Which primary inorganic contaminant poses an immediate health risk?

Nitrates are a concern primarily due to their impact on human health, especially for infants. When consumed in high concentrations, nitrates can lead to a condition known as methemoglobinemia, or "blue baby syndrome," which reduces the ability of blood to carry oxygen. This condition can pose an immediate health risk, especially in vulnerable populations like newborns.

However, it is important to note that lead is often regarded as a more immediate and acute threat because of its harmful effects on neurological development and function, particularly in young children. Lead exposure can occur through contaminated drinking water, especially in older plumbing systems that have lead solder or pipes. It can cause severe health issues such as developmental delays, lower IQ, and various physical health problems, making it a critical inorganic contaminant.

Arsenic also poses significant health risks, particularly its long-term effects which can include cancer and cardiovascular disease. However, acute poisoning from arsenic is less common in typical water supplies, thus making it a less immediate concern compared to lead.

Fluoride, while beneficial in small amounts for dental health, can be harmful in excessive concentrations leading to dental fluorosis or skeletal issues but is generally not viewed as an immediate life-threatening contaminant.

In this context, while