Non-vascular plants include two distantly related groups: 1  Bryophytes-Bryophyta (mosses), Marchantiophyta (liverworts), and Anthocerotophyta (hornworts). 2  In these groups, the primary plants are the haploid gametophytes, with the only diploid portion being the attached sporophyte, consisting of a stalk and sporangium. In these groups, the primary plants are the haploid gametophytes, with the only diploid portion being the attached sporophyte, consisting of a stalk and sporangium. 2  Because these plants lack lignified water-conducting tissues, they can't become as tall as most vascular plants. 3  Algae-especially the green algae.
It is possible that welders are at greater risk of developing skin cancer than the general population, but there is a dearth of well designed studies in this area. The only major study of the relationship between arc welding and skin cancer risk did not reveal an increased incidence of skin cancer in welders.
lung cancer, a pulmonary malignancy attributable in the majority of cases to cigarette smoking. Other predisposing factors are exposure to acronitrile, arsenic, asbestos, beryllium, chloromethyl ether, chromium, coal products, ionizing radiation, iron oxide, mustard gas, nickel, petroleum, uranium, and vinyl chloride.