Cancer Risk Among Residents of Rhineland-Palatinate Winegrowing Communities - Recent Advances and Issues in Environmental Science - page 102

DISCUSSION
In this ecological study, a statistically significant positive association with the extent
of viniculture is observed for non-melanoma skin cancer in males and females, pros-
tate cancer, bladder cancer, and NHL in males, but not in females. Lung cancer risk
is significantly reduced in communities with a large area under cultivation. Our main
hypothesis that pesticides might play a role for the observed associations will be dis-
cussed for specific cancer types in the following.
Specific Tumors
Non-melanotic Skin Cancer
Several studies have shown that the lifetime cumulative sun exposure is responsible
for the development of non-melanotic skin cancer (for an overview, see [24, 25]).
In ecologic studies, squamous cell carcinoma is related more strongly to latitude or
measured ultraviolet (UV) radiation than is basal cell carcinoma. As more outdoor
workers might be occupied in regions with extensive winegrowing, our finding of an
increased non-melanotic skin cancer risk in winegrowing communities appears plau-
sible. In fact, in communities with a large area under cultivation, 14.8% of male skin
cancer patients (C44 ICD-10) with known occupation (as recorded in the cancer regis-
try) had worked as an outdoor worker (farmer, winegrower, gardener, forestry worker,
or construction worker). In communities with medium and a small area under cultiva-
tion, this proportion is 12.2% and 7.5%, respectively. Comparably, the proportion of
outdoor workers among female cancer skin cancer patients (C44 ICD-10) is 7.6%,
5.1%, and 2.6% in communities with a large, medium, and small area under cultiva-
tion, respectively. Previous arsenic exposure has to be considered as an alternative
explanation: arsenical pesticides were applied by Moselle wine growers [26] between
1920 and 1942. The clinical signs of arsenic exposure are arsenical keratoses, which
may progress to squamous cell carcinoma or basal cell carcinoma [27]. Moreover,
arsenic seems to act as a co-carcinogen with UV radiation [27]. As the latency period
of non-melanotic skin cancer is suspected to be very long, an excess in non-melanotic
skin cancers might therefore be partly explained by arsenic exposure, however, this
explanation appears rather speculative. Moreover, risk estimators for non-melanotic
skin cancer do not markedly increase when our analysis is restricted to persons aged
70 or more. The association between sun exposure and melanoma of the skin seems to
be more complex: Intermittent sun exposure and sunburn history rather than lifetime
cumulative sun exposure plays a role in the aetiology of melanoma of the skin [28,
29]. This complex relationship might explain why our study does not reveal a clearly
increased melanoma incidence in communities with a large area under wine cultiva-
tion. Moreover, adjusting for potential confounders as, for example, leisure time UV
exposure, was not possible in this study.
Brain Cancer
While several epidemiological studies point to an increased brain cancer risk among
pesticide exposed persons [13, 14], few studies specifically focus on the residential
population in winegrowing regions. In their ecological study in the province of Trento,
Italy, Ferrari, and Lovaste [30] find the highest incidence rates of intracranial tumors