A recent investigation surveyed 50 largest US cities, and discovered drugs in the drinking water in 24 major metropolitan areas.

Reports say a broad range of prescriptions and over-the-counter medicines were found in the drinking water supplies for at least 41 million U.S. residents.

The quantities are far below the levels of a medical dose, but still, some scientists are concerned that the presence of such drugs in drinking water may have long-term consequences for human health.

Steve Goodbred from U.S. Geological Survey says they did find that the drugs have affected fish.

"We found that fish exposed to contaminants in the waste water have reduced testicular growth, reduced sperm quality and altered hormone ratios."

However, pharmaceutical companies in the U.S. insist there is little to no risk from their products. America's Environmental Protection Agency also insisted that the country's drinking water is safe.

Benjamin Grumbles is the agency's Assistant Administrator for Water.

"We see this as not a risk to public health based on what we know currently, but it is a concern for us and that's why we are aggressively working with utilities, and waste water and drinking water utilities to confront this emerging problem and increase public awareness about it."

A hearing in response to this investigation is expected to held in April.

Some science reports say water contamination is a worldwide problem. More than 100 different pharmaceuticals have been detected in lakes, rivers, reservoirs and streams throughout the world.