Wight Jeffrey, Doucette William
Utah Water Research Laboratory, Utah State University, Logan, Utah, USA.
Environ Toxicol Chem. 2023 Mar;42(3):655-662. doi: 10.1002/etc.5549. Epub 2023 Jan 31.
The high-production-volume chemical 4,4'-methylenedianiline (4,4'-MDA) is an aromatic amine used to manufacture 4,4'-methylenedianiline diisocyanate for polyurethane production. Based on 4,4'-MDA's octanol/water partition coefficient (K ) and correlations with the transpiration stream concentration factor (TSCF), significant plant uptake and root-to-shoot transfer are predicted. However, most correlations between K and TSCF were developed for neutral organics and may not be applicable for ionizable bases such as 4,4'-MDA. To investigate, TSCF values for 4,4'-MDA were measured using pressure chamber and intact plant approaches for tomato, soybean, and wheat (intact plants only). C-labeled 4,4'-MDA was used to increase analytical sensitivity and facilitate measurement of distribution within plant tissues. The TSCF of C-MDA determined using the pressure chamber method was 0.04 ± 0.00 for tomato and 0.17 ± 0.10 for soybean. These values were lower than predicted from log K and within the range of values for C-pyrene also measured in our study (0.14 ± 0.00 for tomato and 0.16 ± 0.09 for soybean). The TSCF values calculated from measurements made from intact plants grown to maturity were statistically equivalent to those obtained from the pressure chamber method for soybean and tomato. The distributions of C within the three plants species were similar, with the roots > leaves ≈ stems > fruit. The log root concentration factors for 4,4'-MDA ranged from 3.68 to 4.33 for the three plant species. This finding indicates that the aromatic amine sorption to root materials is much greater than would be predicted based on its log K and may be the reason for the limited root-to-shoot transfer observed in the pressure chamber and intact plant studies. Environ Toxicol Chem 2023;42:655-662. © 2023 SETAC.
高产量化学品4,4'-亚甲基二苯胺（4,4'-MDA）是一种芳香胺，用于制造用于聚氨酯生产的4,4'-亚甲基二苯胺二异氰酸酯。基于4,4'-MDA的辛醇/水分配系数（K）以及与蒸腾流浓度因子（TSCF）的相关性，预计植物对其有显著吸收和从根到地上部分的转运。然而，大多数K与TSCF之间的相关性是针对中性有机物建立的，可能不适用于像4,4'-MDA这样的可电离碱。为了进行研究，采用压力室法和完整植株法对番茄、大豆和小麦（仅完整植株）测定了4,4'-MDA的TSCF值。使用含¹⁴C标记的4,4'-MDA来提高分析灵敏度并便于测量其在植物组织内的分布。使用压力室法测定的¹⁴C-MDA的TSCF值，番茄为0.04±0.00，大豆为0.17±0.10。这些值低于根据log K预测的值，且在我们研究中测定的¹⁴C-芘的值范围内（番茄为0.14±0.00，大豆为0.16±0.09）。从生长至成熟的完整植株测量值计算得到的TSCF值，对于大豆和番茄而言，在统计学上与从压力室法获得的值相当。¹⁴C在三种植物中的分布相似，根＞叶≈茎＞果实。三种植物中4,4'-MDA的对数根浓度因子范围为3.68至4.33。这一发现表明，该芳香胺对根物质的吸附远大于基于其log K所预测的值这可能是在压力室和完整植株研究中观察到的根到地上部分转运有限的原因。《环境毒理学与化学》2023年；42：655 - 662。©2023 SETAC。
