Question:

1. An adult drinks contaminated water containing 0.05 mg/L benzene and 0.5 mg/L toluene for 9 years.  Estimate the dose of each compound using the appropriate intake equation and exposure parameters.  (Note – benzene is a carcinogen, toluene is not)

2. A child accidentally ingests soil containing 1 mg/kg benzene and 10 mg/kg toluene in a residential setting.  Estimate the dose using the appropriate intake equation and intake parameters. (Note – benzene is a carcinogen, toluene is not)

3. An adult breathes polluted air containing 0.01 mg/m3 benzene and 1.0 mg/m3 toluene daily for 9 years.  Estimate the dose of each compound using the appropriate intake equation and exposure parameters assuming residential conditions.  Discuss your choice of parameters.

4.  An adult showers daily in water from a contaminated groundwater source for 9 years.  The water contains benzene at 0.05 mg/L and toluene at 0.5 mg/L.   He spends 10 minutes in the shower and uses water at a flow rate of 200 l/hr.  Estimate the dermal exposure dose. Discuss your choice of parameters.

5. In the same water as question 2 above, a male child washes his hands every day for 7 years, beginning at age 3. Estimate the dermal exposure dose. Discuss your choice of parameters and any assumptions you may make.

Answer:

Ans1

The adult drinking 0.05 mg/L benzene contaminated water and 0.5 mg/L toluene contaminated water for 9 years has a dose of 0.000176125 and 0.004109589 of benzene and toluene respectively. According to Li et al. (2015), since the exposure has been for a long duration, major effects include harm caused to his bone marrow especially inner soft part of the bone where manufacturing of blood cells are done. It will also cause low count in blood cells that is Anemia making him tired and weak. As per Portengen et al. (2015), a lower count of white blood cell will also cause lowering of body’s ability to prevent infections. Bruising and bleeding will also be experienced due to less count blood platelet. Prolonged exposure to benzene might also cause cancer if the dosage level gets higher.

Although toluene is non carcinogenic substance, it may cause confusion, tiredness, weakness, loss of memory, appetite loss, nausea and drunken actions (Li et al. 2015). Since the adult has been exposed to low toluene for 9 years, it might lead to eventual loss of hearing and color vision.

Ans2.

Since the child has accidently ingested soil containing 1 mg/kg of benzene and 10 mg/kg of toluene, the dosage is approximately calculated as 1.09876E-05 and 0.000127854 for benzene and toluene respectively. Due to greater surface area of lungs, body weight ratio and minute volumes, children receives a larger dose compared top adults. It will cause respiratory tract and mucous membranes problems, vomiting and lead to abnormalities in cardiac system (Portengen et al. 2015). Irregular heart rate may lead to cardiac arrest, renal failure and blood in urine. Liver of the child might damage due to ingestion with potential fatigue, anxiety and insomnia lasting for several days.

Although the benzene exposure is mild, it might cause irritation to respiratory tracts, irritation to eyes and skin. According to Portengen et al. (2015), oral mucous membrane burning, esophagus and stomach irritation is also a result from oral ingestion of benzene in children. Nausea, abdominal pain and vomiting are also found in case of ingestion of low exposure to benzene.

Ans3.

Being exposed to breathing of polluted air containing 0.01 mg/m3 benzene and 1.0 mg/m3 toluene on a regular basis for 9 years has a dosage of 3.5225E-10 and 0.273972603 in benzene and toluene respectively. Li et al. (2015) stated that major risk in low exposure to benzene for a prolonged 9 years might cause cancer especially leukemia and other blood cell cancer. Chronic lymphocytic leukemia, acute lymphocytic leukemia, non-hodgkin lymphoma and multiple myeloma are the few problems that might be found due to the long term exposure. Unconsciousness, tremors, vomiting, stomach irritation, convulsions are few of the symptoms often seen in case of exposure to benzene at mild level for prolonged years.

The adult might experience a decrease in blood components, disruption in blood production and hence lead to excessive bleeding. Portengen et al. (2015) stated that immune system may be damaged due to extended exposure to benzene causing infection and decrease immunity against cancer.

Ans4.

Approximately 0.000176125 and 0.004109589 dosage of benzene and toluene has been exposed through skin to the adult for a long duration of 9 years at a quantity of 0.05 mg/L of benzene and 0.5 mg/L of toluene. Due to such prolonged exposure it might cause skin defects, peeling and cracking (Portengen et al. 2015). Redness and blisters might be formed followed by serious skin problems and rashes.

Exposure to toluene for 9 years will also cause irritation of eyes and skin dermatitis. Skin paleness is also observed due to prolonged exposure. Li et al. (2015) commented that flaking, redness, skin rash, dermatitis and irritation might be suffered. Toluene dissolves natural oil of skin causing skin blistering and burns. It also irritates nose, eyes, throat and causes damage to eye surface.

Ans5.

Due to an exposure of 1mg/kg of benzene and 10mg/kg of toluene for 7 years from a young age of 3 years, the child has a dosage of 1.09876E-05 and 0.000127854 of benzene and toluene through the skin respectively. Portengen et al. (2015) commented that benzene leads to irritation of skin in children and hence causes cracks, peel and redness on hands of the child. It will also cause systemic toxicity due to absorption through skin due to large surface area and weight ratio. Natural oil of the hands will also be decreased due to 7 years of exposure and lead to dry hands and itching. Skin might turn yellow cause dry rash in hands of the child (Li et al. 2015).

High exposure of toluene in comparison to benzene causes skin irritation, dermatitis, redness and blisters. Cracking and peeling of hands will also be experienced by the child. Sometimes toluene exposure might also cause chemical burns and thermal burns of mild nature.

Reference List

Li, J., Lu, S., Liu, G., Zhou, Y., Lv, Y., She, J. and Fan, R., 2015. Co-exposure to polycyclic aromatic hydrocarbons, benzene and toluene and their dose–effects on oxidative stress damage in kindergarten-aged children in Guangzhou, China. Science of the Total Environment, 524(2), pp.74-80.

Portengen, L., Linet, M.S., Li, G.L., Lan, Q., Dores, G.M., Ji, B.T., Hayes, R.B., Yin, S.N., Rothman, N. and Vermeulen, R., 2015. Retrospective benzene exposure assessment for a multi-center case-cohort study of benzene-exposed workers in China. Journal of Exposure Science and Environmental Epidemiology. 87(2), pp.12-23