For example, in parts of Bihar, the ground water and soil carry a lot of arsenic. The plants absorb this from the soil. The population that resides here (the worst affected districts are Buxar, Bhojpur and Bhagalpur) get a lot of this from their drinking water, vegetables etc. Farm produce that goes to the rest of the country from the districts that have high levels of arsenic in the soil will also have high levels of arsenic.
In parts of Punjab, fluorosis is common and they get the excess fluorides from heavy consumption of rock salt. There are parts of the country where ground water has excess fluorides.
Human activity has also contributed a lot to an increase in heavy metal toxicity from several sources. The most common worldwide is mercury toxicity from consuming a lot of fish. Fish in almost all sea waters all over the world is now contaminated with fairly high levels of mercury. Getting the best quality fish is not going to save you. Some very famous people who ate the best fish from the best sources have suffered mercury toxicity from consuming too much fish. A famous recent example is Tony Robbins.
Lead toxicity became common in many places from lead lined water pipes.
One problematic metal which is a source of toxicity is widely seen as benign, but is increasingly suspected to cause Alzheimer’s disease and dementia amongst other conditions. That is aluminium. It’s a good idea to stop using aluminium dishes in our kitchens and move to stainless steel, and to use deodorants and cosmetics that do not use aluminium which gets absorbed by our skin.
It is a good idea for people to get tested for levels of various minerals and heavy metals in their blood. You should do this once every 5 years or so.
If you catch something, it’s not very difficult then to try and understand where the toxicity is coming from and to take preventive action.
Here’s an article on toxic metals testing –