NANJING -- A storm is brewing in East China's Changzhou city over whether toxic waste is responsible for an increased incidence of lymphoma and leukemia among school kids in the city.

Hua Fei, head of a local health authority investigation team, on Tuesday said checks on 597 people associated with Changzhou Foreign Language School had found no cases of leukemia. One case of lymphoma found, occurred before the school moved to its new campus adjacent to a former chemical waste dump last year.

Media reports had said that 500 students had suffered various illnesses, including cancer, since the campus opened in September, but the health department investigation found only 133 people with abnormal indicators (i.e. some signs of illness) including thyroid, lymphatic, hepatic or renal anomalies. However, Xinhua reporters heard a very different story from parents.

Some parents claim that 493 students have suffer from dermatitis, eczema, bronchitis and reduced leucocyte counts.

The campus is one street away from a plot of land that was home to three chemical plants until they were shut down in 2011. The plot, equal in size to a dozen soccer fields, was scheduled to be rehabilitated after an appraisal in June of last year, and was slated to be sold for commercial development after the soil was restored.

Yuan Puqing, head of the Changzhou environmental science institute said the soil restoration should have been conducted under cover, but the contractor, Changzhou Heimudan Construction Investment, carried out the work in the open air.

A strong pungent odor was noticeable in the area during the process and on Dec 25, 2015 the company stopped the operation after complaints from the public. The plot was then reassigned for public greening and communal facilities rather than commercial use.

The government adjusted the restoration plan and, in February, an assessment panel declared the restoration complete, assessing the air quality as meeting national standards.

Parents have observed that building work on the school began in October 2013, well before any environmental appraisal was made.

The ministries of environmental protection and education have sent teams to Changzhou to assist investigations and to ensure the public is kept fully informed.