Safety evaluation of certain food additives - ipcs inchem

110 PHOSPHOLIPASE C EXPRESSED IN PICHIA PASTORIS
No deaths or clinical signs were observed. Body weight was reported to be
unaffected on days 8 and 15, and no visible lesions were observed in any of the
animals at necropsy. The oral median lethal dose (LD50) was considered to be
greater than 2000 mg/kg bw (i.e. 1672 mg TOS/kg bw per day) (Fogleman, 2005a).
2.2.2 Short-term studies of toxicity
In a study conducted in accordance with GLP requirements, groups of
20 male and 20 female Sprague-Dawley rats were dosed by oral gavage daily with
BD16449 phospholipase C enzyme preparation (code DV16449, batch PLC-16449-
PD267B, 83.6% TOS) at 0 (control), 500, 1000 or 2000 mg/kg bw for 13 weeks. The
dose selection was based on the results of an earlier 2-week range-finding study in
rats, in which doses of phospholipase C up to 2000 mg/kg bw per day did not
produce any adverse effects (Fogleman, 2005b). In-life observations were
conducted for mortality/morbidity (twice daily), clinical parameters (pre-dosing and
1 h post-dosing), body weight (weekly), food consumption (weekly) and
ophthalmoscopic changes (once before study initiation and during the final week of
treatment). All surviving rats were sacrificed on day 91 or 92, with haematological
and serum clinical chemistry samples taken prior to sacrifice. A complete gross
necropsy was performed on a variety of weighed organs, including the adrenals,
brain, heart, kidneys, liver, ovaries, spleen and testes. Histopathological samples
were collected and preserved from cardiovascular, digestive, urogenital,
respiratory, lymphoid/haematopoietic, endocrine, skin/musculoskeletal and
nervous tissues.
Three rats, one at 500 mg/kg bw per day and two at 2000 mg/kg bw per day,
died on treatment days 10, 63 and 72, respectively. Based on the absence of any
clinical signs prior to death or a correlation of dose with time to death, these deaths
were considered to be due to gavage misdosing. There were no treatment-related
clinical signs observed throughout the study. Although slight increases or decreases
in group mean body weight gains were reported during the study, these differences
had no effect on the group mean body weights of the treated rats compared with
controls. The mean food consumption among treatment groups was not significantly
different relative to the control groups; however, a statistically significant increased
group mean food consumption was reported for the 500 and 1000 mg/kg bw per
day females on days 15 and 22, respectively, relative to the controls. These changes
were considered incidental and unrelated to the treatment, as no dose–response
was evident. No test article–related ophthalmological findings or effects on
haematological parameters were observed. Although a few statistically significant
changes in haematological parameters in the test article–treated group compared
with the control group were noted, the values remained within the historical control
values for the laboratory and were considered incidental and unrelated to the
treatment. Similarly, a few statistically significant changes in clinical chemistry
parameters were reported for the test article–treated rats relative to concurrent
controls; however, all values remained within the historical control values for the
laboratory and were considered incidental and unrelated to the treatment. No
treatment-related findings were observed with respect to gross necropsy, organ
weight changes or histopathological examination. Overall, it can be concluded