Toxicology 2 Course 6: Environmental Pollution and Heavy Metals

TOXICOLOGY 2 COURSE 6

CONTENTS

POLLUTION . INDUSTRIAL WATER POLLUTION • HEAVY METALS • LEAD • ARSENIC Emanuela Badea assistant professor | DVM | PhD | MSc Faculty of Veterinary Medicine of Bucharest UASVM

III. POLLUTION

Pollution is the introduction of contaminants (named pollutants) into the environment, which cause negative changes.

Human activities contaminate the planet's ecosystems - from one pole to the other, from the highest mountain to the deep ocean. Thus, toxic chemicals are found even in virgin forests and the blood of Arctic animals.

Pollutants can be both foreign substances or energies and naturally encountered contaminants. Pollutants can also be organic and inorganic, including radioactive. Pollution can take the form of chemical or physical factors (noise, heat, or light).

The major forms of pollution are the following: air, soil, water, radioactive, acoustic, visual, and thermal pollution.

Air pollution

Air pollution brings us to think of the black clouds of smoke from factories, from ships, or locomotives, which rise to the sky, but in reality, air pollution comprises various forms.

Air pollution consists of the release of gaseous pollutants or particles into the atmosphere. The most common gaseous pollutants are carbon monoxide, sulphur dioxide, chlorofluorocarbons, and nitrogen oxides, resulting from industries or produced by motorized vehicles.

Burning fossil fuels, both in power plants and in motor vehicles, releases impressive amounts of carbon dioxide into the atmosphere.

Photochemical ozone represents the formation of ozone at the ground level of the troposphere caused by photochemical oxidation of Volatile Organic Compounds (VOCs) and carbon monoxide (CO) in the presence of nitrogen oxides (NOx) and sunlight.

Smog occurs as a result of the reaction of NOx, SO2, ozone, smoke, and other particulates.

Particulate matter is classified according to their size in micrometres, and can be composed from both organic and inorganic particulates.

Organic particulates represent approx. 30% and can be plant-based particulates (starch granules, pollen, vegetal fibres, moulds, spores, etc.) and animal powders (particles of hair and wool fibres, feather residues, scaly cells, bacteria, etc.).

Inorganic powders, which add up to approx. 70% of particulate matter, are composed of particles of coal, silicon, limestone, graphite, quartz, magnesium, iron, zinc, cement, chamotte, city dust (organic particles, smoke, soot, etc.), cosmic dust, salt dust (evaporation of seawater), volcanic dust (gas, mercury, etc. up to a height of over 50 km, airborne thousands of km), eroded soil dust (storm in the desert that also involves organic substances), etc.

Air pollution is particularly harmful to animals when it takes the form of acid rain. When the water in the atmosphere combines with some chemicals (especially sulphur dioxide and nitrogen oxides emitted as a result of the burning of fossil fuel), weak acid compounds are formed. This acid rain can solubilize toxic aluminium from soil which, in low concentrations, 2affects fish in rivers and lakes, and in high concentrations acts lethally. Acid rain can also kill fish in lakes and rivers by lowering water pH. Acid rain affects trees in forests and contributes to air pollution, causing serious damage to humans and animals.

Long-term exposures to different types of air pollution, smog, and acid rain, cause chronic respiratory disease, lung cancer, and cardiopathies. Long-term exposures also produce significant climate change, which can have a substantial impact on food, water, and ecosystems.

Soil pollution

Soil pollution occurs when chemicals are released from underground discharges or leaks, among the most important soil contaminants being hydrocarbons, heavy metals, pesticides, and chemical fertilizers.

Disposal and non-removal of wastes from public or private property, or dumping waste and garbage in unarranged places may also cause the death of animals due to the toxic substances they contain (e.g., motor oil, detergents, pesticides, etc.).

Water pollution

Water pollution occurs as a result of the discharge of wastewater from commercial or industrial waste, intentionally or accidentally, into surface waters. In addition, the discharge of wastes into groundwater or the release of waste and contaminants into surface discharges that flow into surface waters (including urban and agricultural discharges, which may contain fertilizers and pesticides) can be dangerous.

Discharge of untreated domestic water or chemical contaminants (such as chlorine) from the treatment of sewage can both be harmful to the environment.

The disposal of garbage in improper places can lead the waste to leech into ground and surface waters.

Eutrophication is another problem, caused by water pollution with fertilizers. Fertilizers do not have direct toxic action, but their presence can alter nutrient content in freshwater or marine areas. Human activities, especially those in agriculture, have led to increased levels of nitrogen and phosphorus in the environment. In water, this abundance of nutrients, called eutrophication, can stimulate the excessive growth of phytoplankton and algae, which can in some cases have devastating consequences. Eutrophication, or "water flowering", due to toxic algae, known as "red tide" or "brown tide" (for their appearance in the water) can kill fish, mammals, and seabirds and harm humans. When algae and other organisms that have been allowed to develop as a result of excess nutrients eventually die, bacteria can consume all the oxygen in the water as a result of the decomposition process. This hypoxia creates a "dead zone" where fish and other living things cannot survive. More than 400 areas around the world have been identified as being affected by eutrophication, of which 169 are hypoxic.

Plastic objects, as well as other residues, can persist in the waters of the seas and oceans for years, being carried by marine currents. Some of these accumulate in the center of the vortex in the oceans, giving rise to impressive patches of garbage. The term "garbage patch" suggests floating islands of garbage, but in reality, few of these are visible on the surface. Instead, they are areas where there is a high concentration of objects that have been thrown overboard and other residues, especially small plastic fragments. This garbage can distribute toxic chemicals 3across the seas and oceans, destroy corals, and animals can suffer after their ingestion or if they get tangled up in this debris.

Visual pollution

Visual pollution can include both light pollution and actual visual pollution.

Light pollution is the excessive or misdirected use of artificial outdoor lighting, which can have a massive impact on wildlife (the impact on turtle feeding and reproduction is well documented; i.e., adults and freshly hatched offspring are drawn to the lights on the beaches, confusing them with the moonlight). In addition, light pollution interrupts the circadian rhythm for both humans and animals and may even contribute to the development of cancer.

Visual pollution relates to the presence of high-voltage lines, display panels on highways, landscape changes arising from surface mining operations, storage of garbage in open spaces, and residues from space.

Acoustic pollution

Noise pollution includes noise from roads, aircraft, industrial noise, and high-intensity sonars.

Noise pollution becomes an important problem for many animals, especially those living in the seas and oceans.

Due to the increase in shipping and oil drilling that takes place away from shore, noise pollution has begun to affect a very large number of marine mammals, whales and dolphins being the most affected. This is because whales and dolphins use their sense of hearing for many purposes, such as hunting, navigation, migration, reproduction, and for differentiating members of the same species, and all the artificial noise in the oceans make it difficult for them to carry out these actions.

Thermal pollution

Thermal pollution represents a change in water temperature as a result of human influences, such as their use as a coolant in power plants.

Radioactive pollution

Radioactive pollution results from activities in the field of atomic physics, such as nuclear energy generation, nuclear weapons research, and extraction of radioactive ores.

Natural radioactivity involves the existence of natural sources of ionizing radiation, represented by ionizing radiation of cosmic origin and ionizing radiation of terrestrial origin.

The effects of ionizing radiation on the body can be somatic, which occur at short intervals of irradiation in directly exposed organisms, and genetic, manifested in offspring by birth defects.

In conclusion, the effects of pollution on the environment include:

• biomagnification / bioamplification implies the situation in which toxicants pass through trophic levels, becoming exponentially more concentrated; when heavy metals and other toxic chemicals enter the environment, organisms can absorb them through the skin or ingest them with water and food; animals from the higher levels of the food chain accumulate these toxins in increasing concentrations, so that top predators (fish, birds, 4and mammals) may have much higher levels of these toxicants in the body and are prone to diseases, congenital abnormalities, and other effects.
• acidification of the seas and oceans as a result of carbon dioxide from emissions being dissolved in their waters
• global warming caused by greenhouse gas emissions, which affects ecosystems in various ways
• biodiversity loss as a result of competition between native and invasive species; invasive plants can release substances that function as growth inhibitors into the environment, altering the chemical composition of the soil, reducing the competitiveness of native species
• smog and fog can reduce the amount of sunlight received by plants, necessary for photosynthesis, leading to the production of tropospheric ozone, which is harmful to plants
• soil may become infertile and unsuitable for plant development, which will affect other organisms in the food chain;
• sulphur dioxide and nitrogen oxides can cause acid rain, which lowers the pH level in the soil; nitrogen oxides also fertilize the soil, changing the structure of ecosystem species

III. 1. INDUSTRIAL WATER POLLUTION

In animal farming, an essential factor is the insurance of adequate water from a hygienic point of view. Water pollution involves its impurification, dirtying, the appearance of new components, or the excessive development of its components that alter its organoleptic qualities, composition, and physicochemical properties in such a way that the life of the animals or the consumers is put at risk.

According to the nature of the polluting elements that water may contain, the pollution may be chemical, biological, or radioactive, and by the degree of toxicity, it may be:

• acute pollution, which evolves with well-expressed, strongly highlighted manifestations
• chronic pollution, which implies the existence in polluted waters of small quantities of toxic substances; toxicological manifestations are unclear, discrete and inconclusive, specifying the causes requiring laboratory examinations;
• latent pollution, which manifests itself visibly only under special conditions (change in the pH of the water, its temperature, or increase in the concentration of pollutants in the water, such as in case of high heat and prolonged drought).

According to WHO rules, based on the chemical content, water can be classified into three categories:

• water containing chemicals with direct and harmful action on the body (e.g., fluoride, lead, chromium, arsenic, selenium, cyanide, nitrates, etc.) 5