Ecotoxicology is the part of environmental science that melds the fields of ecology and toxicology. Major issues addressed by ecotoxicological studies include chemical element transport (that is, their movement in the environment), fate (for example, biotransformation), and influence (examples include lethality, endocrine disruption and bioaccumulation) within ecological systems. Biomonitoring is a significant tool in ecotoxicology for humans as well as wildlife.

Occupational Toxicology is involved with health effects from exposure to chemicals in the workplace. This field grew out of a need to save workers from toxic substances and to make their work environment safe. Occupational diseases influenced by industrial chemicals account for a large number of death, and new cases of illness each year all over the world.

Food Toxicology is involved in serving a safe and edible supply of food to the consumer. During processing, a number of substances may be mixed to food to make it look, taste, or smell better. Fats, oils, sugars, starches and other substances may be added to change the flavour and taste of food. All of these additives are studied to determine if and at what quantity, they may produce adverse effects. A second area of interest includes food allergies. Almost 30% of the American societies have some food allergy. For example, many people have trouble digesting milk, and are lactose intolerant. In addition, toxic elements such as pesticides may be applied to a food crop in the field, while lead, arsenic, and cadmium are naturally exist in soil and water, and may be absorbed by plants. Toxicologists must determine the acceptable daily intake level for those substances.

Medical Toxicology is a medical subspecialty converging on the diagnosis, management and prevention of poisoning and other adverse health issues due to medications, occupational and environmental toxins, and biological agents. Medical Toxicology is officially known as a medical subspecialty by the American Board of Medical Specialties.

Global warming is the gradual heating of Earth's surface, oceans and atmosphere. Scientific consideration of global warming is increasing. The Intergovernmental Panel on Climate Change (IPCC) reported in 2014 that scientists were more than 95% confident that global warming is being caused mostly by increasing concentrations of greenhouse gases and other common (anthropogenic) activities.

Pollutants ranging from simple inorganic ions to compound organic molecules. The water pollutants are all divided up into many classes. Every class of pollutants has its own specific ways of entering the environment and its own specific risks. All classes have major pollutants in it that are known to many people, because of the various health effects.

Environmental chemistry  treaties  with the study of the origin, transport, reactions, effects and fates of chemical species in the environment. These impacts may be felt on a native scale, through the presence of urban air toxins or toxic substances arising from an organic waste site, or on a global scale, through depletion of stratospheric ozone or global warming. The emphasis in our courses and research actions is upon developing a major understanding of the nature of these chemical methods, so that mankind's activities can be precisely evaluated

In aquatic toxicology, test animals are poikilothermic, i.e., they are cold-blooded; their body temperature is variable and usually rely on environmental temperature; thus toxicity may not be sufficiently predictable. In mammalian toxicology, the ‘dose’ of a test chemical can be calculated directly and accurately, and administered by a number of routes. But in aquatic toxicology, the ‘dose’ is identified only in terms of the concentration of the chemical in water and the dimension of exposure to it; the actual ‘absorbed dose’ is sometimes determined experimentally using bio-concentration and metabolic studies.

The Economic toxicology deals with the use and threats involved in the use of food additives in food preservation and processing, man-made fertilizers and pesticides in advanced agriculture. Poisoning, accidental or occupational, which is so common in the use of man-made pesticides and the contamination of food stuffs by these toxic chemicals are areas of interest in economic toxicology.

Risk assessment generally deals with identification of hazards, analyzing and evaluating the risks associated. The appropriate ways to reduce or to control the hazards is also studied. The General Approaches to Risk assessment involves techniques help in creating awareness about the different potential hazards, identifying the people who pose the major risk because of the biohazards; formulate the control measures and prioritizing the hazards and control measures. The methods of hazard control can be mainly considered under Elimination which also includes substitution, Environmental Engineering controls, administrative controls and specific protective equipment. Risk Assessment involves a lot of documentation such as hazard review, threats associated with the hazards, control measures implemented accordingly.

In most developed countries, domestic waste disposal is funded from a national or local tax which may be related to income, or notional house value. Commercial and industrial waste disposal is typically charged for as a commercial service, often as an integrated charge which includes disposal costs. This practice may encourage disposal contractors to opt for the cheapest disposal option such as landfill rather than the environmentally best solution such as re-use and recycling. In some areas such as Taipei, the city government charges its households and industries for the volume of rubbish they produce. Waste will only be collected by the city council if waste is disposed in government issued rubbish bags. This policy has successfully reduced the amount of waste the city produces and increased the recycling rate.

Environmental health express all the physical, chemical, and biological factors external to a person, and all the related issues impacting behaviours. It is directed towards preventing disease and creating health-supportive environments. A safe place to work is the vital element of environmental safety.