Japanese children of parents whose family business was primarily industry, including agriculture, forestry, and fisheries, had a greater risk of atopic dermatitis (AD) development.
Occupations in agriculture and forestry may increase the risk of atopic dermatitis (AD) in workers' children, according to study findings published in International Journal of Environmental Research and Public Health.
In assessing risk of AD, prevalence has been found to be more common in industrialized countries vs developing nations in which rural residence has been cited as a potential preventive environmental factor for the condition.
However, as countries have become highly industrialized in the modern era, researchers note that previous assumptions regarding rural lifestyles and risk of AD may require further investigation.
“The hygiene hypothesis assumes a low incidence of allergic diseases in families engaging in farming work,” they added. “Environmental exposure to natural allergens may influence the risk of allergic disease among people who live in regions with undisturbed nature. Children whose parents’ business or occupation is primary industry (agriculture, forestry, and fisheries) tend to live near natural plants and animals.”
Deriving data from the Japan Environment and Children’s Study (JECS) project, a large Japanese birth cohort dataset, researchers calculated the accumulated incidence of AD in children aged 6 months and 1, 2, and 3 years by family business, considered as the father’s occupation.
A fixed-effect model was used to calculate the least square means of the accumulated incidence and prevalence of AD at each time point according to the family business and accounted for potential confounding variables of smoking, parents’ history of AD, parents’ educational backgrounds, family income, and whether the family had a dog or a cat.
Data on 41,469 father–child pairs at 6 months of age; 40,067 pairs at 1 year; 38,286 pairs at 2 years; and 36,570 pairs at 3 years were collected.
In their findings, children whose fathers worked in agriculture, forestry, or fisheries (primary industrial business) reported the highest incidence of AD, with 2.5% at 6 months of age, 6.6% at 1 year, 12.0% at 2 years, and 15.4% at 3 years.
Among these 3 primary industries, forestry was associated with the highest incidence of AD at 6 months of age (3.3%), 1 year (6.7%), 2 years (15.8%), and 3 years (25.0%), followed by agriculture (2.4%, 5.9%, 10.8%, and 13.3%, respectively).
The HR of AD was also highest for children whose family business was primary industry. Of the primary industry subcategories, forestry was associated with a 73% greater likelihood of child AD development vs the reference subcategory of agriculture (HR, 1.73; 95% CI, 0.98-3.05).
Discussing the contradicting findings with that of the hygiene hypothesis, the researchers said that a possible explanation may be that only a subset of those in primary industry within the data can be considered to live a farming lifestyle.
“This situation in Japan, which is a highly industrialized country, may have reduced the difference in the incidence and prevalence of AD between occupations," they concluded.
Yokomichi H, Mochizuki M, Kojima R, et al. High incidence of atopic dermatitis among children whose fathers work in primary industry: the Japan Environment and Children’s Study (JECS). Int J Environ Res Public Health. 2022 Feb 3;19(3):1761. doi:10.3390/ijerph19031761