rpST

Comments:

Using data considered at the fiftieth meeting, when recombinant bovine somatotropins were last evaluated, the present meeting concluded that the excess levels of IGF-I residues in edible tissues from use of rpST in pigs are orders of magnitude lower than the amount produced endogenously in humans and are therefore extremely unlikely to represent any health risk for consumers. There was no evidence that pork meat, which contains pST, is allergenic in humans and because rpSTs are antigenically similar to native pST, residues of rpST in food are not likely to cause an allergic response in humans after consumption. In reaching a conclusion on the safety of rpST, the Committee noted the following: the lack of biological activity of rpST in rats after oral administration; the substantial difference in the amino acid sequence of somatotropin from pigs and humans; the absence of binding of rpST to human somatotropin receptors; the lack of effect in humans injected with either pST or serum plasmin-digested pST; and the lack of biological activity of ingested IGF-I. From the above, the Committee concluded that rpST can be used in pigs without any appreciable health risk for consumers from the administered rpST or from IGF-I residues in rpST-treated pigs. It established an ADI 'not specified'1 for rpST, which applies to the three products that were evaluated at the present meeting.

MRL Comment:

MRLs: Muscle, Liver, kidney and fat (pigs): NOT SPECIFIED. The MRLs apply to Grolene®, identified as (8-191)-porcine somatotropin; Reporcin®, identified as methionyl porcine; and Somagrepor®, identified as 1-(N2-(N-L-methionyl L-alpha-aspartyl)-L-glutamine]A6T:S11R:C183E:C191E porcine somatotropin. MRLs not established due to: lack of increased pST residues in edible tissues, lack of biologically-significant increase in IGF-1 intake in people who consume tissue from rpST-treated pigs, and lack of toxicological concern with regard to rpST and exogenous IGF-1 likely to occur in treated pigs.

Intake:

Estimated intake of IGF-1 (µg/p/d): 10.5 (rpST-treated pig tissues) vs 5.3 (untreated pig tissues)

Meeting:

52

Report: 

Tox Monograph: 

Residues: