If permitted measures fail, the operator may use a syntheticsubstance not included in the National List.
如果上述允许的措施无效，操作者可以使用全美允许物质列表以外的合成物质。
2
Last week the issue was some leather cured with a known teratogenic substance, synthetic Nirret or something just as illegal that's still used in third world tanning.
上礼拜的问题是，部分皮革硫化时使用了致畸物质，某种非法但仍在第三世界用来硝制皮革的合成物质。
3
"Food additive" means any synthetic compound or natural substance put into food to improve its quality, colour, fragrance or taste, or for the sake of preservation or processing.