A new study claims that nitrate pollution in drinking water supplies near California’s Central Valley farming communities has worsened in recent decades, and will continue to spread, reports the Los Angeles Times. University of California Davis scientists analyzed ground water data from the southern San Joaquin and Salinas valleys, and concluded that even if all farming operations stopped immediately, nitrates would stay in the water and continue to flow into other areas.

Nitrates from farmers’ fertilizers and manure seep into ground water, which is used for drinking by almost all of approximately 2.65 million people in the areas examined in the study. High nitrate levels have been linked to thyroid cancer, skin rashes, hair loss, birth defects, and methemoglobinemia, otherwise known as blue baby syndrome, a potentially lethal blood disorder in infants.

Those most at risk for drinking water polluted with nitrates are served by small, local water systems that cannot afford treatment or those using private wells. Researchers estimate that nearly 10 percent of people in the region are drinking contaminated water, and believe that 80 percent of residents will face health and financial problems by 2050 if nothing is done to combat the problem.