Table 4: Emblematic RfDo rounding inconsistencies in IRIS/the RSL Table.

Chemical

Mathematical RfDo

RSL Table RfDo

Analysis

bromomethane

 

 

 

1.40E-03

 

1.40E-03

Bromomethane and furan, with identical mathematical RfDos, should have identical RfDos 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 RfDo (i.e., the digits, and discounting the exponent) is slightly higher than that of bromomethane. While bromomethane’s RfDo is not rounded, benzaldehyde’s is rounded, and significantly so (reduced by 30%).

furan

 

 

 

1.40E-03

 

1.00E-03

 

benzaldehyde

 

1.43E-01

 

1.00E-03

 

fenamiphos

 

2.50E-04

2.50E-04

Hexachlorophene’s mathematical RfDo, identical to that for fenamiphos, is rounded up by 20% while fenamiphos’s mathematical RfDo is not adjusted.

hexachlorophene

 

2.50E-04

3.00E-04

 

 

 

methyl methacrylate

 

 

 

 

 

1.36E00

 

 

1.40E00

We would expect methyl methacrylate’s mathematical RfDo 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 non-zero 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 (E-02), and not to 1.40 as occurs with benzaldehyde (above). Of note, trichlorobenzene 1,2,4-’s RfDo reduction through rounding, of 32.43%, is the greatest magnitude adjustment of any RSL Table RfDo.

 

 

trichlorobenzene, 1,2,4-

 

 

 

1.48E-02

 

 

1.00E-02

 

malation

 

 

 

2.30E-02

2.00E-02

The RSL Table contains numerous instances of mathematical RfDos and RfCis 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) RfDo having been reduced just over 13% and acrylic acid’s RfDo being left unchanged.

acrylic acid

 

 

 

5.30E-01

5.30E-01