Everything in the
world around us is made up of chemicals. Living organisms such as plants,
animals and humans are all made up of chemicals. Chemicals are integral part of daily life of people
around the world. Use of chemicals around the world is increasing with the
growing production in countries. Chemicals have played a major
role in the development of human societies – in agriculture and food; in
industry and transport; in housing and in health. The entire World has poisoning itself with
the “miracle of modern chemistry” as found in all the pesticides, plasticizers,
additives, preservatives, detergents and other chemicals. Chemical impacts are complex, unknown. Chemicals can enter the air, water and soil,
when they are produced, used or disposed. These
chemicals are known to exhibit various harmful effects on human biology,
covering everything from neurological and infertility problems to cancer and
hormonal disorders.
Over 11 million
chemical substances are known and some 60,000 to 70,000 are in regular use.
Between 200 and 1000 chemicals are produced in excess of one tonne annually.
Currently new chemicals are entering the market at the rate of about 600 each
month (or over 7000 per year) (Lillibridge 1997). Of the 80,000
chemicals in general use, only about 3,000 have been stringently tested for
health impacts on humans. A new study from the University of California, San
Francisco reveals that 100 percent of expectant mothers are contaminated with
highly toxic synthetic chemicals. The study, published in Environmental Health Perspectives, concluded, “certain PCBs, organochlorine pesticides, PFCs,
phenols, PBDEs, phthalates, polycyclic aromatic
hydrocarbons (PAHS) and perchlorate were detected in 99 to 100%
of pregnant women.”
Chemical
contamination may originate from manufacturing, processing, transportation,
storage, distribution, use and waste disposal. Chemical incidents can happen
anywhere and at anytime. Lorries can spill their contents, rail tankers can overturn
and clouds of chemical vapour can drift anywhere in the wind. More than 4 billion tonnes of hazardous chemicals
are moved each year around the world by motorway, rail, and pipeline systems.
PBT chemicals
Persistent, bioaccumulative and toxic (PBTs) substances are a
class of compounds that have high resistance to degradation by abiotic and
biotic factors, high mobility in the environment and high toxicity to cause
birth defects, cancers and other health effects. PBTs transfer easily among
air, water and land and cross human boundaries. The U.S EPA has identified 31
as PBTs (28 organic chemicals plus 3 metals and their compounds) e.g., Polychlorinated
chemicals (e.g., DDT, PCBs), Poly brominated chemicals (e.g., organo-bromines),
Poly fluorinated chemicals (e.g., organoflurorines), benzopyrene, alkyl-lead
and mercury compounds.
PAH chemicals
Polycyclic aromatic hydrocarbons are a family of long lived
chemicals that cling to sediments, bioaccumulate in fats and difficult to
degrade. PAHs are similar to PCBs and other polychlorinated chemicals but PAHs
do not contain chlorine. They are
produced by incomplete combustion of fossil fuels and wood burning. Natural PAH
sources include forest, grass fires and volcanic eruptions. Air borne PAH
particulates settle on the water, food, crops and other vegetation. The route
of 90% of human exposure to PAHs is from food consumption, especially leafy
vegetables and unrefined grains. Breathing air borne PAH particulates cause respiratory
distress. Benzopyrene is a best known human carcinogen.
VOCs
Volatile organic chemicals (VOCs) are chemicals that
transform quickly from liquid to vapour.
VOCs are found in paints, paint thinners, lacquers, hair sprays,
perfumes, oven cleaners and dry cleaning liquids. VOCs also emanate from wood finishes,
plywood, panelling, fibreboards, particleboards, carpeting, furniture,
permanent- press fabrics, draperies and mattress ticking. Motor vehicle
products such as gasoline and oils emit VOCs. VOCs contribute to the formation
of ground level ozone. VOCs are soluble
in water which can result in pollution. VOCs are flammable and can be toxic to
humans and wildlife. One of the most widespread VOCs is formaldehyde, classified
as a probable human carcinogen by the U.S EPA. It causes nasal cancer in
laboratory animals and it irritates the eyes, nose, throat and lungs. Another
common VOC, chloroform is a by-product of the process used to sanitise drinking
water, in some water treatment plants. VOCs that accumulate in air tight
buildings/cabins of jet planes contribute to ‘sick building syndrome.’
Petrochemicals
They form the basic raw materials in the manufacture of a
large number of materials such as fertilizers (ammonia), plastics, fibres, rubbers
(nylon, polyester, acetate etc.), and paints. They have also been used in the
manufacture of pesticides, lubricants, adhesives and solvents. The production
processes of ammonia, acetone, ethyl alcohol, acetic acid, acetic anhydride,
glycerine significantly based on petrochemicals. Nearly more than 80% of the
organic chemicals used in chemical industry are based on petrochemicals.
Some notable injurious chemicals
Phthalates are
chemical plasticizers. Pharmaceutical pills are often coated with phthalates to
give them a shiny finish. They’re also used in children’s toys, medical
devices, personal care products, sunscreens and even sex toys. On the personal
care side, phthalates are found in perfumes, eye shadow, liquid soap, nail
polish and hair spray. Phthalates are known as “endocrine disruptors” because
they interfere with normal endocrine system function — potentially leading to
obesity and birth defects. Oxybenzone,
the active ingredient in many sunscreens, is a hormone disruptor and could even
damage the nervous system. Perchlorate,
also known as the “rocket fuel chemical,” is used in the manufacture of
automobile airbags and other vehicle parts. It’s also present in many
fireworks, and is frequently found contaminating the water supply. Metal like mercury is highly toxic and its compound methyl mercury is a confirmed neurotoxicant. It builds
up in the food chain, notably in certain food fishes and enters the human food chain.
It damages the developing brain. It is also genotoxic: it is known to pass
through the placental barrier and the blood-brain barrier putting the unborn at
risk. It can cause permanent damage to the central nervous system, lungs and
kidneys. Possible sources of metal contamination include residues
migrating into foods from soldered cans, leaching from utensils, contaminated
water, glazed pottery, painted glassware and paints.
General characteristics of hazardous chemicals
Toxicity is the
inherent property of a chemical to produce adverse biological effect.
Mobility is the ability
of a chemical to travel through the environment.
Persistence is the
ability of the chemical to remain in the environment for a long time.
Synergistic action - the
combined effect of two different chemicals is greater than the individual effect.
Bioaccumulation is
the selective accumulation in the bodies of living organisms.
Biomagnification – the
concentration of bioaccumulated chemical in the bodies of living organisms
increases as they travel up the food chain.
“Be aware of our
potential exposure to hazardous chemicals in the home, workplace and
environment.”
The Stockholm Convention and POPs
The Stockholm convention on persistent organic pollutants (POPs)
2001 is an international agreement by the nations of the world to address the
global chemical pollution. It was signed by 128 country parties in 2001 and
come into force from May 2004. POPs are chemical substances that persist in the
environment, bioaccumulate through the food web and pose a risk of causing
adverse effects to human health and environment. POPs include 12 chemicals (dirty dozen) such
as the organochlorine pesticides: DDT, endrin, dieldrin, aldrin, chlordane,
toxaphene, heptachlor, hexachlorobenzene, mirex; and the industrial chemicals
and by-products: PCBs, dioxins, and furans. The Convention aims to eliminate
the production, use and emissions of POPs.
Green chemistry
Green chemistry is the science – based design of chemicals,
chemical processes and products that minimize the use and generation of
hazardous substances.
12- Guiding principles of green chemistry
1.
Prevention –prevent waste generation.
2.
Atom economy –design efficient design synthetic
methods.
3.
Less hazardous chemical syntheses- design
production methods – less toxic by-products.
4.
Design safer chemicals-minimum toxicity of
products.
5.
Use safer solvents and auxiliaries.
6.
Design for energy efficiency.
7.
Use renewable raw materials.
8.
Reduce derivatives
9.
Use catalytic reagents.
10.
Develop in-process control of hazardous
substances.
11.
Prevent the potential for chemical accidents.
12.
Design for chemical degradation.
Warnings for safe chemical use
Stay informed – be aware of the characteristics for e.g.,
toxicity of chemicals.
Choose non-toxic or less-toxic household products – follow instructions
and warnings for safer use.
Make healthy diet and life style choices – avoid tobacco
products. Choose fresh foods.
Reduce the potential for indoor and outdoor chemical
exposures.
Get involved – participate in public policy development.