' produce to contain levels of heavy metals such as lead in amounts that drastically exceed California's prop 65 standards. Things like avocados and watermelons often have close to 10x more lead than what prop 65 considers acceptable. Spinach, wines, cruciferous vegetables and nuts tend to be even worse. Even when grown in relatively unpolluted soils with 'natural' lead levels (50-400 ppm range), many such produce items STILL drastically exceed prop 65 standards.
That said, I'm not a food safety expert or toxicologist, so I might have an incredibly bad take on this.