His critics reply :
Leuchter 's concern with the safety of gassing methods appears to be a cause of his disbelief in its viability as he believed the venting process would pose a serious threat to the operators .
Leuchter 's critics reply :
Leuchter 's concern with the safety of gassing methods appears to be a cause of his disbelief in its viability as he believed the venting process would pose a serious threat to the operators .