Polycyclic Aromatic Hydrocarbons (PAH) such as benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, dibenzo(a,h)anthracene and indeno(cd)pyrene are potent carcinogens. Human exposure to ambient PAH generally occurs in combination with other carcinogenic substances such as nickel, chromium, silica, soot, asbestos and benzene causing micronuclear structural alterations that occur due to the toxic effects include chromosomal aberrations giving rise to broken pieces of chromosomes that lie close to the nucleus. After absorption, the PAH distributed to tissues are biotransformed by Phase-I metabolic enzymes to chemically reactive intermediates binding covalently to DNA (DNA adducts) leading to tumor initiation. PAH metabolites are mostly conjugated and excreted as hydroxylated metabolites or in a small portion as sulfate. Unconjugated PAH are excreted through the feaces and the urine. Therefore, metabolites of PAH particularly 1-hydroxypyrene is the most important biomarker representing 90 percent of its metabolites. Measurement of this metabolite is thought to reflect exposure to PAH during the first few days.

CPCB Zonal Laboratory, Kolkata in collaboration with West Bengal Pollution Control Board, IICB Kolkata and SSKM Kolkata conducted a study to assess the ambient air quality in terms of particulate concentration of different sizes (2.5 and 10 m ), PAH, organic carbon, metals, various ions etc. and their adverse impact on human health in terms of metabolites in urine, chromosomal aberration, micronuclei etc. in the people who are exposed to traffic air pollution. The six major traffic intersections in Kolkata were covered and traffic police prone to get exposed and few patients admitted in SSKM hospital already suffering from respiratory problems were subject in this study. The samples were analysed for measurement of ions by Ion Chromatograph, metal by AAS, PAH by GC and HPLC, metabolites in urine by HPLC.

The analytical results indicate that PM_2.5 and PM₁₀ were varying from 164 to 370 m g/m³ and 256 to 553 m g/m³ respectively. The ratio of PM_2.5 and PM₁₀ was varying from 0.62 to 0.76. The average ratio of PM_2.5 and PM₁₀ is 0.69 with coefficient of variation of 6.7 percent. The percentage of respiratory particles (i.e.<2.5m ) is significantly high particularly during winter. Also it is established that fine particles are more prone to get enriched with toxic and carcinogenic substances than the coarse particles. Concentration of ions indicates the elemental imposition of particles. Study conducted earlier by WBPCB reported the average ratio of PM_2.5 and PM₁₀ as 0.73 with standard deviation of 0.035.

The problems further aggravates, if such particles are associated with toxic and carcinogenic compounds. Therefore, distribution of 16 PAH compounds namely Naphthalene, Acenaphthylene, Acenapthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Dibenzo(ah)anthracene, Benzo(ghi)perylene, Indeno(1,2,3-cd) pyrene were quantified in PM_2.5 and PM₁₀ Particulate Matter. Concentration of total PAH (sum of 16 compounds) varied from 8.9 to 16.37 ng/m³ in 10 m particulate size with average of 10.73 ng /m³ and CV of 27.02 percent and varied from 9.44 to 17.53ng /m³ in 2.5 m particulate size with average of 11.6 ng /m³ and CV of 26.26 percent. The results revealed that PAH compounds in finer particles i.e respirable particles are 27 percent more than that of coarse particles after normalisation considering negligible variation among the values of different stations. The average concentration (m g/m³) compiling the data of all stations revealed the prevalence of different inorganic ions in PM of studied area. Poor correlation ship among the ions except few (NH₃-SO₄-Na,NO₃-NO₂,F-NO₂-SO₄,Na-NO₂) also indicate independent behavior of the ions present in Particulate Matter which indicate that people exposed to vehicular polluted ambient air are prone to get effected with toxic and carcinogenic chemicals.

Considering the above aspect, chromosomal abberation, micronuclei formation and prevalence of PAH metabolites were studied initially with 30 exposed individuals. Ten subjects from East Midnapur were also recruited for this study to serve as control. The results indicated significant increase in both MN in three cell types and CA in lymphocytes of exposed population, when compared with the control. The presence of 1-HP in urine and significant increase of micronuclear and CA indicates the influence of PAH on human health. Hence the sample size was quite small to comprehensively assess level of exposure and its actual impact on human health.

In West Bengal a rural population of 160.97 lakh people i.e. 27.90% of the state rural population of 577.35 lakhs (2001 census) is under arsenic threat and 75 blocks out of 341 blocks in the State are affected with arsenic related diseases while in urban Areas 120 lakh people out of 224.86 lakh including parts of Kolkata is under threat (PHED 2004). The regular survey revealed an increase of arsenic affected areas, both in West Bengal and Bihar. Problems are further aggravated due to over-extraction of groundwater from sub-surface and deep aquifers as people are mainly dependent on groundwater for domestic and irrigation purposes leading to increase of background level concentration in the soil, vegetation, surface water etc. To tackle the arsenic problem in West Bengal, emphasis was given either on treating the groundwater by adopting different technologies or abstracting river water for potable water supply after proper treatment. Due thought has not been given to the other potential water resources such as pond water, dugwell water, rainwater-harvesting etc., which if utilized, could meet up major portion of water requirements. Extensive use of groundwater has indicated other problems with fluoride, humic acid, nitrate etc. are encountered in different parts of country. Keeping this in view, the water from about 132 dugwells and few ponds were analysed. Analytical results revealed that almost all dugwell waters were more or less safe. Monitoring carried out by SOES, Jadavpur University, West Bengal covering more than 1000 dug wells and ponds showed same trend even in dugwells surrounded by highly contaminated areas. The Central Pollution Control Board, Zonal Laboratory, Kolkata is regularly monitoring tubewell waters, pond waters, dugwell waters, sediments and soils to assess the level of arsenic contamination and prevailing status of water quality in terms of pH, conductivity, calcium, magnesium, alkalinity, chloride, nitrate, nitrite, phosphate, fluoride, sulfide, sulfate, iron, manganese, zinc etc in the affected areas and also performance of Arsenic Removal Units (ARU) installed in different locations. The household arsenic treatment method may be regarded as an alternative for the transitional period, till a permanent solution is found. The details of ARU already developed by different organisation were studied.

Presently most of ARUs are not in use, since piped water supply is made available. Few ARUs in certain districts were found non-functional, due to either lack of proper maintenance or undesirable water quality. In few cases, treated water was inferior to raw water mainly due to lack of backwashing in time, but in few cases even after backwashing ARU failed to produce safe drinking water. Based on water quality of arsenic affected areas proper maintenance schedule with infrastructure support must be framed in addition to upgradation of these plants.

An epidemiological study sponsored by CPCB for 3 year duration is being carried out in Delhi by Chittaranjan National Cancer Institute (CNCI), Kolkata to assess the effect of air pollutants, especially Respirable Suspended Particulate Matter (RSPM) and other Carcinogens, on Human Health. The objectives of the study are:

The scope of work involves health assessment including evaluation of respiratory symptoms through questionnaire survey and clinical examination, assessment of lung function, assessment of cellular lung response to air pollution, assessment of systemic effects of air pollution, assessment of hematological profile, changes in liver and kidney function, assessment of genotoxic effects and correlation between health effects and air quality.

The study is being carried out in Delhi on Health effects of air pollution on Children by the Chittaranjan National Cancer Institute (CNCI), Kolkata. The objectives of the study are:

• Assessment of the respiratory health status of school children chronically exposed to ambient air pollution of Delhi and
• Establishment of a database relating to pollution related respiratory problems among children of the city.

Prevalence, duration and severity of respiratory symptoms will be determined from questionnaire responses and actual tests on various physiological parameters like lung function tests etc. Health camps were held in winter, monsoon and summer seasons at various schools in various parts of Delhi covering North, South, East, West and Central Delhi.