This study gave African ostrich chicks drinking water containing 640 mg/L of sodium borate (printed as natrium biboricum) for 90 days and compared their thymus with untreated birds at 45 and 90 days. Thymic structure was not disrupted, but apoptotic cells tended to increase and autophagy and proliferation markers rose. Toll-like receptor 3 and 4 signaling did not appear to drive the change.
Key numbers
- Exposure: 640 mg/L in drinking water daily for 90 days, n = 3 per group; the paper does not state whether the dose is expressed as boron or as the salt (Methods, Animals).
- This paper reports no boron concentrations in tissue, food or water beyond the dosing level.
Methods (brief)
One-day-old ostriches were randomized to three groups; thymus histology, apoptosis (TUNEL), LC3A/B and PCNA immunostaining and TLR3, TLR4 and downstream gene and protein expression were assessed.
Evidence fitness
Supports an observation of immune-organ cell turnover changes in birds at a very high boron dose. It does not support human exposure, food concentrations or human toxicity claims.
Limitations
Three animals per group; one very high dose; dose expression unclear. Funded by the National Natural Science Foundation of China; no competing interests declared.
Related evidence
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