"Only people out in the open during this battle were in any danger. from it." ? ?

'On 4 January, Sa'adallah Matar Abu Halima and four of his children were killed in a white phosphorus attack on their HOME in the Sayafa area in north-west Gaza.
His wife Sabah was seriously burned and told Amnesty International that she had watched her baby girl Shahed melt in her arms.

Soon after the attack Israeli soldiers shot dead at close range cousins Matar and Muhammad Abu Halima as they tried to take their burned relatives to hospital.'

'At about 6am on 17 January a white phosphorus artillery shell exploded in the UNRWA primary school in Beit Lahia, where more than 1,500 people were sheltering.
Two children – Muhammad al-Ashqar and his brother Bilal – aged five and seven respectively, were killed. More than a dozen other civilians sheltering in the school were injured.'

Amnesty International Report 2010

"....one patient, a three-year-old girl, who was sent for a scan because of a head wound: "After about two hours she came back, we opened the wound, and smoke came out from the wound," he said. Surgeons used forceps to pull out a substance from the wound that was "like dense cotton and it started to burn," he said. "The piece continued to burn until it disappeared." The child, who was from Atatra, in Beit Lahiya, in northern Gaza, died."

deadly burns consistent with white phosphorus

NB 'Phosphorus burns carry a greater risk of mortality than other forms of burns due to the absorption of phosphorus into the body through the burned area, resulting in liver, heart and kidney damage, and in some cases multiple organ failure.
These weapons are particularly dangerous to exposed people because white phosphorus continues to burn unless deprived of oxygen or until it is completely consumed.' - Wiki

During Operation Castlead phosphorus was used in the densely populated Gaza City
Many people were 'out in the open' fleeing from attacks