Elsevier

Environment International

Volume 48, 1 November 2012, Pages 109-120
Environment International

Environmental exposure to organophosphorus and pyrethroid pesticides in South Australian preschool children: A cross sectional study

https://doi.org/10.1016/j.envint.2012.07.007Get rights and content

Abstract

Organophosphorus (OP) and pyrethroid (PYR) compounds are the most widely used insecticides. OPs and PYRs are developmental neurotoxicants. Understanding the extent of exposure in the general population and especially in young children is important for the development of public health policy on regulation and use of these chemicals. Presented here are the results of the first investigation into the extent of environmental exposure to neurotoxic insecticides in preschool children in South Australia (SA).

Children were enrolled from different areas of SA and assigned into urban, periurban and rural groups according to their residential address. Residential proximity to agricultural activity, parental occupational contact to insecticides and use of insecticides within the household were investigated as potential indirect measures of exposure. We used liquid chromatography/tandem mass spectrometry to measure the following metabolites of OPs and PYRs in urine samples as direct indicators of exposure: dialkylphosphates, p-nitrophenol, 3-methyl-4-nitrophenol, 3,5,6-trichloro-2-pyridinol, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, 2-methyl-3phenylbenzoic acid and 3-phenoxybenzoic acid. Results were analysed to assess factors affecting the risk and level of exposure. Results were also compared to the published data in similar age groups from US and German studies.

The results of this study demonstrate that there was widespread chronic exposure to OPs and and PYRs in SA children. OP metabolites were detected more commonly than PYR. Exposure to more than one chemical and contemporaneous exposure to chemicals from both OP and PYR groups was common in the study population. There were some differences in risks and levels of exposure between the study groups. Exposure to some restricted use of chemicals, for example, fenitrothion, was higher in periurban and rural children. There was no difference among the study groups in exposure to chlorpyrifos, used commonly in agriculture and in domestic settings and most frequently found OP pesticide in food in Australia. South Australian children appear to have higher levels of exposure compared their peers in US and Germany.

Highlights

► Organophosphorus and pyrethroid exposures measured in 340 South Australian children ► Biological monitoring of exposure using urinary metabolites ► Widespread chronic exposure to organophosphates and pyrethroids ► Contemporaneous exposure to organophosphates and pyrethroids ► Exposure higher than in comparable populations in US and Germany

Introduction

Insecticides are chemicals used to control insect pests that damage or destroy crops or transmit diseases among humans and animals. Organophosphorus (OP) and pyrethroid (PYR) compounds are the most widely used groups of insecticides in Australia and worldwide. OP and PYR insecticides are neurotoxins. Neurotoxicity is defined as any permanent or reversible adverse effect on the structure or function of the nervous system. The main mode of action of OPs in humans is inhibition of acetylcholinesterase, while the main mode of action of PYRs is modulation of voltage gated ion channels. Apart from main modes of action, both groups act on other biochemical and molecular targets within the nervous system. Extensive experimental data demonstrate that low-level exposure to some commonly used OPs and PYRs can negatively affect the development of nervous system in young laboratory animals via “non-classical” mechanisms that are independent of the main mode of action. International scientific literature shows that there is a concern and need for research into the effects of chronic low level (environmental) exposures to neurotoxic insecticides on the neurobehavioral and emotional development of young children as well as on children's health in general (Bjørling-Poulsen et al., 2008). Understanding the extent of exposure in the general population is essential for evaluating whether chemicals may be linked to adverse health outcomes and for the development of scientifically sound public health policy on regulation and use of these chemicals.

South Australia has a well-developed agriculture sector, which includes wide acreage crops, livestock and horticulture. An estimated 54.1 million ha or 55% of South Australia's land area is used for agricultural activity and there were 14,262 agricultural establishments in the 2002–2003 financial years (ABS, 2003). In addition, ‘lifestyle farming’ on small acreage and backyard gardening are very popular in Australia.

The Australian Pesticide and Veterinary Medicine Authority (APVMA) is Australia's federal regulatory body whose roles are to review and allow (or disallow) chemicals onto the Australian market, to develop regulatory residue limits and to make recommendations on the use of registered chemicals, mostly by means of information collated on the chemical label. The APVMA maintains an online publicly accessible database of registered products, Public Chemical Registration Information System (PUBCRIS) [http://www.apvma.gov.au/pubcris]. The state health authorities are responsible for training and licensing restricted-use chemical users. However, Australian authorities neither have effective control over pesticide use beyond the point of sale nor do they collect information on where, when, how or how much product is being used.

Overall, thirty OP actives and twenty two synthetic PYR actives are included in over 300 and over 1000 of registered commercial formulations respectively (APVMA, 2012). Six OP actives and sixteen PYR actives are allowed for public use in Australia. Publicly accessible OP actives include: chlorpyrifos, diazinon, dichlorvos, fenthion, maldison and omethoate (APVMA, 2012). The OP and PYR formulations are available for domestic use by the general public as indoor surface sprays (fly, spider, cockroach), outdoor plant and barrier sprays, indoor and outdoor powder preparations, concentrate solutions, insect traps, flea bombs, mosquito coils, lice control lotions and shampoos as well as veterinary products. These formulations can be purchased over the counter in hardware stores, supermarkets and pharmacies in Australia. In addition, Australian homes are routinely treated with various insecticides including chlorpyrifos (an OP insecticide) and bifenthrin (a PYR insecticide) for termite control, both before and after construction.

This widespread availability of pesticides to the general public, large variety of registered products (both for public and restricted use) and extensive mixed agricultural land use pattern of South Australia suggests that there is a potential for significant widespread exposure in the general population. The extent of environmental exposure to OPs and PYRs in the Australian general population and its possible health effects so far have not been addressed in the scientific literature and in particular the extent of environmental exposure in children in Australia is unknown.

This study aimed to explore the extent of exposure to OP and PYRs pesticides in South Australian children and to investigate the factors that influence the risk of being exposed and the levels of exposure in the study population.

Section snippets

Subjects

The study took place during 2003–2006. The subjects of this study were 340 healthy children aged 2.5 to 6 years old residing in metropolitan Adelaide (urban group), Adelaide Hills area (peri-urban group) and agricultural areas of South Australia including the Yorke Peninsula, mid-north region, Barossa Valley, Riverland, McLaren Vale and the Murray-Hills area (rural group) (Fig. 1). Study groups were chosen based on a priori descriptive knowledge of pesticide use patterns and the knowledge of

Study population: Descriptive analysis

The samples were collected from various areas of metropolitan Adelaide, Adelaide Hills and rural areas, aiming to include families from different socio-economic backgrounds ensuring that the final sample population reflected the socio-economic gradients existing in the general population in South Australia. A total of 340 children (115 urban, 111 peri-urban, 114 rural) participated in the study. Of those preschools that agreed to participate, the response (participation) rate among eligible

Discussion

Since the human body metabolises OP and PYR insecticides rapidly, urinary metabolites only reflect recent exposure. However, the detection of short lived urinary metabolites in a significant proportion of urine samples from a large group of subjects in a cross-sectional study would be indicative of ongoing (chronic) exposure in the population. As such, the results of this study demonstrate that there is widespread chronic exposure to OPs and PYRs in South Australian children. Furthermore,

Conclusions

Our findings demonstrate widespread chronic exposure to OP and PYR pesticides in young children in South Australia. There are differences in exposure risks and levels in different populations, but only for some chemicals, while the exposure seems to be ubiquitous for other chemicals. There appear to be higher levels of exposure in the study population as compared to similar populations in the US and Germany. Further research into pesticide exposure in the general population in Australia is

Competing interests

Authors declare that they have no competing interests.

Acknowledgements

Authors express their appreciation to the participating families. The urine sample analyses were performed in Flinders Advanced Analytical Laboratory with invaluable help from Dr Daniel Jardine. Analytical standards for DAPs were kindly donated by the WorkCover Laboratories NSW. Kateryna Babina was supported by the FUSA Postgraduate Award (funded by the Flinders University). The study was funded by the Financial Markets for Children Foundation.

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  • Cited by (0)

    1

    Please note, at the time of the study, Dr Babina was not an employee of SA Health and as such, her current affiliation with SA Health bears no relevance to the presented study.

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