The government has been told to “urgently engage” with ASTI after the union announced it is balloting its members on industrial action.
The teachers' union decided to ballot members on a range of issues that have emerged since schools re-opened, including "serious concerns" about the health and safety of school communities.
Issues raised include physical distancing in schools, provision of PPE, testing and provisions for high-risk teachers.
“The fact that high-risk teachers have been asked to work in crowded classrooms is unacceptable to us as a trade union,” ASTI President Ann Piggott said.
She also said teachers are reporting that new work practices are being implemented without any consultation with school staff.
Sinn Féin spokesperson on Education Donnchadh Ó Laoghaire said: "The issues can and must be resolved.
“The fact is that reopening schools safely has been challenging because we have an education system that is overcrowded, underfunded and understaffed.
"We have also raised the issue of high-risk staff.
“It is unconscionable that teachers who are at high-risk or who have relatives at home who are high-risk are being forced to work in an environment in which they do not feel safe.”
A Department of Education spokesperson said: “The reopening of schools has been a very important milestone for children in Ireland.
“The safety and wellbeing of staff students and the whole school community has been of paramount importance in planning for school reopening by the Government.
“The Department has continuing engagement with the Public Health Authorities on a weekly basis so that schools can remain open safely and is working with stakeholders.
“In relation to high risk staff, an enhanced occupational healthcare service has been put in place to categorise staff into one of three Covid 19 risk categories.
“A review process has been put in place where concerns remain.
“The Department will continue to engage with all education partners including ASTI in the coming months.”
Meanwhile, the Irish National Teachers’ Organisation (INTO) has launched a campaign to reduce class sizes in Ireland in the forthcoming budget.
The union, which represents more than 40,000 primary school teachers and principals, says our average class size of 25-30 is well above the European average of 20 pupils per class.
As a result, social distancing is - the union says - severely compromised and “may well challenge Micheál Martin’s great intentions to keep [schools] open”.
In Cork County, for example, the union says 21% of pupils learn in classes of more than 30 children.
And in Cork City, more than 1,600 pupils learn in classes of more than 30 children.
The ASTI ballot will also cover the difficulties faced by returning teachers who are being forced to work precarious contracts and those enduring unequal pay.
Earlier this year, the ASTI central executive council voted to ballot the union’s 17,000-plus members on industrial action over the unequal pay of teachers who entered the profession since 2010.
The ASTI took industrial action, including strike action, over unequal pay in 2016 - one of the last times it took strike action.
Since then there has been some improvement in the pay of new entrants to teaching.
But in January, the union announced that “despite ongoing campaigning by the ASTI and the other teacher unions, unequal pay remains”.