INTRODUCTION:

Mosquito coil comes under the category of mosquito repellant i.e. chemical substances having repellant effect on mosquitoes whereas Hit spray has repellant effect on insects like cockroach, fly, waterbugs e.t.c. Mosquito coil contain pyrethroids like allethrins, a synthetic form of chemical found naturally in the plant Chrysanthemum cinerarifolium. The flower heads of this plant are used and it acts by affecting the nervous system of the insects. D-transallethrin is the active substance present in mosquito coil whereas imiprothrin and cypermethrin are the active ingredients of Hit Spray.

Imiprothrin and cypermethrin are synthetic pyrethroid insecticide. Burning of mosquito coil releases some volatile, semi-volatile organic compounds, polyaromatic hydrocarbons or aerosols in gaseous forms^{[1, 2]}. The use of mosquito repellant has become very common in India. Long term exposure of mosquito coil produces systemic toxicity and affects the growth of foetus during pregnancy. In a ninety-day toxicity study, rats were given exposure of liquid mosquito repellant (LMR) containing allethrin (3.6% w/w) for 8 hrs/day and it was found that the exposure did not produce any toxicity symptoms or death. However, there is significant increase in the relative weight of brain and thyroid in females and liver and adrenals in males^[3].

Some studies shows association between exposure of pyrethroids and parents and the risk of infertility, spontaneous abortions, low birth weight of infants, preterm delivery, still births, birth defects, growth retardation in foetus. Maternal exposure to agricultural pesticides during pregnancy increases the incidences of birth defects in offspring like neural tube defect, cleft lip and palate, congenital heart disease, musculoskeletal defects as well as birth marks (hemangioma)^[4]. The toxic effect of mosquito coil smoke on the lungs of female rats was observed and also reported the causes of toxicity of mosquito coil which was due to the presence of combustion products of coil such as submicron particles coated with heavy metals, allethrin and volatile products like phenol, benzene, o-cresol and toluene^[5]. Some studies shows that exposure of pyrethroids based mosquito repellant causes increase in the BBB permeability and oxidative damage to selected organs in developing rats^[6].

Pyrethroids have subtle effects on the ability of human being and other animals like rats to reproduce. They bind with male sex hormone androgen receptors and disrupt its normal functioning ^[7].

MATERIALS AND METHODS:

Chemical:

Commonly used mosquito coil containing d-transallethrin and Hit Spray containing imiprothrin (0.07%) and cypermethrin (0.2%) was purchased from the local market of Bhimtal India.

Experimental Design:

Initially the experimental protocols with rats were pre-approved by the Institutional Animal Ethics Committee for animal research (Protocol Number KUDOPS/42). The study was carried out on 18 Wistar adult female rats, weighing approximately 200gms were divided in three experimental groups, one group exposed to mosquito coil smoke for a period of 6 hours per day, other group exposed to Hit spray, the spray exposure was given to the rats after every two hours for a period of 6 hours per day throughout their gestation period. The third group is control group not giving any exposure. The animals were given pellet diet and water ad libtum and cared for in accordance with the guidelines given in Guide for Care and Use of Experimental Animals. When the gestation period was confirmed the pregnant animals were kept in plastic unit cages having partition of Perspex sheet with numerous holes. The exposure of coil smoke or Spray was given on the one side of partition and group of rats were placed on the other side of Perspex partition so they are allowed to inhale the exposure of pesticides. All animals of exposed and control group were observed daily for any signs of toxicity and mortality. Body weight was monitored and recorded. After the gestation period of female rats, fifteen rat pups were selected from each group for morphometric and morphological studies which include body weight, crown rump length, brain size, lengths of both limb and hind limbs and length of tail of each pup.

RESULT AND DISCUSSION:

It was observed that in control group all female rats as well as their pups were normal and the morphometric and morphological data of rat pups was uniform (Table 1, 2). In case of exposed group, the body weight of female rats was found lower as compared to control group during their entire gestational period. Figure 1 shows the body weight dynamics of female rats throughout their gestation period. The differences between mean body weight of exposed group and control group during gestation period was recorded and it was found that the weekly weight gain was lower in exposed group (Table 1). Also in exposed group the gestation duration was significantly greater as compared to control group. This duration was correlated to exposure level (Table 2).

Table No. 1 Female Rats body weight during gestation (g)

S.N	Group	Weight/days
S.N	Group	0	7	14	21
1	Control (C)	206.7	250.0	260.0	283.3
2	Exposed (E₁)	201.7	210.0	221.7	236.7*
3	Exposed (E₂)	203.3	213.3	230.0	240.0^*

Table No. 2 Gestation Duration (days)

S.N	Group	Gestation length (days)
S.N	Group	X±Sx	S.D
1	Control (C)	22.33±0.33	0.57
2	Exposed (E₁)	26.67±0.66	1.15
3	Exposed (E₂)	27.00±0.57	1.00

Figure 1 Body Weight dynamics of female rats throughout their gestation period

The data of the rat pups delivered showed significant differences between pups whose mothers were exposed to mosquito coil and Hit Spray as compared to the control group mothers. The morphometric data of exposed group rat pups was measured in parameters like body weight, brain size, and crown rump length, length of forelimb, hind limb and tail as compared to the control group. These differences were observed in Table 3. The body weight and brain sizes of the exposed group had significant differences in comparison with the control group.

Table No. 3 Morphometric Observation Of Rat Pups Recovered From Pregnant Rats

Parameters	Control	E₁rats	E₂rats
Body Weight (mg+ SE)	6243 ± 84.11	5643 ± 36.89*	5514 ± 40.41*
CR length (mm + SE)	53.00 ± 1.069	49.29 ± 1.304	43.00 ± 1.069
Brain size (mm + SE)	12.57± 0.8123	7.429 ± 0.4809	7.857 ± 0.3401
Forelimb size(mm + SE)	12.43 ± 0.6851	9.714 ± 0.7143	8.143 ± 0.6335
Hindlimb size (mm + SE)	11.86 ± 0.5533	8.143 ± 0.4592	7.00 ± 0.6172
Tail length (mm + SE)	15.43 ± 0.4809	12.00± 0.4880	13.14 ± 0.7693

(*= P<0.05)

Figure 2 Morphology of Rat pups showing normal development of brain (B), Forelimb (F),

Crown rump length (CRL), Hind limb (H), and tail (T).

Figure 2 shows morphology of rat pups having normal development of brain (B), forelimb (F), crown rump length (CRL), hind limb (H), and tail (T). The morphological abnormality like micromelia, microcephaly and anopthalmia was not found in any of the exposed group. From this study, it was found that maternal exposure to pesticides throughout their gestation period was associated with statistically significant decrease in birth weight, and morphological parameters (Figure 3). Exposure of pesticides also affects the gestation period as well as maternal body weight.

Figure 3 Changes in the morphological parameters of exposed group rat pups as compared to control group.

CONCLUSION:
The use of pesticides especially insecticides has become very common in different parts of country. The exposure of pesticides to populations of all age groups and sex is inevitable. Long term exposure of these pesticides may lead to systemic toxicity, as well as may affect the reproductive performance in rats. The data on the incidences of pesticides related illness among population of developing countries are scanty. From this study it was concluded that pesticides exposure whether they are indoor pesticides or outdoor pesticides, to human population should be controlled especially among pregnant women as it may affect the foetal growth and development. The concern about environmental teratogens should be incorporated into both preconceptional and prenatal care i.e. exposure to potential teratogens must be reduced before pregnancy is recognized. Prenatal screening and prenatal counseling is required for getting relevant prenatal services.

REFERENCES:

1. Ayorinde AF, Oboh BO, Otubanjo OA, Alimba AC, Odeigah PC. Some toxicological effects of a commonly used mosquito repellant in Lagos State, Nigeria. Research Journal of Environmental Toxicology. 2013. ISSN 1819-3420 / DOI: 10.3923/rjet.2013.

2. Craig RC and Stitzel RE. Modern Pharmacology, sixth edition. Little brown and Company, USA 1994; 33-39.73-82.

3. Srivastava A, Srivastava MK, Raizada RB. Ninety-day toxicity and one generation reproduction study in rats exposed to allethrin-based liquid mosquito repellant. The Journal of Toxicological Sciences. 31(1): 2006: 1-7.

4. Ahmad N, Naveed K, Asmatullah. Exposure to β-cyfluthrin during pregnancy induces teratogenecity in murine foetuses. Pakistan Journal of Zoology. 44(6): 2012: 1515-1519.

5. Okine LKN, Nyarkoi AK, Armah GE, Awumbila B, Owusu Ki, Set-Soafia S, Ofosuhenei M. Adverse effect of mosquito coil smoke on lung, liver and certain drug metabolizing ezymes in male wistar albino rats. Ghana Medical Journal. 38: 2004:1-13.

6. Gupta A, Nigam D, Gupta A, Shukla GS, Agarwal AK. Effect of pyrethroids based liquid mosquito repellant inhalation on the blood brain barrier function and oxidative damage in selected organs of developing rats. Journal of Applied Toxicology. 19:1999: 67-72.

7. Eil C and Nisula BC. The binding properties of pyrethroids to human skin fibroblast androgen receptors and to sex hormone binding globulin. Journal of Steroid Biochemistry. 35: 1990: 409-414.

Received on 26.04.2017 Modified on 31.05.2017

Research J. Pharm. and Tech. 2017; 10(8): 2535-2537.

DOI: 10.5958/0974-360X.2017.00448.6