Edge of Darkness

By moonlight, three bodies float to the surface of the western Massachusetts stretch of the Connecticut river. At South Station, Boston, Thomas Craven (Mel Gibson) picks up his daughter, Emma (Bojana Novakovic), who has returned home to visit. She throws up, while getting into Thomas' car. At home, as he prepares a meal, Emma starts a nosebleed and vomits violently and as they hurriedly leave to find a hospital, a masked gunman yells, Craven, and fires two shotgun blasts at Emma simultaneously. Blasted through the door, she dies in Thomas' arms.At first, everyone believes that Thomas, a police detective, was the gunman's target, but when Thomas finds Emma had a pistol in her night stand, he starts to suspect that Emma was an intended target. He checks the ownership of the pistol and finds that it belongs to her boyfriend David (Shawn Roberts). David is frightened of the company Northmoor where Emma worked and Thomas discovers that Emma became aware that Northmoor was manufacturing nuclear weapons, intended to be traced to foreign nations if they are used as dirty bombs. Following the failed break-in of the activists, Emma was poisoned with thallium through a carton of organic milk. Burning her effects in his lawn, Thomas encounters Jedburgh (Ray Winstone), a "consultant" tasked to prevent Craven from discovering Emma's information, or kill him. Liking each other, instead, Jedburgh leaves Thomas to investigate. Throughout the film, Thomas repeatedly imagines he hears and sees his daughter, even having short conversations and interactions with her.Thomas also has several encounters with Northmoor mercenaries, and he eventually discovers through Emma's activist contact that Jack Bennett (Danny Huston), head of Northmoor, ordered the murder of his daughter, as well as the activists Emma was working with to steal evidence of the illegal nuclear weapons (the bodies in the opening). Northmoor personnel kill a hitman marked as a fall guy after he is set up for killing Emma's boyfriend, and attempt to murder another activist who gave Emma's information to Thomas. After confronting a lawyer and Senator that Emma contacted, revealing that they know almost everything that happened, Bennett has Northmoor operatives allow Thomas to be poisoned with thallium, as his daughter had been.Thomas, now very sick, arrives at Bennett's house and kills the mercenaries, one of whom Thomas realizes is the man who shot his daughter. Bennett shoots Thomas, but Thomas tackles Bennett and pulls out the radioactive milk. He forces it down Bennett's throat and collapses. Bennett runs to his cabinet to get pills to counteract the radioactivity but Tom drags himself over and shoots Bennett through the throat, killing him.Thomas is hospitalized for the gunshot wounds and radioactive poisoning. Jedburgh, who is revealed to be suffering from a terminal illness, meets with Moore, the Senator (for whom he had been working) and the political advisor who assigned Jedburgh to eliminate Craven. He listens to their suggestions as to how to play the Northmoor incident in a positive light. He tells them that he is done and then suggests an assassination attempt on the Senator should be the feature story, to drive Bennetts death out of the tabloids. They are happy to go along with the story until Jedburgh tells the senator that he is on the wrong side of the equation. Jedburgh then pulls out his gun and shoots all three men dead before a young Massachusetts State Trooper comes in, gun drawn. Jedburgh gets the drop on the trooper and asks if the young man has a family and kids. The young man says yes and Jedburgh lowers his gun, and is instantly shot and killed by the trooper.As Thomas lies dying in the hospital, we see Emma walk into his room, then lean down at his bedside and whisper in his ear. Across town, a young reporter opens a letter from Thomas with DVDs revealing the conspiracy, with Thomas's good luck wishes, ensuring the company's end. As he dies, Emma comforts him. Then the father and daughter leave the hospital together, walking down the corridor into a bright, white light.

Question: what is Tomas and Emma poisoned with?
Answer: Thallium