Immunotoxicity of pesticides in orchid farmers and in experimental animals | |
| Author | Soraya Aroonvilairat |
| Call Number | AIT Diss. no.EV-15-04 |
| Subject(s) | Methylmercury--Environmental aspects Pesticides Immunotoxicology Chemicals--Toxicology |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering and Management Inter-University Program on Environmenta l Toxicology, Technology and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-15-04 |
| Abstract | Various studies have found that most Thai or chid farmers use pestic ides excessively and without proper protective gear and were likel y to have suffered from pesticide exposure. However, no toxicological study has yet been made. The aims of this study were to investigate whether the orchid farmers exhibi ted any biological altera tions, and if so, to carry out studies on th e immunotoxicity of these pesticid es in laboratory animals. The cross-sectional study was aimed to evalua te the immunological, hematological and biochemical statuses of pesticide exposed orch id farmers. Sixty-four orchid farmers and 60 matched controls participated in the st udy were interviewed using a structured questionnaire and blood samples were coll ected. Plasma cholinesterase activity, the percentage and absolute number of B-lymphocytes (CD19 + ) were significantly lower in the farmer group (3,966.32 ± 1,165.48 U/l, 11.61 ± 4.09% and 312.26 ± 164.83 cells/mm 3 , respectively) as compared to those of controls (5,048.85 ± 1,139.40 U/l, 14.32 ± 4.23%, 420.34 ± 195.18 cell/mm 3 , respectively). There was a significantly higher level of serum IgE among orchid farmers (0.031 ± 0.011 mg/dl vs. 0.018 ± 0.007 mg/dl) but not IgG, IgA, IgM levels. Serum lysozyme level, lymphocyte proliferative responses to mitogens, hematological parameters and kidn ey function test, were not significantly different between the two groups. The liver fu nction profiles showed significantly lower levels of albumin and serum pr otein in the farmer group. The immunotoxicity of the 3 pesticide mixt ure most often used in the orchid farms (cypermethrin, chlorpyrifos and captan) was also investigated in the experimental animal. Adult male Wistar rats topically trea ted with 1/100, 1/50, 1/25 of dermal LD 50 of cypermethrin and chlorpyrifos and 5 mg/ kg BW captan or vehicle control for 28 consecutive days. Blood samples and selected organs were collected and evaluated for hematological, biochemical and immunological parameters. The terminal body weight of the middle-dose and high-dose pesticide trea tment groups was significantly lower than that of controls. The relative weights of liv ers and kidneys were higher in the high-dose treated group than those in ve hicle controls. Liver function parameters including aspartate aminotransferase (AST), alkaline phospha tase (ALP), albumi n, total protein and cholesterol in the treatment groups differed fr om those of controls, which may indicate hepatotoxicity. The cholinesterase levels in red blood cells and in plasma were significantly decreased as compared to th ose of the vehicle co ntrol group in a dose- response manner. The splenocyte subpopulations , including % total T cell, % total B cell and % NK cell, of the treatment rats were not different from t hose of controls. The proliferative response to LPS (the measurement of B cell f unction) in the high-dose group was significantly decreased as compared to th at of controls while the response to Con A (the measurement of T cell function) in the treatment groups did not differ from controls. As for serum immunoglobulins, only IgG but not Ig M and IgA levels in the high-dose groups were significantly increased as compared to the control group. It is highly significant that th e highest dose employed in this study was far below that was expected to have any harmful effect in an imals when used individually. This observation indicates that, when used as mixture, these pesticides exhibited synergistic effect.The findings, both in orchid farmers and in experimental animal, have clearly shown that frequent exposure to the pestic ide mixture resulted in subtle changes in some important biological parameters both in farmers and in rats. These changes, although they may not be clinically significant in human, strongly indicated that ca ution in handling pesticides by these farmers is warranted |
| Year | 2015 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-15-04 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Kavi Ratanabanangkoon ;Thammarat Koottatep (Co-Chairpeson) |
| Examination Committee(s) | Panida Navasumrit ;Vilas Nitivattananon |
| Scholarship Donor(s) | Chulabhorn Research Institute ;Mahidol University ;Asian Institute of Technology Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2014 |