What Is the Hazardous Materials Identification System?

Hazard identification refers to the process of identifying basic properties such as the way and characteristics of a substance that causes adverse effects on people and organisms (individual organisms, sensitive groups or ecosystems), and determining the probability or degree of specific adverse effects caused by chronic or acute exposure . It is the primary work in the site risk assessment process, and it is also one of the core contents of establishing a site conceptual model. Identification of hazards and environmental factors should be based on field observations and surveys and collected data to identify actual and potential hazards to the identified assessment objects as much as possible. ^[1]

Evaluate adverse health effects based on evaluations of all available toxicity and mode of action data. It mainly solves two problems: the properties of any factor that may cause human health hazards; a clear hazard condition may appear ^[3]

Hazard identification is based on the analysis of a variety of data derived from observational studies of humans and livestock, animal experiments, laboratory in vitro studies, and analysis of structure-activity relationships. From the existing experimental and observational studies, it is possible to determine the properties of any toxic and adverse health effects and the target organ or target tissue of the toxic effect ^[3]

Absorption, distribution, metabolism, excretion studies

At the beginning of the experiment, the absorption, distribution, metabolism, and excretion (ADME) of the substance should be studied first, which will help determine the appropriate experimental animal species and toxicology experimental dose for animal experiments. The qualitative or quantitative differences in ADME between test animals and humans should be understood as comprehensively and accurately as possible, which can provide important information for identifying the harm caused by exposure and the subsequent risk assessment process ^[4] .

Animal experiment

Because epidemiological research is expensive, the process is complex, and information is often lacking or difficult to obtain; compared to in vitro experiments, animal experiments usually provide more comprehensive toxicological data, so most of the toxicological information in hazard identification comes from animals experiment. Animal experiments can provide information on the following aspects: first, the absorption, distribution, metabolism, and excretion of the toxicant; second, the toxic effect indicators, threshold doses or no harmful effects of the toxicant; and third, the toxicological action mechanism And its influencing factors; the fourth is the interaction between substances; the fifth is the body's metabolic pathways to poisons, the enzymes and metabolites involved in metabolism; the sixth is the possibility of chronic toxicity and its target organs or tissues. Animal experiments commonly used for hazard identification include: acute toxicity experiments, repeated administration toxicity experiments, reproductive development toxicity experiments, genetic toxicity experiments, etc. ^[4] .

In vitro experiments

In vitro toxicology experiments are mainly used for toxicity screening to provide more comprehensive toxicological information, and can also be used to study specific toxic effects of local tissues or target organs. Commonly used in vitro experiments for hazard identification include: alternative methods for acute toxicity experiments, in vitro methods for genotoxicity / mutagenicity experiments, in vitro methods for repeated dose exposure experiments, in vitro methods for carcinogenicity experiments, and in vitro methods for reproduction and development toxicity experiments. The rapid advances in biotechnology such as molecular biology, cell tissue and organ culture have provided good technical support for the development of in vitro experiments ^[4] .

Epidemiological information

What the epidemiological investigation obtained is human toxicity data, which is very important for the identification of hazards in food, and is the most valuable data for hazard identification. Data may come from controlled experiments, monitoring studies, epidemiological studies of populations with different exposure levels, and experimental or epidemiological studies, clinical reports, case investigations, etc. conducted in specific populations. Epidemiological studies used for risk assessment must be performed in accordance with accepted standard procedures. When designing epidemiological studies or applying positive data for epidemiological studies, individual differences in human sensitivity need to be considered, as well as factors that may affect susceptibility and other confounding factors such as genetics, age, gender, socioeconomics, nutritional status ^{[ 4]} .

Quantitative structure-activity relationship

Structure-activity relationship is the structure-activity relationship, which is used to indicate the relationship between the biological activity of a substance and its structure and functional groups. This method is very effective when using known structural analogues of chemical homologues or using identified target data to predict chemical activity. Quantitative structure-activity relationship analysis can use a quantitative structure-activity relationship (QSAR) model, which can be used to screen, understand, and predict the activity of chemicals, estimate the physicochemical properties and toxicity of chemicals, and use the classification method to optimize chemicals Next experiment. However, the model also has certain limitations.For example, the prediction results of the model can only be used for the type of activity selected as the basis of the correlation; biological data describing standard effects are required when modeling, because the experimental conditions (such as temperature, Ionic strength, species, age, etc.) may affect the comparability between biological effects; QSAR models can predict the activity of a group of chemicals with the same mechanism of action, but cannot predict an unexpected type of activity, etc.

Structure-activity relationship analysis is widely used in hazard identification, such as potential genotoxicity and ecological toxicity. Based on the toxicity analysis results of a large number of existing chemicals, the structure-activity relationship analysis can be used to predict the potential toxicity of a new chemical. At present, this method has been applied to the evaluation of packaging materials migratory substances and fragrances ^[4] .