Study of congenital anomalies in four pregnant farmers in Valencian Autonomous Community Spain

Flores Reos, Eva Mª

Department of Occupational Health. Public Health Centre of Alicante. Conselleria de Sanidad / Plaza de España , 6 / 03010 Alicante, España

+34 96 647 85 68 / flores_eva@gva.es

Pascual del Pobil Ferré, Mariam

Department of Occupational Health. Public Health Centre of Alicante. Conselleria de Sanidad / Plaza de España , 6 / 03010 Alicante, España

+34 96 647 85 69 / pascualdelpobil_des@gva.es

Andrés Gordaliza, Ana

Department of Occupational Health. Public Health Centre of Alicante. Conselleria de Sanidad / Plaza de España , 6 / 03010 Alicante, España

+34 96 647 85 67 / andres_ana@gva.es

ABSTRACT

ABSTRACT

Abstract

a possible cluster of congenital anomalies in four pregnant women who worked in greenhouses of the same farm was reported to the Public Health Centre of Alicante in the Valencian Autonomous Community, Spain.

Aims: to determine the origin of the congenital anomalies found, and to establish risk factors, and properly preventive measures.

Methods: medical records of the cases were studied, and the women were interviewed. We studied the label and FDS of the pesticides used and we make and epidemiologic analyse of the results.

Results: the congenital anomalies happened between 2003-2007. These farm women did not apply pesticides directly, but the period of time that they waited before entering the treated greenhouses was from 5 to 24 hours maximum, without any personal protective equipments.

Conclusions: despite the suggested evidences, a causal link between pesticides exposure and these congenital anomalies could no be established. However, prenatal pesticides exposures in farmers are cause for concern. Farmers need greater protections against pesticides. Preventive improvements were implemented.

Key words

Key words

Congenital anomalies, adverse pregnancies outcomes, farmers pesticides, toxicity, prevention and control.

BACKGROUND

In August 2006 the Gynaecology Service of San Juan Hospital of Alicante- Spain, reported to the Health Public Centre of Alicante, which is part of the General

Direction of Public Health of the Valencian Autonomous Community of Spain, congenital anomalies in three pregnant women who had been working in tomato greenhouses which belong to the same company. In August 2007 a new case of similar features was reported.

The grouping of cases in the same company and job, suggests possible common exposure as the origin of these adverse pregnancy outcomes.

There is a significant public health concern about congenital malformations. The infant mortality rate during the period 2003-2007 in our Community is 4,06 infant deaths (one year of age or younger) per 1000 live births, and the infant mortality rate for congenital malformations, deformations and chromosomal abnormalities is about 0,92, deaths per 1000 live birth, so the proportional mortality for this cause is 22.64% (Sanidad 2003-2007). Estimates of adverse reproductive outcomes demonstrate widespread impact, for example, it is estimated that 10% to 20% of recognized pregnancies end in spontaneous abortion, and that 3% of all live births have major malformations (Lawson, 2003). Regarding the potential effects of occupational exposure to toxic substances on reproductive outcomes have been estimated that 3% of major malformations are due to toxic exposure, 23% are due to multifactorial causes, and 40% are due to unknown causes (CDC, 1995).

Despite public health and its widespread impact, progress has been limited in identifying occupational reproductive hazards and in separating the contributions of potential occupational hazards from other etiologic factors.

 AIMS                                                                                                                                           

The purpose of our study was: to establish the possible cause of the congenital malformations, to assess risk factors associated with the pesticide used, such as knowledge, attitude and practice among farm workers and to take preventive measures against pesticides misuse.

MATERIALS AND METHODS

The research of the cluster included the review of the medical records of the women who had been reported. They were used to confirm the adverses pregnancies outcomes diagnosis, their antecedents, and the contact information.

Each of these women were interviewed in order to know more about their workplace conditions and any other exposures of concern of them or their partners. Specific questionnaires on occupational exposure to pesticides and reproductive health hazards at the workplace were used.

Dates of the occupational risks, pesticides used and the schedule of pesticide applications were obtained through the company. Labels of pesticides products used, and Material Safety Data Sheets were evaluated as well.

The maximal sensitivity periods during organogenesis of each case were calculated from the estimated date of conception to the eighth gestational week.

In the evaluation of the relationship between congenital malformations and pesticides exposure during pregnancy as potential causal agents, the following criteria were used: biologic plausibility, consistency, occupational exposure, temporal correlation, experimental analysis and clinical support and lack of nosological affiliation.

RESULTS

The number of adverse pregnancy outcomes in these four women amounted to eight and they occurred between 2003 and 2007. All of them were diagnosed during the first trimester of pregnancy, and they ended in miscarriages or therapeutic abortions, (table 1). Some of these women had more than one pregnancy with adverse outcomes congenital anomalies, so more than one outcome belongs to the same woman. The mean age of the woman at time of pregnant interruption was 29.87 + 1 years. Moreover, table 1 shows the estimate date of conception, the maximal sensitive period after conception during which women were potentially exposed to pesticides, the gestational week of miscarriages or therapeutic abortions and the congenital defects diagnosis.

All of these farmer women shared the same exposure at work. They performed tasks that included planting, harvesting, cleaning and maintenance care of the crop and they did not refer to any activity that involves direct contact with pesticides. However, the re-entry time into the greenhouse which had been treated with pesticide was 24 hours maximum and sometimes they entered a few hours later and always without preventive individual protection. They also said that it often smelt strongly like pesticides while they were working, even when they did not work in treated greenhouses, but near greenhouses where pesticides had been applied. They worked eight or ten hours every day and did not know anything about the adverse health impact of pesticides.

Though we considered as “maximal sensitivity period” the first two months of pregnancy, the possible pesticide exposure also occurred before pregnancy, because all these women had been working in the same company and at the same job several years early.

Table 2 shows the products used in the greenhouses during the most vulnerable period in human development of each pregnancy, the number of days that each product was used during this period and some of their effects.

Some of the pesticides used in the company, have proved to have toxic effects on the reproduction in animals such as cyiproconazole, mancozeb, myclobutanil and tebuconazole. Human reproduction disorders include everything from the ability to conceive new individuals to the feasibility, development and health of offspring before and after birth.(A. M. Garcia, 1998)

In the same way carcinogenic effects have been described for other used pesticides like: clortalonil, iprodiona, mepanipirin propargita and, tiacloprid. But none of the pesticides used had known mutagenic action.

The most used products in maximal sensitivity period were: chlorothalonil, pyridaben, pyriproxyfen, lamdda-cyhalothrin, buprofezin, abamectin and procymidone.

These products were used in at least 50% of the outcomes.

All pregnant women had the potential exposure to pesticide mixtures. The number of pesticides used during maximal sensitivity period in each adverse pregnancy outcome is shown in table 3.

Case 1: the firs adverse pregnancy outcome of this woman was a Cystic Hygroma / Turner Syndrome. Nine different types of pesticides were used during 13 days of the critic period, three of which are cataloged as carcinogenic cat.3

Her second outcome was a Trisomie 47 XY+22. Five different types of pesticides were used during 12 days of the critic period and one of which is cataloged as toxic to reproduction cat.3.

Case 2: This woman had three adverse pregnancy outcomes. The first one was a Miscarryage. Eleven different types of pesticides were used during 39 days of the critic period, two of which are cataloged as toxic to reproduction and one as carcinogenic cat.3. The diagnostic of the second one was Gestational Trophoblastic Disease. Twenty different types of pesticides were used during 54 days of the critic period, two of which are cataloged as toxic to reproduction cat.3 and two as carcinogenic cat.3. Her third adverse pregnancy outcome was a Cystic Hygroma. Thirteen different types of pesticides were used during 17 days of the critic period, and one of which is cataloged as toxic to reproduction cat.3

Case 3: This woman had two adverse pregnancy outcomes. The firs one was a Dandy Walker syndrome. Nine different types of pesticides were used during 31 days of the critic period, one of which are cataloged as toxic to reproduction cat.3 and two as carcinogenic cat.3. Secondly this woman had a Miscarryage. Twenty two different types of pesticides were used during 44 days of the critic period, two of which are cataloged as toxic to reproduction cat.3 and two as carcinogenic cat.3.

Case 4: The adverse pregnancy outcome of this woman was a Hydrocephalus / Corpus Callosum Agenesis. Fourteen different types of pesticides were used during 9 days of the critic period, two of which are cataloged as toxic to reproduction cat.3 and two as carcinogenic cat.3.

No extra labour outside the company that could be related to pesticide or any other exposures of concern was referred by any of them. Their partners did not work in agricultural tasks.

Regarding tobacco, three of the women were non-smokers and one smoked 3 cigarettes per day. None of the four women reported alcohol use.

Genetic evaluation, including karyotypes was made in two of the couples and no anomalies were found.

We searched for other adverse pregnancy outcomes among other mothers who could be exposure to agricultural pesticides, but no additional cases were identified.

The epidemiological criteria used to research the relationship between congenital malformations and pesticides exposure during pregnancy are described below:

• 1. Biologic plausibility: toxic reproductive effects of some pesticides which these women were exposed are known.
• 2. Consistency: some studies about exposure to pesticides report similar results.
• 3. Occupational exposure: all pregnant women were exposure to pesticide during the “maximal sensitivity  period”, although we do not know accurate individual information of specific hours and doses of exposure to each pesticide.
• 4. Temporal correlation: the pesticides are present in the workplace before women become pregnant and during the pregnancy.
• 5. Experimental analysis: there is direct experimental evidence about toxic reproduction effects of pesticides in animals.
• 6. Clinical support and lack of nosological affiliation: some other possible causes of congenital anomalies were discarded.

TABLAS

Table 1. Demographic and work history information of the women and their congenital anomalies

Table 3. Intensity of exposure: Nº days of maximal sensitive period in which pesticides were used and Nº different types of pesticides used

Table 2. Pesticides which women were potentially expose to, during the maximum sensitive period after conception, number of days that each product was used in every outcome in that period and Toxic to Reproduction and Cancerigen effects of pesticides

*Outcomes diagnosis: 1. CYSTIC HYGROMA / S. TURNER, 2. TRISOMIE 47 XY+22, 3. MISCARRYAGE,4. GESTATIONAL TROPHOBLASTIC DISEASE, 5. CYSTIC HYGROMA, 6. S. DANDY WALKER,

7. MISCARRYAGE, 8. HYDROCEPHALUS / CORPUS CALLOSUM AGENESIS

DISCUSSION

Although there is enough evidence of the adverse reproductive effect of some pesticide in experimental research (Machera, 1995), epidemiological studies are inconclusive.

Some studies have not found increased risk of spontaneous abortion in in vitro fertilized pregnancies, attributable to paternal agricultural application of pesticides (Hjollund, 2004), but the result of other epidemiological studies support the association between agricultural work and the exposure to pesticides of the father (Regidor, 2004), of the mother or both (Garcia, 1997; Lawson, 2003). Some of the adverse reproductive effects that have been reported are fetal loss, reduced fertility and congenital malformations such as anencephaly associate to the exposure to agricultural work during the periconcepcional period, mainly in the case of maternal exposure (Lacasaña, 2006). The results of some experimental studies showed the definite potential for pesticides in the triazole family such as cyproconazole, to increase the risk of lower birth weight, lower body length, resorptions (similar to an early miscarriage), as well as strongly increasing the risk of cleft palate and hydrocephalus (Machera, 1995).

Some studies have even found long term effects, like childhood hematopoietic malignancies, associated with the paternal and maternal use of domestic pesticides, specially during pregnancy (Rudant, 2007).

Research on reproductive outcomes is complicated because of the intricate biology of reproduction, the multiple targets involved (male, female, offspring), the uncertainties in extrapolating from model species to humans, and the problems involved in accurately characterizing exposure-related outcomes in epidemiology investigations (Lawson, 2003).

As a congenital defect register is not available in Valencia Community, it had not been possible to compare the observed rate with a reference rate, how is recommended in the cluster investigation of birth defects, to determinate if an excess of cases has occurred. However in case that exposure is shared, identifying cases and examining exposure information can promote resource efficiency even without a direct comparison to control (Willians, 2002), because the exposures that occur in most case-patient of a cluster but are very rare in general population raise the highest index of suspicion in congenital anomalies cluster. An epidemiologic study case-control could neither be done because control group was not available.

The adverse pregnancy outcomes of this possible cluster had not are the same diagnosis, and this may question if it is a true cluster, however these differences can be attributable to differences in the periconceptional time of exposure, type of pesticide and effect of the mixtures.

Adverse pregnancy outcomes such as spontaneous abortion are no routinely reported (Lawson, 2003), therefore it is important including them in studies if they are known. During the first trimester, the most common cause of miscarriage is chromosomal abnormality. Most chromosomal abnormalities are the cause of a faulty egg or sperm cell, or are due to a problem at the time that the zygote went through the division process.

In previous reports of cluster of birth defects associated with pesticide exposure in farmer mothers (Calvert, 2007), some of the potential pesticides were the same as pesticides assess in this study (e.g., mancozeb, copper hydroxide, bacillus thuringiensis, spinosad, azadirachtin, bacillus subtillis, abamectin chlorothalonil, and methomyl).

Toxicological studies have clearly established that the timing of exposure during fetal development is crucial to determining the outcome, however, studies that detail the relationship between specific exposures and adverse reproductive outcomes are much less common (Bell, 2001; Lawson, 2003).

Most of the studies exposure assessment is only based on job of the father or mother, but no specific individual information on types and level of pesticides exposure. Luckily, in this study, the type of products used in the greenhouses during the most vulnerable period in human development of each pregnancy, and the number of days that each product was used in these periods, were available. However, we did not know neither if these women were exactly inside treated greenhouses or near of them, nor the specific hours and doses of exposure to each product.

All the women studied were potentially exposure to pesticide mixtures, and little is known about the toxic reproductive effects of exposure to mixtures (Calvert, 2007), but it is reasonable to assume that pesticide mixtures can produce developmental effects that would not be predict or to be more severe than the known toxicology of each individual pesticide, for synergies and strengthening mechanisms (Lezaum, 2003). In fact the more common human scenario at work is to mixtures of toxicants at low concentrations, episodically and over the long term.

It is very important to take into account, that some of the defects findings in this research can be the result of exposures to different pesticide products before the conception, because these women have been working in the same company and at the same job during several years and the pesticide treatment in greenhouse tomato monoculture, performed during almost all year because they can be affected by different pests with different biological cycles.

Despite of the presence of several adverse pregnancies outcomes in two of these women, the assess the patient‘s risk of chromosomal or genetic disorder was made in them and their partners, and no anomalies were found. Moreover, these women were exposure to pesticides in all the adverse pregnancies outcomes.

In Spain all the worker that apply or handling pesticides have to pass a course of 20-60 hour which include an exam in order to get a card that allows them to use these products. They have formation and information about the risk and the preventive measures and they usually wear protective equipment when they are working.

However, most of the women who work in agricultural tasks are not involved in the application or direct handling of pesticide, so in most cases they are not considered to be at risk of pesticide exposure. This is what happened with the women of this cluster. So they did not wear protective clothing, did not have training, neither information about this risk. Nevertheless, they have probably been highly exposed to a lot of different pesticides, when they entered only few hours later that the greenhouse was treated and they breathed contaminated air and handled treated plants without gloves. Because of this, all these women had the potential for at least two routes of exposure: dermal and inhalation, during the periconcepcional period. Oral exposure could take place if the women did not wash their hands before eating. Given that some studies have even found that fetal death is more probably among mothers who are living within a 9-square mile area in which commercial pesticide spaying takes place during pregnancy (Bell, 2001), it seems logical to think that the women of this study had a greater risk.

Therefore when the company assed the risk and safety of these farmer women’s job they did not evaluated properly their occupational hazards so they did not prevent the risk and that was an important irregularity.

There are strict laws on the type of products that can be used on each crop in Spain and laws that establish the interval between the final pesticide application and harvest in the different crops, in order to avoid residues of pesticides in food. In the other hand biocides, that are the pesticides used in urban pest control, have a safety period of re-entry to treated areas indicated on their label (Ministerio de la Presidencia, 2002). Nevertheless, there is not any law or indication on the labels of agriculture pesticides which establish a restricted entry interval for agriculture workers in treated fields.

In other countries like the USA there are restricted entry intervals (REI) to limit the exposure of pesticides residues to workers or other persons not involved in the application of pesticides. The REI is the time between the end of a pesticide application and the beginning of unlimited access to the treated field. The federal REI information is listened on the pesticide labelling, although some state regulations like California regulations, may require longer REIs than listed on the labelling for certain pesticides, used on certain crops or when a mixture of pesticides is applied. The REI for a given product may be different for different crops, different climates, different crop activities (irrigation, pruning, etc.), or different application methods. The REIs are usually based on toxicity of a pesticide product’s active ingredients and it usually last from 12 hours to 3 days, but exceptions to this general rule are common, for example, a few fungicides and soil-fumigants have REIs as long as 120 hours (5 days) and other like Bacillus thuringiensis have REIs as short as 4 hours because of their low toxicity to humans (Fouche, 2000; PNW, 2007).

CONCLUSIONS

• Despite the suggestive epidemiologic evidences, a causal link between pesticides exposure and these congenital anomalies could no be established. However, prenatal pesticides exposures in farmers are cause for concern.

• The main risk factors found in this study were: the intense exposure in the maximal sensitive period of pregnant to a lot of different types of pesticides, the worker women’s lack of knowledge and formation about pesticide risk and preventive measures, the non-use of protective equipments, the short re-entry period in treated greenhouses and the incorrect assessment of workplace risks.

• Farmer women, who work in greenhouses, were identified like a target population of great potential occupational exposure to reproductive toxicants pesticides, although they do not handle or apply pesticides directly.

• It is necessary provide better information and training among female agriculture who work with pesticides and promoting a preventive culture in the agriculture companies. It is very important that worker women know the possible reproductive risk in their work before conception, because by the time pregnant women have their first prenatal visit, it may be too late to prevent some adverse pregnacy outcomes or birth defects.

• Notification of research result in a manner that is timely, accessible and easily understood must be an essential component of reproductive studies. The results of this study were communicated to Preventive Service of the company in order them to take prevent measures and to inform workers.

• Preventive improvements were implemented: all the women worker are now informed of any known or susceptive hazard in their workplace including effects on reproduction of pesticides and protective clothing is provided by the company. Cluster studies like this give the opportunity to intervene and better protect the reproductive health of the other farmers through taking preventive measures against pesticides.

• More epidemiological studies about adverse  reproductive  effect  of  some pesticide should be done, specially assess the effects of mixtures of pesticides exposures and cumulative exposure over years of a working lifetime.
• Legally regularisation of a safety period of reentry in treated field with agricultural pesticides based on scientific evidences should be established in our country, particularly in greenhouses where hazard is greater than outdoors.

ACKNOWLEDGEMENTS

We acknowledge the director of the Public Health Centre of Alicante his support, encouragement and enthusiasm to the development of research studies.

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