One in four Bay State nurses says that patient deaths are “directly attributable” to having too many people in their care at one time, according to a new survey.

The survey, commissioned by the Massachusetts Nurses Association/National Nurses United, also found 46 percent of nurses said understaffing has resulted in injury to patients, 51 percent said it has led to longer hospital stays, and 57 percent said it has led to medication errors. Research firm Anderson Robbins did the survey of randomly selected nurses.

“It is unacceptable that erratic staffing decisions lead to medical errors, complications, readmissions and death,” said state Rep. Denise Garlick (D-Needham), who is also a nurse.

Garlick is a co-sponsor of the Patient Safety Act, which would allow the state Department of Public Health to limit the number of patients a nurse could have. A proposed ballot initiative would limit the number to four.

The Massachusetts Hospital Association called the survey “not credible” and said it was “troubling that the union, to advance its political agenda, would issue such unsubstantiated safety claims that run counter to the publicly available data and evidence.”

Joshua Archambault, director of health care policy at the Pioneer Institute, a Boston think tank, said: “Without question patient safety remains an issue for the medical industry to wrestle with, as the survey finds. However, efforts to mandate nurse staffing ratios are misguided and packed with unintended consequences. They reduce flexibility at a health system and send ripple effects far outside a patients’ room.”