Nanomaterials in the food industry are used as food additives, and the main function of these food additives is to improve food qualities including texture, flavor, color, consistency, preservation, and nutrient bioavailability. This review aims to provide an overview of the distribution, fate, and environmental and health impacts of food additive nanomaterials in soil and aquatic ecosystems. Some of the major nanomaterials in food additives include titanium dioxide, silver, gold, silicon dioxide, iron oxide, and zinc oxide. Ingestion of food products containing food additive nanomaterials via dietary intake is considered to be one of the major pathways of human exposure to nanomaterials. Food additive nanomaterials reach the terrestrial and aquatic environments directly through the disposal of food wastes in landfills and the application of food waste-derived soil amendments. A significant amount of ingested food additive nanomaterials (> 90 %) is excreted, and these nanomaterials are not efficiently removed in the wastewater system, thereby reaching the environment indirectly through the disposal of recycled water and sewage sludge in agricultural land. Food additive nanomaterials also reach the environments directly through the disposal of food wastes in landfills and the application of food waste-derived soil amendments. Food additive nanomaterials undergo various transformation and reaction processes, such as adsorption, aggregation-sedimentation, desorption, degradation, dissolution, and bio-mediated reactions in the environment. These processes significantly impact the transport and bioavailability of nanomaterials as well as their behaviour and fate in the environment. These nanomaterials are toxic to soil and aquatic organisms, and reach the food chain through plant uptake and animal transfer. The environmental and health risks of food additive nanomaterials can be overcome by eliminating their emission through recycled water and sewage sludge.

Recent outbreak of geogenic arsenic (As) contamination in the Gangetic Delta basin of Bihar drew due attention of researchers as prolonged consumption of As-contaminated drinking water and food leads to arsenicosis, with the symptoms of pigmentation and keratosis in human. Although some information on As content in rice grain grown on contaminated soil is available specific to some areas of Bihar, practically no such information is available on wheat and maize crops. The present field experiment was conducted to evaluate the efficacy of organic amendments in reducing the availability of As in contaminated soils, followed by its uptake by wheat and maize. Accumulation of total As in wheat and maize grains varied from 0.02 to 0.11 mg kg⁻¹ and from 0.23 to 0.29 mg kg⁻¹, respectively, whereas available As in post-harvest soil varied from 1.07 to 1.33 mg kg⁻¹ for wheat and from 1.10 to 1.24 mg kg⁻¹ for maize. The organic amendments reduced the As accumulation in wheat grain to the extent of 84% (sugarcane bagasse (SB)), 50% (rice straw) and 40% (paddy husk (PH)) compared with control. Similarly, As content in maize grain was the lowest in SB-treated soil followed by rice straw and PH. Solubility-free ion activity model, based on pH, organic carbon and Olsen extractable As, was effective in predicting the As uptake by wheat and maize grains to the extent of 75% and 87%, respectively. Impact of organics in reducing health hazard for intake of As through consumption of wheat and maize grains grown on contaminated soil was also reflected in the values of the corresponding hazard quotient (HQ).

It is now well-established that not just drinking water, but irrigation water contaminated with arsenic (As) is an important source of human As exposure through water-soil-rice transfer. While drinking water As has a permissible, or guideline value, quantification of guideline values for soil and irrigation water is limited. Using published data from 26 field studies (not pot-based experiments) from Asia, each of which reported irrigation water, soil and rice grain As concentrations from the same site, this meta-analysis quantitatively evaluated the relationship between soil and irrigation water As concentrations and the As concentration in the rice grain. A generalized linear regression model revealed As in soil to be a stronger predictor of As in rice than As in irrigation water (beta of 16.72 and 0.6, respectively, p < 0.01). Based on the better performing decision tree model, using soil and irrigation water As as independent variables we determined that Asian paddy soil As concentrations greater than 14 mg kg⁻¹ may result in rice grains exceeding the Codex recommended maximum allowable inorganic As (i-As) concentrations of 0.2 mg kg⁻¹ for polished rice and 0.35 mg kg⁻¹ for husked rice. Both logistic regression and decision tree models, identified soil As as the main determining factor and irrigation water to be a non-significant factor, preventing determination of any guideline value for irrigation water. The seemingly non-significant contribution of irrigation water in predicting grain i-As concentrations below or above the Codex recommendation may be due to the complexity in the relationship between irrigation water As and rice grains. Despite modeling limitations and heterogeneity in meta-data, our findings can inform the maximum permissible As concentrations in Asian paddy soil.