Developers have submitted plans to build 72 homes on land bordering Bourne Street and Cedar Avenue in the Coseley area of Dudley.
The site was formerly an open cast coal workings before it became a tip between the 1950s and1980s. It is contaminated with asbestos.
Marco Longhi, MP for Dudley North, has written to residents, raising concerns about the "instability of local mine shafts and the amount of contaminated land".
He also expressed concerns about a "lack of diligence" from planning officers in assessing potential issues around developing the land.
Mr Longhi said a report that developers were asked to carry out, on behalf of planning officers, contained details from a different planning application in Dudley.
He has threatened to raise his concerns with the Government's housing secretary.
"I was very disappointed to see that parts of the report seem to be copied from a report about another contaminated site in the borough - Cochrane Road," said Mr Longhi.
"This suggests to me officers have not read this detailed report."
In his letter to residents, Mr Longhi cited findings from the developer's report, including methane concentration, ground gas and potential ground movements that could affect nearby properties.
He said: "All of the above really should act as a red flag to officers.
"What is really concerning is methane concentration has increased from less than five per cent in July 2016 to 10 per cent in January 2021.
"Carbon dioxide concentration shows a rise of approximately five per cent to 20 per cent over the same period.
"Therefore, the toxicity of the site is getting worse rather than improving.
"It should be noted that the land was previously deemed so toxic by Dudley MBC [metropolitan borough council] that a planned urban forest was stopped as it was dangerous to disturb the soil.
"Conditions of the site have deteriorated since then.
"To conclude, I am so concerned by the lack of diligence and some of the judgements being employed by some officers of the planning department at Dudley Council that I intend to write to the Secretary of State for Housing, Communities and Local Government to highlight my concerns."
The planning application was made in September by Countryside Properties, however Dudley Council has not yet fixed a date for its planning committee to discuss the plans.
Dudley Council rejected an outline planning application for the site in October 2017.
More than 500 people signed a petition against plans.
However a successful appeal was made to the Government's Planning Inspectorate on March 2019.