The children were treated for breathing problems, dizziness, nausea, and eye and skin irritation after being admitted to three hospitals in Si Racha district.
Most of the children's conditions were not severe and they were soon discharged after primary treatment, permanent secretary for public health Narong Sahametapat said.
Only 14 patients were asked by doctors to stay at the hospitals for further observation.
The affected children are studying at a nursery centre, Thetsaban schools 1, 2 and 3 and Wat Ban Na School, which are not far from the port.
An initial investigation showed most children did not inhale large amounts of the chemical, Dr Narong said. He said the chemical would later be discharged naturally through urination.
"They will recover soon,” he said.
However, he warned people living near Laem Chabang port to protect themselves by covering their noses with a wet cloth and washing themselves if they smelled the chemical.
The chemical was identified as butyl acrylate, a clear colourless liquid with a fruity odour.
It is used in paint, coatings, and adhesive manufacturing as well as in a wide range of other industrial products.
People who are exposed to the chemical can develop eye and body irritation. If ingested in large volumes, the chemical can cause disorders in the lungs and reproductive organs.
Officials said the chemical was kept in tanks on a Chinese-flagged container ship, Pearl River Bridge, which was docking at the port after arriving from Jakarta, Indonesia. The accident occurred as the tanks were being unloaded onto the dock. One of the tanks fell from a crane to the ground and its casing was damaged, causing the chemical to leak.
An initial inspection of the container showed its casing had been torn open, and it could not be sealed easily, prompting officials to ask the Marine Department to tow the ship away from the port to keep the chemical away from people, said Lt Yutthana Mokkhao, director for operations at Laem Chabang port.
The ship is now anchored near Nok island, about 3km from the mainland.
Officials instructed the ship's crew to keep the damaged tank under close watch and keep it away from sparks or fire to prevent a possible explosion.
They were also told to make sure the chemical does not leak into the sea.