Chemical Category Formation: Toxicology and REACH . Dr Steven Enoch Liverpool John Moores University 14 th May 2009. Is Regulatory Toxicology Important?. Number of stories about the toxicity of chemicals. Is Regulatory Toxicology Important?.
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Dr Steven Enoch
Liverpool John Moores University
14th May 2009
1Aptula AO and Roberts DW (2006) Chem ResToxicol 19; 1097-1105
2Enoch SJ et al (2008) SAR QSAR Environ Sci 19; 555-578
X = electron withdrawing substituent e.g. CO, CHO, NO2, CO2R.
3Enoch SJ et al (2008) Chem Res Toxicol 21; 513-520
pEC3 = NC, w = 1.10
pEC3 = 0.55, w = 1.49
pEC3 = 1.82, w = 1.55
Increasing electrophilicity (w)
Increasing skin sensitising potential (pEC3)
pEC3 = 1.25, w = 1.61
pEC3 = 1.64, w = 2.10
pEC3 = 4.04, w = 3.90
w = 1.61,EC3 = 5.5, pEC3 = 1.25
w = 1.73
Pred. pEC3 = 1.29 (1.31)
Pred. EC3 = 9.87 (9.30)
w = 1.80,EC3 = 7.5, pEC3 = 1.30
What about category formation when we don’t know about the mechanism of action?
Can we use chemical similarity to form categories?4
Read-Across within a Toxicological Category
4Enoch SJ et al (2009) QSAR Comb Sci in-press
Read-across prediction (atom environment similarity): D / X
Actual classification: D
Read-across prediction (fingerprint similarity): B
Actual classification: B