Well I don't know what exactly they said to you but that is odd because theres no reference to that in the atsdr report except for huge amounts of chlorite
Here is what it says
Respiratory Effects. Extremely limited information is available regarding respiratory effects inhumans following oral exposure to chlorine dioxide or chlorite. Respiratory distress was diagnosed in a patient who had ingested 10 g of sodium chlorite dissolved in 100 mL of water (Lin and Lim 1993).
However, the respiratory distress was likely secondary to other effects such as severe methemoglobinemia.
No adverse effects on respiration rate were seen in healthy adult males who ingested
chlorine dioxide or chlorite every 3 days (for 16 days) at increasing doses of 0.1, 1, 5, 10, 18, and 24 mg/day or 0.01, 0.1, 0.5, 1.0, 1.8, and 2.4 mg/day, respectively (Lubbers et al. 1981). Assuming an average body weight of 70 kg, the individual doses were approximately 0.0014, 0.014, 0.070, 0.140, 0.26, and 0.34 mg/kg/day, respectively, for chlorine dioxide and a factor of 10 lower for respective chlorite doses. No adverse effects on respiration rate were observed in other healthy adult males who ingested chlorine dioxide or chlorite in daily amounts of 2.5 mg (0.04 mg/kg/day) for 12 weeks (Lubbers et al.
1981).
Information regarding respiratory effects in orally-exposed animals is limited to a report of a significantly increased incidence of nasal lesions (goblet cell hyperplasia and inflammation of nasal turbinates) following 90 days of exposure to chlorine dioxide in the drinking water at concentrations that resulted in estimated doses as low as 2 mg/kg/day in males and 8 mg/kg/day in females (Daniel et al. 1990). These nasal effects were likely caused by inhalation of chlorine dioxide vapors released from the water rather than a systemic respiratory effect following oral exposure
So we can safely say there is no direct effect on the lungs by ingestion. the effect at huge doses is due to the effect on the blood cells ie likely methemoglobinanemia
I know this myself having suffered severe anaemia and repiratory distress as a result
Also as far as I know they don't believe chlorine dioxide gets into the blood
do they, only as chlorite, unless they are confirming Jim Humbles theories now