Academic journal article Scandinavian Journal of Work, Environment & Health

Risk of Cryptorchidism among Sons of Horticultural Workers and Farmers in Denmark

Academic journal article Scandinavian Journal of Work, Environment & Health

Risk of Cryptorchidism among Sons of Horticultural Workers and Farmers in Denmark

Article excerpt

Farming and horticulture constitute two main occupa- tions with possible exposure of employees to pesticides. In Denmark, about 80% of female horticultural work- ers use pesticides in work while about 20% of female farmers spray pesticides (1). For male farmers, pesticide exposure is considerably more common (2, 3). Chemi- cals applied in farming and horticulture have various biologic actions and toxicities and especially some pesticides have known estrogenic or antiandrogenic effects (4, 5). Adverse effects on genital development have been demonstrated in various animal male fetuses for instance for mixtures of epoxiconazole, mancozeb, prochloraz, tebuconazole, and procymidone (6-9). How- ever, the long-term consequences of pesticide exposure in humans are generally unknown. Concern has espe- cially focused on pregnant workers regarding possible adverse effects on normal fetal development and, con- sidering the antiandrogenic effects, malformations of the male reproductive organs in particular. Cryptorchidism is characterized by incomplete testicular descent and is a common malformation seen in about 2% of boys at three months of age (10-12). Previous studies from Denmark have indicated an increased risk of cryptorchi- dism among sons of women (i) working in horticulture during pregnancy and (ii) with high pesticide levels in breast milk. In contrast, no associations have been found for maternal farmers or fathers working in horticulture or farming (13-16). These studies have generally been small or case-control studies, and larger studies prefer- ably with a cohort design are clearly warranted.

In this cohort study using information on parental occupation and cryptorchidism from nationwide regis- ters in Denmark, we estimated the risk of cryptorchidism among sons with a mother or father working in horti- culture or farming at the time of pregnancy compared to the risk among sons of parents in other occupations.

Methods

Data sources

Information on childbirths, hospital contacts, and employment status was obtained from national regis- ters: the Danish Civil Registration System, the Danish National Patient Registry, the Fertility Database, and the Employment Classification Module from Statistics Denmark. The Danish Civil Registration System is a continuously updated demographic database that covers the entire Danish population (17). It was established on 1 April 1968 and, thereafter, all Danish inhabitants have been assigned a unique 10-digit identification number at birth. This register was used to identify children born in Denmark between 1980-2007. Children and parents were linked through the Fertility Database (18). The Danish National Patient Registry includes information about inpatient hospital contacts in Danish hospitals from 1 January 1977 onwards and outpatient hospital contacts from 1 January 1995 onwards (19) and was used to identify boys diagnosed with cryptorchidism. Since 1976, the Employment Classification Module has registered annual data on every citizen ≥15 years old, who pays tax in Denmark according to economic and employment status (20). This module was used to extract information on parents' occupation in the relevant time period relative to child birth.

Cohort

The cohort included boys born in Denmark from 1 July 1980 to 31 December 2007 with one or both parents in active employment. We restricted our analyses to male infants of singleton pregnancies. For births in January through June, we applied the prior year's employment status while the current year's status was used for births in July through December. An active employment status indicated that the most important source of income for a person in a given year came from employment in the public or private sector.

Exposure

Exposed boys had at least one parent employed in farm- ing or horticulture while unexposed boys had parents working in other occupations. To identify maternal and paternal occupation, we used occupational and industrial classification codes from the Employment Classification Module, Statistics Denmark. …

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