During the early 20th century most substances that people were likely to encounter in their daily lives were derived with little modification from the earth, the animals, vegetables, crops or the mineral sources. Today there is an extensive existence of synthetic chemicals in the environment, a class which was not present until their creation by human scientific and industrial efforts. The domination of chemicals is increasing in our lives-can we imagine life without agro-chemicals, pharmaceuticals, preservatives, disinfecting agents, colorants, plastics etc.? Regrettably, this dependency on chemicals has resulted in too many cases of their misuse, especially in their disposal, or mal-or over-use in agriculture. Chemicals such as phthalate esters and polychlorinated biphenyls are considered to disturb human hormone messengers and effect fetal reproductive development. Reckless use of chemicals, careless disposal of chemical wastes causing ecological imbalance, and the lack of farsightedness contribute to a global threat. A major concern has been the prevalence of the common environmental contaminants in food,that is,pesticides and heavy metals. These metals, even if occurring in low concentrations pose a threat of being bioconcentrated and magnified in the higher trophic organisms of the food chain after being used for human consumption.National programmes to create mass awareness on pesticides and other food contaminants, and to assess their environmental impact, need to be launched and sustained.
It is an irony that the very disinfectants used for purifying drinking water can also be hazardous. Although unintended, chemical disinfection by-products cause health hazards. Numerous workshops and conferences have been organised by international bodies like EPA, CDC, NCI etc. to address these new health concerns.
|Odds & Ends|
Basic chromium (III) sulphate is widely used in the leather industry as basic tanning agent. The tannery workers are exposed to this element, mainly in the inorganic Cr (III) form or in the protein bound form (leather dust). Workers from tanning and retanning departments showed an inverse relationship between urine chromium and hemoglobin. Kornhauser and co-workers from Universidad de Guanajnato, Mexico observed lower urinary excretion of iron with increasing chromium serum in these same subjects. Their results suggest an adverse effect of chromium which is related with iron metabolism alterations and which can be observed in subjects with excessive chromium accumulation in the organism. They have recommended chromium urine test for the diagnosis of the observed adverse effect, but have also suggested the need for further studies to characterize quantitatively the relation between urinary excretion and the hemoglobin alterations.
( Ind. Hlth., April, 2002).
It is an irony that the chemical disinfectants used for purifying water can also be hazardous. Although pathogenic organisms provide the primary health risk from drinking water, chemical disinfection byproducts (DBPs) are another, albeit unintended health hazard. Disinfectants are powerful oxidants that convert organic matter and naturally occurring bromide in source waters to DBPs. Chlorine, ozone, chlorine dioxide and chloroamine are the most common disinfectants in use today, and each produces its own group of chemical DBPs in drinking water.
After the identification of the first DBPs, chloroform and other trihalomethanes (THMs) in chlorinated drinking water in 1974, an important public health and regulatory issue was born. Today, many drinking water utilities are switching from chlorine to alternative disinfectants such as ozone, chlorine dioxide, and chloramine in order to control THMs and haloacetic acids (HAAs), but this has created new issues. Source water conditions, including bromide, iodide, and natural organic matter (NOM) concentrations, and pH, can affect the levels and types of DBP species formed. For example, ozone use can significantly reduce or eliminate THM and HAA formation, however, it can produce bromate,a potent carcinogen in laboratory animal in source waters with elevated bromide levels.
DBPs that have been quantified in drinking water are generally present at nanogram to microgram per liter levels. Another concern is that although ~ 500 DBPs are known, few have been investigated for their quantitative occurrence and health effects. However, there are still unknown DBPs; only ~ 50 % of total organic halide (TOX) formed during drinking water chlorination has been identified. Studies are underway to uncover the missing DBP fraction, such as unidentified TOX and assimable organic carbon compounds in ozonated water. Numerous workshops and conferences have been organised to address the concern about-DBPs and new human exposure work is also being conducted (at CDC, NCI, EPA and other laboratories) in which blood and urine are being monitored for DBP.
National Cancer Institute (NCI) had linked chloroform to cancer in laboratory animals. DBPs effects on reproduction and development, including low birth weight, intrauterine growth retardation, spontaneous abortion are raising new concerns.
(Environ.Sci. Technol., May, 2002).
Dioxins are a heterogeneous mixture of chlorinated dibenzo-p-dioxin and dibenzofuran congeners. They are highly toxic by-products of incineration processes and of production of chloro-organic chemicals. Accidental poisonings have occurred repeatedly, the main human exposure being via the dietary route. Ruminants accumulate the dioxin emissions which are released mainly through industrial and municipal incineration and pyrolysis processes. Cow's milk and milk products, bovine adipose tissue, hen's eggs and fish are the main contributors to human dioxin exposure in adults. The highest exposure in the human population occurs in infants via breast-feeding.
So far there are no reports to show that acute toxic responses occur in humans under normal dietary habits generating background dioxin body burdens. Also no signs of chronic toxicity have been reported under these conditions. However, there are reports from accidentally highly exposed workers who had an increased incidence of infectious diseases suggesting a weakened immune system.Species comparison for dioxin body burden and effects based on adipose tissue concentrations conducted by W. Parzefall of the
University of Vienna, Austria, lead to the conclusions that (a) toxic symptoms are observed in rats and humans at similar endogenous dioxin concentrations (b) meals of high dioxin content will increase human body burden. (c) a single high intake by a normal adult individual does not pose any health risks. In any case, repeated intake of dioxin contaminated food must be avoided.
(Fd. Chem. Toxicol., 2002)
The common environmental contaminants of greatest concern in food are heavy metals, most notably cadmium, lead and mercury. Unlike some other metals these have no known beneficial nutritional value for humans, play no known role in metabolism, as no enzyme has been identified which specifically requires cadmium, lead or mercury as a cofactor. Among these two metals are however, extremely hazardous to life and have been involved in historic poisoning episodes of human populations and wildlife resulting from ingestion of contaminated foods and prey. The concentrations of cadmium and mercury are increasing in both anthropogenic inputs, and this continues to be a concern to toxicologists. The importance of individual food types as sources of Pb, Cd and Hg in the diet indicate fruits and vegetables as the biggest sources of Pb and Cd and sea food the biggest source of Hg. Heavy metals content of cooked foods, milk and water are also higher in certain areas. Contents of heavy metals were determined in raw milk samples obtained from 3 regions of Turkey differing in environmental pollution. Highest heavy metal concentrations were generally found in milk samples from the industrial region, followed by the intense-traffic region.
In recent years recycling in agriculture is a common method of disposal or utilization of waste. In general, raw sewage effluents, sludges and sewage-irrigated soils contain very high amounts of cations, anions, organics and heavy metals. Dispersion by leaching of the metals from irrigated soil and from settled bottom sludge in wetland sewage channels are the principal cause of groundwater contamination. A dietary survey was carried out on men from low and medium income groups belonging to sewage and tube well irrigated areas and were found to be more than WHO tolerable limits. Crops especially garlic, leafy vegetables grown in sewage water irrigated areas were found to contain higher concentration of Pb, Cd and Ni than those grown in tube well irrigated soils. Activated sludge, recommended as a cheap supplement in cattle and poultry feed is also contaminated with heavy metals along with pesticides and organic pollutants. In a study this sludge was found to contain Zn (1.82 mg/g), Ni (0.27 mg/g), Pb (0.17 mg/g), Cu (0.05 mg/g), Cr (0.006 mg/g) and Cd (0.005 mg/g). Even though sludge is a rich source of nitrogen matter, its supplementation in poultry and animals feed should be done cautiously otherwise, the metal contaminants in sludge biomagnify in the food chain.
Uptake of heavy metals in farmers fields varied widely among species and parts of plants. In many plants the roots tended to retain heavy metals more than foliage or above ground plant parts. Rice samples from 15 areas of Asia had been analyzed for Pb and Cd content. A study conducted in South India showed rice to be a major source of Cd and Pb among the rural population and economically deprived class. Concentration of Cd, Pb and Hg in organically grown grain (wheat, barley, millet, buckwheat, peas, mixed grains) and milled products ( wheat flour and bran ) obtained from 1993 and 1994 harvests in the Czech Republic were lower in organic samples than in corresponding crops grown in the same year by conventional intensive farming methods. In a survey by the Indian Council of Medical Research, a total of 198 samples of 20 brands of infant formula milk were collected from retail shops in and around Pune, Mumbai, Mysore, Lucknow and Ludhiana, and analysed for pesticides and metals. The study indicated high levels of metal contamination (As, Cd, Pb, Cu and Zn).
Heavy metals, even if occurring in low concentration pose a threat of being bioconcentrated and magnified in the higher trophic organisms of the food chain after being used for human consumption. Water samples from hand pumps, dug well, spring, stream and river were assessed for heavy metals. Hand pump water sample exhibited the highest degree of metal contamination.
A monitoring survey for Hg, Pb and Cd in a range of sea food (fish, bivalves and cephalopods) indicate that Pb bioaccumulation in marine food chains is declining. Hg levels determined in fish samples showed considerably less variation than Cd levels, indicating that Hg is being readily bioaccumulated in marine food chains. It is concluded that effective measures should be implemented to restrict levels of Hg and Cd entering the marine environment and human diets.
Lead has been recognized as a health hazard for centuries. One of the most studied metals, much information has been accumulated on its toxicity which is caused by acute or chronic environmental exposure is a constraint to the control, reduction, prevention, and intervention strategies although because of health concerns, lead from gasoline, paints, ceramic products and pipe solder has been dramatically reduced. Dietary exposure of it falling as a result of measures taken to reduce Pb contamination of the environment and food UK population ( 0.026 mg/day ) to Pb. The major sources of lead in drinking water are lead plumbing, soil carried into water by rain and wind, pesticides and fertilizers and wastewater from industries that use lead. Most individuals ingest lead almost daily via food which can contain lead by dust deposition on crops while growing or through food containers. Lead has been used for centuries as glazing and for the bright colours on ceramic pots and dishes. The amount of Pb that leaches from a dish depends on how the dish is used and the kind of food stored in it. Acidic food and drinks will leach Pb out of the dishes much faster than non acidic foods. The longer the food stays in contact with a dish surface, more the chances of Pb leaching into the food. Heating up food in Pb containing dish can speed up the Pb leaching process. However, the major exposure of Pb to the general population in food is through grains, vegetables and fruits.Exposure of General Population through Pb Contamination in Food
Lead levels in food samples from Ahmedabad were found to range from 0.55-2.5 ?g/gm in food grains, vegetables, fruits and cooked food (Pandya et al, 1983). Srikanth et al (1995) suggested that rice could be a source for higher lead intake in South Indian rural population while comparing the intake among different socio-economic groups. Dietary intake of Pb of population in Greater Bombay was estimated and found to be 245 ug/day from the Pb content in different food groups and the amount that group consumed by an average resident. For a suburban resident 85 % of the Pb intake comes from food.
Lead has been found in the blood and milk from urban Indian cattle and buffaloes. The consumption of milk from affected cattle or the consumption of crops raised in these areas could be dangerous to humans. A 10 year survey of coloured foodstuff in U.P. revealed the use of 5 non-permitted colours containing Pb levels higher than permissible levels.
Other sources of poisoning identified is the migration of lead from food containers. A study has reported the re coating of the inner surface of brass utensils with a mixture of Pb and tin, ("tinning"), this is widely practiced by artisans in India. The Sn-Pb alloy contained 55 to 70% lead levels, and water containing tamarind had 400-500 ug Pb/L after boiling for 5 min. Such acidic foods can leach out Pb. Lead leaching from Indian pressure cookers while cooking especially from the rubber gasket and safety valve, are minor sources of Pb concentration of cooked food. Migration of Pb solder used in flour mills is another example of Pb contamination.
Lead in the food chain comes mostly from direct deposit from the air to plants and from livestock eating soil laced with Pb as they eat the plants. As people have been encouraged to take calcium supplements, several investigators have drawn attention to their potential Pb toxicity. Because calcium carbonate is the most popular supplement the potential uptake of Pb from this product should be verified in a more comprehensive investigation, especially of young children.Cadmium
While cadmium is naturally present in low concentrations in soil ( Plants grown on sludge treated soil accumulate cadmium in a range from 0.1 - 3 ppm. The extent of accumulation depends on numerous factors, including the species of plant, the pH of the soil, and the ability of the soil to bind cations.Studies have shown that animals that graze on pastures that have been amended with surface applied sludge will ingest the sludge with the plants. Grazing cattle ingest 1-18% of dry matter as soil; sheep may ingest as much as 30%. Zinc, iron, and copper may also be elevated both in the sludges and the plants that grow from them, and may provide adequate protection against cadmium. for most agricultural animals it is the organ meats which accumulate cadmium to the greatest extent 5-200 ppm depending on the amount of exposure) and present the greatest hazard to humans; contamination of (or concentration in) muscle meats is a fraction of that in organ meats (usually 1- 50 ppb). No significant amounts are transferred to milk, and it is interesting that, unlike most other trace elements, cadmium exposure in laying poultry results in very little transfer to the eggs.
The problem of sludge contamination is not so much of a hazard to animals used in agriculture, although the potential for risk to human health through contamination of their food products hasn't been adequately assessed. However, there is a real potential for much greater exposure to wildlife such as birds, due to the accumulation in high concentrations (60-140 ppm) in invertebrates such as earthworms inhabiting contaminated sites. Cadmium also is a significant hazard to aquatic wildlife, as its bioconcentration factors are much greater for aquatic environments than terrestrial environments. Thus, it is found in greatest concentration in fish organs and shellfish. It also accumulates in very high concentrations in plankton.
The most well-known cadmium poisoning was first recognized in the Fuchu area of Japan in post-menopausal, multiparous women during the 1940's. The number of cases peaked in the years between 1955-1960. The syndrome, called Itai-Itai (Ouch!Ouch!) disease, includes severe bone deformities (osteomalacia). Exposure to cadmium resulted from consumption of rice from paddies that were contaminated with mining wastes. The estimated cadmium intake of Itai-Itai victims was 1 mg/day. This is 20 times the Maximal Permissible Exposure set by OSHA, and 200 times the normal intake in unexposed populations. While cadmium was recognized as a necessary player in this disease, nutritional deficiencies such as Vitamin D and calcium have also been suspected to play a role. Also, milling of rice removes most of the Zn, Fe, and phytate, but little of the Cd. Other crops, and shellfish as well, usually have increased Zn associated with increases in Cd, but this was not the case in Japan.Mercury
Sea foods are the biggest source of mercury. Hg levels in some fish species are so high that pregnant women are advised not to eat fresh water fish in Sweden. Similarly in the USA there are restriction on consuming fish from lakes in 32 out of 50 states. Increasing use of Hg in developing countries (chlor-alkali plants; gold extraction with Hg) particularly China , Brazil, India, Ghana and many South East Asia countries have resulted in accumulation of Hg in fish and poisoning of humans eating fish with high Hg content. While treatment of grain with mercury compounds used as fungicides has resulted in poisonings of wildlife and humans, fish present the greatest source of mercury contamination in food today. The FDA has set the maximal permissible level of mercury in fish at 1 ppm. Effects on the fetus as a result of maternal consumption of contaminated fish are the greatest concern, as epidemiologic studies have shown psychomotor retardation occurs at lower exposures, 800- 1700 ng/kg/day. Japan was also host of perhaps the worst outbreak of mercury poisoning in the world. This resulted when an acetaldehyde plant adjacent to Minamata Bay discharged metallic mercury into the bay. That metallic mercury was converted to methyl mercury by plants and microorganisms, and the MeHg accumulated in fish and shellfish. Cats around the bay were found staggering, and local fisherman suffered horrible deaths. Daily intake of methylmercury and total Hg from sea food (by the Mumbai population) was estimated at 0.5 and 0.8 mg, respectively. Iraq was the site of three major epidemics of mercury poisoning occurring from the mid-50's to the early 70's. This resulted from the consumption of bread made from seed grains treated with organomercurial antifungal agents by farmers. Levels of Hg in the diet of indigenous peoples of Canada showed high Hg exposure among communities with high consumption of marine mammals.Chromium and Nickel
The total intake of Cr through air, water and food works out to be 54 m/ug/day for the the adult population of Mumbai city. The dietary intake through food is the major contributor to the total intake of Cr. Cr and Ni leaching from various stainless steel utensils used in Indian cooking to acidic drinks (fruits juice, sweetened lime water, salted curd) was studied. Excessive ingestion of Ni was found whereas levels of Cr appeared relatively safe.CURRENT CONCERNS
Just one year after the declaration of a ban on endosulfan, the Kerala government had lifted this ban on the use of the pesticide on crops and plantation. However, the aerial spraying of endosulfan will continue to be prohibited for all crops. Specific clauses in the regulatory order have to be completed with, i.e. health safeguards for workers engaged in spraying and for nearby inhabitants.REGULATORY TRENDS
National Conference on "soil contamination and Bio-Diversity"
The Indian Network for Soil Contamination Research (INSCR) organised a conference on "Soil Contamination and Bio-diversity" at ITRC during Feburary 8-10, 2002 and was attended by more than 60 delegates from all over the country.The conference was inaugurated by Prof. S.A.H.Abidi,Member,Agriculture Services Recruitment Board,Govt. of India.
An INSCR oration on "Transgenic crops towards cleaner and safer environment" was delivered by Dr. George B Fuller of Mansanto Corporation, USA.Seminar on "Waste Management through Vermiculture: A Bane or Boon"
Great concern has been expressed in recent times on the environmental risks of solid waste, sediment and sludge from industrial and municipal sources. The major problem with respect to the hazardous waste management in India is the absence of a systematic assessment of the quality and pollution potential of hazardous industrial and municipal wastes.Vermicomposting is an ecofriendly way of treating solid wastes,hence a need was felt to discuss and share views of scientist and NGO's regarding risk/benefit of vermiculture. A seminar was held on "Waste Management through Vermiculture: A Bane or Boon" organised by WWF-India and ITRC Lucknow on 22nd March 2002IN A LIGHTER VEIN
Although this question has defied being answered conclusively, one scientist has taken on a related problem: the accumulation of unmatched socks in a drawer over time. In the March-April 1996 issue of Mathematics Today, Robert A.J. Mathews, an Oxford-based scientist and correspondent, explained the process: when one sock is lost, an old sock remains. Because pairs initially outnumber old socks, the next sock to be lost will most likely come from a pair. He even devised a complex equation to describe the old-sock phenomenon and concluded that the best solution, mathematically and practically speaking, is to "get rid of all your existing socks, choose two favorite designs, and stick to them."MINIPROFILE OF MERCURY
|Synonyms & Trade name:||Quick silver; Colloidal mercury; metallic mercury.|
|Properties:||Odourless, silvery, mobile, heavy liquid with a metallic lustre.b.p. 357°C; m.p.-39°C; r.d. (water=l) 13.6; r.v.d. (air=l) 7.0; v.p. in mbar at 20°C: 0.0016; sol. in water: none. Reacts with many metals forming amalgams, except with iron. Reacts with ammonia, amines, acetylene and oxalic acid to form compounds that are sensitive to mechanical shock. Incompatible with O2, oxidants, ethylene oxide. Attacks Cu &. Cu alloys.|
|Analytical Methods:||Collect mercury with a 3- section solid phase sampler, followed by analysis with atomic absorption spectrophotometer. NIOSH Manual of Analytical Methods, 2nd Ed. Vol. 6, 1980.|
|Uses:||Electrical apparatus, industrial control instruments, agricultural and industrial poisons, catalyst, preservatives, antifouling paint in thermometers, barometers, manometers, mercury vapour & fluorescent lamps, chlorine production. In biolers &: turbines for generation of electricity. In manufacture of explosives, in preparation of amalgams for artificial jewellery.|
|Hazards:||HAZARD RATING: HIGHLY HAZARDOUS|
|Environmental Quality Standards:||TLV : Air : 0.05 mg/m3 (skin); STEL : Air: 0.15 mg/m3|
inh-rat TCLo: 890 ng/m3/24 H (16 W male inh-rat TCLO: 7440 ng/m3/24 H (16 W male) inh-wmn TCLO: 150 ug/m3/46 D: GIT,CNS inh-rbt TCLO: 29 mg/m3/30 H
ROUTE SYMPTOMS FIRST AID TARGET ORGAN
inh Sore throat, headache, Fresh air, rest, artificail Resp. tract, CNS, GIT, & nausea brain-injury may resp, keep warm, rinse Kidney ing occur, dyspnea erythema, mouth drink plenty of water, tremors salivation,loose induce vomit if not unconscious teeth,vomiting,diarrhoea kidney injury may occur, stomatitis personality change. cont. Irr of skin & eyes, redness, Remove contaminated clothes, skin & eyes sensitization dermatitis wash with water & soap, rinse eyes with water CALL A DOCTOR
Examination for presence of tremor at rest or with movement, thyroid function tests, neurologic examination, serum creatinine, blod-urea,nitrogen; urine sediment; assay of mercury in urine, other indices of kidney function.
|Special High Risk Groups:||Pregnant women, foetus, fish consumers, individuals with diseases of CNS, skin, lungs, liver, kidneys and GIT.|
|Disposal||Bury in an approved dumping site or in an area where is no risk of contamination of ground or surface water.|
|Personal Protective Equipments:||Protective gloves, protective safety g oggles, breathing face shield (8" minimum).|
|Disaster Management:||When spilfled the substance breaks up into very fine droplets which scatter all over the place and become readily attached to clothing and the skin. Consult an expert, sweep up spilled substance, suck up droplets with special equipment, cover remainder with zinc powder, copper powder or special absorbent and collect carefully. After cleaning up, measure the mercury vapour pressure. Ventilate area of spill.|
|Packaging & Labelling:||Airtight unbreakable packaging.|
|Storage:||Cool, ventilation along the floor.|
|Transport:||Poison label required. TREMCARD for mercury to be carried by the driver of the vehicle.|
|Indian Context:||ISI Code of Safety: IS: 7812 -1975.|
|Notes:||The vapour pressure at room temperature is far above the MAC value, so that chronic poisoning is a hazard. It is advisable to inspect rooms where mercury is handled (including mercury filled instruments) regularly with the aid of special equipment. The substance pollutes the environment. Blanketing spilled mercury with sulfur is only effective as long as the mercury remains covered up.|
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