Chemical Risk Assessment: Importance, Toxicity Testing, And ADI Determination Essay.

Types of Toxicity Testing

Discuss about the Food Additive Related Question Answers.

Chemical risk assessment is an important process that is used to protect the society and the surroundings from unnecessary hazardous materials it utilizes several regulatory actions such as hazard identification, dose response assessment and assessment related to exposure so that the risk characterization can be carried out and regulatory action against that can be taken (Crevel et al. 2014). The assessment of the hazardous material can be carried out using several core biological and toxicological in vitro and in-vivo studies. These toxicity studies are general systemic toxicity, acute toxicity, genotoxicity, carcinogenicity and neurotoxicology. Whereas, the biological tests are determined to understand the level of arsenic, cadmium, led and mercury and several other heavy metals that affect the health of humans (Weir et al. 2012). These in vitro and in vivo testing are used to understand the mechanism of toxicity and to characterize the metabolism of the chemicals.

The general systemic toxicity is determined to understand the target organs for the toxic material. This is generally dependent on the principles of repeated dose protocol. For the testing, dose selection is an important aspect as the higher dose should not lead to death and the lower dose should not determine any adverse effect (Covello and Merkhober 2013). This testing is conducted over a duration as repeated dosing are important. For the tests, the subjects are divided into three sections of sub-acute, sub chronic and chronic and they are separated by the dose of toxic material ingested to determine the effectiveness (Bolon et al. 2012). The observation of the toxicity is determined by observing the mortality, body weight and feed intake of the test animal, hematological and ophthalmological tests, urinalyses, necropsy and reversibility to previous condition.

Acute toxicity is the response of an organism which has been exposed, ingested or injected with a chemical toxicant as a single or multiple exposure dose. The time span for acute toxicity is shorter and within that shorter span, the effect of the toxic substance on the organism is determined (Wood et al. 2012). This testing is not generally carried out as human system requires much longer and higher dose and time span to feel or observe the adverse effect of chemical substance on human body, however if the food material is contained with high microbial or heavy metal related load, acute effects are observed. Hence, it is involved in food product regulatory testing (Hermanns?Clausen et al. 2013). Therefore, it is necessary to develop ARfD related study in food and drinking water and appropriate observation and evaluation should be carried out related to single or multiple dose studies so that effect of these chemical toxins can be determined effectively (Wood et al. 2012).

General Systemic Toxicity

Genotoxicity and neurotoxicity are two important toxicological and chemical testing that are carried out to determine the adverse effects of toxic substances. Where Genotoxicity determines the adverse effect of the toxic substance of inherited genetic material, the neurotoxicity determines the effectiveness of toxic materials that exerts adverse effect on the nervous system of the humans (Pieper et al., 2014). The assay that are conducted to understand the degree of genotoxicity are DNA repair related toxicity, gene mutation related toxicity and chromosomal aberration. In these clinical studies both in vitro and in vivo approach is carried out using which somatic cell assay, germ line cell assay, specific locus test is carried out in mice (in vivo), and Mouse lymphoma L5178Y, Mouse lymphoma P388F (Wang 2013), Human lymphocytes and several other testing are carried out in vitro. The biological tests, which are carried out to understand the effectiveness of heavy metals on the health of the consumers. The inorganic and organic arsenic, cadmium, lead and mercury related testing are carried out which are found not only in food, water and beverages but also in cosmetics, environmental pollutions, dental amalgam diet, vaccine related diet and so on. There are several analytical methods, using which such levels in these products are determined. These methods are primarily determine and quantify the effect of these heavy metals on the health of the consumers (Pieper et al. 2014).

In the above section, the required toxicological and biological tests have been mentioned, which is required to conduct prior to dispatch in the market and national and international agencies such as European chemical Agency, European Food safety authority and medicine agency should check the compliance of the product with the guidelines so that consumer safety can be determined. However, there are situations, when it is not required to carry out a full set of toxicological studies (Covello and Merkhober 2013). For example, if the genotoxicity testing has been carried out for the additive or medicinal product and the result shows the harmful effect of the product, then it is not required to carry out acute toxicity or neurotoxicity. Therefore, in such situation where utilization of one toxicological test can determine the adversity of any substance, it is not required to carry out another steps (Pieper et al. 2014).

According to the World Health Organization (2018), The Acceptable Daily Intake or ADI is the estimated amount of chemical present in food, drinking water or beverages, that can be ingested to human body and that do not exert any adverse effect on the human body. This chemical is expressed in food or drink on a body weight basis and is evaluated as milligram of chemical on kilogram of body weight. Products which are generally put under scrutiny for determination of toxic substances and their ADI are food additives, drugs, usage of pesticides and residues while preparation of that food product (Huang et al. 2014). Depending on this concept, there are several other levels such as acceptable risk, acceptable reference dose, adverse effects and acceptable level of treatment are determined. According to current research, ADI is the standard within which the chemical food additive does not show any adverse effect on the humans and therefore is meant safe for the consumption of a healthy human being. The process that determines the level of toxicity is dependent on two aspects, which are No observed adverse effect level and the safety factors (Shahidi and Ambigaipalan 2015).

Acute Toxicity

The no observed adverse effect level is determined by the toxic endpoints and is dependent on number of factors including the source of animal, its sex, genetic variation, age, diet, environmental variations and histological criteria used by pathologists. Hence, it is the highest amount of dose that do not exert any adverse effect on the health of the consumer (Geissler and Powers 2017).  However, there are researches that determine the endpoint in animal samples as the adverse effects that is visible with lowest duration of exposure. However, in both the conditions, the adverse effect should not be visible in the research animal. The other concept that helps to determine the Acceptable Daily Intake is the safety factors. Use of this factor is dependent on the observation, that determines that within food and drinking products toxic chemicals are present in amount or threshold that do not produce toxic effects in the consumer. Tis safety factors needs animal and human testing both as the level of selectivity, threshold acceptability and effects are different for both humans and animals (dos Santos et al. 2013).

These two factors are important for determination of ADI and according to (), it is estimated by dividing the Non observed effect level or NOEL of the test substance by the safety factor of the product. The determination of NOEL is expressed in mg per kg of body weight of the test animal and While consumption, the food additive below the level of ADI is termed as estimated daily intake and determined as safe for the consumption purpose (Huang et al. 2014). The primary reason behind the concept is that, ADI is calculated to understand the most sensitive level at which the human body cannot retain the adverse effect of the chemical ingested as it is the highest exposure of that ingredient. This is the ADI is determined and the NOEL and safety factors are the type of data or studies which is required to determine the level of ADI (Shahidi and Ambigaipalan 2015).

There are several in vitro and in vivo studies that are need to be carried out by the risk assessor as risk assessment while complying the existing policies and frameworks.  The risk assessment steps are composed of four steps such as hazard identification, hazard characterization, exposure assessment and risk characterization (Judsonet al. 2014). According to these steps, the tests or studies that are carried out are chemistry or specification related tests, toxicological studies, exposure assessment and so on. Further, characterization of Acceptable Daily Intake or ADI is also carried out. Further depending on the activity of the toxicological substances, the toxic substances present in food additives are divided in three categories such as reduction, replacement and refinement (Peters et al. 2012). For the in vitro testing of the toxic substances absorption studies are conducted as well as in vitro gastrointestinal metabolism are carried out. On the other hand, for in vivo assessment absorption, distribution, metabolism and excretion are taken out. Besides these toxicokinetics, with experimental animals, or the human kinetics data are also conducted so that the effectiveness of these in human system can be predicated. Further for food additives, in vitro mammalian cell micronucleus tests, and bacterial reverse mutation assay are also conducted complying with the OECD guidelines and within in vitro testing micronucleus test, comet assay and transgenic rodent assay are carried out prior to safety declaration of any food product (Denys et al. 2012).

Genotoxicity and Neurotoxicity

While risk assessment, it is important for any food additive or chemical used in the production, preservation or packaging of the product to comply with the guidelines of the safety levels of that chemical in human ingested amount (Peters et al. 2012). Therefore, while assessment, if any food additive was found with negative result while in vitro and in vivo genotoxicity assay, and the two yearlong chronic toxicity testing determines its adverse effects as tumors, then the food additive will not be include in the safety list and the ADI will be calculated for the specific product and the accepted risk factor will be assessed for the same so that the safe quality can be included in the food product for human consumption (Denys et al. 2012).

Trans-generational toxicity is the study of toxic effects faced by the current generation and defines the adverse conditions that will be faced by the next generation. For Trans generational studies researchers focused on aspects such as chemical toxicity, early life related nutrition, radiation, smoking and food and water related toxins that this assignment has discussed in the previous answers. Schoevers et al. (2012) determines that the hazardous food additives this generation is consuming, directly hampers the child of the next generation through the mother. Therefore, need of a pre-defined protective approach for the chemical and toxin related risk assessment becomes important. Researchers, conducted a study to understand the effect of hazardous material on a pregnant women and the fetus inside her and determined that the hazardous material alters the genetic structure of the fetus and hence, the mutation or structural change sin DNA can occur up to third generation offspring. In this experiments general and easily available hazardous materials were used such as plastic additives, jet fuel, bug repellent and pregnant rats were involved in the study to determine the adverse effect of such chemicals (Yu et al. 2012). Further to determine the Trans generational effect of the chemical, the rats were bred for three generations and those generations were not exposed to further chemical toxins. It was found that the third generation rats have damaged reproductive system, the female rats had earlier onset of puberty, and male rats had dead sperm cells. Further they had increased risk of obesity. Kim, Kwak and An (2012) determined the effect of Trans generational responses on the development, growth and health of consumers in their research and from this research the implications of trans generational toxins can be easily determined (Kim, Kwak and An 2012). They researched regarding the genetic material that transfers the chemical mutation from one generation to another and they found that non-coding RNAs and epigenetic inheritance is the primary reason for the transfer of such mutated genes from the first generation to all the offspring. Therefore, from this research example, it is evident that the trans-generational toxic effects can be observed up to third generation and the effects can vary from damaged reproductive system to abnormalities in somatic cells. Further in the generation which is exposed to those hazardous chemicals, mutation is the primary effects that alters their cellular and physiological appearances and exerts effects such as obesity, infertility and cancer (Schoevers et al. 2012).

Steps in Risk Assessment

Trans-generational toxicity is the concept according to which, if the pregnant woman is exposed to hazardous chemicals for a longer duration of time, the adverse effect is transferred to the third generation of offspring and numerous physical and cellular adverse effects are observed in all those offspring (Liu et al. 2015). There are evidences from relevant researches that determine the concept and its reality. In a research conducted by Wang et al. (2013), the researchers were determined to observe the Trans generational toxic effect on tomato plant and the chemical that was used to determine the effect was cerium oxide nanoparticles. This product is used as polishing and engine enhancement agents. They treated the tomato plant with the chemical throughout their life and observed the tomato plant seed for any changes. After the study, in the second generation, the tomato plant developed extensive root hairs, as well as they generated higher amount of ceria and the quality of tomatoes also degraded due to the exposed chemical. Hence, this research determines the truth and effectiveness related to trans-generational toxic effects (Stem et al. 2014).

Another research was conducted by Schoevers et al. (2012) and they were destined to determine the effects of Zearalenone (Zen) which is a mycotoxin in Pig. This mycotoxin was generated through food and feed commodities, and the mode of disruption was its endocrine disruption. The effect of this chemical was observed in the F-1 generation of the pig and oocyte of that pig was collected for that purpose. When the observations were carried out, it was found that the follicle dynamics were not modified, but the follicle integrity decreases and the Zen concentration increases. Further, the quality of the healthy follicles decreased and it leads to premature oocyte depletion in adulthood. On the other hand, research conducted by Schwindt (2015), were targeted for the Trans generational toxic effects in aquatic animals and endocrine disrupting compounds effects were calculated in the research. The endocrine disrupting compounds were used in this experiment on the aquatic animals and for a longer period of time and after the experiment, alteration at multiple level was observed. The experiment determined the generational consequences of EDCs however, a clear demonstration of heritable generational consequences was not observed. Hence, this research article do not provided positive implication for trans generational toxic effects. However, depending on the other three research articles from Wang et al. (2013) and Schoevers et al. (2012), trans generational toxic effect is an important aspect and it occurs if the exposure to chemical is longer and effective.

Hazard Identification

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