WASHINGTON (AP) — The Environmental Protection Agency on Monday said it would propose a drinking water limit for perchlorate, a harmful chemical in rockets and other explosives, but also said doing so wouldn’t significantly benefit public health and that it was acting only because a court ordered it. The agency said it will seek input on how strict the limit should be for perchlorate, which is particularly dangerous for infants, and require utilities to test. The agency’s move is the latest in a more than decade-long battle over whether to regulate perchlorate. The EPA said that the public benefit of the regulation did not justify its expected cost. “Due to infrequent perchlorate levels of health concern, the vast majority of the approximately 66,000 water systems that would be subject to the rule will incur substantial administrative and monitoring costs with limited or no corresponding public health benefits as a whole,” the agency wrote in its proposal. Perchlorate is used to make rockets, fireworks and other explosives, although it can also occur naturally. At some defense, …