Perfect response! Of course that data point makes the entire research to be almost certainly wrong.
Different mechanism. Per the article, the lowest dosage was below the body’s threshold for instigating a physical response i.e. inflammation. Higher dosages caused the body to encyst the aluminum before it could get anywhere, but the lowest dosage didn’t trigger this response, leaving the aluminum free to travel throughout the body where it could be absorbed by other tissues.
The formation of granulomas, if indeed they were actually observed (doubtful), makes the entire experiment invalid. That the alum was in small particles at the high rates is a further disqualification. Further, there is no evidence the authors studied the presence of other possible causes for the response at the low dose. It appears this work was rushed out for publication without a complete and true rate study being done. The conclusions outlined by the author of the article are far too sweeping for the quality of the work.
The only valid conclusion would be, “The results are suggestive and merit further study to develop a rate-response curve without the confounding effects observed at high doses.”