Table 4: Emblematic RfDo rounding inconsistencies in IRIS/the RSL Table.
Chemical 
Mathematical RfD_{o} 
RSL Table RfD_{o} 
Analysis 
bromomethane

1.40E03 
1.40E03 
Bromomethane and furan, with identical mathematical RfD_{o}s, should have identical RfD_{o}s appearing on the RSL Table as well. Instead, bromomethane was not rounded, and furan was rounded down (by just over some 28%).
Benzaldehyde’s mathematical RfD_{o} (i.e., the digits, and discounting the exponent) is slightly higher than that of bromomethane. While bromomethane’s RfD_{o} is not rounded, benzaldehyde’s is rounded, and significantly so (reduced by 30%). 
furan

1.40E03 
1.00E03 

benzaldehyde 
1.43E01 
1.00E03 



fenamiphos

2.50E04 
2.50E04 
Hexachlorophene’s mathematical RfD_{o}, identical to that for fenamiphos, is rounded up by 20% while fenamiphos’s mathematical RfD_{o} is not adjusted. 
hexachlorophene

2.50E04 
3.00E04 



methyl methacrylate

1.36E00 
1.40E00 
We would expect methyl methacrylate’s mathematical RfD_{o} to be rounded in some way since its last (i.e., hundredths place) digit is not a 0 or a 5, and given that benzaldehyde (in this table’s first example) is so handled on the RSL Table. It is curious that trichlorobenzene 1,2,4, a chemical with a nonzero hundredths place value (i.e., before the exponent) that is larger than methyl methacrylate’s hundredths place value (i.e., 8 vs. 6), and with the entire value being so close to 1.5, is rounded down to 1.00 (E02), and not to 1.40 as occurs with benzaldehyde (above). Of note, trichlorobenzene 1,2,4’s RfD_{o }reduction through rounding, of 32.43%, is the greatest magnitude adjustment of any RSL Table RfD_{o}. 
trichlorobenzene, 1,2,4

1.48E02 
1.00E02 



malation

2.30E02 
2.00E02 
The RSL Table contains numerous instances of mathematical RfD_{o}s and RfC_{i}s with decimals of 0.30 or 0.40 being rounded (either up or down), as occurs here with malathion. While their exponents are different (something that this paper’s analysis did not show to be a factor in rounding direction), malathion and acrylic acid are very differently treated, with malathion’s actual (i.e., RSL Table) RfD_{o} having been reduced just over 13% and acrylic acid’s RfD_{o }being left unchanged. 
acrylic acid

5.30E01 
5.30E01 