Industrial Toxicology Research Centre,Lucknow(U.P.)
| No. 3
In everyday life all human beings are getting exposed to chemicals directly or indirectly. The outcome of such exposure depends upon the awareness and the nature of the chemicals on one hand and the physiological status of the individual on the other. An immature baby or aged man or a malnourished individual could be more sensitive to the same amount of the chemicals. Likewise, the inert and insoluble chemicals may not pose much adverse effects as compared to highly reactive chemicals.
An understanding of the possible health effects of low level long-term exposure is therefore essential. The information already available in this respect should be widely publicized so as to create awareness among persons. All out efforts to reduce exposure to chemicals should be understood as prevention is always better than cure. Data on the health effects of chemical exposure in early life and its impact on development, reproductive and nervous system and immune function need to be generated.
The introduction of the genetically modified food has aroused health and environmental safety concerns all over the world. It may be true that these products are not likely to cause health hazards, yet it is essential to assure the safety of the new products using science based approaches and even employing new test systems and models.
Odds & Ends
Deep Water Dumping slows down Global Warming
Peter Brewer and colleagues from the Monterey Bay research Institute in Moss Landing, California, argue that global warming could be slowed down by removing carbon dioxide, a key green house gas and one of the main causes of global warming, from the earth's atmosphere and dumping it into the bottom of the sea. They managed to dispose off several litres of liquid carbon dioxide by the surface of the Pacific Ocean. Deep sea dumping has always been seen as an attractive option because of the ocean's great size and its capacity to store carbon dioxide.
Liquid carbon dioxide at depths in excess of 2.6 km and temperature below 2oC, is denser than sea water, and so should sink to the bottom of the ocean. But some may prefer a hydrate, a heavy ice like solid formed in a physical reaction between carbon dioxide and water at low temperatures and high pressures, made up of cages of water molecules containing trapped carbon dioxide. If the idea proves correct, it raises the prospect of a hybrid storage system with liquid carbon dioxide on the sea bed under an icy crust of hydrates.
(Chem. Indust. Digest, Sept-Oct 1999)
Xenorem- A Process to Degrade Chlorinated Pesticides
A new process Xenorem is developed by scientists at Mississauga, USA, which uses local soil bacteria that feeds on organic waste to convert chlorinated pesticides to less toxic byproducts. The researchers mixed the soil with large amounts of the waste and the heap of soil was aerated every few weeks to provide a cycle of alternating anaerobic and aerobic conditions for the bacteria to degrade the pesticides. DDT is considered to be one of the worst pollutants because its breakdown products such as DDE (dichloro diphenyl dichloro ethane) were thought to be indestructible. But now it is shown that it can be degraded. The new process could remove a wide range of contaminants by approximate one half to two thirds. This technology is very cost effective..
(Chem. Indust. Digest, Sept-Oct 1999)
Developing countries can reduce emissions and improve their economies
A new report shows how developing countries can reduce air emissions from power generation without sacrificing economic growth. Prepared by the metal and recycling groups, fifteen government subsidies for the timber, mining, oil, energy and waste disposal industries are listed. According to the authors, these subsidies lower the cost of products made from new materials, giving them a competitive advantage over those made from recycled materials. They state that federal subsidies, which may amount to as much as US$ 13 billon over the next five years, "are part of a complex system of economic preferences discouraging recycling."
The system of tax and spending subsidies was created decades ago, at a time when natural resources Pew Center on Global Climate Change, Developing Countries and Global Climate Change outlined four strategies to degrade CO2 and other emissions that contribute to global warming. The levels of those emissions are expected to triple in the next 20 years, to 10% of all global emissions, if present trends continue.
The report examines the costs and benefits of using natural gas and renewable energy sources for power generation and privatizing state-run power monopolies. It finds that renewable energy options were economically viable when electricity delivery costs were considered part of the costs of electricity delivery generation. Increased use of natural gas and renewable energy sources would reduce CO2 emissions by almost 25% over current energy sources. The report predicts that privatization would slightly reduce CO2 emission and increase overall economic benefits, while improving the efficiency of electricity supply and demand could reduce CO2 emission by as much as 10%.
This study is based on an aggregated analysis , and its authors warn that the results may not be applicable to all countries. They note that countries could also participate in the Clean Development Mechanism, in order to increase available financing to accomplish necessary, country-specific reforms.
The Pew Centre's next step in this ongoing project is to conduct detailed follow-up case studies on power generation in Argentina, Brazil, China, India and South Korea. (www.pewclimate.org)
Faster phase-out of CFC production
Under the Montreal Protocol, developing countries must reduce the production of CFCs to 1995-97 average levels starting 1 July 1999, and then they must cut back rapidly to 50% by the year 2005. These chemicals be completely phased out by the year 2010. The multilateral funds to help China, the world's largest producer of CFC's and halons, close down its production facilities for these chemicals by the 2010 deadline. It is negotiating with India, which has the second largest production capacity among developing countries, to develop a programme to close its production facilities.
The Scientific Assessment Panel presented a report prepared jointly with the Inter-governmental panel on Climate Change, Aviation and the Global Atmosphere, which assess aviation's impact on ozone depletion and climate change. The report concludes that aircraft emission will increase to 5% of all greenhouse gas emission by 2050 (compared to 3.5% in 1992) unless they are controlled. The impacts would be most significant if a large fleet of supersonic aircraft went into service.
The meeting took place amid growing concern that global warming may already be making ozone depletion worse than predicted. Greenhouse gases that trap heat in the lower atmosphere near the earth's surface prevent heat from escaping into the lower stratosphere, where the ozone layer is located. The resulting lower temperature can accelerate the chemical processes that destroy ozone. Reports presented by the 1998 panels on the assessment of the ozone layer, and on environmental impacts and technological and economic aspects, showed that the total amount of chemicals in the lower atmosphere has peaked, though some gases such as halons are still increasing. The Working Groups concluded that recovery of the ozone layer will be observable over the next two decades if the Protocol is fully implemented by all the countries. (www.unep.org/ozone)
Asian countries to limit trade in hazardous chemicals
The Asian region workshop was the first to promote implementation and ratification and to inform national authorities about the Rotterdam Convention's obligations. Such information is essential to the Convention's implementation. Participating countries (which include Bangladesh, Bhutan, China, India, Indonesia, Japan, Korea, Laos, Malaysia, Mongolia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand and Viet Nam) identified needs for implementing the Rotterdam Convention, including national enforcement legislation and strengthened infrastructure. The proceedings, now available in report form, contributed to the sixth session of the Intergovernmental Negotiating Committee working under the new global agreement on trade in hazardous chemicals and pesticides on 12-16 July 1999 in Rome.
Substance subject to the Conventions requirements include, chloradane, chloridmeform, chlorobenzilate, DDT, dieldrin, dinoseb, 1,2-dibromomethane (EDB), fluoroacetamide, hexachlorocyclo hexane (HCH), heptachlor, hexachlorobenzene, lindane, and mercury compounds, and certain formulations of monocrotophos, methamidophos, phosphamidon, methyl-parathion, and parathion. Industrial chemicals included in the Convention are crocidolite asbestos, polybrominated biphenylks(PBBs), polychlorinated biphenyls (PCBs. Polychlorinated terphenyls (PCTs, and tris (2,3 dibromoprophyl) phosphate.
Agrobiotechnology: A Boon for Mankind
Dr. P.N. Viswanathan
Industrial Toxicology Research Centre
The last century saw a phenomenal rise of chemical technology and natural resource utilization to impart an overall better quality of life, but the outfall was considerable side effects on man, material and environment. This century it is biotechnology, with its meteoric upsurge, causing obvious apprehensions about its long term impact, sustainability and safety. Fortunately man has learned from his earlier mistakes and safety can be built into biotechnology unlike in the chemical revolution. With the high precision of powerful tools of molecular biology, selection of specific genes with the desired quality, their transfer in a safe, error free, stable way and monitoring field performance through specific markers are more effective than with multitude of man made chemicals. Agrobiotechnology also gained from the experience of quality and safety assurance guidelines, test protocols and surveillance methods evolved to achieve chemical safety. FDA guidelines for substantial equivalence that any natural toxicant present in the parent should not increase by more than 10% and that the principal nutrients should not decrease by more than 20% as compared to parent and selection of gene, donor and acceptor based on familiarity, helps to build in safety with the technology.
It would be self contradictory and scientifically unjustifiable if we readily accept foods produced by the traditional methods of genetic modification that entails thousands of recombination events, most of which are uncertain, unpredictable and unknown on the one hand, and on the other be apprehensive of accepting agrobiotechnology products which are much more precisely designed and controlled. As nature is the biggest set up in genetic engineering, it is also the biggest and most objective, time tested, rigid and effective safety assurance facility. Apart from ease of availability and wholesomeness, safety was also a consideration collectively acquired by local society during evolution of food preferences. When selective breeding, optimization of production, storage and household use and industrial processing underwent evolution for better product, the acceptability of the modified material was not questioned in terms of safety, so long as final product was desirable. After all the strains of rice and wheat, reaching every house in India, are derived from, but not exactly the same, as what the previous generation took. Yet our food habits remain the same.
The approach for safety assessment of whole food items or major ingredients in food such as proteins is quite different from that for toxicity evaluation of environmental chemicals and substances added in small amounts as food additives, cosmetic ingredients and pharmaceuticals. The influence of the food component administered in usual amounts on growth and gross physiological processes as compared to a suitable control diet and not a placebo, is followed. In the case of proteins, protein related specific parameters such as catalytic activity, special effects like hemagglutination and enzyme inhibition, allergenicity, unusual and toxic amino acids, membrane damaging and antinutrient effects and influence on essential trace elements also have to be checked in addition to biological value and digestibility. With novel bulk proteins, such as petroleum based single cell proteins or algal proteins, all these testing are easy. In the case of transgenic food proteins, unless expressed in bacteria, sufficient testing is difficult and unrealistic in relation to diet composition. However, sequence homology comparisons for predicting effects are possible. All these approaches are needed in the safety assessment of specific genetically engineered proteins in food crops and the safety of the whole crop is to be evaluated, rather than the protein alone.
Wholesomeness and substantial equivalence have been conclusively established in the case of all approval transgenic crops such as glyphosate tolerant cotton and soybeans, Bt expressed cotton, tomato and soybeans, canola, delayed ripening tomatoes and others. A widely used bacterial pesticide Bt protein, when engineered into a plant it becomes a new delivery system for an approved pesticide and not a new plant product. As in the case of chemical pesticides if the added ingredient is within safety level for residues the whole product can be generally recognized as safe.
The safety of the engineered Bt protein through multispecies testing and sequence homology analysis was proved beyond doubt. Detailed molecular characterization, digestibility, acute minimum level toxicity test, and other mandatory data were also made available. With microbial pesticides like Bt, extensive studies on toxicity were done before field release and the information will be applicable for Bt engineered crops also. Further to establishing of substantial equivalence and wholesomeness, it is essential to quantify all potentially risk factors including allergens, toxicants and anti nutrients. Whereas highly allergenic ovalbumin and B lactoglobulin were stable even at 60 min, Bt insecticidal protein and most other engineered proteins were digested within 30 secs. The high target specificity of Bt protein is due to the fact that only the target insects cannot digest the protein and all mammals completely break it. If the donor of the gene, has not allergenic history and the gene product is not allergenic, or has not homology with known allergens, the chances of food allergy is remote for transgenic product. It is considered that if a protein is expressed at levels more than 1% of total protein, allergy testing is needed. while engineered proteins like Bt are below 0.01%.
Safety Evaluation Studies
With transgenic tomatoes, rendered insect resistant by engineering BT. CRY A-b insecticidal protein and its marker NPT II detailed studies were conducted on rodent model. The test material was expressed in E. coli to facilitate production of large amounts. In Brown Norway rats no binding with G1 trace or any histological lesions seen in target larvae were found. Immunochemical methods did not show any receptor for the protein. Digestibility was also established in the Brown Norway rat fistulated ileum model and on simulated gastro intestinal in vitro models. The dose of protein administered when computed to whole tomato contents was around 2000 kg daily. Yet at this dose there was no toxicity. No peptide capable of eliciting reaction could be detected after digestion. Oral feeding to NMRI mice daily, through water, for 28 days and New Zealand white rabbits fed for 31 days also did not show any treatment related toxicity. Detailed chemical analysis, including toxic alpha-tomatin showed no significant variation with non transgenic crops. A 90 days rat study with lyophilized tomato (transgenic and control) also did not show any adverse effects using all standard toxicity indicating parameters. Issues regarding any influence of post translational modification (tomato Vs E coli) may not be serious since glyphosate resistance protein expressed in soybean and E coli had same sequence and 3D structure.
Bacillus thuringiensis based transgenic crops have been thoroughly studied on various models even at very high doses for any oral, dermal, pulmonary toxicity as well as all mandatory ecotoxicological tests. There was no evidence of human or other non target risks. The proteins disappear in environment rapidly. These studies along with comparative studies on feeding Bt expressed and control seeds in different animal models prove the absence of any risk..Thus a science backed approach, can remove apprehensions about safety of transgenic crops.
A genuine concern for any adverse impact on environment and biodiversity, often get exaggerated.The removal of gnosophobia by mass awareness generation, as done in controlled field trial of transgenic crops with free accessibility to society, is the responsibility of all concerned with technology development, propagation, mass production, sale regulation and surveillance. The initial hostility is gradually subsiding and societal needs are considered along with hypothetical ethical issues. All viable agrotechnologies so far are based on already familiar crops, gene donors, trait altered and phenotype is not altered. No new life is created, only better survival and performance assured which man was always doing progressively since early agriculture. The chance of the gene from decayed plants getting taken up by soil microflora deleting the plant promoter and adding its promoter and expressing is difficult. Stable, spontaneous, specific genetic exchanges and recombination's are not as frequent as imagined by some, in nature. If so, evolution would have been a much faster process and the biodiversity and its time tested interrelations would have been in disarray. Genetic out crossing through pollination, resistance development and weediness are also not as serious as conceived and the experience with random cross breeding success stories will tell us that in organized agriculture, that can be anticipated and avoided. the same applies to non target effects as evident from the current data on monarch butterflies. In over 25000 field trials, so far, no adverse environmental impact has been encountered because risks had been anticipated hence, safety precautions built in. Further, the release of millions of tons of more hazardous, less predictable, manufactured biocide chemicals can be avoided. Biotechnology also has potential for rehabilitation of damaged sites through clean up, protection of threatened germplasm and assisting in better health. On the whole, biotechnology has consolidated all the benefits of natural productivity such as quality; quantity, stability, acceptability and environmental friendliness built into it through efficient, small, well defined, expressed, amplified and maintained trait improvement. Similar to artificial intelligence, biotechnology is speeding up the natural processes for desired needs only and not greed to provide better health better food an improved overall quality of life for mankind in the new millennium.
Air Pollution Reduction :- 27 Nations Sign Protocols
Environmental officials from 27 countries have agreed to cut down on environmentally harmful emissions from electricity generating power plants, motor vehicles, agricultural and other sources. The agreement calls for a reduction of volatile organic compounds by 40%, sulphur by 63% and ammonia by 17% by the end of this decade. The lowering is in comparison to those prevailing in 1990. The signing countries include most of the European nations and the United States of America. The protocol is an important milestone in abating acidification, eutrophication and ground level ozone.
(Chem.Indus.Digest, Jan-Feb, 2000).
Draft Notification for noise pollution control issued by the government
The Ministry of Environment & Forests has issued a draft notification proposing the Noise Pollution (Control & Regulations) Rule 1999. The Rule specifies the ambient noise standards for industrial, commercial and sensitive zones. The categorization of areas into these zones will be undertaken by the Central Govt or its designated authorities.
These rules were long-awaited by a large cross section of the populace given the ignorance about the ill-effects of continuous exposure to noise-pollution.
In A lighter vein
A man met an old friend who had been ill for some time and asked him how he was feeling. The afflicted one replied "Fine. I am feeling much better. I go to another doctor now. He gives me iron shots, iron tablets and iron intravenously. " I am glad to hear that", the first man said, "and do you feel better?"
"Sure I do, as long as I face north" he replied.
Did you Know?
Some 600,00 lives would be saved every year if available safety precaution and appropriate information were used.
(Asian_Pacific Newslett. Occup.Hlth.Safety, 7, 2000)
A MINIPROFILE OF TOLUENE
Synonyms: Methyl benzene; methyl benzol; phenylmethane; toluol.
NIOSH #: X5 5250000
CAS RN: 108883
Molecular formula: C7H8
Molecular weight: 92.15.
Colourless liquid with characteristic odour. b.p. 111 C; m.p. -9.5 C; f.p. 4 C; a.p. 510 C; r.d. (water=1) 0.9; r.v.d (air=1) 3.2; v.p. in mbar at 20 C: 29; sol. in water: none; e.l.vol. % in air: 1.2-.7
Vapour heavier than air, distant ignition possible. Insoluble in water. On reaction with sulfuric acid emits heat. Reacts with strong oxidizers.
Solvent for paints and coatings, rubber, oils, resins, etc.; manufacture of benzene, detergent, dyes, drugs, host for TNT, TDI; component of gasoline, fuel, lacquers, paints, varnishes.
Fire: Slight, when exposed to heat, flame or oxidizers.
Explosion: MOD; when exposed to flame or reacted with (H2SO4 + HNO3), N2O4, AgClO4, BrF3, UF6.
Others: MOD dangerous, when heated emits irr. fumes, can react vigorously with oxidizing material.
No open flames, no sparks, no smoking, closed system, ventilation, proper earthing, and explosion protected electrical equipment. Ascertain benzene content of all toluene used. Physical examination of exposed personnel annually, with special attention to the eyes and nervous system, and including complete blood count, urinalysis and liver function studies.
inh-hmn TCLo: 200 ppm: CNS
inh-hmn TCLo : 100 ppm: PSY
skn-rbt LD50: 14 g/kg
eye-rbt : 2 mg/24 H SEV
eye-hmn : 300 ppm
|| First aid
|| Target organs
|Fatigue, dizziness, headache,
dilated pupils, euphoria,
confusion, muscular fatigue
|Fresh air, rest, artificial resp.
PNS, resp. tract.
|May cause pneumonia,
abdominal spasm, headache,
|Rinse mouth, drink water,
|Irr. eyes and skin.
redness of eyes and skin
clothes, wash with water
|Skin and eyes
Blood glucose, rectal temperature, neurological examination, increased hippuric acid in urine, benzoic acid above 2 g in urine in 24 H indicates exposure; toluene in blood.
Special High Risk groups: Individuals with diseases of central nervous system and liver.
Use of alcoholic beverages enhances toxicity. Agitation generates electrostatic charges in the liquid.
INTERNATIONAL CONFERENCE ON ENVIRONMENTAL &
OCCUPATIONAL RESPIRATORY DISEASES
October 29 -Nov 2, 2000
INDUSTRIAL TOXICOLOGY RESEARCH CENTRE
Conference Deadlines : July 15, 2000
Receipt of Abstract : September 1, 2000 at US $ 350
Spot Registration : October 29, 2000 at US $ 450
DR. QAMAR RAHMAN
Industrial Toxicology Research Centre
P.O. Box No. 80, M.G. Marg,