CHEMICALS HAZARDS AND TOXICITY

Hazard A hazard is generally anything that can hurt you or make you ill.

Hazardous chemical

A material that has physical or chemical characteristic of potential for causing harm human injury, damage to property, damage to environment or some combination of these is known as hazardous chemical.

Chemical Hazard

The undesired effects which are caused with the absorption of hazardous chemicals by the human body- are called chemical hazards. The hazardous chemicals alone in concentration, or when mixed with other chemical substance, can cause injury, disease or death.

TYPES OF CHEMICAL HAZARD

HEALTH HAZARD

PHYSICAL HAZARD

PHYSICAL HAZARD• Flammable gases• Flammable aerosols• Oxidizing gases• Gases under

pressure• Flammable liquids• Flammable solids• Self-reactive

substances and mixtures

• Pyrophoric liquids

• contact with water, emit flammable gases

• Oxidizing liquids• Oxidizing solids• Organic peroxides• Corrosive to metals• Combustible dusts• Pyrophoric gases

HEALTH HAZARD• Acute toxicity• Skin

corrosion/irritation• Serious eye

damage/eye irritation• Respiratory or skin

sensitization• Germ cell

mutagenicity• Carcinogenicity• Reproductive toxicity

• Specific target organ toxicity – single exposure

• Specific target organ toxicity – repeated exposure

• Aspiration hazard• Bio hazardous

infectious materials

Types Of Chemical Hazard

Naturally Occurring ChemicalsEx. Mycrotoxin, Pyrrolizidine AlkaloidesIntentionally Added ChemicalsEx. Preservatives: Nitrite and Sulfiting agents.Unintentionally Or Incidentally Added ChemicalsEx. Pesticides, Lead, Arsenic, Mercury.

WHMISWorkplace Hazardous Materials Information System

Goals- Prevent Health Hazards Reduce Accidents

The effect a certain chemical depends on several factors

• The routes of entry - The physical properties of the substances- Work practices- The nature of the exposure- Combined exposures- The susceptibility of workers- Toxicity

Effect Of Chemicals

- Causing irritation - Allergies- Lack of oxygen - Systemic poisoning- Cancer- Damage to the unborn fetus- Effects on the future generations- Pneumoconiosis (Dusty lung)

Controlling Chemical Hazards in the Workplace

• Reduce or eliminate the use of hazardous chemicals whenever possible.

• Maintain adequate ventilation systems to reduce concentrations of airborne chemicals.

• Practicing good personal hygiene (e.g. washing hands) and maintaining regular workplace

cleaning routines.

• Learn how to avoid carrying hazardous substances home.

• Introduce administrative controls to minimize exposure to chemicals (e.g. rotate workers through different jobs or locations.

• Perform maintenance work in off-hours so that accidental release of toxic substances will affect fewer workers).

• Use personal protective equipment and devices.

• Maintain equipment in good order to prevent leaks and breakdowns that may release toxic substances.

General Tips for Chemical Safety

Know how to protect yourself from the health hazards of the chemicals you use.

Read the warning labels on any chemical before you use it.

Remember that an unlabeled chemical is a dangerous one.

Never sniff or smell an unlabeled chemical.

Always follow the directions and precautions listed on the label.Always dispose of a chemical properly.

TOXICOLOGY

“All substance are poisons”; there is none, which is not a poison. The dose differentiates a poison and a remedy.

Sources of Toxin:

• Environment• Food/Feed/Water• Drugs

Environment

Air Pollution Carbone monoxide Nitrogen oxides Smoke

Poor Ventilation Ammonia, Hydrogen Sulfide

Volatile Compounds Chlorine, Hydrocarbon fuels

Toxicity Toxicity is the degree to which a substance can damage an organism.

Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant

as well as the effect on a substructure of the organism, such as a cell (cytotoxicity)

or an organ such as the liver (hepatotoxicity).

Toxicity is the capacity of a chemical compound to produce injury.

Some possible outcomes of Toxicant:

- Death after a short period of time- Acute toxicity

- Cancer / mutation in DNA

- Skin / eye irritation

- Fertility problems

- Carcinogenicity / mutagenicity

- Reproduction effects

- Sudden heart failure and death

Types of ToxicityAcute toxicity

Sub-acute toxicity

Sub-chronic toxicity

Chronic toxicity

Conditions of strong poisoning

1. High temperature2. Deep or rapid breathing3. Long working hours4. Combination of two or more poisonous substance

Median Lethal Dose (LD50) LD50 may be defined as the statistically derived single dose of a chemical (mgkg-1) that can be expected to cause death to 50% of a given population of organisms under a defined set of experimental conditions. LD50 is used to classify and compare toxicity among chemicals. The toxicant can be graded according to their LD50 values are as follows:

Degree of harmfulness LD50 (mg/kg ) Degree of harmfulness LD50 (mg/kg )

Extremely toxic < 1 Slightly toxic 501 – 5000

Highly toxic 1 – 50 Practically non-toxic 5001 – 15000 Moderately toxic 51 – 500 Relatively harmless > 15000

Median Lethal Concentration (LC50)

LC50: Concentration of a toxicant (mg/m3) in air to kill 50% of the animals exposed for the specific length of time.

Maximum allowable concentration (MAC) of toxic chemicalsIt is the maximum concentration of toxic chemicals that healthy male adults can breath for 8 hours a day over a period of years without any harmful effects on his health 

The lower the MAC value, the more poisonous is the substance.

Odour perception limit (Threshold of smell) The concentration of the substance in the air at which the smell of the substance becomes noticeable is called odour perception limit. It is not directly related to MAC value. Some poisons such as C0 has no smell at all. MAC value of toxic substances may be higher or lower than the odour perception limit of those substances. It is obvious that the smell is not only the condition of a toxic hazard.

MAC/odour perception limit of some chemicals:

Chemical MAC value (ppm) Odour perception limit (ppm) Ammonia Benzene Carbon tetrachloride Toluene

25 10 10 100

5 100 70 50

Human Health and Heavy Metal Exposure

Metals, a major category of globally-distributed pollutants, are natural elements that have been extracted from the earth and harnessed for human industry and products for millennia.

Metals are notable for their wide environmental dispersion from such activity; their tendency to accumulate in select tissues of the human body;

and their overall potential to be toxic even at relatively minor levels of exposure.

Adverse health effects of metals are illustrated in following table:

Name of Metal Adverse Health Effects Metal Exposure Arsenic, As Skin pigmentation, Hyper keratosis,

Nasal congestion, Abdominal pain, Cancer- Skin, Lungs, Lump glands

Drinking water, inorganic arsenic compounds formerly used in pesticide sprays, Wood preservatives, arsenic containing fossil fuels, leaching of mine tailing, smelter runoff, paints and Microelectronics industry.

Lead, Pb Hypertension, Anemia, Hemoglobin Synthesis, Convulsion, Coma, Renal failure, Death.

Combustion leaded gasoline, Drinking water (lead pipe, lead solder.) Solder used in food can, paint, ceramic ware etc. Pigments, glaze solder, automobile batteries, cable sheathing, weights.

Cadmium, Cd Kidney damage, Painful bone, Joint disease (Rice contaminated),Cancer- Liver, Prostate

Contaminated in river by tannery wastage. Smelting plants, Pigments, metal plating, Cigarette, and some plastic and batteries.

Chromium Dermatitis, Nasal cavity, Ulcers on the hands and arms, Inflammation of larynx, Liver and Bronchitis, Lung cancer.

Contaminated in river by tannery wastage, Dyeing, Paints industry.

Mercury Kidney damage, memory loss, insomnia, timidity and delirium.

Manufacture of fluorescent lamps, Dental amalgams, Building industries, Chemical and metal processing