DeForest David K, Brix Kevin V, Adams William J
Parametrix, Inc., 411 108th Avenue NE, Suite 1800, Bellevue, WA 98004, USA.
Aquat Toxicol. 2007 Aug 30;84(2):236-46. doi: 10.1016/j.aquatox.2007.02.022. Epub 2007 Jun 16.
Bioaccumulation potential in aquatic biota is typically expressed using ratios of chemical concentrations in organism tissue (typically whole body) relative to chemical exposure concentrations, such as bioconcentration factors (BCFs). Past reviews of metal BCFs for aquatic biota, which account for water-only exposures, have shown that BCFs are often highly variable between organisms and generally inversely related to exposure concentration. This paper further evaluates trends in metal bioaccumulation data by evaluating data for bioaccumulation factors (BAFs) and trophic transfer factors (TTFs). Bioaccumulation factor data were compiled from field studies that account for combined waterborne and dietary metal exposures. Trophic transfer factor data for metals were compiled from laboratory studies in which aquatic food chains were simulated. Natural aquatic food webs are rarely sufficiently understood to properly evaluate exact predator-prey relationships (i.e., TTFs). Results indicate that field BAFs, like laboratory BCFs, tend to be significantly (p < or = 0.05) inversely related to exposure concentration. Bioaccumulation factors are frequently 100-1000 times larger than BCFs for the same metal and species. This difference is attributed to both lower exposure levels in the field and inclusion of the dietary exposure route. Trophic transfer factors for the metals reviewed, including selenium and methyl mercury were also observed to be inversely related to exposure concentration, particularly at lower exposure concentrations. These inverse relationships have important implications for environmental regulations (e.g., hazard classification and tissue residue-based water quality criteria) and for the use of metal bioaccumulation data in site-specific environmental evaluations, such as ecological and human health risk assessments. Data presented indicate that for metals and metalloids, unlike organic substances, no one BAF or TTF can be used to express bioaccumulation and/or trophic transfer without consideration of the exposure concentration.
水生生物群中的生物累积潜力通常用生物体组织（通常为整个身体）中的化学物质浓度与化学物质暴露浓度的比值来表示，例如生物富集因子（BCF）。过去对仅考虑水体暴露的水生生物群金属BCF的综述表明，BCF在生物体之间通常变化很大，并且一般与暴露浓度呈负相关。本文通过评估生物累积因子（BAF）和营养转移因子（TTF）的数据，进一步评估金属生物累积数据的趋势。生物累积因子数据来自考虑了水体和饮食中金属暴露的实地研究。金属的营养转移因子数据来自模拟水生食物链的实验室研究。天然水生食物网很少被充分了解，无法正确评估确切的捕食者 - 猎物关系（即TTF）。结果表明，实地BAF与实验室BCF一样，往往与暴露浓度呈显著负相关（p≤0.05）。对于相同的金属和物种，生物累积因子通常比BCF大100 - 1000倍。这种差异归因于实地较低的暴露水平以及饮食暴露途径的纳入。所审查的金属（包括硒和甲基汞）的营养转移因子也被观察到与暴露浓度呈负相关，特别是在较低暴露浓度下。这些负相关关系对环境法规（例如危害分类和基于组织残留的水质标准）以及在特定场地环境评估（如生态和人类健康风险评估）中使用金属生物累积数据具有重要意义。所呈现的数据表明，对于金属和类金属，与有机物质不同，如果不考虑暴露浓度，就不能用单一的BAF或TTF来表示生物累积和/或营养转移。
