The US's Environmental Protection Agency (EPA) has decided that levels of Perchlorate - a component of rocket fuel - will not be monitored in the country's drinking water.
National monitoring will not take place, the EPA announced, despite both California and Massachusetts passing laws on the drinking water debate.
According to a statement, the agency said it would instead work with "states and localities to ensure public health is protected", relayed ens-newswire.com.
"States have the right to establish and enforce drinking water standards and EPA encourages state-specific situations to be addressed at the local level," said the organisation.
Drinking water, lettuce and milk in 15 states were all found to contain the substance during a 2004 study by the Food and Drug Administration.
California became the first state in the country to introduce the regulation of Ammonium Perchlorate four years ago.