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6 Exposure of experimental animals in farm and laboratory
environment (1) Chemical substances in farm and
laboratory environment
(a) Bisphenol A in feeds and litter
BPA concentration in feeds (n = 40) were in a range from less
than the detection limit (ND) to 2.9 ppb. Most of the samples
showed a level close to the detection limit (1 ng/g). The
highest BPA level, 2.9 ng/g, means that a mouse would take 17.4
ng BPA per day (assuming that a daily intake of 6 g) and a rat
72.5 ng/day (for a daily intake of 25 g).
The maximum BPA concentration in litter (n = 14) was 704 ppb.
None of feed water samples (n = 3) showed BPA (<0.02 ng/ml).
(b) Phthalic acid esters in feeds and litter
Feed samples (n = 12) were found to contain 116-511 ng/g DEHP,
25.1-944 ng/g DBP, and 22.2-157 ng/g BBP. The total PEA content
(sum of five PEAs) was 141-157 ng/g, corresponding to daily
intakes of 846-8460 ng/day for a mouse (assuming a daily feed
intake of 6 g) and 3525-35,250 ng/day for a rat (daily feed
intake of 25 g).
Litter samples (n = 13) contained 16.0-5070 ng/g DEHP, 19.6-1390
ng/g DEP, 440-900 ng/g DEP, and 198 ng/g DiNP; animal housing
air (n = 4) 27.6-32.1 ng/m3 DEHP and 261-357 ng/m3 DBP. No PAE
was found in feed water (n = 3).
(c) 4-Nonylphenol in feeds and litter
Of 35 feed samples, one showed no NP, and the rest contained
4.9-117.0 ng/g NP, corresponding to daily intake of 29.4-702 ng
for a mouse (assuming a daily feed intake of 6 g) and 122.5-2925
ng for a rat (daily feed intake 25 g).
All the litter samples (n = 15) contained NP. Specifically,
litter derived from waste newsprint showed 620-1020 ng/g and
others 2.3-65.3 ng/g. It is recommended to avoid litter with
high NP content, because exposure via litter is difficult to
estimate.
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