Confirmation of uterotrophic activity for 4-MBC in the immature rat - Correspondence

Schlumpf et al. (1,2) reported that the ultraviolet (UV) sunscreen component 3-(4-methylbenzylidine)camphor (4-MBC) is uterotrophic when administered either in diet to immature Long-Evans rats or by whole body immersion of immature hairless hr/hr rats into an oil solution of 4-MBC. Subsequently, Bolt et al. (3) questioned the validity of those data and referred to two negative unpublished immature rat uterotrophic assays of 4-MBC (4,5).

When the discussion between Bolt et al. (3) and Schlumpf et al. (6) appeared, we had already studied the uterotrophic activity of 4-MBC in immature rat uterotrophic assays using both oral gavage and subcutaneous injection as the route of administration. The report on these studies has been submitted for publication (7). Of particular relevance to the recent discussion (3,6), we found 4-MBC to be clearly positive in our standard immature rat uterotrophic assay (8). Activity was apparent in the oral study at 500 and 800 mg/kg/day and in the subcutaneous injection study at 500 and 1,000 mg/kg/day. In the oral gavage study (7), uterine weights were 22.0 [+ or -] 2.5 for controls and 32.5 [+ or -] 6.5 and 42.4 [+ or -] 6.0 for 500 and 800 mg/kg 4-MBC, respectively (mean + SD; p < 0.01 by analysis of variance and analysis of covariance with terminal body weight).

John Ashby
Syngenta Central Toxicology Laboratory
Alderley Park, Cheshire, United Kingdom
E-mail: john.ashby@syngenta.com

REFERENCES AND NOTES

(1.) Schlumpf M, Cotton B, Conscience M, Haller V, Steinmann B, Lichtensteiger W. In vitro and in vivo estrogenicity of UV screens. Environ Health Perspect 109:239-244 (2001).

(2.) Schlumpf M, Berger L, Cotton B, Conscience-Egli M, Durrer S, Flelschmann I, Haller V, Maerkel K, Lichtensteiger W. Estrogen active UV screens. Seifen-Ole-Fette-Wachse 127:10-18 (2001).

(3.) Bolt HM, Guhe C, Degen GH. Comments on "In vitro and in vivo estrogenicity of UV screens" [Letter]. Environ Health Perspect 109:A358-359 (2001).

(4.) Comotto L, Bussi R. Unpublished data.

(5.) Bachmann S, Hellwig J. Unpublished data.

(6.) Schlumpf M, Lichtensteiger W. "in vitro and in vivo estrogenicity of UV screens": Response [Letter]. Environ Health Perspect 109:A359-360 (2001).

(7.) Tinwell H, Lefevre PA, Moffat GJ, Burns A, Odum J, Ashby J. Unpublished data.

(8.) Ashby J, Tinwell H. Uterotrophic activity of bisphenol A in the immature rat. Environ Health Perspect 106:719-720 (1998).

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