Reconstruction of historical exposures at a Welsh nickel refinery (1953-2000).

Past epidemiological studies of workers in a nickel refinery in Clydach, Wales, have shown evidence of large excess respiratory cancer mortality risks [lung cancer relative risk (RR) ≈ 3; nasal cancer RR ≈ 140] in those employed prior to 1930, with risks dropping dramatically in workers hired subsequently. The pre-1930 risks have generally been attributed to high exposures to mixtures of nickel compounds. More recent studies of this refinery's workers have focused on those first hired in 1953, when many of the operations that presumably gave rise to the high exposures were no longer in operation. While these studies have shown greatly decreased lung cancer risks overall (RR ≈ 1.4), and no substantive evidence of increased nasal cancer risk, the absence of reliable exposure estimates have made it difficult to ascertain whether the increased lung cancer risks are nickel related or due to other factors. This study uses nickel measurements from the 1970s to the present, documentation of process changes, and dust measurements taken around the 1950s to construct an exposure matrix for the recent cohort. It provides evidence of at least 30-fold decreases in levels of nickel exposure from the 1950s to the present, with estimated inhalable nickel concentrations in the 1950s in excess of 5mg Ni m(-3).

Reconstruction of historical exposures in the US nickel alloy industry and the implications for carcinogenic hazard and risk assessments.

Recently, various regulatory authorities have been reexamining the potential carcinogenic hazards and risks associated with exposures to nickel and certain nickel compounds. In making their assessments, the authorities have focused on occupational cohorts at facilities where nickel-containing sulfidic ores were processed and where increased lung and nasal cancer risks were found in specific groups of workers. Little attention, however, has been paid to the vast number of workers in nickel-using industries, where no excess respiratory cancer risks have been observed. In this paper, the historical exposures of one such group of workers engaged in the production of nickel alloys are reconstructed, and the implications for cancer risk assessments are analyzed. The results indicate that nickel alloy workers were exposed to insoluble oxidic and metallic nickel species at levels comparable to those found in certain nickel processing cohorts; yet they experienced no increase in respiratory cancer risks. This suggests that extrapolating risks from certain primary nickel producers to other nickel industry sectors may not be appropriate.

Species-specific inhalable exposures in the nickel industry: a new approach for deriving inhalation occupational exposure limits.

The American Conference of Governmental Industrial Hygienists (ACGIH) and some regulatory authorities have revised their exposure limits for nickel and nickel compounds in workplaces based upon new sampling standards for inhalable nickel exposures. Others may be in the process of doing so. Safe standards for workplace exposures should utilize the most up-to-date health data on individual nickel species and should incorporate the principles of new sampling conventions that have been developed over the recent decades. The purpose of this paper is to review the basis for setting inhalable occupational exposure standards for the principal inorganic nickel species. It is hoped that this paper will (1) prompt companies in various nickel industry sectors to begin collecting the necessary inhalable aerosol measurements, speciation data, and particle-size information required to implement health-based sampling programs in the future, and (2) encourage regulators to derive species-specific, inhalable-based workplace standards for nickel and its inorganic compounds.

Assessment of respiratory carcinogenicity associated with exposure to metallic nickel: a review.

Human studies prior to 1990 have shown an association between respiratory cancer and exposure to some nickel compounds, but not to metallic nickel. Numerous reviews have examined the nature of the association between nickel compounds and respiratory cancer, but little has been published on metallic nickel. This paper reviews the animal and human cancer-related data on metallic nickel to determine whether the conclusions regarding metallic nickel reached a decade ago still apply. Based upon past and current human studies, metallic nickel appears to show little evidence of carcinogenicity when present at the same or higher concentrations than those seen in current workplace environments. By comparison, animal studies currently available have shown mixed results. A number of studies have shown evidence of carcinogenicity in animals exposed to nickel powders via injection, but other studies have shown no or inconsistent results in animals exposed via inhalation or intratracheal instillation. Further studies in animals via inhalation and humans would be helpful in elucidating the respiratory carcinogenic potential of metallic nickel.