1. Solvents and pollution
Domina Petric, MD

2. Solvents can be devided into:
Halogenated aliphatic hydrocarbons
Aromatic hydrocarbons

3. Halogenated aliphatic hydrocarbons (HAH)
carbon tetrachloride
chloroform
trichloroethylene
tetrachloroethylene (perchloroethylene)
1,1,1-trichloroethane (methyl chloroform)

4. HAH
Perchloroethylene and trichloroethane are still in use for dry cleaning and solvent degreasing.
Dry cleaning is listed as a class 2B carcinogenic activity by the International Agency for Research Against Cancer.

5. HAH
The common halogenated aliphatic solvents also create serious problems as persistent water pollutants.
They are widely found in both groundwater and drinking water as a result of poor disposal practices.

6. Mechanism of action, clinical effects
These substances are depressants of the central nervous system in humans.
Chloroform is the most potent depressant.

7. Mechanism of action, clinical effects
Chronic exposure to tetrachloroethylene and 1,1,1-trichloroethane can cause impaired memory and peripheral neuropathy.

8. Mechanism of action, clinical effects
Hepatotoxicity is also a common toxic effect that can occur in humans after acute or chronic exposure.
Carbon tetrachloride is the most potent to cause hepatotoxicity.

9. Mechanism of action, clinical effects
Nephrotoxicity can occur in humans exposed to carbon tetrachloride, chloroform and trichloroethylene.

10. Mechanism of action, clinical effects
There is significant association between exposure to the HAHs and RENAL, PROSTATE and TESTICULAR CANCER.

11. Neurotoxicity Hepatotoxicity Nephrotoxicity Cancerogenesis
HAH toxicity
Neurotoxicity
Hepatotoxicity
Nephrotoxicity
Cancerogenesis

12. Treatment
There is no specific treatment for acute intoxication resulting from exposure to halogenated hydrocarbons.

13. Aromatic hydrocarbons (AH)
Benzene
Toluene
Xylene

14. Benzene
Benzene is used for its solvent properties and as an intermediate in the synthesis of other chemicals.
It is important component of gasoline.
Permissible exposure limit (PEL) is 1 ppm in the air and 5 ppm limit for skin exposure.

15. Benzene
The acute toxic effect of benzene is depression of the central nervous system.
Exposure to 7500 ppm for 30 minutes can be fatal.

16. Benzene
Vertigo, drowsiness, headache and nausea may occur at concentrations ranging from 250 to 500 ppm.
Exposure to concentrations larger than 3000 ppm may cause euphoria, nausea, locomotor problems and coma.

17. There is no specific treatment for the acute toxic effect of benzene.

18. Chronic exposure leads to bone marrow injury.
Benzene
Chronic exposure leads to bone marrow injury.

19. Benzene (chronic effects)
aplastic anemia
leukopenia
pancytopenia
thrombocytopenia
leukemia
lymphomas
myeloma
myelodysplastic syndrome

20. Benzene Leukemia can occur following exposures as low as 2 ppm-years.
The pluri-potent bone marrow stem cells are target of benzene and its metabolites.
Benzene is a human carcinogen!

21. Toluene (methylbenzene)
It is a central nervous system depressant and a skin and eye irritant.
It is also fetotoxic.
Exposure to 800 ppm can lead to severe fatigue and ataxia.
ppm can produce rapid loss of consciousness.

22. Xylene (dimethylbenzene)
It is a central nervous system depressant.
Treshold limit values for time weighted average is 100 ppm and for short-term exposure is 150 ppm.

23. Katzung, Masters, Trevor. Basic and clinical pharmacology.